--- a/src/hotspot/share/runtime/synchronizer.cpp Wed Aug 28 07:41:57 2019 -0700
+++ b/src/hotspot/share/runtime/synchronizer.cpp Wed Aug 28 10:56:50 2019 -0400
@@ -117,18 +117,18 @@
static volatile intptr_t gInflationLocks[NINFLATIONLOCKS];
// global list of blocks of monitors
-PaddedEnd<ObjectMonitor> * volatile ObjectSynchronizer::gBlockList = NULL;
-// global monitor free list
-ObjectMonitor * volatile ObjectSynchronizer::gFreeList = NULL;
-// global monitor in-use list, for moribund threads,
-// monitors they inflated need to be scanned for deflation
-ObjectMonitor * volatile ObjectSynchronizer::gOmInUseList = NULL;
-// count of entries in gOmInUseList
-int ObjectSynchronizer::gOmInUseCount = 0;
+PaddedObjectMonitor* volatile ObjectSynchronizer::g_block_list = NULL;
+// Global ObjectMonitor free list. Newly allocated and deflated
+// ObjectMonitors are prepended here.
+ObjectMonitor* volatile ObjectSynchronizer::g_free_list = NULL;
+// Global ObjectMonitor in-use list. When a JavaThread is exiting,
+// ObjectMonitors on its per-thread in-use list are prepended here.
+ObjectMonitor* volatile ObjectSynchronizer::g_om_in_use_list = NULL;
+int ObjectSynchronizer::g_om_in_use_count = 0; // # on g_om_in_use_list
-static volatile intptr_t gListLock = 0; // protects global monitor lists
-static volatile int gMonitorFreeCount = 0; // # on gFreeList
-static volatile int gMonitorPopulation = 0; // # Extant -- in circulation
+static volatile intptr_t gListLock = 0; // protects global monitor lists
+static volatile int g_om_free_count = 0; // # on g_free_list
+static volatile int g_om_population = 0; // # Extant -- in circulation
#define CHAINMARKER (cast_to_oop<intptr_t>(-1))
@@ -155,7 +155,7 @@
// the monitorexit operation. In that case the JIT could fuse the operations
// into a single notifyAndExit() runtime primitive.
-bool ObjectSynchronizer::quick_notify(oopDesc * obj, Thread * self, bool all) {
+bool ObjectSynchronizer::quick_notify(oopDesc* obj, Thread* self, bool all) {
assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
assert(self->is_Java_thread(), "invariant");
assert(((JavaThread *) self)->thread_state() == _thread_in_Java, "invariant");
@@ -170,7 +170,7 @@
}
if (mark.has_monitor()) {
- ObjectMonitor * const mon = mark.monitor();
+ ObjectMonitor* const mon = mark.monitor();
assert(oopDesc::equals((oop) mon->object(), obj), "invariant");
if (mon->owner() != self) return false; // slow-path for IMS exception
@@ -183,12 +183,12 @@
} else {
DTRACE_MONITOR_PROBE(notify, mon, obj, self);
}
- int tally = 0;
+ int free_count = 0;
do {
mon->INotify(self);
- ++tally;
+ ++free_count;
} while (mon->first_waiter() != NULL && all);
- OM_PERFDATA_OP(Notifications, inc(tally));
+ OM_PERFDATA_OP(Notifications, inc(free_count));
}
return true;
}
@@ -204,26 +204,26 @@
// Note that we can't safely call AsyncPrintJavaStack() from within
// quick_enter() as our thread state remains _in_Java.
-bool ObjectSynchronizer::quick_enter(oop obj, Thread * Self,
+bool ObjectSynchronizer::quick_enter(oop obj, Thread* self,
BasicLock * lock) {
assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
- assert(Self->is_Java_thread(), "invariant");
- assert(((JavaThread *) Self)->thread_state() == _thread_in_Java, "invariant");
+ assert(self->is_Java_thread(), "invariant");
+ assert(((JavaThread *) self)->thread_state() == _thread_in_Java, "invariant");
NoSafepointVerifier nsv;
if (obj == NULL) return false; // Need to throw NPE
const markWord mark = obj->mark();
if (mark.has_monitor()) {
- ObjectMonitor * const m = mark.monitor();
+ ObjectMonitor* const m = mark.monitor();
assert(oopDesc::equals((oop) m->object(), obj), "invariant");
- Thread * const owner = (Thread *) m->_owner;
+ Thread* const owner = (Thread *) m->_owner;
// Lock contention and Transactional Lock Elision (TLE) diagnostics
// and observability
// Case: light contention possibly amenable to TLE
// Case: TLE inimical operations such as nested/recursive synchronization
- if (owner == Self) {
+ if (owner == self) {
m->_recursions++;
return true;
}
@@ -240,7 +240,7 @@
// and last are the inflated Java Monitor (ObjectMonitor) checks.
lock->set_displaced_header(markWord::unused_mark());
- if (owner == NULL && Atomic::replace_if_null(Self, &(m->_owner))) {
+ if (owner == NULL && Atomic::replace_if_null(self, &(m->_owner))) {
assert(m->_recursions == 0, "invariant");
return true;
}
@@ -325,7 +325,7 @@
// Monitor owner's stack and update the BasicLocks because a
// Java Monitor can be asynchronously inflated by a thread that
// does not own the Java Monitor.
- ObjectMonitor * m = mark.monitor();
+ ObjectMonitor* m = mark.monitor();
assert(((oop)(m->object()))->mark() == mark, "invariant");
assert(m->is_entered(THREAD), "invariant");
}
@@ -416,8 +416,8 @@
// -----------------------------------------------------------------------------
// Internal VM locks on java objects
// standard constructor, allows locking failures
-ObjectLocker::ObjectLocker(Handle obj, Thread* thread, bool doLock) {
- _dolock = doLock;
+ObjectLocker::ObjectLocker(Handle obj, Thread* thread, bool do_lock) {
+ _dolock = do_lock;
_thread = thread;
_thread->check_for_valid_safepoint_state(false);
_obj = obj;
@@ -457,7 +457,7 @@
return dtrace_waited_probe(monitor, obj, THREAD);
}
-void ObjectSynchronizer::waitUninterruptibly(Handle obj, jlong millis, TRAPS) {
+void ObjectSynchronizer::wait_uninterruptibly(Handle obj, jlong millis, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke(obj, THREAD);
assert(!obj->mark().has_bias_pattern(), "biases should be revoked by now");
@@ -520,11 +520,11 @@
char _pad_prefix[DEFAULT_CACHE_LINE_SIZE];
// These are highly shared mostly-read variables.
// To avoid false-sharing they need to be the sole occupants of a cache line.
