author | mikael |
Fri, 28 Sep 2018 14:11:21 -0700 | |
changeset 51960 | bb1d5dd64897 |
parent 51860 | 54aafb3ba9ab |
child 52450 | 2790da836dc3 |
permissions | -rw-r--r-- |
6975 | 1 |
/* |
49012 | 2 |
* Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved. |
6975 | 3 |
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 |
* |
|
5 |
* This code is free software; you can redistribute it and/or modify it |
|
6 |
* under the terms of the GNU General Public License version 2 only, as |
|
7 |
* published by the Free Software Foundation. |
|
8 |
* |
|
9 |
* This code is distributed in the hope that it will be useful, but WITHOUT |
|
10 |
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
|
11 |
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
|
12 |
* version 2 for more details (a copy is included in the LICENSE file that |
|
13 |
* accompanied this code). |
|
14 |
* |
|
15 |
* You should have received a copy of the GNU General Public License version |
|
16 |
* 2 along with this work; if not, write to the Free Software Foundation, |
|
17 |
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
|
18 |
* |
|
19 |
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
|
20 |
* or visit www.oracle.com if you need additional information or have any |
|
21 |
* questions. |
|
22 |
* |
|
23 |
*/ |
|
24 |
||
7397 | 25 |
#include "precompiled.hpp" |
26 |
#include "classfile/vmSymbols.hpp" |
|
50113 | 27 |
#include "jfr/jfrEvents.hpp" |
28 |
#include "jfr/support/jfrThreadId.hpp" |
|
48157 | 29 |
#include "memory/allocation.inline.hpp" |
7397 | 30 |
#include "memory/resourceArea.hpp" |
31 |
#include "oops/markOop.hpp" |
|
32 |
#include "oops/oop.inline.hpp" |
|
40655
9f644073d3a0
8157907: Incorrect inclusion of atomic.hpp instead of atomic.inline.hpp
dholmes
parents:
39702
diff
changeset
|
33 |
#include "runtime/atomic.hpp" |
7397 | 34 |
#include "runtime/handles.inline.hpp" |
49449
ef5d5d343e2a
8199263: Split interfaceSupport.hpp to not require including .inline.hpp files
coleenp
parents:
49038
diff
changeset
|
35 |
#include "runtime/interfaceSupport.inline.hpp" |
7397 | 36 |
#include "runtime/mutexLocker.hpp" |
37 |
#include "runtime/objectMonitor.hpp" |
|
38 |
#include "runtime/objectMonitor.inline.hpp" |
|
50429
83aec1d357d4
8204301: Make OrderAccess functions available to hpp rather than inline.hpp files
coleenp
parents:
50113
diff
changeset
|
39 |
#include "runtime/orderAccess.hpp" |
7397 | 40 |
#include "runtime/osThread.hpp" |
47881
0ce0ac68ace7
8189941: Implementation JEP 312: Thread-local handshake
rehn
parents:
47634
diff
changeset
|
41 |
#include "runtime/safepointMechanism.inline.hpp" |
49593
4dd58ecc9912
8200105: Remove cyclic dependency between oop.inline.hpp and collectedHeap.inline.hpp
stefank
parents:
49449
diff
changeset
|
42 |
#include "runtime/sharedRuntime.hpp" |
7397 | 43 |
#include "runtime/stubRoutines.hpp" |
14583
d70ee55535f4
8003935: Simplify the needed includes for using Thread::current()
stefank
parents:
13728
diff
changeset
|
44 |
#include "runtime/thread.inline.hpp" |
7397 | 45 |
#include "services/threadService.hpp" |
46 |
#include "utilities/dtrace.hpp" |
|
18025 | 47 |
#include "utilities/macros.hpp" |
7397 | 48 |
#include "utilities/preserveException.hpp" |
50113 | 49 |
#if INCLUDE_JFR |
50 |
#include "jfr/support/jfrFlush.hpp" |
|
51 |
#endif |
|
6975 | 52 |
|
53 |
#ifdef DTRACE_ENABLED |
|
54 |
||
55 |
// Only bother with this argument setup if dtrace is available |
|
56 |
// TODO-FIXME: probes should not fire when caller is _blocked. assert() accordingly. |
|
57 |
||
10739 | 58 |
|
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
59 |
#define DTRACE_MONITOR_PROBE_COMMON(obj, thread) \ |
10739 | 60 |
char* bytes = NULL; \ |
61 |
int len = 0; \ |
|
62 |
jlong jtid = SharedRuntime::get_java_tid(thread); \ |
|
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
63 |
Symbol* klassname = ((oop)obj)->klass()->name(); \ |
10739 | 64 |
if (klassname != NULL) { \ |
65 |
bytes = (char*)klassname->bytes(); \ |
|
66 |
len = klassname->utf8_length(); \ |
|
67 |
} |
|
68 |
||
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
69 |
#define DTRACE_MONITOR_WAIT_PROBE(monitor, obj, thread, millis) \ |
10739 | 70 |
{ \ |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
71 |
if (DTraceMonitorProbes) { \ |
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
72 |
DTRACE_MONITOR_PROBE_COMMON(obj, thread); \ |
10739 | 73 |
HOTSPOT_MONITOR_WAIT(jtid, \ |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
74 |
(monitor), bytes, len, (millis)); \ |
10739 | 75 |
} \ |
76 |
} |
|
77 |
||
78 |
#define HOTSPOT_MONITOR_contended__enter HOTSPOT_MONITOR_CONTENDED_ENTER |
|
79 |
#define HOTSPOT_MONITOR_contended__entered HOTSPOT_MONITOR_CONTENDED_ENTERED |
|
80 |
#define HOTSPOT_MONITOR_contended__exit HOTSPOT_MONITOR_CONTENDED_EXIT |
|
81 |
#define HOTSPOT_MONITOR_notify HOTSPOT_MONITOR_NOTIFY |
|
82 |
#define HOTSPOT_MONITOR_notifyAll HOTSPOT_MONITOR_NOTIFYALL |
|
83 |
||
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
84 |
#define DTRACE_MONITOR_PROBE(probe, monitor, obj, thread) \ |
10739 | 85 |
{ \ |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
86 |
if (DTraceMonitorProbes) { \ |
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
87 |
DTRACE_MONITOR_PROBE_COMMON(obj, thread); \ |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
88 |
HOTSPOT_MONITOR_##probe(jtid, \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
89 |
(uintptr_t)(monitor), bytes, len); \ |
10739 | 90 |
} \ |
91 |
} |
|
92 |
||
6975 | 93 |
#else // ndef DTRACE_ENABLED |
94 |
||
13728
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
95 |
#define DTRACE_MONITOR_WAIT_PROBE(obj, thread, millis, mon) {;} |
882756847a04
6964458: Reimplement class meta-data storage to use native memory
coleenp
parents:
10739
diff
changeset
|
96 |
#define DTRACE_MONITOR_PROBE(probe, obj, thread, mon) {;} |
6975 | 97 |
|
98 |
#endif // ndef DTRACE_ENABLED |
|
99 |
||
100 |
// Tunables ... |
|
101 |
// The knob* variables are effectively final. Once set they should |
|
102 |
// never be modified hence. Consider using __read_mostly with GCC. |
|
103 |
||
50083 | 104 |
int ObjectMonitor::Knob_SpinLimit = 5000; // derived by an external tool - |
105 |
||
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
106 |
static int Knob_Bonus = 100; // spin success bonus |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
107 |
static int Knob_BonusB = 100; // spin success bonus |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
108 |
static int Knob_Penalty = 200; // spin failure penalty |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
109 |
static int Knob_Poverty = 1000; |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
110 |
static int Knob_FixedSpin = 0; |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
111 |
static int Knob_PreSpin = 10; // 20-100 likely better |
6975 | 112 |
|
51960 | 113 |
DEBUG_ONLY(static volatile bool InitDone = false;) |
6975 | 114 |
|
115 |
// ----------------------------------------------------------------------------- |
|
116 |
// Theory of operations -- Monitors lists, thread residency, etc: |
|
117 |
// |
|
118 |
// * A thread acquires ownership of a monitor by successfully |
|
119 |
// CAS()ing the _owner field from null to non-null. |
|
120 |
// |
|
121 |
// * Invariant: A thread appears on at most one monitor list -- |
|
122 |
// cxq, EntryList or WaitSet -- at any one time. |
|
123 |
// |
|
124 |
// * Contending threads "push" themselves onto the cxq with CAS |
|
125 |
// and then spin/park. |
|
126 |
// |
|
127 |
// * After a contending thread eventually acquires the lock it must |
|
128 |
// dequeue itself from either the EntryList or the cxq. |
|
129 |
// |
|
130 |
// * The exiting thread identifies and unparks an "heir presumptive" |
|
131 |
// tentative successor thread on the EntryList. Critically, the |
|
132 |
// exiting thread doesn't unlink the successor thread from the EntryList. |
|
133 |
// After having been unparked, the wakee will recontend for ownership of |
|
134 |
// the monitor. The successor (wakee) will either acquire the lock or |
|
135 |
// re-park itself. |
|
136 |
// |
|
137 |
// Succession is provided for by a policy of competitive handoff. |
|
138 |
// The exiting thread does _not_ grant or pass ownership to the |
|
139 |
// successor thread. (This is also referred to as "handoff" succession"). |
|
140 |
// Instead the exiting thread releases ownership and possibly wakes |
|
141 |
// a successor, so the successor can (re)compete for ownership of the lock. |
|
142 |
// If the EntryList is empty but the cxq is populated the exiting |
|
143 |
// thread will drain the cxq into the EntryList. It does so by |
|
144 |
// by detaching the cxq (installing null with CAS) and folding |
|
145 |
// the threads from the cxq into the EntryList. The EntryList is |
|
146 |
// doubly linked, while the cxq is singly linked because of the |
|
147 |
// CAS-based "push" used to enqueue recently arrived threads (RATs). |
|
148 |
// |
|
149 |
// * Concurrency invariants: |
|
150 |
// |
|
151 |
// -- only the monitor owner may access or mutate the EntryList. |
|
152 |
// The mutex property of the monitor itself protects the EntryList |
|
153 |
// from concurrent interference. |
|
154 |
// -- Only the monitor owner may detach the cxq. |
|
155 |
// |
|
156 |
// * The monitor entry list operations avoid locks, but strictly speaking |
|
157 |
// they're not lock-free. Enter is lock-free, exit is not. |
|
32622
7ed47d0b888a
8135002: Fix or remove broken links in objectMonitor.cpp comments
dbuck
parents:
32614
diff
changeset
|
158 |
// For a description of 'Methods and apparatus providing non-blocking access |
7ed47d0b888a
8135002: Fix or remove broken links in objectMonitor.cpp comments
dbuck
parents:
32614
diff
changeset
|
159 |
// to a resource,' see U.S. Pat. No. 7844973. |
6975 | 160 |
// |
161 |
// * The cxq can have multiple concurrent "pushers" but only one concurrent |
|
162 |
// detaching thread. This mechanism is immune from the ABA corruption. |
|
163 |
// More precisely, the CAS-based "push" onto cxq is ABA-oblivious. |
|
164 |
// |
|
165 |
// * Taken together, the cxq and the EntryList constitute or form a |
|
166 |
// single logical queue of threads stalled trying to acquire the lock. |
|
167 |
// We use two distinct lists to improve the odds of a constant-time |
|
22551 | 168 |
// dequeue operation after acquisition (in the ::enter() epilogue) and |
6975 | 169 |
// to reduce heat on the list ends. (c.f. Michael Scott's "2Q" algorithm). |
170 |
// A key desideratum is to minimize queue & monitor metadata manipulation |
|
171 |
// that occurs while holding the monitor lock -- that is, we want to |
|
172 |
// minimize monitor lock holds times. Note that even a small amount of |
|
173 |
// fixed spinning will greatly reduce the # of enqueue-dequeue operations |
|
174 |
// on EntryList|cxq. That is, spinning relieves contention on the "inner" |
|
175 |
// locks and monitor metadata. |
|
176 |
// |
|
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
177 |
// Cxq points to the set of Recently Arrived Threads attempting entry. |
6975 | 178 |
// Because we push threads onto _cxq with CAS, the RATs must take the form of |
179 |
// a singly-linked LIFO. We drain _cxq into EntryList at unlock-time when |
|
180 |
// the unlocking thread notices that EntryList is null but _cxq is != null. |
|
181 |
// |
|
182 |
// The EntryList is ordered by the prevailing queue discipline and |
|
183 |
// can be organized in any convenient fashion, such as a doubly-linked list or |
|
184 |
// a circular doubly-linked list. Critically, we want insert and delete operations |
|
185 |
// to operate in constant-time. If we need a priority queue then something akin |
|
186 |
// to Solaris' sleepq would work nicely. Viz., |
|
187 |
// http://agg.eng/ws/on10_nightly/source/usr/src/uts/common/os/sleepq.c. |
|
188 |
// Queue discipline is enforced at ::exit() time, when the unlocking thread |
|
189 |
// drains the cxq into the EntryList, and orders or reorders the threads on the |
|
190 |
// EntryList accordingly. |
|
191 |
// |
|
192 |
// Barring "lock barging", this mechanism provides fair cyclic ordering, |
|
193 |
// somewhat similar to an elevator-scan. |
|
194 |
// |
|
195 |
// * The monitor synchronization subsystem avoids the use of native |
|
196 |
// synchronization primitives except for the narrow platform-specific |
|
197 |
// park-unpark abstraction. See the comments in os_solaris.cpp regarding |
|
198 |
// the semantics of park-unpark. Put another way, this monitor implementation |
|
199 |
// depends only on atomic operations and park-unpark. The monitor subsystem |
|
200 |
// manages all RUNNING->BLOCKED and BLOCKED->READY transitions while the |
|
201 |
// underlying OS manages the READY<->RUN transitions. |
|
202 |
// |
|
203 |
// * Waiting threads reside on the WaitSet list -- wait() puts |
|
204 |
// the caller onto the WaitSet. |
|
205 |
// |
|
206 |
// * notify() or notifyAll() simply transfers threads from the WaitSet to |
|
207 |
// either the EntryList or cxq. Subsequent exit() operations will |
|
208 |
// unpark the notifyee. Unparking a notifee in notify() is inefficient - |
|
209 |
// it's likely the notifyee would simply impale itself on the lock held |
|
210 |
// by the notifier. |
|
211 |
// |
|
212 |
// * An interesting alternative is to encode cxq as (List,LockByte) where |
|
213 |
// the LockByte is 0 iff the monitor is owned. _owner is simply an auxiliary |
|
214 |
// variable, like _recursions, in the scheme. The threads or Events that form |
|
215 |
// the list would have to be aligned in 256-byte addresses. A thread would |
|
216 |
// try to acquire the lock or enqueue itself with CAS, but exiting threads |
|
217 |
// could use a 1-0 protocol and simply STB to set the LockByte to 0. |
|
218 |
// Note that is is *not* word-tearing, but it does presume that full-word |
|
219 |
// CAS operations are coherent with intermix with STB operations. That's true |
|
220 |
// on most common processors. |
|
221 |
// |
|
222 |
// * See also http://blogs.sun.com/dave |
|
223 |
||
224 |
||
48157 | 225 |
void* ObjectMonitor::operator new (size_t size) throw() { |
226 |
return AllocateHeap(size, mtInternal); |
|
227 |
} |
|
228 |
void* ObjectMonitor::operator new[] (size_t size) throw() { |
|
229 |
return operator new (size); |
|
230 |
} |
|
231 |
void ObjectMonitor::operator delete(void* p) { |
|
232 |
FreeHeap(p); |
|
233 |
} |
|
234 |
void ObjectMonitor::operator delete[] (void *p) { |
|
235 |
operator delete(p); |
|
236 |
} |
|
237 |
||
6975 | 238 |
// ----------------------------------------------------------------------------- |
239 |
// Enter support |
|
240 |
||
37092
0e56e3c9d545
8151593: Cleanup definition/usage of INLINE/NOINLINE macros and add xlC support
simonis
parents:
36384
diff
changeset
|
241 |
void ObjectMonitor::enter(TRAPS) { |
6975 | 242 |
// The following code is ordered to check the most common cases first |
243 |
// and to reduce RTS->RTO cache line upgrades on SPARC and IA32 processors. |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
244 |
Thread * const Self = THREAD; |
6975 | 245 |
|
47634
6a0c42c40cd1
8188220: Remove Atomic::*_ptr() uses and overloads from hotspot
coleenp
parents:
47216
diff
changeset
|
246 |
void * cur = Atomic::cmpxchg(Self, &_owner, (void*)NULL); |
6975 | 247 |
if (cur == NULL) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
248 |
// Either ASSERT _recursions == 0 or explicitly set _recursions = 0. |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
249 |
assert(_recursions == 0, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
250 |
assert(_owner == Self, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
251 |
return; |
6975 | 252 |
} |
253 |
||
254 |
if (cur == Self) { |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
255 |
// TODO-FIXME: check for integer overflow! BUGID 6557169. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
256 |
_recursions++; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
257 |
return; |
6975 | 258 |
} |
259 |
||
260 |
if (Self->is_lock_owned ((address)cur)) { |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
261 |
assert(_recursions == 0, "internal state error"); |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
262 |
_recursions = 1; |
6975 | 263 |
// Commute owner from a thread-specific on-stack BasicLockObject address to |
264 |
// a full-fledged "Thread *". |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
265 |
_owner = Self; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
266 |
return; |
6975 | 267 |
} |
268 |
||
269 |
// We've encountered genuine contention. |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
270 |
assert(Self->_Stalled == 0, "invariant"); |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
271 |
Self->_Stalled = intptr_t(this); |
6975 | 272 |
|
273 |
// Try one round of spinning *before* enqueueing Self |
|
274 |
// and before going through the awkward and expensive state |
|
275 |
// transitions. The following spin is strictly optional ... |
|
276 |
// Note that if we acquire the monitor from an initial spin |
|
277 |
// we forgo posting JVMTI events and firing DTRACE probes. |
|
51860 | 278 |
if (TrySpin(Self) > 0) { |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
279 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
280 |
assert(_recursions == 0, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
281 |
assert(((oop)(object()))->mark() == markOopDesc::encode(this), "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
282 |
Self->_Stalled = 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
283 |
return; |
6975 | 284 |
} |
285 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
286 |
assert(_owner != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
287 |
assert(_succ != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
288 |
assert(Self->is_Java_thread(), "invariant"); |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
289 |
JavaThread * jt = (JavaThread *) Self; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