- volatile int stwRandom;
- volatile int stwCycle;
+ volatile int stw_random;
+ volatile int stw_cycle;
DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int) * 2);
// Hot RW variable -- Sequester to avoid false-sharing
- volatile int hcSequence;
+ volatile int hc_sequence;
DEFINE_PAD_MINUS_SIZE(2, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));
};
@@ -532,7 +532,7 @@
static int MonitorScavengeThreshold = 1000000;
static volatile int ForceMonitorScavenge = 0; // Scavenge required and pending
-static markWord ReadStableMark(oop obj) {
+static markWord read_stable_mark(oop obj) {
markWord mark = obj->mark();
if (!mark.is_being_inflated()) {
return mark; // normal fast-path return
@@ -546,7 +546,7 @@
}
// The object is being inflated by some other thread.
- // The caller of ReadStableMark() must wait for inflation to complete.
+ // The caller of read_stable_mark() must wait for inflation to complete.
// Avoid live-lock
// TODO: consider calling SafepointSynchronize::do_call_back() while
// spinning to see if there's a safepoint pending. If so, immediately
@@ -582,7 +582,7 @@
Thread::muxAcquire(gInflationLocks + ix, "gInflationLock");
while (obj->mark() == markWord::INFLATING()) {
// Beware: NakedYield() is advisory and has almost no effect on some platforms
- // so we periodically call Self->_ParkEvent->park(1).
+ // so we periodically call self->_ParkEvent->park(1).
// We use a mixed spin/yield/block mechanism.
if ((YieldThenBlock++) >= 16) {
Thread::current()->_ParkEvent->park(1);
@@ -601,21 +601,21 @@
// hashCode() generation :
//
// Possibilities:
-// * MD5Digest of {obj,stwRandom}
-// * CRC32 of {obj,stwRandom} or any linear-feedback shift register function.
+// * MD5Digest of {obj,stw_random}
+// * CRC32 of {obj,stw_random} or any linear-feedback shift register function.
// * A DES- or AES-style SBox[] mechanism
// * One of the Phi-based schemes, such as:
// 2654435761 = 2^32 * Phi (golden ratio)
-// HashCodeValue = ((uintptr_t(obj) >> 3) * 2654435761) ^ GVars.stwRandom ;
+// HashCodeValue = ((uintptr_t(obj) >> 3) * 2654435761) ^ GVars.stw_random ;
// * A variation of Marsaglia's shift-xor RNG scheme.
-// * (obj ^ stwRandom) is appealing, but can result
+// * (obj ^ stw_random) is appealing, but can result
// in undesirable regularity in the hashCode values of adjacent objects
// (objects allocated back-to-back, in particular). This could potentially
// result in hashtable collisions and reduced hashtable efficiency.
// There are simple ways to "diffuse" the middle address bits over the
// generated hashCode values:
-static inline intptr_t get_next_hash(Thread * Self, oop obj) {
+static inline intptr_t get_next_hash(Thread* self, oop obj) {
intptr_t value = 0;
if (hashCode == 0) {
// This form uses global Park-Miller RNG.
@@ -626,26 +626,26 @@
// This variation has the property of being stable (idempotent)
// between STW operations. This can be useful in some of the 1-0
// synchronization schemes.
- intptr_t addrBits = cast_from_oop<intptr_t>(obj) >> 3;
- value = addrBits ^ (addrBits >> 5) ^ GVars.stwRandom;
+ intptr_t addr_bits = cast_from_oop<intptr_t>(obj) >> 3;
+ value = addr_bits ^ (addr_bits >> 5) ^ GVars.stw_random;
} else if (hashCode == 2) {
value = 1; // for sensitivity testing
} else if (hashCode == 3) {
- value = ++GVars.hcSequence;
+ value = ++GVars.hc_sequence;
} else if (hashCode == 4) {
value = cast_from_oop<intptr_t>(obj);
} else {
// Marsaglia's xor-shift scheme with thread-specific state
// This is probably the best overall implementation -- we'll
// likely make this the default in future releases.
- unsigned t = Self->_hashStateX;
+ unsigned t = self->_hashStateX;
t ^= (t << 11);
- Self->_hashStateX = Self->_hashStateY;
- Self->_hashStateY = Self->_hashStateZ;
- Self->_hashStateZ = Self->_hashStateW;
- unsigned v = Self->_hashStateW;
+ self->_hashStateX = self->_hashStateY;
+ self->_hashStateY = self->_hashStateZ;
+ self->_hashStateZ = self->_hashStateW;
+ unsigned v = self->_hashStateW;
v = (v ^ (v >> 19)) ^ (t ^ (t >> 8));
- Self->_hashStateW = v;
+ self->_hashStateW = v;
value = v;
}
@@ -655,7 +655,7 @@
return value;
}
-intptr_t ObjectSynchronizer::FastHashCode(Thread * Self, oop obj) {
+intptr_t ObjectSynchronizer::FastHashCode(Thread* self, oop obj) {
if (UseBiasedLocking) {
// NOTE: many places throughout the JVM do not expect a safepoint
// to be taken here, in particular most operations on perm gen
@@ -666,7 +666,7 @@
// thread-local storage.
if (obj->mark().has_bias_pattern()) {
// Handle for oop obj in case of STW safepoint
- Handle hobj(Self, obj);
+ Handle hobj(self, obj);
// Relaxing assertion for bug 6320749.
assert(Universe::verify_in_progress() ||
!SafepointSynchronize::is_at_safepoint(),
@@ -682,14 +682,14 @@
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
!SafepointSynchronize::is_at_safepoint(), "invariant");
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
- Self->is_Java_thread() , "invariant");
+ self->is_Java_thread() , "invariant");
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
- ((JavaThread *)Self)->thread_state() != _thread_blocked, "invariant");
+ ((JavaThread *)self)->thread_state() != _thread_blocked, "invariant");
ObjectMonitor* monitor = NULL;
markWord temp, test;
intptr_t hash;
- markWord mark = ReadStableMark(obj);
+ markWord mark = read_stable_mark(obj);
// object should remain ineligible for biased locking
assert(!mark.has_bias_pattern(), "invariant");
@@ -699,7 +699,7 @@
if (hash != 0) { // if it has hash, just return it
return hash;
}
- hash = get_next_hash(Self, obj); // allocate a new hash code
+ hash = get_next_hash(self, obj); // allocate a new hash code
temp = mark.copy_set_hash(hash); // merge the hash code into header
// use (machine word version) atomic operation to install the hash
test = obj->cas_set_mark(temp, mark);
@@ -718,7 +718,7 @@
return hash;
}
// Skip to the following code to reduce code size
- } else if (Self->is_lock_owned((address)mark.locker())) {
+ } else if (self->is_lock_owned((address)mark.locker())) {
temp = mark.displaced_mark_helper(); // this is a lightweight monitor owned
assert(temp.is_neutral(), "invariant: header=" INTPTR_FORMAT, temp.value());
hash = temp.hash(); // by current thread, check if the displaced
@@ -736,21 +736,22 @@
}
// Inflate the monitor to set hash code
- monitor = inflate(Self, obj, inflate_cause_hash_code);
+ monitor = inflate(self, obj, inflate_cause_hash_code);
// Load displaced header and check it has hash code
mark = monitor->header();
assert(mark.is_neutral(), "invariant: header=" INTPTR_FORMAT, mark.value());
hash = mark.hash();
if (hash == 0) {
- hash = get_next_hash(Self, obj);
+ hash = get_next_hash(self, obj);
temp = mark.copy_set_hash(hash); // merge hash code into header
assert(temp.is_neutral(), "invariant: header=" INTPTR_FORMAT, temp.value());
uintptr_t v = Atomic::cmpxchg(temp.value(), (volatile uintptr_t*)monitor->header_addr(), mark.value());
test = markWord(v);
if (test != mark) {
- // The only update to the ObjectMonitor's header/dmw field
- // is to merge in the hash code. If someone adds a new usage
- // of the header/dmw field, please update this code.
+ // The only non-deflation update to the ObjectMonitor's
+ // header/dmw field is to merge in the hash code. If someone
+ // adds a new usage of the header/dmw field, please update
+ // this code.
hash = test.hash();
assert(test.is_neutral(), "invariant: header=" INTPTR_FORMAT, test.value());
assert(hash != 0, "Trivial unexpected object/monitor header usage.");
@@ -777,7 +778,7 @@
assert(thread == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
- markWord mark = ReadStableMark(obj);
+ markWord mark = read_stable_mark(obj);
// Uncontended case, header points to stack
if (mark.has_locker()) {
@@ -816,7 +817,7 @@
assert(self == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
- markWord mark = ReadStableMark(obj);
+ markWord mark = read_stable_mark(obj);
// CASE: stack-locked. Mark points to a BasicLock on the owner's stack.
if (mark.has_locker()) {
@@ -828,7 +829,7 @@
// The Object:ObjectMonitor relationship is stable as long as we're
// not at a safepoint.
if (mark.has_monitor()) {
- void * owner = mark.monitor()->_owner;
+ void* owner = mark.monitor()->_owner;
if (owner == NULL) return owner_none;
return (owner == self ||
self->is_lock_owned((address)owner)) ? owner_self : owner_other;
@@ -853,7 +854,7 @@
oop obj = h_obj();
address owner = NULL;
- markWord mark = ReadStableMark(obj);
+ markWord mark = read_stable_mark(obj);
// Uncontended case, header points to stack
if (mark.has_locker()) {
@@ -883,34 +884,27 @@
// Visitors ...
void ObjectSynchronizer::monitors_iterate(MonitorClosure* closure) {
- PaddedEnd<ObjectMonitor> * block = OrderAccess::load_acquire(&gBlockList);
+ PaddedObjectMonitor* block = OrderAccess::load_acquire(&g_block_list);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
for (int i = _BLOCKSIZE - 1; i > 0; i--) {
ObjectMonitor* mid = (ObjectMonitor *)(block + i);
oop object = (oop)mid->object();
if (object != NULL) {
+ // Only process with closure if the object is set.
closure->do_monitor(mid);
}
}
- block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
+ block = (PaddedObjectMonitor*)block->_next_om;
}
}
-// Get the next block in the block list.
-static inline PaddedEnd<ObjectMonitor>* next(PaddedEnd<ObjectMonitor>* block) {
- assert(block->object() == CHAINMARKER, "must be a block header");
- block = (PaddedEnd<ObjectMonitor>*) block->FreeNext;
- assert(block == NULL || block->object() == CHAINMARKER, "must be a block header");
- return block;
-}
-
static bool monitors_used_above_threshold() {
- if (gMonitorPopulation == 0) {
+ if (g_om_population == 0) {
return false;
}
- int monitors_used = gMonitorPopulation - gMonitorFreeCount;
- int monitor_usage = (monitors_used * 100LL) / gMonitorPopulation;
+ int monitors_used = g_om_population - g_om_free_count;
+ int monitor_usage = (monitors_used * 100LL) / g_om_population;
return monitor_usage > MonitorUsedDeflationThreshold;
}
@@ -929,18 +923,18 @@
void ObjectSynchronizer::global_used_oops_do(OopClosure* f) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
- list_oops_do(gOmInUseList, f);
+ list_oops_do(g_om_in_use_list, f);
}
void ObjectSynchronizer::thread_local_used_oops_do(Thread* thread, OopClosure* f) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
- list_oops_do(thread->omInUseList, f);
+ list_oops_do(thread->om_in_use_list, f);
}
void ObjectSynchronizer::list_oops_do(ObjectMonitor* list, OopClosure* f) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
ObjectMonitor* mid;
- for (mid = list; mid != NULL; mid = mid->FreeNext) {
+ for (mid = list; mid != NULL; mid = mid->_next_om) {
if (mid->object() != NULL) {
f->do_oop((oop*)mid->object_addr());
}
@@ -951,10 +945,10 @@
// -----------------------------------------------------------------------------
// ObjectMonitor Lifecycle
// -----------------------
-// Inflation unlinks monitors from the global gFreeList and
+// Inflation unlinks monitors from the global g_free_list and
// associates them with objects. Deflation -- which occurs at
// STW-time -- disassociates idle monitors from objects. Such
-// scavenged monitors are returned to the gFreeList.
+// scavenged monitors are returned to the g_free_list.
//
// The global list is protected by gListLock. All the critical sections
// are short and operate in constant-time.
@@ -963,13 +957,15 @@
//
// Lifecycle:
// -- unassigned and on the global free list
-// -- unassigned and on a thread's private omFreeList
+// -- unassigned and on a thread's private om_free_list
// -- assigned to an object. The object is inflated and the mark refers
// to the objectmonitor.
// Constraining monitor pool growth via MonitorBound ...
//
+// If MonitorBound is not set (<= 0), MonitorBound checks are disabled.
+//
// The monitor pool is grow-only. We scavenge at STW safepoint-time, but the
// the rate of scavenging is driven primarily by GC. As such, we can find
// an inordinate number of monitors in circulation.
@@ -983,8 +979,14 @@
// See also: GuaranteedSafepointInterval
//
// The current implementation uses asynchronous VM operations.
+//
+// If MonitorBound is set, the boundry applies to
+// (g_om_population - g_om_free_count)
+// i.e., if there are not enough ObjectMonitors on the global free list,
+// then a safepoint deflation is induced. Picking a good MonitorBound value
+// is non-trivial.
-static void InduceScavenge(Thread * Self, const char * Whence) {
+static void InduceScavenge(Thread* self, const char * Whence) {
// Induce STW safepoint to trim monitors
// Ultimately, this results in a call to deflate_idle_monitors() in the near future.