290 |
assert(!SafepointSynchronize::is_at_safepoint(), "invariant"); |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
291 |
assert(jt->thread_state() != _thread_blocked, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
292 |
assert(this->object() != NULL, "invariant"); |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
293 |
assert(_count >= 0, "invariant"); |
6975 | 294 |
|
295 |
// Prevent deflation at STW-time. See deflate_idle_monitors() and is_busy(). |
|
296 |
// Ensure the object-monitor relationship remains stable while there's contention. |
|
27165
785a8d56024c
8049737: Contended Locking reorder and cache line bucket
dcubed
parents:
26684
diff
changeset
|
297 |
Atomic::inc(&_count); |
6975 | 298 |
|
50113 | 299 |
JFR_ONLY(JfrConditionalFlushWithStacktrace<EventJavaMonitorEnter> flush(jt);) |
18025 | 300 |
EventJavaMonitorEnter event; |
50113 | 301 |
if (event.should_commit()) { |
302 |
event.set_monitorClass(((oop)this->object())->klass()); |
|
303 |
event.set_address((uintptr_t)(this->object_addr())); |
|
304 |
} |
|
18025 | 305 |
|
6975 | 306 |
{ // Change java thread status to indicate blocked on monitor enter. |
307 |
JavaThreadBlockedOnMonitorEnterState jtbmes(jt, this); |
|
308 |
||
46765
07298ebd9367
8185164: GetOwnedMonitorInfo() returns incorrect owned monitor
ysuenaga
parents:
46630
diff
changeset
|
309 |
Self->set_current_pending_monitor(this); |
07298ebd9367
8185164: GetOwnedMonitorInfo() returns incorrect owned monitor
ysuenaga
parents:
46630
diff
changeset
|
310 |
|
6975 | 311 |
DTRACE_MONITOR_PROBE(contended__enter, this, object(), jt); |
312 |
if (JvmtiExport::should_post_monitor_contended_enter()) { |
|
313 |
JvmtiExport::post_monitor_contended_enter(jt, this); |
|
22753
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
314 |
|
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
315 |
// The current thread does not yet own the monitor and does not |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
316 |
// yet appear on any queues that would get it made the successor. |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
317 |
// This means that the JVMTI_EVENT_MONITOR_CONTENDED_ENTER event |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
318 |
// handler cannot accidentally consume an unpark() meant for the |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
319 |
// ParkEvent associated with this ObjectMonitor. |
6975 | 320 |
} |
321 |
||
322 |
OSThreadContendState osts(Self->osthread()); |
|
323 |
ThreadBlockInVM tbivm(jt); |
|
324 |
||
325 |
// TODO-FIXME: change the following for(;;) loop to straight-line code. |
|
326 |
for (;;) { |
|
327 |
jt->set_suspend_equivalent(); |
|
328 |
// cleared by handle_special_suspend_equivalent_condition() |
|
329 |
// or java_suspend_self() |
|
330 |
||
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
331 |
EnterI(THREAD); |
6975 | 332 |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
333 |
if (!ExitSuspendEquivalent(jt)) break; |
6975 | 334 |
|
335 |
// We have acquired the contended monitor, but while we were |
|
336 |
// waiting another thread suspended us. We don't want to enter |
|
337 |
// the monitor while suspended because that would surprise the |
|
338 |
// thread that suspended us. |
|
339 |
// |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
340 |
_recursions = 0; |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
341 |
_succ = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
342 |
exit(false, Self); |
6975 | 343 |
|
344 |
jt->java_suspend_self(); |
|
345 |
} |
|
346 |
Self->set_current_pending_monitor(NULL); |
|
24832
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
347 |
|
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
348 |
// We cleared the pending monitor info since we've just gotten past |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
349 |
// the enter-check-for-suspend dance and we now own the monitor free |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
350 |
// and clear, i.e., it is no longer pending. The ThreadBlockInVM |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
351 |
// destructor can go to a safepoint at the end of this block. If we |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
352 |
// do a thread dump during that safepoint, then this thread will show |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
353 |
// as having "-locked" the monitor, but the OS and java.lang.Thread |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
354 |
// states will still report that the thread is blocked trying to |
26a834fb508d
8036823: Stack trace sometimes shows 'locked' instead of 'waiting to lock'
dcubed
parents:
24351
diff
changeset
|
355 |
// acquire it. |
6975 | 356 |
} |
357 |
||
27165
785a8d56024c
8049737: Contended Locking reorder and cache line bucket
dcubed
parents:
26684
diff
changeset
|
358 |
Atomic::dec(&_count); |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
359 |
assert(_count >= 0, "invariant"); |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
360 |
Self->_Stalled = 0; |
6975 | 361 |
|
362 |
// Must either set _recursions = 0 or ASSERT _recursions == 0. |
|
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
363 |
assert(_recursions == 0, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
364 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
365 |
assert(_succ != Self, "invariant"); |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
366 |
assert(((oop)(object()))->mark() == markOopDesc::encode(this), "invariant"); |
6975 | 367 |
|
368 |
// The thread -- now the owner -- is back in vm mode. |
|
369 |
// Report the glorious news via TI,DTrace and jvmstat. |
|
370 |
// The probe effect is non-trivial. All the reportage occurs |
|
371 |
// while we hold the monitor, increasing the length of the critical |
|
372 |
// section. Amdahl's parallel speedup law comes vividly into play. |
|
373 |
// |
|
374 |
// Another option might be to aggregate the events (thread local or |
|
375 |
// per-monitor aggregation) and defer reporting until a more opportune |
|
376 |
// time -- such as next time some thread encounters contention but has |
|
377 |
// yet to acquire the lock. While spinning that thread could |
|
378 |
// spinning we could increment JVMStat counters, etc. |
|
379 |
||
380 |
DTRACE_MONITOR_PROBE(contended__entered, this, object(), jt); |
|
381 |
if (JvmtiExport::should_post_monitor_contended_entered()) { |
|
382 |
JvmtiExport::post_monitor_contended_entered(jt, this); |
|
22753
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
383 |
|
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
384 |
// The current thread already owns the monitor and is not going to |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
385 |
// call park() for the remainder of the monitor enter protocol. So |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
386 |
// it doesn't matter if the JVMTI_EVENT_MONITOR_CONTENDED_ENTERED |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
387 |
// event handler consumed an unpark() issued by the thread that |
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
388 |
// just exited the monitor. |
6975 | 389 |
} |
18025 | 390 |
if (event.should_commit()) { |
50113 | 391 |
event.set_previousOwner((uintptr_t)_previous_owner_tid); |
18025 | 392 |
event.commit(); |
393 |
} |
|
32614
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
394 |
OM_PERFDATA_OP(ContendedLockAttempts, inc()); |
6975 | 395 |
} |
396 |
||
397 |
// Caveat: TryLock() is not necessarily serializing if it returns failure. |
|
398 |
// Callers must compensate as needed. |
|
399 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
400 |
int ObjectMonitor::TryLock(Thread * Self) { |
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
401 |
void * own = _owner; |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
402 |
if (own != NULL) return 0; |
48488 | 403 |
if (Atomic::replace_if_null(Self, &_owner)) { |
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
404 |
// Either guarantee _recursions == 0 or set _recursions = 0. |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
405 |
assert(_recursions == 0, "invariant"); |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
406 |
assert(_owner == Self, "invariant"); |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
407 |
return 1; |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
408 |
} |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
409 |
// The lock had been free momentarily, but we lost the race to the lock. |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
410 |
// Interference -- the CAS failed. |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
411 |
// We can either return -1 or retry. |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
412 |
// Retry doesn't make as much sense because the lock was just acquired. |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
413 |
return -1; |
6975 | 414 |
} |
415 |
||
31856 | 416 |
#define MAX_RECHECK_INTERVAL 1000 |
417 |
||
37092
0e56e3c9d545
8151593: Cleanup definition/usage of INLINE/NOINLINE macros and add xlC support
simonis
parents:
36384
diff
changeset
|
418 |
void ObjectMonitor::EnterI(TRAPS) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
419 |
Thread * const Self = THREAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
420 |
assert(Self->is_Java_thread(), "invariant"); |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
421 |
assert(((JavaThread *) Self)->thread_state() == _thread_blocked, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
422 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
423 |
// Try the lock - TATAS |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
424 |
if (TryLock (Self) > 0) { |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
425 |
assert(_succ != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
426 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
427 |
assert(_Responsible != Self, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
428 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
429 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
430 |
|
51960 | 431 |
assert(InitDone, "Unexpectedly not initialized"); |
6975 | 432 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
433 |
// We try one round of spinning *before* enqueueing Self. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
434 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
435 |
// If the _owner is ready but OFFPROC we could use a YieldTo() |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
436 |
// operation to donate the remainder of this thread's quantum |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
437 |
// to the owner. This has subtle but beneficial affinity |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
438 |
// effects. |
6975 | 439 |
|
51860 | 440 |
if (TrySpin(Self) > 0) { |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
441 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
442 |
assert(_succ != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
443 |
assert(_Responsible != Self, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
444 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
445 |
} |
6975 | 446 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
447 |
// The Spin failed -- Enqueue and park the thread ... |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
448 |
assert(_succ != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
449 |
assert(_owner != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
450 |
assert(_Responsible != Self, "invariant"); |
6975 | 451 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
452 |
// Enqueue "Self" on ObjectMonitor's _cxq. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
453 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
454 |
// Node acts as a proxy for Self. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
455 |
// As an aside, if were to ever rewrite the synchronization code mostly |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
456 |
// in Java, WaitNodes, ObjectMonitors, and Events would become 1st-class |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
457 |
// Java objects. This would avoid awkward lifecycle and liveness issues, |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
458 |
// as well as eliminate a subset of ABA issues. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
459 |
// TODO: eliminate ObjectWaiter and enqueue either Threads or Events. |
6975 | 460 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
461 |
ObjectWaiter node(Self); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
462 |
Self->_ParkEvent->reset(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
463 |
node._prev = (ObjectWaiter *) 0xBAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
464 |
node.TState = ObjectWaiter::TS_CXQ; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
465 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
466 |
// Push "Self" onto the front of the _cxq. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
467 |
// Once on cxq/EntryList, Self stays on-queue until it acquires the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
468 |
// Note that spinning tends to reduce the rate at which threads |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
469 |
// enqueue and dequeue on EntryList|cxq. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
470 |
ObjectWaiter * nxt; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
471 |
for (;;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
472 |
node._next = nxt = _cxq; |
47634
6a0c42c40cd1
8188220: Remove Atomic::*_ptr() uses and overloads from hotspot
coleenp
parents:
47216
diff
changeset
|
473 |
if (Atomic::cmpxchg(&node, &_cxq, nxt) == nxt) break; |
6975 | 474 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
475 |
// Interference - the CAS failed because _cxq changed. Just retry. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
476 |
// As an optional optimization we retry the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
477 |
if (TryLock (Self) > 0) { |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
478 |
assert(_succ != Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
479 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
480 |
assert(_Responsible != Self, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
481 |
return; |
6975 | 482 |
} |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
483 |
} |
6975 | 484 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
485 |
// Check for cxq|EntryList edge transition to non-null. This indicates |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
486 |
// the onset of contention. While contention persists exiting threads |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
487 |
// will use a ST:MEMBAR:LD 1-1 exit protocol. When contention abates exit |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
488 |
// operations revert to the faster 1-0 mode. This enter operation may interleave |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
489 |
// (race) a concurrent 1-0 exit operation, resulting in stranding, so we |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
490 |
// arrange for one of the contending thread to use a timed park() operations |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
491 |
// to detect and recover from the race. (Stranding is form of progress failure |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
492 |
// where the monitor is unlocked but all the contending threads remain parked). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
493 |
// That is, at least one of the contended threads will periodically poll _owner. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
494 |
// One of the contending threads will become the designated "Responsible" thread. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
495 |
// The Responsible thread uses a timed park instead of a normal indefinite park |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
496 |
// operation -- it periodically wakes and checks for and recovers from potential |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
497 |
// strandings admitted by 1-0 exit operations. We need at most one Responsible |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
498 |
// thread per-monitor at any given moment. Only threads on cxq|EntryList may |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
499 |
// be responsible for a monitor. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
500 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
501 |
// Currently, one of the contended threads takes on the added role of "Responsible". |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
502 |
// A viable alternative would be to use a dedicated "stranding checker" thread |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
503 |
// that periodically iterated over all the threads (or active monitors) and unparked |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
504 |
// successors where there was risk of stranding. This would help eliminate the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
505 |
// timer scalability issues we see on some platforms as we'd only have one thread |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
506 |
// -- the checker -- parked on a timer. |
6975 | 507 |
|
51704 | 508 |
if (nxt == NULL && _EntryList == NULL) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
509 |
// Try to assume the role of responsible thread for the monitor. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
510 |
// CONSIDER: ST vs CAS vs { if (Responsible==null) Responsible=Self } |
48488 | 511 |
Atomic::replace_if_null(Self, &_Responsible); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
512 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
513 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
514 |
// The lock might have been released while this thread was occupied queueing |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
515 |