// More precisely, trigger an asynchronous STW safepoint as the number
@@ -1000,86 +1002,86 @@
}
}
-ObjectMonitor* ObjectSynchronizer::omAlloc(Thread * Self) {
+ObjectMonitor* ObjectSynchronizer::om_alloc(Thread* self) {
// A large MAXPRIVATE value reduces both list lock contention
// and list coherency traffic, but also tends to increase the
- // number of objectMonitors in circulation as well as the STW
+ // number of ObjectMonitors in circulation as well as the STW
// scavenge costs. As usual, we lean toward time in space-time
// tradeoffs.
const int MAXPRIVATE = 1024;
stringStream ss;
for (;;) {
- ObjectMonitor * m;
+ ObjectMonitor* m;
- // 1: try to allocate from the thread's local omFreeList.
+ // 1: try to allocate from the thread's local om_free_list.
// Threads will attempt to allocate first from their local list, then
// from the global list, and only after those attempts fail will the thread
// attempt to instantiate new monitors. Thread-local free lists take
// heat off the gListLock and improve allocation latency, as well as reducing
// coherency traffic on the shared global list.
- m = Self->omFreeList;
+ m = self->om_free_list;
if (m != NULL) {
- Self->omFreeList = m->FreeNext;
- Self->omFreeCount--;
+ self->om_free_list = m->_next_om;
+ self->om_free_count--;
guarantee(m->object() == NULL, "invariant");
- m->FreeNext = Self->omInUseList;
- Self->omInUseList = m;
- Self->omInUseCount++;
+ m->_next_om = self->om_in_use_list;
+ self->om_in_use_list = m;
+ self->om_in_use_count++;
return m;
}
- // 2: try to allocate from the global gFreeList
+ // 2: try to allocate from the global g_free_list
// CONSIDER: use muxTry() instead of muxAcquire().
// If the muxTry() fails then drop immediately into case 3.
// If we're using thread-local free lists then try
// to reprovision the caller's free list.
- if (gFreeList != NULL) {
- // Reprovision the thread's omFreeList.
+ if (g_free_list != NULL) {
+ // Reprovision the thread's om_free_list.
// Use bulk transfers to reduce the allocation rate and heat
// on various locks.
- Thread::muxAcquire(&gListLock, "omAlloc(1)");
- for (int i = Self->omFreeProvision; --i >= 0 && gFreeList != NULL;) {
- gMonitorFreeCount--;
- ObjectMonitor * take = gFreeList;
- gFreeList = take->FreeNext;
+ Thread::muxAcquire(&gListLock, "om_alloc(1)");
+ for (int i = self->om_free_provision; --i >= 0 && g_free_list != NULL;) {
+ g_om_free_count--;
+ ObjectMonitor* take = g_free_list;
+ g_free_list = take->_next_om;
guarantee(take->object() == NULL, "invariant");
take->Recycle();
- omRelease(Self, take, false);
+ om_release(self, take, false);
}
Thread::muxRelease(&gListLock);
- Self->omFreeProvision += 1 + (Self->omFreeProvision/2);
- if (Self->omFreeProvision > MAXPRIVATE) Self->omFreeProvision = MAXPRIVATE;
+ self->om_free_provision += 1 + (self->om_free_provision/2);
+ if (self->om_free_provision > MAXPRIVATE) self->om_free_provision = MAXPRIVATE;
const int mx = MonitorBound;
- if (mx > 0 && (gMonitorPopulation-gMonitorFreeCount) > mx) {
- // We can't safely induce a STW safepoint from omAlloc() as our thread
+ if (mx > 0 && (g_om_population-g_om_free_count) > mx) {
+ // Not enough ObjectMonitors on the global free list.
+ // We can't safely induce a STW safepoint from om_alloc() as our thread
// state may not be appropriate for such activities and callers may hold
// naked oops, so instead we defer the action.
- InduceScavenge(Self, "omAlloc");
+ InduceScavenge(self, "om_alloc");
}
continue;
}
// 3: allocate a block of new ObjectMonitors
// Both the local and global free lists are empty -- resort to malloc().
- // In the current implementation objectMonitors are TSM - immortal.
+ // In the current implementation ObjectMonitors are TSM - immortal.
// Ideally, we'd write "new ObjectMonitor[_BLOCKSIZE], but we want
// each ObjectMonitor to start at the beginning of a cache line,
// so we use align_up().
// A better solution would be to use C++ placement-new.
// BEWARE: As it stands currently, we don't run the ctors!
assert(_BLOCKSIZE > 1, "invariant");
- size_t neededsize = sizeof(PaddedEnd<ObjectMonitor>) * _BLOCKSIZE;
- PaddedEnd<ObjectMonitor> * temp;
+ size_t neededsize = sizeof(PaddedObjectMonitor) * _BLOCKSIZE;
+ PaddedObjectMonitor* temp;
size_t aligned_size = neededsize + (DEFAULT_CACHE_LINE_SIZE - 1);
- void* real_malloc_addr = (void *)NEW_C_HEAP_ARRAY(char, aligned_size,
- mtInternal);
- temp = (PaddedEnd<ObjectMonitor> *)
- align_up(real_malloc_addr, DEFAULT_CACHE_LINE_SIZE);
+ void* real_malloc_addr = (void*)NEW_C_HEAP_ARRAY(char, aligned_size,
+ mtInternal);
+ temp = (PaddedObjectMonitor*)align_up(real_malloc_addr, DEFAULT_CACHE_LINE_SIZE);
// NOTE: (almost) no way to recover if allocation failed.
// We might be able to induce a STW safepoint and scavenge enough
- // objectMonitors to permit progress.
+ // ObjectMonitors to permit progress.
if (temp == NULL) {
vm_exit_out_of_memory(neededsize, OOM_MALLOC_ERROR,
"Allocate ObjectMonitors");
@@ -1090,16 +1092,16 @@
// initialize the linked list, each monitor points to its next
// forming the single linked free list, the very first monitor
// will points to next block, which forms the block list.
- // The trick of using the 1st element in the block as gBlockList
+ // The trick of using the 1st element in the block as g_block_list
// linkage should be reconsidered. A better implementation would
// look like: class Block { Block * next; int N; ObjectMonitor Body [N] ; }
for (int i = 1; i < _BLOCKSIZE; i++) {
- temp[i].FreeNext = (ObjectMonitor *)&temp[i+1];
+ temp[i]._next_om = (ObjectMonitor *)&temp[i+1];
}
// terminate the last monitor as the end of list
- temp[_BLOCKSIZE - 1].FreeNext = NULL;
+ temp[_BLOCKSIZE - 1]._next_om = NULL;
// Element [0] is reserved for global list linkage
temp[0].set_object(CHAINMARKER);
@@ -1108,160 +1110,155 @@
// block in hand. This avoids some lock traffic and redundant
// list activity.
- // Acquire the gListLock to manipulate gBlockList and gFreeList.
+ // Acquire the gListLock to manipulate g_block_list and g_free_list.
// An Oyama-Taura-Yonezawa scheme might be more efficient.
- Thread::muxAcquire(&gListLock, "omAlloc(2)");
- gMonitorPopulation += _BLOCKSIZE-1;
- gMonitorFreeCount += _BLOCKSIZE-1;
+ Thread::muxAcquire(&gListLock, "om_alloc(2)");
+ g_om_population += _BLOCKSIZE-1;
+ g_om_free_count += _BLOCKSIZE-1;
- // Add the new block to the list of extant blocks (gBlockList).
- // The very first objectMonitor in a block is reserved and dedicated.
+ // Add the new block to the list of extant blocks (g_block_list).
+ // The very first ObjectMonitor in a block is reserved and dedicated.
// It serves as blocklist "next" linkage.
- temp[0].FreeNext = gBlockList;
- // There are lock-free uses of gBlockList so make sure that
- // the previous stores happen before we update gBlockList.
- OrderAccess::release_store(&gBlockList, temp);
+ temp[0]._next_om = g_block_list;
+ // There are lock-free uses of g_block_list so make sure that
+ // the previous stores happen before we update g_block_list.
+ OrderAccess::release_store(&g_block_list, temp);
- // Add the new string of objectMonitors to the global free list
- temp[_BLOCKSIZE - 1].FreeNext = gFreeList;
- gFreeList = temp + 1;
+ // Add the new string of ObjectMonitors to the global free list
+ temp[_BLOCKSIZE - 1]._next_om = g_free_list;
+ g_free_list = temp + 1;
Thread::muxRelease(&gListLock);
}
}
-// Place "m" on the caller's private per-thread omFreeList.
+// Place "m" on the caller's private per-thread om_free_list.
// In practice there's no need to clamp or limit the number of
-// monitors on a thread's omFreeList as the only time we'll call
-// omRelease is to return a monitor to the free list after a CAS
-// attempt failed. This doesn't allow unbounded #s of monitors to
+// monitors on a thread's om_free_list as the only non-allocation time
+// we'll call om_release() is to return a monitor to the free list after
+// a CAS attempt failed. This doesn't allow unbounded #s of monitors to
// accumulate on a thread's free list.
//
// Key constraint: all ObjectMonitors on a thread's free list and the global
// free list must have their object field set to null. This prevents the
-// scavenger -- deflate_monitor_list() -- from reclaiming them.
+// scavenger -- deflate_monitor_list() -- from reclaiming them while we
+// are trying to release them.
-void ObjectSynchronizer::omRelease(Thread * Self, ObjectMonitor * m,
- bool fromPerThreadAlloc) {
+void ObjectSynchronizer::om_release(Thread* self, ObjectMonitor* m,
+ bool from_per_thread_alloc) {
guarantee(m->header().value() == 0, "invariant");
guarantee(m->object() == NULL, "invariant");
stringStream ss;
guarantee((m->is_busy() | m->_recursions) == 0, "freeing in-use monitor: "
"%s, recursions=" INTPTR_FORMAT, m->is_busy_to_string(&ss),
m->_recursions);
- // Remove from omInUseList
- if (fromPerThreadAlloc) {
+ // _next_om is used for both per-thread in-use and free lists so
+ // we have to remove 'm' from the in-use list first (as needed).
+ if (from_per_thread_alloc) {
+ // Need to remove 'm' from om_in_use_list.
ObjectMonitor* cur_mid_in_use = NULL;
bool extracted = false;
- for (ObjectMonitor* mid = Self->omInUseList; mid != NULL; cur_mid_in_use = mid, mid = mid->FreeNext) {
+ for (ObjectMonitor* mid = self->om_in_use_list; mid != NULL; cur_mid_in_use = mid, mid = mid->_next_om) {
if (m == mid) {
// extract from per-thread in-use list
- if (mid == Self->omInUseList) {
- Self->omInUseList = mid->FreeNext;
+ if (mid == self->om_in_use_list) {
+ self->om_in_use_list = mid->_next_om;
} else if (cur_mid_in_use != NULL) {
- cur_mid_in_use->FreeNext = mid->FreeNext; // maintain the current thread in-use list
+ cur_mid_in_use->_next_om = mid->_next_om; // maintain the current thread in-use list
}
extracted = true;
- Self->omInUseCount--;
+ self->om_in_use_count--;
break;
}
}
assert(extracted, "Should have extracted from in-use list");
}
- // FreeNext is used for both omInUseList and omFreeList, so clear old before setting new
- m->FreeNext = Self->omFreeList;
- Self->omFreeList = m;
- Self->omFreeCount++;
+ m->_next_om = self->om_free_list;
+ self->om_free_list = m;
+ self->om_free_count++;
}
-// Return the monitors of a moribund thread's local free list to
-// the global free list. Typically a thread calls omFlush() when
-// it's dying. We could also consider having the VM thread steal
-// monitors from threads that have not run java code over a few
-// consecutive STW safepoints. Relatedly, we might decay
-// omFreeProvision at STW safepoints.
-//
-// Also return the monitors of a moribund thread's omInUseList to
-// a global gOmInUseList under the global list lock so these
-// will continue to be scanned.
+// Return ObjectMonitors on a moribund thread's free and in-use
+// lists to the appropriate global lists. The ObjectMonitors on the
+// per-thread in-use list may still be in use by other threads.
//
-// We currently call omFlush() from Threads::remove() _before the thread
-// has been excised from the thread list and is no longer a mutator.
-// This means that omFlush() cannot run concurrently with a safepoint and
-// interleave with the deflate_idle_monitors scavenge operator. In particular,
-// this ensures that the thread's monitors are scanned by a GC safepoint,
-// either via Thread::oops_do() (if safepoint happens before omFlush()) or via
-// ObjectSynchronizer::oops_do() (if it happens after omFlush() and the thread's
-// monitors have been transferred to the global in-use list).
+// We currently call om_flush() from Threads::remove() before the
+// thread has been excised from the thread list and is no longer a
+// mutator. This means that om_flush() cannot run concurrently with
+// a safepoint and interleave with deflate_idle_monitors(). In
+// particular, this ensures that the thread's in-use monitors are
+// scanned by a GC safepoint, either via Thread::oops_do() (before
+// om_flush() is called) or via ObjectSynchronizer::oops_do() (after
+// om_flush() is called).
-void ObjectSynchronizer::omFlush(Thread * Self) {
- ObjectMonitor * list = Self->omFreeList; // Null-terminated SLL
- ObjectMonitor * tail = NULL;
- int tally = 0;
- if (list != NULL) {
- ObjectMonitor * s;
- // The thread is going away. Set 'tail' to the last per-thread free
- // monitor which will be linked to gFreeList below under the gListLock.