// itself onto _cxq. To close the race and avoid "stranding" and |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
516 |
// progress-liveness failure we must resample-retry _owner before parking. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
517 |
// Note the Dekker/Lamport duality: ST cxq; MEMBAR; LD Owner. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
518 |
// In this case the ST-MEMBAR is accomplished with CAS(). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
519 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
520 |
// TODO: Defer all thread state transitions until park-time. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
521 |
// Since state transitions are heavy and inefficient we'd like |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
522 |
// to defer the state transitions until absolutely necessary, |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
523 |
// and in doing so avoid some transitions ... |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
524 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
525 |
int nWakeups = 0; |
31856 | 526 |
int recheckInterval = 1; |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
527 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
528 |
for (;;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
529 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
530 |
if (TryLock(Self) > 0) break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
531 |
assert(_owner != Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
532 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
533 |
// park self |
51704 | 534 |
if (_Responsible == Self) { |
31856 | 535 |
Self->_ParkEvent->park((jlong) recheckInterval); |
536 |
// Increase the recheckInterval, but clamp the value. |
|
537 |
recheckInterval *= 8; |
|
538 |
if (recheckInterval > MAX_RECHECK_INTERVAL) { |
|
539 |
recheckInterval = MAX_RECHECK_INTERVAL; |
|
540 |
} |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
541 |
} else { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
542 |
Self->_ParkEvent->park(); |
6975 | 543 |
} |
544 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
545 |
if (TryLock(Self) > 0) break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
546 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
547 |
// The lock is still contested. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
548 |
// Keep a tally of the # of futile wakeups. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
549 |
// Note that the counter is not protected by a lock or updated by atomics. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
550 |
// That is by design - we trade "lossy" counters which are exposed to |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
551 |
// races during updates for a lower probe effect. |
51702 | 552 |
|
32614
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
553 |
// This PerfData object can be used in parallel with a safepoint. |
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
554 |
// See the work around in PerfDataManager::destroy(). |
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
555 |
OM_PERFDATA_OP(FutileWakeups, inc()); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
556 |
++nWakeups; |
6975 | 557 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
558 |
// Assuming this is not a spurious wakeup we'll normally find _succ == Self. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
559 |
// We can defer clearing _succ until after the spin completes |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
560 |
// TrySpin() must tolerate being called with _succ == Self. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
561 |
// Try yet another round of adaptive spinning. |
51860 | 562 |
if (TrySpin(Self) > 0) break; |
6975 | 563 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
564 |
// We can find that we were unpark()ed and redesignated _succ while |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
565 |
// we were spinning. That's harmless. If we iterate and call park(), |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
566 |
// park() will consume the event and return immediately and we'll |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
567 |
// just spin again. This pattern can repeat, leaving _succ to simply |
51860 | 568 |
// spin on a CPU. |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
569 |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
570 |
if (_succ == Self) _succ = NULL; |
6975 | 571 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
572 |
// Invariant: after clearing _succ a thread *must* retry _owner before parking. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
573 |
OrderAccess::fence(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
574 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
575 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
576 |
// Egress : |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
577 |
// Self has acquired the lock -- Unlink Self from the cxq or EntryList. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
578 |
// Normally we'll find Self on the EntryList . |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
579 |
// From the perspective of the lock owner (this thread), the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
580 |
// EntryList is stable and cxq is prepend-only. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
581 |
// The head of cxq is volatile but the interior is stable. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
582 |
// In addition, Self.TState is stable. |
6975 | 583 |
|
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
584 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
585 |
assert(object() != NULL, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
586 |
// I'd like to write: |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
587 |
// guarantee (((oop)(object()))->mark() == markOopDesc::encode(this), "invariant") ; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
588 |
// but as we're at a safepoint that's not safe. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
589 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
590 |
UnlinkAfterAcquire(Self, &node); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
591 |
if (_succ == Self) _succ = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
592 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
593 |
assert(_succ != Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
594 |
if (_Responsible == Self) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
595 |
_Responsible = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
596 |
OrderAccess::fence(); // Dekker pivot-point |
6975 | 597 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
598 |
// We may leave threads on cxq|EntryList without a designated |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
599 |
// "Responsible" thread. This is benign. When this thread subsequently |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
600 |
// exits the monitor it can "see" such preexisting "old" threads -- |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
601 |
// threads that arrived on the cxq|EntryList before the fence, above -- |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
602 |
// by LDing cxq|EntryList. Newly arrived threads -- that is, threads |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
603 |
// that arrive on cxq after the ST:MEMBAR, above -- will set Responsible |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
604 |
// non-null and elect a new "Responsible" timer thread. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
605 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
606 |
// This thread executes: |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
607 |
// ST Responsible=null; MEMBAR (in enter epilogue - here) |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
608 |
// LD cxq|EntryList (in subsequent exit) |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
609 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
610 |
// Entering threads in the slow/contended path execute: |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
611 |
// ST cxq=nonnull; MEMBAR; LD Responsible (in enter prolog) |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
612 |
// The (ST cxq; MEMBAR) is accomplished with CAS(). |
6975 | 613 |
// |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
614 |
// The MEMBAR, above, prevents the LD of cxq|EntryList in the subsequent |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
615 |
// exit operation from floating above the ST Responsible=null. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
616 |
} |
6975 | 617 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
618 |
// We've acquired ownership with CAS(). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
619 |
// CAS is serializing -- it has MEMBAR/FENCE-equivalent semantics. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
620 |
// But since the CAS() this thread may have also stored into _succ, |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
621 |
// EntryList, cxq or Responsible. These meta-data updates must be |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
622 |
// visible __before this thread subsequently drops the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
623 |
// Consider what could occur if we didn't enforce this constraint -- |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
624 |
// STs to monitor meta-data and user-data could reorder with (become |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
625 |
// visible after) the ST in exit that drops ownership of the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
626 |
// Some other thread could then acquire the lock, but observe inconsistent |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
627 |
// or old monitor meta-data and heap data. That violates the JMM. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
628 |
// To that end, the 1-0 exit() operation must have at least STST|LDST |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
629 |
// "release" barrier semantics. Specifically, there must be at least a |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
630 |
// STST|LDST barrier in exit() before the ST of null into _owner that drops |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
631 |
// the lock. The barrier ensures that changes to monitor meta-data and data |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
632 |
// protected by the lock will be visible before we release the lock, and |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
633 |
// therefore before some other thread (CPU) has a chance to acquire the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
634 |
// See also: http://gee.cs.oswego.edu/dl/jmm/cookbook.html. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
635 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
636 |
// Critically, any prior STs to _succ or EntryList must be visible before |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
637 |
// the ST of null into _owner in the *subsequent* (following) corresponding |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
638 |
// monitorexit. Recall too, that in 1-0 mode monitorexit does not necessarily |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
639 |
// execute a serializing instruction. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
640 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
641 |
return; |
6975 | 642 |
} |
643 |
||
644 |
// ReenterI() is a specialized inline form of the latter half of the |
|
645 |
// contended slow-path from EnterI(). We use ReenterI() only for |
|
646 |
// monitor reentry in wait(). |
|
647 |
// |
|
51860 | 648 |
// In the future we should reconcile EnterI() and ReenterI(). |
6975 | 649 |
|
37092
0e56e3c9d545
8151593: Cleanup definition/usage of INLINE/NOINLINE macros and add xlC support
simonis
parents:
36384
diff
changeset
|
650 |
void ObjectMonitor::ReenterI(Thread * Self, ObjectWaiter * SelfNode) { |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
651 |
assert(Self != NULL, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
652 |
assert(SelfNode != NULL, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
653 |
assert(SelfNode->_thread == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
654 |
assert(_waiters > 0, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
655 |
assert(((oop)(object()))->mark() == markOopDesc::encode(this), "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
656 |
assert(((JavaThread *)Self)->thread_state() != _thread_blocked, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
657 |
JavaThread * jt = (JavaThread *) Self; |
6975 | 658 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
659 |
int nWakeups = 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
660 |
for (;;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
661 |
ObjectWaiter::TStates v = SelfNode->TState; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
662 |
guarantee(v == ObjectWaiter::TS_ENTER || v == ObjectWaiter::TS_CXQ, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
663 |
assert(_owner != Self, "invariant"); |
6975 | 664 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
665 |
if (TryLock(Self) > 0) break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
666 |
if (TrySpin(Self) > 0) break; |
6975 | 667 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
668 |
// State transition wrappers around park() ... |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
669 |
// ReenterI() wisely defers state transitions until |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
670 |
// it's clear we must park the thread. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
671 |
{ |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
672 |
OSThreadContendState osts(Self->osthread()); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
673 |
ThreadBlockInVM tbivm(jt); |
6975 | 674 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
675 |
// cleared by handle_special_suspend_equivalent_condition() |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
676 |
// or java_suspend_self() |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
677 |
jt->set_suspend_equivalent(); |
51704 | 678 |
Self->_ParkEvent->park(); |
6975 | 679 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
680 |
// were we externally suspended while we were waiting? |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
681 |
for (;;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
682 |
if (!ExitSuspendEquivalent(jt)) break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
683 |
if (_succ == Self) { _succ = NULL; OrderAccess::fence(); } |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
684 |
jt->java_suspend_self(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
685 |
jt->set_suspend_equivalent(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
686 |
} |
6975 | 687 |
} |
688 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
689 |
// Try again, but just so we distinguish between futile wakeups and |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
690 |
// successful wakeups. The following test isn't algorithmically |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
691 |
// necessary, but it helps us maintain sensible statistics. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
692 |
if (TryLock(Self) > 0) break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
693 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
694 |
// The lock is still contested. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
695 |
// Keep a tally of the # of futile wakeups. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
696 |
// Note that the counter is not protected by a lock or updated by atomics. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
697 |
// That is by design - we trade "lossy" counters which are exposed to |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
698 |
// races during updates for a lower probe effect. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
699 |
++nWakeups; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
700 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
701 |
// Assuming this is not a spurious wakeup we'll normally |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
702 |
// find that _succ == Self. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
703 |
if (_succ == Self) _succ = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
704 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
705 |
// Invariant: after clearing _succ a contending thread |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
706 |
// *must* retry _owner before parking. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
707 |
OrderAccess::fence(); |
6975 | 708 |
|
32614
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
709 |
// This PerfData object can be used in parallel with a safepoint. |
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
710 |
// See the work around in PerfDataManager::destroy(). |
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
711 |
OM_PERFDATA_OP(FutileWakeups, inc()); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
712 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
713 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
714 |
// Self has acquired the lock -- Unlink Self from the cxq or EntryList . |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
715 |
// Normally we'll find Self on the EntryList. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
716 |
// Unlinking from the EntryList is constant-time and atomic-free. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
717 |
// From the perspective of the lock owner (this thread), the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
718 |
// EntryList is stable and cxq is prepend-only. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
719 |
// The head of cxq is volatile but the interior is stable. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