+void ObjectSynchronizer::om_flush(Thread* self) {
+ ObjectMonitor* free_list = self->om_free_list;
+ ObjectMonitor* free_tail = NULL;
+ int free_count = 0;
+ if (free_list != NULL) {
+ ObjectMonitor* s;
+ // The thread is going away. Set 'free_tail' to the last per-thread free
+ // monitor which will be linked to g_free_list below under the gListLock.
stringStream ss;
- for (s = list; s != NULL; s = s->FreeNext) {
- tally++;
- tail = s;
+ for (s = free_list; s != NULL; s = s->_next_om) {
+ free_count++;
+ free_tail = s;
guarantee(s->object() == NULL, "invariant");
guarantee(!s->is_busy(), "must be !is_busy: %s", s->is_busy_to_string(&ss));
}
- guarantee(tail != NULL, "invariant");
- assert(Self->omFreeCount == tally, "free-count off");
- Self->omFreeList = NULL;
- Self->omFreeCount = 0;
+ guarantee(free_tail != NULL, "invariant");
+ assert(self->om_free_count == free_count, "free-count off");
+ self->om_free_list = NULL;
+ self->om_free_count = 0;
}
- ObjectMonitor * inUseList = Self->omInUseList;
- ObjectMonitor * inUseTail = NULL;
- int inUseTally = 0;
- if (inUseList != NULL) {
+ ObjectMonitor* in_use_list = self->om_in_use_list;
+ ObjectMonitor* in_use_tail = NULL;
+ int in_use_count = 0;
+ if (in_use_list != NULL) {
+ // The thread is going away, however the ObjectMonitors on the
+ // om_in_use_list may still be in-use by other threads. Link
+ // them to in_use_tail, which will be linked into the global
+ // in-use list g_om_in_use_list below, under the gListLock.
ObjectMonitor *cur_om;
- // The thread is going away, however the omInUseList inflated
- // monitors may still be in-use by other threads.
- // Link them to inUseTail, which will be linked into the global in-use list
- // gOmInUseList below, under the gListLock
- for (cur_om = inUseList; cur_om != NULL; cur_om = cur_om->FreeNext) {
- inUseTail = cur_om;
- inUseTally++;
+ for (cur_om = in_use_list; cur_om != NULL; cur_om = cur_om->_next_om) {
+ in_use_tail = cur_om;
+ in_use_count++;
}
- guarantee(inUseTail != NULL, "invariant");
- assert(Self->omInUseCount == inUseTally, "in-use count off");
- Self->omInUseList = NULL;
- Self->omInUseCount = 0;
+ guarantee(in_use_tail != NULL, "invariant");
+ assert(self->om_in_use_count == in_use_count, "in-use count off");
+ self->om_in_use_list = NULL;
+ self->om_in_use_count = 0;
}
- Thread::muxAcquire(&gListLock, "omFlush");
- if (tail != NULL) {
- tail->FreeNext = gFreeList;
- gFreeList = list;
- gMonitorFreeCount += tally;
+ Thread::muxAcquire(&gListLock, "om_flush");
+ if (free_tail != NULL) {
+ free_tail->_next_om = g_free_list;
+ g_free_list = free_list;
+ g_om_free_count += free_count;
}
- if (inUseTail != NULL) {
- inUseTail->FreeNext = gOmInUseList;
- gOmInUseList = inUseList;
- gOmInUseCount += inUseTally;
+ if (in_use_tail != NULL) {
+ in_use_tail->_next_om = g_om_in_use_list;
+ g_om_in_use_list = in_use_list;
+ g_om_in_use_count += in_use_count;
}
Thread::muxRelease(&gListLock);
LogStreamHandle(Debug, monitorinflation) lsh_debug;
LogStreamHandle(Info, monitorinflation) lsh_info;
- LogStream * ls = NULL;
+ LogStream* ls = NULL;
if (log_is_enabled(Debug, monitorinflation)) {
ls = &lsh_debug;
- } else if ((tally != 0 || inUseTally != 0) &&
+ } else if ((free_count != 0 || in_use_count != 0) &&
log_is_enabled(Info, monitorinflation)) {
ls = &lsh_info;
}
if (ls != NULL) {
- ls->print_cr("omFlush: jt=" INTPTR_FORMAT ", free_monitor_tally=%d"
- ", in_use_monitor_tally=%d" ", omFreeProvision=%d",
- p2i(Self), tally, inUseTally, Self->omFreeProvision);
+ ls->print_cr("om_flush: jt=" INTPTR_FORMAT ", free_count=%d"
+ ", in_use_count=%d" ", om_free_provision=%d",
+ p2i(self), free_count, in_use_count, self->om_free_provision);
}
}
@@ -1287,7 +1284,7 @@
inflate(Thread::current(), obj, inflate_cause_vm_internal);
}
-ObjectMonitor* ObjectSynchronizer::inflate(Thread * Self,
+ObjectMonitor* ObjectSynchronizer::inflate(Thread* self,
oop object,
const InflateCause cause) {
// Inflate mutates the heap ...
@@ -1310,7 +1307,7 @@
// CASE: inflated
if (mark.has_monitor()) {
- ObjectMonitor * inf = mark.monitor();
+ ObjectMonitor* inf = mark.monitor();
markWord dmw = inf->header();
assert(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
assert(oopDesc::equals((oop) inf->object(), object), "invariant");
@@ -1325,7 +1322,7 @@
// Currently, we spin/yield/park and poll the markword, waiting for inflation to finish.
// We could always eliminate polling by parking the thread on some auxiliary list.
if (mark == markWord::INFLATING()) {
- ReadStableMark(object);
+ read_stable_mark(object);
continue;
}
@@ -1344,14 +1341,14 @@
// critical INFLATING...ST interval. A thread can transfer
// multiple objectmonitors en-mass from the global free list to its local free list.
// This reduces coherency traffic and lock contention on the global free list.
- // Using such local free lists, it doesn't matter if the omAlloc() call appears
+ // Using such local free lists, it doesn't matter if the om_alloc() call appears
// before or after the CAS(INFLATING) operation.
- // See the comments in omAlloc().
+ // See the comments in om_alloc().
LogStreamHandle(Trace, monitorinflation) lsh;
if (mark.has_locker()) {
- ObjectMonitor * m = omAlloc(Self);
+ ObjectMonitor* m = om_alloc(self);
// Optimistically prepare the objectmonitor - anticipate successful CAS
// We do this before the CAS in order to minimize the length of time
// in which INFLATING appears in the mark.
@@ -1361,7 +1358,7 @@
markWord cmp = object->cas_set_mark(markWord::INFLATING(), mark);
if (cmp != mark) {
- omRelease(Self, m, true);
+ om_release(self, m, true);
continue; // Interference -- just retry
}
@@ -1374,17 +1371,17 @@
// mark-word from the stack-locked value directly to the new inflated state?
// Consider what happens when a thread unlocks a stack-locked object.