720 |
// In addition, Self.TState is stable. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
721 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
722 |
assert(_owner == Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
723 |
assert(((oop)(object()))->mark() == markOopDesc::encode(this), "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
724 |
UnlinkAfterAcquire(Self, SelfNode); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
725 |
if (_succ == Self) _succ = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
726 |
assert(_succ != Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
727 |
SelfNode->TState = ObjectWaiter::TS_RUN; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
728 |
OrderAccess::fence(); // see comments at the end of EnterI() |
6975 | 729 |
} |
730 |
||
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
731 |
// By convention we unlink a contending thread from EntryList|cxq immediately |
6975 | 732 |
// after the thread acquires the lock in ::enter(). Equally, we could defer |
733 |
// unlinking the thread until ::exit()-time. |
|
734 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
735 |
void ObjectMonitor::UnlinkAfterAcquire(Thread *Self, ObjectWaiter *SelfNode) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
736 |
assert(_owner == Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
737 |
assert(SelfNode->_thread == Self, "invariant"); |
6975 | 738 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
739 |
if (SelfNode->TState == ObjectWaiter::TS_ENTER) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
740 |
// Normal case: remove Self from the DLL EntryList . |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
741 |
// This is a constant-time operation. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
742 |
ObjectWaiter * nxt = SelfNode->_next; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
743 |
ObjectWaiter * prv = SelfNode->_prev; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
744 |
if (nxt != NULL) nxt->_prev = prv; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
745 |
if (prv != NULL) prv->_next = nxt; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
746 |
if (SelfNode == _EntryList) _EntryList = nxt; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
747 |
assert(nxt == NULL || nxt->TState == ObjectWaiter::TS_ENTER, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
748 |
assert(prv == NULL || prv->TState == ObjectWaiter::TS_ENTER, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
749 |
} else { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
750 |
assert(SelfNode->TState == ObjectWaiter::TS_CXQ, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
751 |
// Inopportune interleaving -- Self is still on the cxq. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
752 |
// This usually means the enqueue of self raced an exiting thread. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
753 |
// Normally we'll find Self near the front of the cxq, so |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
754 |
// dequeueing is typically fast. If needbe we can accelerate |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
755 |
// this with some MCS/CHL-like bidirectional list hints and advisory |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
756 |
// back-links so dequeueing from the interior will normally operate |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
757 |
// in constant-time. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
758 |
// Dequeue Self from either the head (with CAS) or from the interior |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
759 |
// with a linear-time scan and normal non-atomic memory operations. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
760 |
// CONSIDER: if Self is on the cxq then simply drain cxq into EntryList |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
761 |
// and then unlink Self from EntryList. We have to drain eventually, |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
762 |
// so it might as well be now. |
6975 | 763 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
764 |
ObjectWaiter * v = _cxq; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
765 |
assert(v != NULL, "invariant"); |
47634
6a0c42c40cd1
8188220: Remove Atomic::*_ptr() uses and overloads from hotspot
coleenp
parents:
47216
diff
changeset
|
766 |
if (v != SelfNode || Atomic::cmpxchg(SelfNode->_next, &_cxq, v) != v) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
767 |
// The CAS above can fail from interference IFF a "RAT" arrived. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
768 |
// In that case Self must be in the interior and can no longer be |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
769 |
// at the head of cxq. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
770 |
if (v == SelfNode) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
771 |
assert(_cxq != v, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
772 |
v = _cxq; // CAS above failed - start scan at head of list |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
773 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
774 |
ObjectWaiter * p; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
775 |
ObjectWaiter * q = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
776 |
for (p = v; p != NULL && p != SelfNode; p = p->_next) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
777 |
q = p; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
778 |
assert(p->TState == ObjectWaiter::TS_CXQ, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
779 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
780 |
assert(v != SelfNode, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
781 |
assert(p == SelfNode, "Node not found on cxq"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
782 |
assert(p != _cxq, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
783 |
assert(q != NULL, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
784 |
assert(q->_next == p, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
785 |
q->_next = p->_next; |
6975 | 786 |
} |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
787 |
} |
6975 | 788 |
|
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
789 |
#ifdef ASSERT |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
790 |
// Diagnostic hygiene ... |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
791 |
SelfNode->_prev = (ObjectWaiter *) 0xBAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
792 |
SelfNode->_next = (ObjectWaiter *) 0xBAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
793 |
SelfNode->TState = ObjectWaiter::TS_RUN; |
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
794 |
#endif |
6975 | 795 |
} |
796 |
||
797 |
// ----------------------------------------------------------------------------- |
|
798 |
// Exit support |
|
799 |
// |
|
800 |
// exit() |
|
801 |
// ~~~~~~ |
|
802 |
// Note that the collector can't reclaim the objectMonitor or deflate |
|
803 |
// the object out from underneath the thread calling ::exit() as the |
|
804 |
// thread calling ::exit() never transitions to a stable state. |
|
805 |
// This inhibits GC, which in turn inhibits asynchronous (and |
|
806 |
// inopportune) reclamation of "this". |
|
807 |
// |
|
808 |
// We'd like to assert that: (THREAD->thread_state() != _thread_blocked) ; |
|
809 |
// There's one exception to the claim above, however. EnterI() can call |
|
810 |
// exit() to drop a lock if the acquirer has been externally suspended. |
|
811 |
// In that case exit() is called with _thread_state as _thread_blocked, |
|
812 |
// but the monitor's _count field is > 0, which inhibits reclamation. |
|
813 |
// |
|
814 |
// 1-0 exit |
|
815 |
// ~~~~~~~~ |
|
816 |
// ::exit() uses a canonical 1-1 idiom with a MEMBAR although some of |
|
817 |
// the fast-path operators have been optimized so the common ::exit() |
|
37251
9fc139ad74b5
8152358: code and comment cleanups found during the hunt for 8077392
dcubed
parents:
37092
diff
changeset
|
818 |
// operation is 1-0, e.g., see macroAssembler_x86.cpp: fast_unlock(). |
6975 | 819 |
// The code emitted by fast_unlock() elides the usual MEMBAR. This |
820 |
// greatly improves latency -- MEMBAR and CAS having considerable local |
|
821 |
// latency on modern processors -- but at the cost of "stranding". Absent the |
|
822 |
// MEMBAR, a thread in fast_unlock() can race a thread in the slow |
|
823 |
// ::enter() path, resulting in the entering thread being stranding |
|
824 |
// and a progress-liveness failure. Stranding is extremely rare. |
|
825 |
// We use timers (timed park operations) & periodic polling to detect |
|
826 |
// and recover from stranding. Potentially stranded threads periodically |
|
827 |
// wake up and poll the lock. See the usage of the _Responsible variable. |
|
828 |
// |
|
829 |
// The CAS() in enter provides for safety and exclusion, while the CAS or |
|
830 |
// MEMBAR in exit provides for progress and avoids stranding. 1-0 locking |
|
37251
9fc139ad74b5
8152358: code and comment cleanups found during the hunt for 8077392
dcubed
parents:
37092
diff
changeset
|
831 |
// eliminates the CAS/MEMBAR from the exit path, but it admits stranding. |
6975 | 832 |
// We detect and recover from stranding with timers. |
833 |
// |
|
834 |
// If a thread transiently strands it'll park until (a) another |
|
835 |
// thread acquires the lock and then drops the lock, at which time the |
|
836 |
// exiting thread will notice and unpark the stranded thread, or, (b) |
|
837 |
// the timer expires. If the lock is high traffic then the stranding latency |
|
838 |
// will be low due to (a). If the lock is low traffic then the odds of |
|
839 |
// stranding are lower, although the worst-case stranding latency |
|
840 |
// is longer. Critically, we don't want to put excessive load in the |
|
841 |
// platform's timer subsystem. We want to minimize both the timer injection |
|
842 |
// rate (timers created/sec) as well as the number of timers active at |
|
843 |
// any one time. (more precisely, we want to minimize timer-seconds, which is |
|
844 |
// the integral of the # of active timers at any instant over time). |
|
845 |
// Both impinge on OS scalability. Given that, at most one thread parked on |
|
846 |
// a monitor will use a timer. |
|
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
847 |
// |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
848 |
// There is also the risk of a futile wake-up. If we drop the lock |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
849 |
// another thread can reacquire the lock immediately, and we can |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
850 |
// then wake a thread unnecessarily. This is benign, and we've |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
851 |
// structured the code so the windows are short and the frequency |
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
852 |
// of such futile wakups is low. |
6975 | 853 |
|
37092
0e56e3c9d545
8151593: Cleanup definition/usage of INLINE/NOINLINE macros and add xlC support
simonis
parents:
36384
diff
changeset
|
854 |
void ObjectMonitor::exit(bool not_suspended, TRAPS) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
855 |
Thread * const Self = THREAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
856 |
if (THREAD != _owner) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
857 |
if (THREAD->is_lock_owned((address) _owner)) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
858 |
// Transmute _owner from a BasicLock pointer to a Thread address. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
859 |
// We don't need to hold _mutex for this transition. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
860 |
// Non-null to Non-null is safe as long as all readers can |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
861 |
// tolerate either flavor. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
862 |
assert(_recursions == 0, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
863 |
_owner = THREAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
864 |
_recursions = 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
865 |
} else { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
866 |
// Apparent unbalanced locking ... |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
867 |
// Naively we'd like to throw IllegalMonitorStateException. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
868 |
// As a practical matter we can neither allocate nor throw an |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
869 |
// exception as ::exit() can be called from leaf routines. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
870 |
// see x86_32.ad Fast_Unlock() and the I1 and I2 properties. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
871 |
// Upon deeper reflection, however, in a properly run JVM the only |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
872 |
// way we should encounter this situation is in the presence of |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
873 |
// unbalanced JNI locking. TODO: CheckJNICalls. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
874 |
// See also: CR4414101 |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
875 |
assert(false, "Non-balanced monitor enter/exit! Likely JNI locking"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
876 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
877 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
878 |
} |
6975 | 879 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
880 |
if (_recursions != 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
881 |
_recursions--; // this is simple recursive enter |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
882 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
883 |
} |
6975 | 884 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
885 |
// Invariant: after setting Responsible=null an thread must execute |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
886 |
// a MEMBAR or other serializing instruction before fetching EntryList|cxq. |
51704 | 887 |
_Responsible = NULL; |
6975 | 888 |
|
50113 | 889 |
#if INCLUDE_JFR |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
890 |
// get the owner's thread id for the MonitorEnter event |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
891 |
// if it is enabled and the thread isn't suspended |
50113 | 892 |
if (not_suspended && EventJavaMonitorEnter::is_enabled()) { |
893 |
_previous_owner_tid = JFR_THREAD_ID(Self); |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
894 |
} |
18025 | 895 |
#endif |
896 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
897 |
for (;;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
898 |
assert(THREAD == _owner, "invariant"); |
6975 | 899 |
|
51860 | 900 |
// release semantics: prior loads and stores from within the critical section |
901 |
// must not float (reorder) past the following store that drops the lock. |
|
902 |
// On SPARC that requires MEMBAR #loadstore|#storestore. |
|
903 |
// But of course in TSO #loadstore|#storestore is not required. |
|
904 |
OrderAccess::release_store(&_owner, (void*)NULL); // drop the lock |
|
905 |
OrderAccess::storeload(); // See if we need to wake a successor |
|
906 |
if ((intptr_t(_EntryList)|intptr_t(_cxq)) == 0 || _succ != NULL) { |
|
907 |
return; |
|
908 |
} |
|
909 |
// Other threads are blocked trying to acquire the lock. |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
910 |
|
51860 | 911 |
// Normally the exiting thread is responsible for ensuring succession, |
912 |
// but if other successors are ready or other entering threads are spinning |
|
913 |
// then this thread can simply store NULL into _owner and exit without |
|
914 |
// waking a successor. The existence of spinners or ready successors |
|
915 |
// guarantees proper succession (liveness). Responsibility passes to the |
|
916 |
// ready or running successors. The exiting thread delegates the duty. |
|
917 |
// More precisely, if a successor already exists this thread is absolved |
|
918 |
// of the responsibility of waking (unparking) one. |
|
919 |
// |
|
920 |
// The _succ variable is critical to reducing futile wakeup frequency. |
|
921 |
// _succ identifies the "heir presumptive" thread that has been made |
|
922 |
// ready (unparked) but that has not yet run. We need only one such |
|
923 |
// successor thread to guarantee progress. |
|
924 |
// See http://www.usenix.org/events/jvm01/full_papers/dice/dice.pdf |
|
925 |
// section 3.3 "Futile Wakeup Throttling" for details. |
|
926 |
// |
|
927 |
// Note that spinners in Enter() also set _succ non-null. |
|
928 |
// In the current implementation spinners opportunistically set |
|
929 |
// _succ so that exiting threads might avoid waking a successor. |
|
930 |
// Another less appealing alternative would be for the exiting thread |
|
931 |
// to drop the lock and then spin briefly to see if a spinner managed |
|
932 |
// to acquire the lock. If so, the exiting thread could exit |
|
933 |
// immediately without waking a successor, otherwise the exiting |
|
934 |
// thread would need to dequeue and wake a successor. |
|
935 |
// (Note that we'd need to make the post-drop spin short, but no |
|
936 |
// shorter than the worst-case round-trip cache-line migration time. |
|
937 |
// The dropped lock needs to become visible to the spinner, and then |
|
938 |
// the acquisition of the lock by the spinner must become visible to |
|
939 |
// the exiting thread). |
|
6975 | 940 |
|
51860 | 941 |
// It appears that an heir-presumptive (successor) must be made ready. |
942 |
// Only the current lock owner can manipulate the EntryList or |
|
943 |
// drain _cxq, so we need to reacquire the lock. If we fail |
|
944 |
// to reacquire the lock the responsibility for ensuring succession |
|
945 |
// falls to the new owner. |
|
946 |
// |
|
947 |
if (!Atomic::replace_if_null(THREAD, &_owner)) { |
|
948 |
return; |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
949 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
950 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
951 |
guarantee(_owner == THREAD, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
952 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
953 |
ObjectWaiter * w = NULL; |
6975 | 954 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
955 |
w = _EntryList; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
956 |
if (w != NULL) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
957 |
// I'd like to write: guarantee (w->_thread != Self). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
958 |
// But in practice an exiting thread may find itself on the EntryList. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
959 |
// Let's say thread T1 calls O.wait(). Wait() enqueues T1 on O's waitset and |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
960 |
// then calls exit(). Exit release the lock by setting O._owner to NULL. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
961 |
// Let's say T1 then stalls. T2 acquires O and calls O.notify(). The |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
962 |
// notify() operation moves T1 from O's waitset to O's EntryList. T2 then |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
963 |
// release the lock "O". T2 resumes immediately after the ST of null into |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
964 |
// _owner, above. T2 notices that the EntryList is populated, so it |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
965 |
// reacquires the lock and then finds itself on the EntryList. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
966 |
// Given all that, we have to tolerate the circumstance where "w" is |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
967 |
// associated with Self. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
968 |
assert(w->TState == ObjectWaiter::TS_ENTER, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
969 |
ExitEpilog(Self, w); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
970 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
971 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
972 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
973 |
// If we find that both _cxq and EntryList are null then just |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
974 |
// re-run the exit protocol from the top. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
975 |
w = _cxq; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
976 |
if (w == NULL) continue; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
977 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
978 |
// Drain _cxq into EntryList - bulk transfer. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
979 |
// First, detach _cxq. |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
980 |
// The following loop is tantamount to: w = swap(&cxq, NULL) |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
981 |
for (;;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
982 |
assert(w != NULL, "Invariant"); |
47634
6a0c42c40cd1
8188220: Remove Atomic::*_ptr() uses and overloads from hotspot
coleenp
parents:
47216
diff
changeset
|
983 |
ObjectWaiter * u = Atomic::cmpxchg((ObjectWaiter*)NULL, &_cxq, w); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
984 |
if (u == w) break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
985 |
w = u; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
986 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
987 |
|
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
988 |
assert(w != NULL, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
989 |
assert(_EntryList == NULL, "invariant"); |
6975 | 990 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
991 |
// Convert the LIFO SLL anchored by _cxq into a DLL. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
992 |
// The list reorganization step operates in O(LENGTH(w)) time. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
993 |
// It's critical that this step operate quickly as |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
994 |
// "Self" still holds the outer-lock, restricting parallelism |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
995 |
// and effectively lengthening the critical section. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
996 |
// Invariant: s chases t chases u. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
997 |
// TODO-FIXME: consider changing EntryList from a DLL to a CDLL so |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
998 |
// we have faster access to the tail. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
999 |
|
51860 | 1000 |
_EntryList = w; |
1001 |
ObjectWaiter * q = NULL; |
|
1002 |
ObjectWaiter * p; |
|
1003 |
for (p = w; p != NULL; p = p->_next) { |
|
1004 |
guarantee(p->TState == ObjectWaiter::TS_CXQ, "Invariant"); |
|
1005 |
p->TState = ObjectWaiter::TS_ENTER; |
|
1006 |
p->_prev = q; |
|
1007 |
q = p; |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1008 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1009 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1010 |
// In 1-0 mode we need: ST EntryList; MEMBAR #storestore; ST _owner = NULL |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1011 |
// The MEMBAR is satisfied by the release_store() operation in ExitEpilog(). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1012 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1013 |
// See if we can abdicate to a spinner instead of waking a thread. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1014 |
// A primary goal of the implementation is to reduce the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1015 |
// context-switch rate. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1016 |
if (_succ != NULL) continue; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1017 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1018 |
w = _EntryList; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1019 |
if (w != NULL) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1020 |
guarantee(w->TState == ObjectWaiter::TS_ENTER, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1021 |
ExitEpilog(Self, w); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1022 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1023 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1024 |
} |
6975 | 1025 |
} |
1026 |
||
1027 |
// ExitSuspendEquivalent: |
|
1028 |
// A faster alternate to handle_special_suspend_equivalent_condition() |
|
1029 |
// |
|
1030 |
// handle_special_suspend_equivalent_condition() unconditionally |
|
1031 |
// acquires the SR_lock. On some platforms uncontended MutexLocker() |
|
1032 |
// operations have high latency. Note that in ::enter() we call HSSEC |
|
1033 |
// while holding the monitor, so we effectively lengthen the critical sections. |
|
1034 |
// |
|
1035 |
// There are a number of possible solutions: |
|
1036 |
// |
|
1037 |
// A. To ameliorate the problem we might also defer state transitions |
|
1038 |
// to as late as possible -- just prior to parking. |
|
1039 |
// Given that, we'd call HSSEC after having returned from park(), |
|
1040 |
// but before attempting to acquire the monitor. This is only a |
|
1041 |
// partial solution. It avoids calling HSSEC while holding the |
|
1042 |
// monitor (good), but it still increases successor reacquisition latency -- |
|
1043 |
// the interval between unparking a successor and the time the successor |
|
1044 |
// resumes and retries the lock. See ReenterI(), which defers state transitions. |
|
1045 |
// If we use this technique we can also avoid EnterI()-exit() loop |
|
1046 |
// in ::enter() where we iteratively drop the lock and then attempt |
|
1047 |
// to reacquire it after suspending. |
|
1048 |
// |
|
1049 |
// B. In the future we might fold all the suspend bits into a |
|
1050 |
// composite per-thread suspend flag and then update it with CAS(). |
|
1051 |
// Alternately, a Dekker-like mechanism with multiple variables |
|
1052 |
// would suffice: |
|
1053 |
// ST Self->_suspend_equivalent = false |
|
1054 |
// MEMBAR |
|
1055 |
// LD Self_>_suspend_flags |
|
1056 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1057 |
bool ObjectMonitor::ExitSuspendEquivalent(JavaThread * jSelf) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1058 |
return jSelf->handle_special_suspend_equivalent_condition(); |
6975 | 1059 |
} |
1060 |
||
1061 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1062 |
void ObjectMonitor::ExitEpilog(Thread * Self, ObjectWaiter * Wakee) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1063 |
assert(_owner == Self, "invariant"); |
6975 | 1064 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1065 |
// Exit protocol: |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1066 |
// 1. ST _succ = wakee |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1067 |
// 2. membar #loadstore|#storestore; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1068 |
// 2. ST _owner = NULL |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1069 |
// 3. unpark(wakee) |
6975 | 1070 |
|
51860 | 1071 |
_succ = Wakee->_thread; |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1072 |
ParkEvent * Trigger = Wakee->_event; |
6975 | 1073 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1074 |
// Hygiene -- once we've set _owner = NULL we can't safely dereference Wakee again. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1075 |
// The thread associated with Wakee may have grabbed the lock and "Wakee" may be |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1076 |
// out-of-scope (non-extant). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1077 |
Wakee = NULL; |
6975 | 1078 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1079 |
// Drop the lock |
47634
6a0c42c40cd1
8188220: Remove Atomic::*_ptr() uses and overloads from hotspot
coleenp
parents:
47216
diff
changeset
|
1080 |
OrderAccess::release_store(&_owner, (void*)NULL); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1081 |
OrderAccess::fence(); // ST _owner vs LD in unpark() |
6975 | 1082 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1083 |
DTRACE_MONITOR_PROBE(contended__exit, this, object(), Self); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1084 |
Trigger->unpark(); |
6975 | 1085 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1086 |
// Maintain stats and report events to JVMTI |
32614
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
1087 |
OM_PERFDATA_OP(Parks, inc()); |
6975 | 1088 |
} |
1089 |
||
1090 |
||
1091 |
// ----------------------------------------------------------------------------- |
|
1092 |
// Class Loader deadlock handling. |
|
1093 |
// |
|
1094 |
// complete_exit exits a lock returning recursion count |
|
1095 |
// complete_exit/reenter operate as a wait without waiting |
|
1096 |
// complete_exit requires an inflated monitor |
|
1097 |
// The _owner field is not always the Thread addr even with an |
|
1098 |
// inflated monitor, e.g. the monitor can be inflated by a non-owning |
|
1099 |
// thread due to contention. |
|
1100 |
intptr_t ObjectMonitor::complete_exit(TRAPS) { |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1101 |
Thread * const Self = THREAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1102 |
assert(Self->is_Java_thread(), "Must be Java thread!"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1103 |
JavaThread *jt = (JavaThread *)THREAD; |
6975 | 1104 |
|
51960 | 1105 |
assert(InitDone, "Unexpectedly not initialized"); |
6975 | 1106 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1107 |
if (THREAD != _owner) { |
6975 | 1108 |
if (THREAD->is_lock_owned ((address)_owner)) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1109 |
assert(_recursions == 0, "internal state error"); |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1110 |
_owner = THREAD; // Convert from basiclock addr to Thread addr |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1111 |
_recursions = 0; |
6975 | 1112 |
} |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1113 |
} |
6975 | 1114 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1115 |
guarantee(Self == _owner, "complete_exit not owner"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1116 |
intptr_t save = _recursions; // record the old recursion count |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1117 |
_recursions = 0; // set the recursion level to be 0 |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1118 |
exit(true, Self); // exit the monitor |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1119 |
guarantee(_owner != Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1120 |
return save; |
6975 | 1121 |
} |
1122 |
||
1123 |
// reenter() enters a lock and sets recursion count |
|
1124 |
// complete_exit/reenter operate as a wait without waiting |
|
1125 |
void ObjectMonitor::reenter(intptr_t recursions, TRAPS) { |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1126 |
Thread * const Self = THREAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1127 |
assert(Self->is_Java_thread(), "Must be Java thread!"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1128 |
JavaThread *jt = (JavaThread *)THREAD; |
6975 | 1129 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1130 |
guarantee(_owner != Self, "reenter already owner"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1131 |
enter(THREAD); // enter the monitor |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1132 |
guarantee(_recursions == 0, "reenter recursion"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1133 |
_recursions = recursions; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1134 |
return; |
6975 | 1135 |
} |
1136 |
||
1137 |
||
1138 |
// ----------------------------------------------------------------------------- |
|
1139 |
// A macro is used below because there may already be a pending |
|
1140 |
// exception which should not abort the execution of the routines |
|
1141 |
// which use this (which is why we don't put this into check_slow and |
|
1142 |
// call it with a CHECK argument). |
|
1143 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1144 |
#define CHECK_OWNER() \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1145 |
do { \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1146 |
if (THREAD != _owner) { \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1147 |
if (THREAD->is_lock_owned((address) _owner)) { \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1148 |
_owner = THREAD; /* Convert from basiclock addr to Thread addr */ \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1149 |
_recursions = 0; \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1150 |
} else { \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1151 |
THROW(vmSymbols::java_lang_IllegalMonitorStateException()); \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1152 |
} \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1153 |
} \ |
6975 | 1154 |
} while (false) |
1155 |
||
1156 |
// check_slow() is a misnomer. It's called to simply to throw an IMSX exception. |
|
1157 |
// TODO-FIXME: remove check_slow() -- it's likely dead. |
|
1158 |
||
1159 |
void ObjectMonitor::check_slow(TRAPS) { |
|
1160 |
assert(THREAD != _owner && !THREAD->is_lock_owned((address) _owner), "must not be owner"); |
|
1161 |
THROW_MSG(vmSymbols::java_lang_IllegalMonitorStateException(), "current thread not owner"); |
|
1162 |
} |
|
1163 |
||
50113 | 1164 |
static void post_monitor_wait_event(EventJavaMonitorWait* event, |
1165 |
ObjectMonitor* monitor, |
|
1166 |
jlong notifier_tid, |
|
1167 |
jlong timeout, |
|
1168 |
bool timedout) { |
|
36384 | 1169 |
assert(event != NULL, "invariant"); |
50113 | 1170 |
assert(monitor != NULL, "invariant"); |
1171 |
event->set_monitorClass(((oop)monitor->object())->klass()); |
|
36384 | 1172 |
event->set_timeout(timeout); |
50113 | 1173 |
event->set_address((uintptr_t)monitor->object_addr()); |
36384 | 1174 |
event->set_notifier(notifier_tid); |
1175 |
event->set_timedOut(timedout); |
|
18025 | 1176 |
event->commit(); |
1177 |
} |
|
1178 |
||
6975 | 1179 |
// ----------------------------------------------------------------------------- |
1180 |
// Wait/Notify/NotifyAll |
|
1181 |
// |
|
1182 |
// Note: a subset of changes to ObjectMonitor::wait() |
|
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
1183 |
// will need to be replicated in complete_exit |
6975 | 1184 |
void ObjectMonitor::wait(jlong millis, bool interruptible, TRAPS) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1185 |
Thread * const Self = THREAD; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1186 |
assert(Self->is_Java_thread(), "Must be Java thread!"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1187 |
JavaThread *jt = (JavaThread *)THREAD; |
6975 | 1188 |
|
51960 | 1189 |
assert(InitDone, "Unexpectedly not initialized"); |
6975 | 1190 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1191 |
// Throw IMSX or IEX. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1192 |
CHECK_OWNER(); |
6975 | 1193 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1194 |
EventJavaMonitorWait event; |
18025 | 1195 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1196 |
// check for a pending interrupt |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1197 |
if (interruptible && Thread::is_interrupted(Self, true) && !HAS_PENDING_EXCEPTION) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1198 |
// post monitor waited event. Note that this is past-tense, we are done waiting. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1199 |
if (JvmtiExport::should_post_monitor_waited()) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1200 |
// Note: 'false' parameter is passed here because the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1201 |
// wait was not timed out due to thread interrupt. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1202 |
JvmtiExport::post_monitor_waited(jt, this, false); |
22753
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