// It attempts to use CAS to swing the displaced header value from the
- // on-stack basiclock back into the object header. Recall also that the
+ // on-stack BasicLock back into the object header. Recall also that the
// header value (hash code, etc) can reside in (a) the object header, or
// (b) a displaced header associated with the stack-lock, or (c) a displaced
- // header in an objectMonitor. The inflate() routine must copy the header
- // value from the basiclock on the owner's stack to the objectMonitor, all
+ // header in an ObjectMonitor. The inflate() routine must copy the header
+ // value from the BasicLock on the owner's stack to the ObjectMonitor, all
// the while preserving the hashCode stability invariants. If the owner
// decides to release the lock while the value is 0, the unlock will fail
// and control will eventually pass from slow_exit() to inflate. The owner
// will then spin, waiting for the 0 value to disappear. Put another way,
// the 0 causes the owner to stall if the owner happens to try to
- // drop the lock (restoring the header from the basiclock to the object)
+ // drop the lock (restoring the header from the BasicLock to the object)
// while inflation is in-progress. This protocol avoids races that might
// would otherwise permit hashCode values to change or "flicker" for an object.
// Critically, while object->mark is 0 mark.displaced_mark_helper() is stable.
@@ -1404,7 +1401,7 @@
m->set_header(dmw);
// Optimization: if the mark.locker stack address is associated
- // with this thread we could simply set m->_owner = Self.
+ // with this thread we could simply set m->_owner = self.
// Note that a thread can inflate an object
// that it has stack-locked -- as might happen in wait() -- directly
// with CAS. That is, we can avoid the xchg-NULL .... ST idiom.
@@ -1421,7 +1418,7 @@
// to avoid false sharing on MP systems ...
OM_PERFDATA_OP(Inflations, inc());
if (log_is_enabled(Trace, monitorinflation)) {
- ResourceMark rm(Self);
+ ResourceMark rm(self);
lsh.print_cr("inflate(has_locker): object=" INTPTR_FORMAT ", mark="
INTPTR_FORMAT ", type='%s'", p2i(object),
object->mark().value(), object->klass()->external_name());
@@ -1435,16 +1432,16 @@
// CASE: neutral
// TODO-FIXME: for entry we currently inflate and then try to CAS _owner.
// If we know we're inflating for entry it's better to inflate by swinging a
- // pre-locked objectMonitor pointer into the object header. A successful
+ // pre-locked ObjectMonitor pointer into the object header. A successful
// CAS inflates the object *and* confers ownership to the inflating thread.
// In the current implementation we use a 2-step mechanism where we CAS()
- // to inflate and then CAS() again to try to swing _owner from NULL to Self.
+ // to inflate and then CAS() again to try to swing _owner from NULL to self.
// An inflateTry() method that we could call from enter() would be useful.
// Catch if the object's header is not neutral (not locked and
// not marked is what we care about here).
assert(mark.is_neutral(), "invariant: header=" INTPTR_FORMAT, mark.value());
- ObjectMonitor * m = omAlloc(Self);
+ ObjectMonitor* m = om_alloc(self);
// prepare m for installation - set monitor to initial state
m->Recycle();
m->set_header(mark);
@@ -1456,7 +1453,7 @@
m->set_header(markWord::zero());
m->set_object(NULL);
m->Recycle();
- omRelease(Self, m, true);
+ om_release(self, m, true);
m = NULL;
continue;
// interference - the markword changed - just retry.
@@ -1468,7 +1465,7 @@
// cache lines to avoid false sharing on MP systems ...
OM_PERFDATA_OP(Inflations, inc());
if (log_is_enabled(Trace, monitorinflation)) {
- ResourceMark rm(Self);
+ ResourceMark rm(self);
lsh.print_cr("inflate(neutral): object=" INTPTR_FORMAT ", mark="
INTPTR_FORMAT ", type='%s'", p2i(object),
object->mark().value(), object->klass()->external_name());
@@ -1485,7 +1482,7 @@
//
// deflate_thread_local_monitors() scans a single thread's in-use list, while
// deflate_idle_monitors() scans only a global list of in-use monitors which
-// is populated only as a thread dies (see omFlush()).
+// is populated only as a thread dies (see om_flush()).
//
// These operations are called at all safepoints, immediately after mutators
// are stopped, but before any objects have moved. Collectively they traverse
@@ -1505,8 +1502,8 @@
// Deflate a single monitor if not in-use
// Return true if deflated, false if in-use
bool ObjectSynchronizer::deflate_monitor(ObjectMonitor* mid, oop obj,
- ObjectMonitor** freeHeadp,
- ObjectMonitor** freeTailp) {
+ ObjectMonitor** free_head_p,
+ ObjectMonitor** free_tail_p) {
bool deflated;
// Normal case ... The monitor is associated with obj.
const markWord mark = obj->mark();
@@ -1540,14 +1537,22 @@
assert(mid->object() == NULL, "invariant: object=" INTPTR_FORMAT,
p2i(mid->object()));
- // Move the object to the working free list defined by freeHeadp, freeTailp
- if (*freeHeadp == NULL) *freeHeadp = mid;
- if (*freeTailp != NULL) {
- ObjectMonitor * prevtail = *freeTailp;
- assert(prevtail->FreeNext == NULL, "cleaned up deflated?");
- prevtail->FreeNext = mid;
+ // Move the deflated ObjectMonitor to the working free list
+ // defined by free_head_p and free_tail_p.
+ if (*free_head_p == NULL) *free_head_p = mid;
+ if (*free_tail_p != NULL) {
+ // We append to the list so the caller can use mid->_next_om
+ // to fix the linkages in its context.
+ ObjectMonitor* prevtail = *free_tail_p;
+ // Should have been cleaned up by the caller:
+ assert(prevtail->_next_om == NULL, "cleaned up deflated?");
+ prevtail->_next_om = mid;
}
- *freeTailp = mid;
+ *free_tail_p = mid;
+ // At this point, mid->_next_om still refers to its current
+ // value and another ObjectMonitor's _next_om field still
+ // refers to this ObjectMonitor. Those linkages have to be
+ // cleaned up by the caller who has the complete context.
deflated = true;
}
return deflated;
@@ -1566,57 +1571,58 @@
// See also ParallelSPCleanupTask and
// SafepointSynchronize::do_cleanup_tasks() in safepoint.cpp and
// Threads::parallel_java_threads_do() in thread.cpp.
-int ObjectSynchronizer::deflate_monitor_list(ObjectMonitor** listHeadp,
- ObjectMonitor** freeHeadp,
- ObjectMonitor** freeTailp) {
+int ObjectSynchronizer::deflate_monitor_list(ObjectMonitor** list_p,
+ ObjectMonitor** free_head_p,
+ ObjectMonitor** free_tail_p) {
ObjectMonitor* mid;
ObjectMonitor* next;
ObjectMonitor* cur_mid_in_use = NULL;
int deflated_count = 0;
- for (mid = *listHeadp; mid != NULL;) {
+ for (mid = *list_p; mid != NULL;) {
oop obj = (oop) mid->object();
- if (obj != NULL && deflate_monitor(mid, obj, freeHeadp, freeTailp)) {
- // if deflate_monitor succeeded,
- // extract from per-thread in-use list
- if (mid == *listHeadp) {
- *listHeadp = mid->FreeNext;
+ if (obj != NULL && deflate_monitor(mid, obj, free_head_p, free_tail_p)) {
+ // Deflation succeeded and already updated free_head_p and
+ // free_tail_p as needed. Finish the move to the local free list
+ // by unlinking mid from the global or per-thread in-use list.