1203 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1204 |
// In this short circuit of the monitor wait protocol, the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1205 |
// current thread never drops ownership of the monitor and |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1206 |
// never gets added to the wait queue so the current thread |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1207 |
// cannot be made the successor. This means that the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1208 |
// JVMTI_EVENT_MONITOR_WAITED event handler cannot accidentally |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1209 |
// consume an unpark() meant for the ParkEvent associated with |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1210 |
// this ObjectMonitor. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1211 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1212 |
if (event.should_commit()) { |
50113 | 1213 |
post_monitor_wait_event(&event, this, 0, millis, false); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1214 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1215 |
THROW(vmSymbols::java_lang_InterruptedException()); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1216 |
return; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1217 |
} |
18025 | 1218 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1219 |
assert(Self->_Stalled == 0, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1220 |
Self->_Stalled = intptr_t(this); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1221 |
jt->set_current_waiting_monitor(this); |
6975 | 1222 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1223 |
// create a node to be put into the queue |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1224 |
// Critically, after we reset() the event but prior to park(), we must check |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1225 |
// for a pending interrupt. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1226 |
ObjectWaiter node(Self); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1227 |
node.TState = ObjectWaiter::TS_WAIT; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1228 |
Self->_ParkEvent->reset(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1229 |
OrderAccess::fence(); // ST into Event; membar ; LD interrupted-flag |
6975 | 1230 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1231 |
// Enter the waiting queue, which is a circular doubly linked list in this case |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1232 |
// but it could be a priority queue or any data structure. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1233 |
// _WaitSetLock protects the wait queue. Normally the wait queue is accessed only |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1234 |
// by the the owner of the monitor *except* in the case where park() |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1235 |
// returns because of a timeout of interrupt. Contention is exceptionally rare |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1236 |
// so we use a simple spin-lock instead of a heavier-weight blocking lock. |
6975 | 1237 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1238 |
Thread::SpinAcquire(&_WaitSetLock, "WaitSet - add"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1239 |
AddWaiter(&node); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1240 |
Thread::SpinRelease(&_WaitSetLock); |
6975 | 1241 |
|
51704 | 1242 |
_Responsible = NULL; |
1243 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1244 |
intptr_t save = _recursions; // record the old recursion count |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1245 |
_waiters++; // increment the number of waiters |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1246 |
_recursions = 0; // set the recursion level to be 1 |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1247 |
exit(true, Self); // exit the monitor |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1248 |
guarantee(_owner != Self, "invariant"); |
6975 | 1249 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1250 |
// The thread is on the WaitSet list - now park() it. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1251 |
// On MP systems it's conceivable that a brief spin before we park |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1252 |
// could be profitable. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1253 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1254 |
// TODO-FIXME: change the following logic to a loop of the form |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1255 |
// while (!timeout && !interrupted && _notified == 0) park() |
6975 | 1256 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1257 |
int ret = OS_OK; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1258 |
int WasNotified = 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1259 |
{ // State transition wrappers |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1260 |
OSThread* osthread = Self->osthread(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1261 |
OSThreadWaitState osts(osthread, true); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1262 |
{ |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1263 |
ThreadBlockInVM tbivm(jt); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1264 |
// Thread is in thread_blocked state and oop access is unsafe. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1265 |
jt->set_suspend_equivalent(); |
6975 | 1266 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1267 |
if (interruptible && (Thread::is_interrupted(THREAD, false) || HAS_PENDING_EXCEPTION)) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1268 |
// Intentionally empty |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1269 |
} else if (node._notified == 0) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1270 |
if (millis <= 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1271 |
Self->_ParkEvent->park(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1272 |
} else { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1273 |
ret = Self->_ParkEvent->park(millis); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1274 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1275 |
} |
6975 | 1276 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1277 |
// were we externally suspended while we were waiting? |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1278 |
if (ExitSuspendEquivalent (jt)) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1279 |
// TODO-FIXME: add -- if succ == Self then succ = null. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1280 |
jt->java_suspend_self(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1281 |
} |
6975 | 1282 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1283 |
} // Exit thread safepoint: transition _thread_blocked -> _thread_in_vm |
6975 | 1284 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1285 |
// Node may be on the WaitSet, the EntryList (or cxq), or in transition |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1286 |
// from the WaitSet to the EntryList. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1287 |
// See if we need to remove Node from the WaitSet. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1288 |
// We use double-checked locking to avoid grabbing _WaitSetLock |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1289 |
// if the thread is not on the wait queue. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1290 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1291 |
// Note that we don't need a fence before the fetch of TState. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1292 |
// In the worst case we'll fetch a old-stale value of TS_WAIT previously |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1293 |
// written by the is thread. (perhaps the fetch might even be satisfied |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1294 |
// by a look-aside into the processor's own store buffer, although given |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1295 |
// the length of the code path between the prior ST and this load that's |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1296 |
// highly unlikely). If the following LD fetches a stale TS_WAIT value |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1297 |
// then we'll acquire the lock and then re-fetch a fresh TState value. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1298 |
// That is, we fail toward safety. |
6975 | 1299 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1300 |
if (node.TState == ObjectWaiter::TS_WAIT) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1301 |
Thread::SpinAcquire(&_WaitSetLock, "WaitSet - unlink"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1302 |
if (node.TState == ObjectWaiter::TS_WAIT) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1303 |
DequeueSpecificWaiter(&node); // unlink from WaitSet |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1304 |
assert(node._notified == 0, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1305 |
node.TState = ObjectWaiter::TS_RUN; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1306 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1307 |
Thread::SpinRelease(&_WaitSetLock); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1308 |
} |
6975 | 1309 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1310 |
// The thread is now either on off-list (TS_RUN), |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1311 |
// on the EntryList (TS_ENTER), or on the cxq (TS_CXQ). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1312 |
// The Node's TState variable is stable from the perspective of this thread. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1313 |
// No other threads will asynchronously modify TState. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1314 |
guarantee(node.TState != ObjectWaiter::TS_WAIT, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1315 |
OrderAccess::loadload(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1316 |
if (_succ == Self) _succ = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1317 |
WasNotified = node._notified; |
6975 | 1318 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1319 |
// Reentry phase -- reacquire the monitor. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1320 |
// re-enter contended monitor after object.wait(). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1321 |
// retain OBJECT_WAIT state until re-enter successfully completes |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1322 |
// Thread state is thread_in_vm and oop access is again safe, |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1323 |
// although the raw address of the object may have changed. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1324 |
// (Don't cache naked oops over safepoints, of course). |
6975 | 1325 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1326 |
// post monitor waited event. Note that this is past-tense, we are done waiting. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1327 |
if (JvmtiExport::should_post_monitor_waited()) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1328 |
JvmtiExport::post_monitor_waited(jt, this, ret == OS_TIMEOUT); |
22753
749328896281
8028073: race condition in ObjectMonitor implementation causing deadlocks
dcubed
parents:
22551
diff
changeset
|
1329 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1330 |
if (node._notified != 0 && _succ == Self) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1331 |
// In this part of the monitor wait-notify-reenter protocol it |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1332 |
// is possible (and normal) for another thread to do a fastpath |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1333 |
// monitor enter-exit while this thread is still trying to get |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1334 |
// to the reenter portion of the protocol. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1335 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1336 |
// The ObjectMonitor was notified and the current thread is |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1337 |
// the successor which also means that an unpark() has already |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1338 |
// been done. The JVMTI_EVENT_MONITOR_WAITED event handler can |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1339 |
// consume the unpark() that was done when the successor was |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1340 |
// set because the same ParkEvent is shared between Java |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1341 |
// monitors and JVM/TI RawMonitors (for now). |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1342 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1343 |
// We redo the unpark() to ensure forward progress, i.e., we |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1344 |
// don't want all pending threads hanging (parked) with none |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1345 |
// entering the unlocked monitor. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1346 |
node._event->unpark(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1347 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1348 |
} |
18025 | 1349 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1350 |
if (event.should_commit()) { |
50113 | 1351 |
post_monitor_wait_event(&event, this, node._notifier_tid, millis, ret == OS_TIMEOUT); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1352 |
} |
18025 | 1353 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1354 |
OrderAccess::fence(); |
6975 | 1355 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1356 |
assert(Self->_Stalled != 0, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1357 |
Self->_Stalled = 0; |
6975 | 1358 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1359 |
assert(_owner != Self, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1360 |
ObjectWaiter::TStates v = node.TState; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1361 |
if (v == ObjectWaiter::TS_RUN) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1362 |
enter(Self); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1363 |
} else { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1364 |
guarantee(v == ObjectWaiter::TS_ENTER || v == ObjectWaiter::TS_CXQ, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1365 |
ReenterI(Self, &node); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1366 |
node.wait_reenter_end(this); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1367 |
} |
6975 | 1368 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1369 |
// Self has reacquired the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1370 |
// Lifecycle - the node representing Self must not appear on any queues. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1371 |
// Node is about to go out-of-scope, but even if it were immortal we wouldn't |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1372 |
// want residual elements associated with this thread left on any lists. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1373 |
guarantee(node.TState == ObjectWaiter::TS_RUN, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1374 |
assert(_owner == Self, "invariant"); |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1375 |
assert(_succ != Self, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1376 |
} // OSThreadWaitState() |
6975 | 1377 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1378 |
jt->set_current_waiting_monitor(NULL); |
6975 | 1379 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1380 |
guarantee(_recursions == 0, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1381 |
_recursions = save; // restore the old recursion count |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1382 |
_waiters--; // decrement the number of waiters |
6975 | 1383 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1384 |
// Verify a few postconditions |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1385 |
assert(_owner == Self, "invariant"); |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1386 |
assert(_succ != Self, "invariant"); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1387 |
assert(((oop)(object()))->mark() == markOopDesc::encode(this), "invariant"); |
6975 | 1388 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1389 |
// check if the notification happened |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1390 |
if (!WasNotified) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1391 |
// no, it could be timeout or Thread.interrupt() or both |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1392 |
// check for interrupt event, otherwise it is timeout |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1393 |
if (interruptible && Thread::is_interrupted(Self, true) && !HAS_PENDING_EXCEPTION) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1394 |
THROW(vmSymbols::java_lang_InterruptedException()); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1395 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1396 |
} |
6975 | 1397 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1398 |
// NOTE: Spurious wake up will be consider as timeout. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1399 |
// Monitor notify has precedence over thread interrupt. |
6975 | 1400 |
} |
1401 |
||
1402 |
||
1403 |
// Consider: |
|
1404 |
// If the lock is cool (cxq == null && succ == null) and we're on an MP system |
|
1405 |
// then instead of transferring a thread from the WaitSet to the EntryList |
|
1406 |
// we might just dequeue a thread from the WaitSet and directly unpark() it. |
|
1407 |
||
31856 | 1408 |
void ObjectMonitor::INotify(Thread * Self) { |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1409 |
Thread::SpinAcquire(&_WaitSetLock, "WaitSet - notify"); |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1410 |
ObjectWaiter * iterator = DequeueWaiter(); |
6975 | 1411 |
if (iterator != NULL) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1412 |
guarantee(iterator->TState == ObjectWaiter::TS_WAIT, "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1413 |
guarantee(iterator->_notified == 0, "invariant"); |
31856 | 1414 |
// Disposition - what might we do with iterator ? |
1415 |
// a. add it directly to the EntryList - either tail (policy == 1) |
|
1416 |
// or head (policy == 0). |
|
1417 |
// b. push it onto the front of the _cxq (policy == 2). |
|
1418 |
// For now we use (b). |
|
51860 | 1419 |
|
1420 |
iterator->TState = ObjectWaiter::TS_ENTER; |
|
1421 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1422 |
iterator->_notified = 1; |
50113 | 1423 |
iterator->_notifier_tid = JFR_THREAD_ID(Self); |
6975 | 1424 |
|
31856 | 1425 |
ObjectWaiter * list = _EntryList; |
1426 |
if (list != NULL) { |
|
1427 |
assert(list->_prev == NULL, "invariant"); |
|
1428 |
assert(list->TState == ObjectWaiter::TS_ENTER, "invariant"); |
|
1429 |
assert(list != iterator, "invariant"); |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1430 |
} |
6975 | 1431 |
|
51860 | 1432 |
// prepend to cxq |
1433 |
if (list == NULL) { |
|
1434 |
iterator->_next = iterator->_prev = NULL; |
|
1435 |
_EntryList = iterator; |
|
1436 |
} else { |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1437 |
iterator->TState = ObjectWaiter::TS_CXQ; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1438 |
for (;;) { |
51860 | 1439 |
ObjectWaiter * front = _cxq; |
1440 |
iterator->_next = front; |
|
1441 |
if (Atomic::cmpxchg(iterator, &_cxq, front) == front) { |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1442 |
break; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1443 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1444 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1445 |
} |
6975 | 1446 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1447 |
// _WaitSetLock protects the wait queue, not the EntryList. We could |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1448 |
// move the add-to-EntryList operation, above, outside the critical section |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1449 |
// protected by _WaitSetLock. In practice that's not useful. With the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1450 |
// exception of wait() timeouts and interrupts the monitor owner |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1451 |
// is the only thread that grabs _WaitSetLock. There's almost no contention |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1452 |
// on _WaitSetLock so it's not profitable to reduce the length of the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1453 |
// critical section. |
31856 | 1454 |
|
51860 | 1455 |
iterator->wait_reenter_begin(this); |
6975 | 1456 |
} |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1457 |
Thread::SpinRelease(&_WaitSetLock); |
31856 | 1458 |
} |
6975 | 1459 |
|
31856 | 1460 |
// Consider: a not-uncommon synchronization bug is to use notify() when |
1461 |
// notifyAll() is more appropriate, potentially resulting in stranded |
|
1462 |
// threads; this is one example of a lost wakeup. A useful diagnostic |
|
1463 |
// option is to force all notify() operations to behave as notifyAll(). |
|
1464 |
// |
|
1465 |
// Note: We can also detect many such problems with a "minimum wait". |
|
1466 |
// When the "minimum wait" is set to a small non-zero timeout value |
|
1467 |
// and the program does not hang whereas it did absent "minimum wait", |
|
51704 | 1468 |
// that suggests a lost wakeup bug. |
31856 | 1469 |
|
1470 |
void ObjectMonitor::notify(TRAPS) { |
|
1471 |
CHECK_OWNER(); |
|
1472 |
if (_WaitSet == NULL) { |
|
1473 |
return; |
|
1474 |
} |
|
1475 |
DTRACE_MONITOR_PROBE(notify, this, object(), THREAD); |
|
1476 |
INotify(THREAD); |
|
32614
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
1477 |
OM_PERFDATA_OP(Notifications, inc(1)); |
6975 | 1478 |
} |
1479 |
||
1480 |
||
31856 | 1481 |
// The current implementation of notifyAll() transfers the waiters one-at-a-time |
1482 |
// from the waitset to the EntryList. This could be done more efficiently with a |
|
1483 |
// single bulk transfer but in practice it's not time-critical. Beware too, |
|
1484 |
// that in prepend-mode we invert the order of the waiters. Let's say that the |
|
1485 |
// waitset is "ABCD" and the EntryList is "XYZ". After a notifyAll() in prepend |
|
1486 |
// mode the waitset will be empty and the EntryList will be "DCBAXYZ". |
|
1487 |
||
6975 | 1488 |
void ObjectMonitor::notifyAll(TRAPS) { |
1489 |
CHECK_OWNER(); |
|
1490 |
if (_WaitSet == NULL) { |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1491 |
return; |
6975 | 1492 |
} |
31856 | 1493 |
|
6975 | 1494 |
DTRACE_MONITOR_PROBE(notifyAll, this, object(), THREAD); |
31856 | 1495 |
int tally = 0; |
1496 |
while (_WaitSet != NULL) { |
|
1497 |
tally++; |
|
1498 |
INotify(THREAD); |
|
6975 | 1499 |
} |
1500 |
||
32614
b7b2407bc7e5
8049304: race between VM_Exit and _sync_FutileWakeups->inc()
dcubed
parents:
31856
diff
changeset
|
1501 |
OM_PERFDATA_OP(Notifications, inc(tally)); |
6975 | 1502 |
} |
1503 |
||
1504 |
// ----------------------------------------------------------------------------- |
|
1505 |
// Adaptive Spinning Support |
|
1506 |
// |
|
1507 |
// Adaptive spin-then-block - rational spinning |
|
1508 |
// |
|
1509 |
// Note that we spin "globally" on _owner with a classic SMP-polite TATAS |
|
1510 |
// algorithm. On high order SMP systems it would be better to start with |
|
1511 |
// a brief global spin and then revert to spinning locally. In the spirit of MCS/CLH, |
|
1512 |
// a contending thread could enqueue itself on the cxq and then spin locally |
|
1513 |
// on a thread-specific variable such as its ParkEvent._Event flag. |
|
1514 |
// That's left as an exercise for the reader. Note that global spinning is |
|
27165
785a8d56024c
8049737: Contended Locking reorder and cache line bucket
dcubed
parents:
26684
diff
changeset
|
1515 |
// not problematic on Niagara, as the L2 cache serves the interconnect and |
785a8d56024c
8049737: Contended Locking reorder and cache line bucket
dcubed
parents:
26684
diff
changeset
|
1516 |
// has both low latency and massive bandwidth. |
6975 | 1517 |
// |
1518 |
// Broadly, we can fix the spin frequency -- that is, the % of contended lock |
|
1519 |
// acquisition attempts where we opt to spin -- at 100% and vary the spin count |
|
1520 |
// (duration) or we can fix the count at approximately the duration of |
|
1521 |
// a context switch and vary the frequency. Of course we could also |
|
1522 |
// vary both satisfying K == Frequency * Duration, where K is adaptive by monitor. |
|
32622
7ed47d0b888a
8135002: Fix or remove broken links in objectMonitor.cpp comments
dbuck
parents:
32614
diff
changeset
|
1523 |
// For a description of 'Adaptive spin-then-block mutual exclusion in |
7ed47d0b888a
8135002: Fix or remove broken links in objectMonitor.cpp comments
dbuck
parents:
32614
diff
changeset
|
1524 |
// multi-threaded processing,' see U.S. Pat. No. 8046758. |
6975 | 1525 |
// |
1526 |
// This implementation varies the duration "D", where D varies with |
|
1527 |
// the success rate of recent spin attempts. (D is capped at approximately |
|
1528 |
// length of a round-trip context switch). The success rate for recent |
|
1529 |
// spin attempts is a good predictor of the success rate of future spin |
|
1530 |
// attempts. The mechanism adapts automatically to varying critical |
|
1531 |
// section length (lock modality), system load and degree of parallelism. |
|
1532 |
// D is maintained per-monitor in _SpinDuration and is initialized |
|
1533 |
// optimistically. Spin frequency is fixed at 100%. |
|
1534 |
// |
|
1535 |
// Note that _SpinDuration is volatile, but we update it without locks |
|
1536 |
// or atomics. The code is designed so that _SpinDuration stays within |
|
1537 |
// a reasonable range even in the presence of races. The arithmetic |
|
1538 |
// operations on _SpinDuration are closed over the domain of legal values, |
|
1539 |
// so at worst a race will install and older but still legal value. |
|
1540 |
// At the very worst this introduces some apparent non-determinism. |
|
1541 |
// We might spin when we shouldn't or vice-versa, but since the spin |
|
1542 |
// count are relatively short, even in the worst case, the effect is harmless. |
|
1543 |
// |
|
1544 |
// Care must be taken that a low "D" value does not become an |
|
1545 |
// an absorbing state. Transient spinning failures -- when spinning |
|
1546 |
// is overall profitable -- should not cause the system to converge |
|
1547 |
// on low "D" values. We want spinning to be stable and predictable |
|
1548 |
// and fairly responsive to change and at the same time we don't want |
|
1549 |
// it to oscillate, become metastable, be "too" non-deterministic, |
|
1550 |
// or converge on or enter undesirable stable absorbing states. |
|
1551 |
// |
|
1552 |
// We implement a feedback-based control system -- using past behavior |
|
1553 |
// to predict future behavior. We face two issues: (a) if the |
|
1554 |
// input signal is random then the spin predictor won't provide optimal |
|
1555 |
// results, and (b) if the signal frequency is too high then the control |
|
1556 |
// system, which has some natural response lag, will "chase" the signal. |
|
1557 |
// (b) can arise from multimodal lock hold times. Transient preemption |
|
1558 |
// can also result in apparent bimodal lock hold times. |
|
1559 |
// Although sub-optimal, neither condition is particularly harmful, as |
|
1560 |
// in the worst-case we'll spin when we shouldn't or vice-versa. |
|
1561 |
// The maximum spin duration is rather short so the failure modes aren't bad. |
|
1562 |
// To be conservative, I've tuned the gain in system to bias toward |
|
1563 |
// _not spinning. Relatedly, the system can sometimes enter a mode where it |
|
1564 |
// "rings" or oscillates between spinning and not spinning. This happens |
|
1565 |
// when spinning is just on the cusp of profitability, however, so the |
|
1566 |
// situation is not dire. The state is benign -- there's no need to add |
|
1567 |
// hysteresis control to damp the transition rate between spinning and |
|
1568 |
// not spinning. |
|
1569 |
||
1570 |
// Spinning: Fixed frequency (100%), vary duration |
|
39702 | 1571 |
int ObjectMonitor::TrySpin(Thread * Self) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1572 |
// Dumb, brutal spin. Good for comparative measurements against adaptive spinning. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1573 |
int ctr = Knob_FixedSpin; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1574 |
if (ctr != 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1575 |
while (--ctr >= 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1576 |
if (TryLock(Self) > 0) return 1; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1577 |
SpinPause(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1578 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1579 |
return 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1580 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1581 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1582 |
for (ctr = Knob_PreSpin + 1; --ctr >= 0;) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1583 |
if (TryLock(Self) > 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1584 |
// Increase _SpinDuration ... |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1585 |
// Note that we don't clamp SpinDuration precisely at SpinLimit. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1586 |
// Raising _SpurDuration to the poverty line is key. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1587 |
int x = _SpinDuration; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1588 |
if (x < Knob_SpinLimit) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1589 |
if (x < Knob_Poverty) x = Knob_Poverty; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1590 |
_SpinDuration = x + Knob_BonusB; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1591 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1592 |
return 1; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1593 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1594 |
SpinPause(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1595 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1596 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1597 |
// Admission control - verify preconditions for spinning |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1598 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1599 |
// We always spin a little bit, just to prevent _SpinDuration == 0 from |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1600 |
// becoming an absorbing state. Put another way, we spin briefly to |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1601 |
// sample, just in case the system load, parallelism, contention, or lock |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1602 |
// modality changed. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1603 |
// |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1604 |
// Consider the following alternative: |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1605 |
// Periodically set _SpinDuration = _SpinLimit and try a long/full |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1606 |
// spin attempt. "Periodically" might mean after a tally of |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1607 |
// the # of failed spin attempts (or iterations) reaches some threshold. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1608 |
// This takes us into the realm of 1-out-of-N spinning, where we |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1609 |
// hold the duration constant but vary the frequency. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1610 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1611 |
ctr = _SpinDuration; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1612 |
if (ctr <= 0) return 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1613 |
|
51860 | 1614 |
if (NotRunnable(Self, (Thread *) _owner)) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1615 |
return 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1616 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1617 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1618 |
// We're good to spin ... spin ingress. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1619 |
// CONSIDER: use Prefetch::write() to avoid RTS->RTO upgrades |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1620 |
// when preparing to LD...CAS _owner, etc and the CAS is likely |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1621 |
// to succeed. |
51860 | 1622 |
if (_succ == NULL) { |
1623 |
_succ = Self; |
|
1624 |
} |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1625 |
Thread * prv = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1626 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1627 |
// There are three ways to exit the following loop: |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1628 |
// 1. A successful spin where this thread has acquired the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1629 |
// 2. Spin failure with prejudice |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1630 |
// 3. Spin failure without prejudice |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1631 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1632 |
while (--ctr >= 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1633 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1634 |
// Periodic polling -- Check for pending GC |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1635 |
// Threads may spin while they're unsafe. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1636 |
// We don't want spinning threads to delay the JVM from reaching |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1637 |
// a stop-the-world safepoint or to steal cycles from GC. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1638 |
// If we detect a pending safepoint we abort in order that |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1639 |
// (a) this thread, if unsafe, doesn't delay the safepoint, and (b) |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1640 |
// this thread, if safe, doesn't steal cycles from GC. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1641 |
// This is in keeping with the "no loitering in runtime" rule. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1642 |
// We periodically check to see if there's a safepoint pending. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1643 |
if ((ctr & 0xFF) == 0) { |
47881
0ce0ac68ace7
8189941: Implementation JEP 312: Thread-local handshake
rehn
parents:
47634
diff
changeset
|
1644 |
if (SafepointMechanism::poll(Self)) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1645 |
goto Abort; // abrupt spin egress |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1646 |
} |
51860 | 1647 |
SpinPause(); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1648 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1649 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1650 |
// Probe _owner with TATAS |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1651 |
// If this thread observes the monitor transition or flicker |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1652 |
// from locked to unlocked to locked, then the odds that this |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1653 |
// thread will acquire the lock in this spin attempt go down |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1654 |
// considerably. The same argument applies if the CAS fails |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1655 |
// or if we observe _owner change from one non-null value to |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1656 |
// another non-null value. In such cases we might abort |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1657 |
// the spin without prejudice or apply a "penalty" to the |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1658 |
// spin count-down variable "ctr", reducing it by 100, say. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1659 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1660 |
Thread * ox = (Thread *) _owner; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1661 |
if (ox == NULL) { |
47634
6a0c42c40cd1
8188220: Remove Atomic::*_ptr() uses and overloads from hotspot
coleenp
parents:
47216
diff
changeset
|
1662 |
ox = (Thread*)Atomic::cmpxchg(Self, &_owner, (void*)NULL); |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1663 |
if (ox == NULL) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1664 |
// The CAS succeeded -- this thread acquired ownership |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1665 |
// Take care of some bookkeeping to exit spin state. |
51860 | 1666 |
if (_succ == Self) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1667 |
_succ = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1668 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1669 |
|
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1670 |
// Increase _SpinDuration : |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1671 |
// The spin was successful (profitable) so we tend toward |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1672 |
// longer spin attempts in the future. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1673 |
// CONSIDER: factor "ctr" into the _SpinDuration adjustment. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1674 |
// If we acquired the lock early in the spin cycle it |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1675 |
// makes sense to increase _SpinDuration proportionally. |
6975 | 1676 |
// Note that we don't clamp SpinDuration precisely at SpinLimit. |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1677 |
int x = _SpinDuration; |
6975 | 1678 |
if (x < Knob_SpinLimit) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1679 |
if (x < Knob_Poverty) x = Knob_Poverty; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1680 |
_SpinDuration = x + Knob_Bonus; |
6975 | 1681 |
} |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1682 |
return 1; |
6975 | 1683 |
} |
1684 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1685 |
// The CAS failed ... we can take any of the following actions: |
51860 | 1686 |
// * penalize: ctr -= CASPenalty |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1687 |
// * exit spin with prejudice -- goto Abort; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1688 |
// * exit spin without prejudice. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1689 |
// * Since CAS is high-latency, retry again immediately. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1690 |
prv = ox; |
51860 | 1691 |
goto Abort; |
6975 | 1692 |
} |
1693 |
||
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1694 |
// Did lock ownership change hands ? |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1695 |
if (ox != prv && prv != NULL) { |
51860 | 1696 |
goto Abort; |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1697 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1698 |
prv = ox; |
6975 | 1699 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1700 |
// Abort the spin if the owner is not executing. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1701 |
// The owner must be executing in order to drop the lock. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1702 |
// Spinning while the owner is OFFPROC is idiocy. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1703 |
// Consider: ctr -= RunnablePenalty ; |
51860 | 1704 |
if (NotRunnable(Self, ox)) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1705 |
goto Abort; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1706 |
} |
51860 | 1707 |
if (_succ == NULL) { |
1708 |
_succ = Self; |
|
1709 |
} |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1710 |
} |
6975 | 1711 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1712 |
// Spin failed with prejudice -- reduce _SpinDuration. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1713 |
// TODO: Use an AIMD-like policy to adjust _SpinDuration. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1714 |
// AIMD is globally stable. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1715 |
{ |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1716 |
int x = _SpinDuration; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1717 |
if (x > 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1718 |
// Consider an AIMD scheme like: x -= (x >> 3) + 100 |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1719 |
// This is globally sample and tends to damp the response. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1720 |
x -= Knob_Penalty; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1721 |
if (x < 0) x = 0; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1722 |
_SpinDuration = x; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1723 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1724 |
} |
6975 | 1725 |
|
1726 |
Abort: |
|
51860 | 1727 |
if (_succ == Self) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1728 |
_succ = NULL; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1729 |
// Invariant: after setting succ=null a contending thread |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1730 |
// must recheck-retry _owner before parking. This usually happens |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1731 |
// in the normal usage of TrySpin(), but it's safest |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1732 |
// to make TrySpin() as foolproof as possible. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1733 |
OrderAccess::fence(); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1734 |
if (TryLock(Self) > 0) return 1; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1735 |
} |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1736 |
return 0; |
6975 | 1737 |
} |
1738 |
||
1739 |
// NotRunnable() -- informed spinning |
|
1740 |
// |
|
1741 |
// Don't bother spinning if the owner is not eligible to drop the lock. |
|
51376
181e6a03249b
8164683: Solaris: JVM abuses thread preemption control
coleenp
parents:
51258
diff
changeset
|
1742 |
// Spin only if the owner thread is _thread_in_Java or _thread_in_vm. |
6975 | 1743 |
// The thread must be runnable in order to drop the lock in timely fashion. |
1744 |
// If the _owner is not runnable then spinning will not likely be |
|
1745 |
// successful (profitable). |
|
1746 |
// |
|
1747 |
// Beware -- the thread referenced by _owner could have died |
|
1748 |
// so a simply fetch from _owner->_thread_state might trap. |
|
1749 |
// Instead, we use SafeFetchXX() to safely LD _owner->_thread_state. |
|
51376
181e6a03249b
8164683: Solaris: JVM abuses thread preemption control
coleenp
parents:
51258
diff
changeset
|
1750 |
// Because of the lifecycle issues, the _thread_state values |
6975 | 1751 |
// observed by NotRunnable() might be garbage. NotRunnable must |
1752 |
// tolerate this and consider the observed _thread_state value |
|
1753 |
// as advisory. |
|
1754 |
// |
|
1755 |
// Beware too, that _owner is sometimes a BasicLock address and sometimes |
|
27165
785a8d56024c
8049737: Contended Locking reorder and cache line bucket
dcubed
parents:
26684
diff
changeset
|
1756 |
// a thread pointer. |
6975 | 1757 |
// Alternately, we might tag the type (thread pointer vs basiclock pointer) |
51376
181e6a03249b
8164683: Solaris: JVM abuses thread preemption control
coleenp
parents:
51258
diff
changeset
|
1758 |
// with the LSB of _owner. Another option would be to probabilistically probe |
6975 | 1759 |
// the putative _owner->TypeTag value. |
1760 |
// |
|
1761 |
// Checking _thread_state isn't perfect. Even if the thread is |
|
1762 |
// in_java it might be blocked on a page-fault or have been preempted |
|
51376
181e6a03249b
8164683: Solaris: JVM abuses thread preemption control
coleenp
parents:
51258
diff
changeset
|
1763 |
// and sitting on a ready/dispatch queue. |
6975 | 1764 |
// |
1765 |
// The return value from NotRunnable() is *advisory* -- the |
|
1766 |
// result is based on sampling and is not necessarily coherent. |
|
1767 |
// The caller must tolerate false-negative and false-positive errors. |
|
1768 |
// Spinning, in general, is probabilistic anyway. |
|
1769 |
||
1770 |
||
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1771 |
int ObjectMonitor::NotRunnable(Thread * Self, Thread * ox) { |
27165
785a8d56024c
8049737: Contended Locking reorder and cache line bucket
dcubed
parents:
26684
diff
changeset
|
1772 |
// Check ox->TypeTag == 2BAD. |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1773 |
if (ox == NULL) return 0; |
6975 | 1774 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1775 |
// Avoid transitive spinning ... |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1776 |
// Say T1 spins or blocks trying to acquire L. T1._Stalled is set to L. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1777 |
// Immediately after T1 acquires L it's possible that T2, also |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1778 |
// spinning on L, will see L.Owner=T1 and T1._Stalled=L. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1779 |
// This occurs transiently after T1 acquired L but before |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1780 |
// T1 managed to clear T1.Stalled. T2 does not need to abort |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1781 |
// its spin in this circumstance. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1782 |
intptr_t BlockedOn = SafeFetchN((intptr_t *) &ox->_Stalled, intptr_t(1)); |
6975 | 1783 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1784 |
if (BlockedOn == 1) return 1; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1785 |
if (BlockedOn != 0) { |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1786 |
return BlockedOn != intptr_t(this) && _owner == ox; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1787 |
} |
6975 | 1788 |
|
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1789 |
assert(sizeof(((JavaThread *)ox)->_thread_state == sizeof(int)), "invariant"); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1790 |
int jst = SafeFetch32((int *) &((JavaThread *) ox)->_thread_state, -1);; |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1791 |
// consider also: jst != _thread_in_Java -- but that's overspecific. |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1792 |
return jst == _thread_blocked || jst == _thread_in_native; |
6975 | 1793 |
} |
1794 |
||
1795 |
||
1796 |
// ----------------------------------------------------------------------------- |
|
1797 |
// WaitSet management ... |
|
1798 |
||
1799 |
ObjectWaiter::ObjectWaiter(Thread* thread) { |
|
1800 |
_next = NULL; |
|
1801 |
_prev = NULL; |
|
1802 |
_notified = 0; |
|
48185
d5610f86423f
8179083: Uninitialized notifier in Java Monitor Wait tracing event
egahlin
parents:
48157
diff
changeset
|
1803 |
_notifier_tid = 0; |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1804 |
TState = TS_RUN; |
6975 | 1805 |
_thread = thread; |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1806 |
_event = thread->_ParkEvent; |
6975 | 1807 |
_active = false; |
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1808 |
assert(_event != NULL, "invariant"); |
6975 | 1809 |
} |
1810 |
||
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
1811 |
void ObjectWaiter::wait_reenter_begin(ObjectMonitor * const mon) { |
6975 | 1812 |
JavaThread *jt = (JavaThread *)this->_thread; |
1813 |
_active = JavaThreadBlockedOnMonitorEnterState::wait_reenter_begin(jt, mon); |
|
1814 |
} |
|
1815 |
||
25472
381638db28e6
8047104: cleanup misc issues prior to Contended Locking reorder and cache
dcubed
parents:
25468
diff
changeset
|
1816 |
void ObjectWaiter::wait_reenter_end(ObjectMonitor * const mon) { |
6975 | 1817 |
JavaThread *jt = (JavaThread *)this->_thread; |
1818 |
JavaThreadBlockedOnMonitorEnterState::wait_reenter_end(jt, _active); |
|
1819 |
} |
|
1820 |
||
1821 |
inline void ObjectMonitor::AddWaiter(ObjectWaiter* node) { |
|
31782
b23b74f8ae8d
8130448: thread dump improvements, comment additions, new diagnostics inspired by 8077392
dcubed
parents:
27165
diff
changeset
|
1822 |
assert(node != NULL, "should not add NULL node"); |
6975 | 1823 |
assert(node->_prev == NULL, "node already in list"); |
1824 |
assert(node->_next == NULL, "node already in list"); |
|
1825 |
// put node at end of queue (circular doubly linked list) |
|
1826 |
if (_WaitSet == NULL) { |
|
1827 |
_WaitSet = node; |
|
1828 |
node->_prev = node; |
|
1829 |
node->_next = node; |
|
1830 |
} else { |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1831 |
ObjectWaiter* head = _WaitSet; |
6975 | 1832 |
ObjectWaiter* tail = head->_prev; |
1833 |
assert(tail->_next == head, "invariant check"); |
|
1834 |
tail->_next = node; |
|
1835 |
head->_prev = node; |
|
1836 |
node->_next = head; |
|
1837 |
node->_prev = tail; |
|
1838 |
} |
|
1839 |
} |
|
1840 |
||
1841 |
inline ObjectWaiter* ObjectMonitor::DequeueWaiter() { |
|
1842 |
// dequeue the very first waiter |
|
1843 |
ObjectWaiter* waiter = _WaitSet; |
|
1844 |
if (waiter) { |
|
1845 |
DequeueSpecificWaiter(waiter); |
|
1846 |
} |
|
1847 |
return waiter; |
|
1848 |
} |
|
1849 |
||
1850 |
inline void ObjectMonitor::DequeueSpecificWaiter(ObjectWaiter* node) { |
|
1851 |
assert(node != NULL, "should not dequeue NULL node"); |
|
1852 |
assert(node->_prev != NULL, "node already removed from list"); |
|
1853 |
assert(node->_next != NULL, "node already removed from list"); |
|
1854 |
// when the waiter has woken up because of interrupt, |
|
1855 |
// timeout or other spurious wake-up, dequeue the |
|
1856 |
// waiter from waiting list |
|
1857 |
ObjectWaiter* next = node->_next; |
|
1858 |
if (next == node) { |
|
1859 |
assert(node->_prev == node, "invariant check"); |
|
1860 |
_WaitSet = NULL; |
|
1861 |
} else { |
|
1862 |
ObjectWaiter* prev = node->_prev; |
|
1863 |
assert(prev->_next == node, "invariant check"); |
|
1864 |
assert(next->_prev == node, "invariant check"); |
|
1865 |
next->_prev = prev; |
|
1866 |
prev->_next = next; |
|
1867 |
if (_WaitSet == node) { |
|
1868 |
_WaitSet = next; |
|
1869 |
} |
|
1870 |
} |
|
1871 |
node->_next = NULL; |
|
1872 |
node->_prev = NULL; |
|
1873 |
} |
|
1874 |
||
1875 |
// ----------------------------------------------------------------------------- |
|
1876 |
// PerfData support |
|
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1877 |
PerfCounter * ObjectMonitor::_sync_ContendedLockAttempts = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1878 |
PerfCounter * ObjectMonitor::_sync_FutileWakeups = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1879 |
PerfCounter * ObjectMonitor::_sync_Parks = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1880 |
PerfCounter * ObjectMonitor::_sync_Notifications = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1881 |
PerfCounter * ObjectMonitor::_sync_Inflations = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1882 |
PerfCounter * ObjectMonitor::_sync_Deflations = NULL; |
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1883 |
PerfLongVariable * ObjectMonitor::_sync_MonExtant = NULL; |
6975 | 1884 |
|
1885 |
// One-shot global initialization for the sync subsystem. |
|
1886 |
// We could also defer initialization and initialize on-demand |
|
1887 |
// the first time we call inflate(). Initialization would |
|
1888 |
// be protected - like so many things - by the MonitorCache_lock. |
|
1889 |
||
25064
244218e6ec0a
8046758: cleanup non-indent white space issues prior to Contended Locking cleanup bucket
dcubed
parents:
24832
diff
changeset
|
1890 |
void ObjectMonitor::Initialize() { |
51960 | 1891 |
assert(!InitDone, "invariant"); |
1892 |
||
1893 |
if (!os::is_MP()) { |
|
1894 |
Knob_SpinLimit = 0; |
|
1895 |
Knob_PreSpin = 0; |
|
1896 |
Knob_FixedSpin = -1; |
|
1897 |
} |
|
1898 |
||
6975 | 1899 |
if (UsePerfData) { |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1900 |
EXCEPTION_MARK; |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1901 |
#define NEWPERFCOUNTER(n) \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1902 |
{ \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1903 |
n = PerfDataManager::create_counter(SUN_RT, #n, PerfData::U_Events, \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1904 |
CHECK); \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1905 |
} |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1906 |
#define NEWPERFVARIABLE(n) \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1907 |
{ \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1908 |
n = PerfDataManager::create_variable(SUN_RT, #n, PerfData::U_Events, \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1909 |
CHECK); \ |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1910 |
} |
26683
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1911 |
NEWPERFCOUNTER(_sync_Inflations); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1912 |
NEWPERFCOUNTER(_sync_Deflations); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1913 |
NEWPERFCOUNTER(_sync_ContendedLockAttempts); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1914 |
NEWPERFCOUNTER(_sync_FutileWakeups); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1915 |
NEWPERFCOUNTER(_sync_Parks); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1916 |
NEWPERFCOUNTER(_sync_Notifications); |
a02753d5a0b2
8057107: cleanup indent white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
25633
diff
changeset
|
1917 |
NEWPERFVARIABLE(_sync_MonExtant); |
26684
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1918 |
#undef NEWPERFCOUNTER |
d1221849ea3d
8057109: manual cleanup of white space issues prior to Contended Locking reorder and cache line bucket
dcubed
parents:
26683
diff
changeset
|
1919 |
#undef NEWPERFVARIABLE |
6975 | 1920 |
} |
51960 | 1921 |
|
1922 |
DEBUG_ONLY(InitDone = true;) |
|
6975 | 1923 |
} |