+ if (mid == *list_p) {
+ *list_p = mid->_next_om;
} else if (cur_mid_in_use != NULL) {
- cur_mid_in_use->FreeNext = mid->FreeNext; // maintain the current thread in-use list
+ cur_mid_in_use->_next_om = mid->_next_om; // maintain the current thread in-use list
}
- next = mid->FreeNext;
- mid->FreeNext = NULL; // This mid is current tail in the freeHeadp list
+ next = mid->_next_om;
+ mid->_next_om = NULL; // This mid is current tail in the free_head_p list
mid = next;
deflated_count++;
} else {
cur_mid_in_use = mid;
- mid = mid->FreeNext;
+ mid = mid->_next_om;
}
}
return deflated_count;
}
void ObjectSynchronizer::prepare_deflate_idle_monitors(DeflateMonitorCounters* counters) {
- counters->nInuse = 0; // currently associated with objects
- counters->nInCirculation = 0; // extant
- counters->nScavenged = 0; // reclaimed (global and per-thread)
- counters->perThreadScavenged = 0; // per-thread scavenge total
- counters->perThreadTimes = 0.0; // per-thread scavenge times
+ counters->n_in_use = 0; // currently associated with objects
+ counters->n_in_circulation = 0; // extant
+ counters->n_scavenged = 0; // reclaimed (global and per-thread)
+ counters->per_thread_scavenged = 0; // per-thread scavenge total
+ counters->per_thread_times = 0.0; // per-thread scavenge times
}
void ObjectSynchronizer::deflate_idle_monitors(DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
bool deflated = false;
- ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged monitors
- ObjectMonitor * freeTailp = NULL;
+ ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors
+ ObjectMonitor* free_tail_p = NULL;
elapsedTimer timer;
if (log_is_enabled(Info, monitorinflation)) {
timer.start();
}
- // Prevent omFlush from changing mids in Thread dtor's during deflation
+ // Prevent om_flush from changing mids in Thread dtor's during deflation
// And in case the vm thread is acquiring a lock during a safepoint
// See e.g. 6320749
Thread::muxAcquire(&gListLock, "deflate_idle_monitors");
@@ -1624,30 +1630,30 @@
// Note: the thread-local monitors lists get deflated in
// a separate pass. See deflate_thread_local_monitors().
- // For moribund threads, scan gOmInUseList
+ // For moribund threads, scan g_om_in_use_list
int deflated_count = 0;
- if (gOmInUseList) {
- counters->nInCirculation += gOmInUseCount;
- deflated_count = deflate_monitor_list((ObjectMonitor **)&gOmInUseList, &freeHeadp, &freeTailp);
- gOmInUseCount -= deflated_count;
- counters->nScavenged += deflated_count;
- counters->nInuse += gOmInUseCount;
+ if (g_om_in_use_list) {
+ counters->n_in_circulation += g_om_in_use_count;
+ deflated_count = deflate_monitor_list((ObjectMonitor **)&g_om_in_use_list, &free_head_p, &free_tail_p);
+ g_om_in_use_count -= deflated_count;
+ counters->n_scavenged += deflated_count;
+ counters->n_in_use += g_om_in_use_count;
}
- // Move the scavenged monitors back to the global free list.
- if (freeHeadp != NULL) {
- guarantee(freeTailp != NULL && counters->nScavenged > 0, "invariant");
- assert(freeTailp->FreeNext == NULL, "invariant");
- // constant-time list splice - prepend scavenged segment to gFreeList
- freeTailp->FreeNext = gFreeList;
- gFreeList = freeHeadp;
+ if (free_head_p != NULL) {
+ // Move the deflated ObjectMonitors back to the global free list.
+ guarantee(free_tail_p != NULL && counters->n_scavenged > 0, "invariant");
+ assert(free_tail_p->_next_om == NULL, "invariant");
+ // constant-time list splice - prepend scavenged segment to g_free_list
+ free_tail_p->_next_om = g_free_list;
+ g_free_list = free_head_p;
}
Thread::muxRelease(&gListLock);
timer.stop();
LogStreamHandle(Debug, monitorinflation) lsh_debug;
LogStreamHandle(Info, monitorinflation) lsh_info;
- LogStream * ls = NULL;
+ LogStream* ls = NULL;
if (log_is_enabled(Debug, monitorinflation)) {
ls = &lsh_debug;
} else if (deflated_count != 0 && log_is_enabled(Info, monitorinflation)) {
@@ -1663,9 +1669,9 @@
// monitors. Note: if the work is split among more than one
// worker thread, then the reported time will likely be more
// than a beginning to end measurement of the phase.
- log_info(safepoint, cleanup)("deflating per-thread idle monitors, %3.7f secs, monitors=%d", counters->perThreadTimes, counters->perThreadScavenged);
+ log_info(safepoint, cleanup)("deflating per-thread idle monitors, %3.7f secs, monitors=%d", counters->per_thread_times, counters->per_thread_scavenged);
- gMonitorFreeCount += counters->nScavenged;
+ g_om_free_count += counters->n_scavenged;
if (log_is_enabled(Debug, monitorinflation)) {
// exit_globals()'s call to audit_and_print_stats() is done
@@ -1673,26 +1679,26 @@
ObjectSynchronizer::audit_and_print_stats(false /* on_exit */);
} else if (log_is_enabled(Info, monitorinflation)) {
Thread::muxAcquire(&gListLock, "finish_deflate_idle_monitors");
- log_info(monitorinflation)("gMonitorPopulation=%d, gOmInUseCount=%d, "
- "gMonitorFreeCount=%d", gMonitorPopulation,
- gOmInUseCount, gMonitorFreeCount);
+ log_info(monitorinflation)("g_om_population=%d, g_om_in_use_count=%d, "
+ "g_om_free_count=%d", g_om_population,
+ g_om_in_use_count, g_om_free_count);
Thread::muxRelease(&gListLock);
}
ForceMonitorScavenge = 0; // Reset
- OM_PERFDATA_OP(Deflations, inc(counters->nScavenged));
- OM_PERFDATA_OP(MonExtant, set_value(counters->nInCirculation));
+ OM_PERFDATA_OP(Deflations, inc(counters->n_scavenged));
+ OM_PERFDATA_OP(MonExtant, set_value(counters->n_in_circulation));
- GVars.stwRandom = os::random();
- GVars.stwCycle++;
+ GVars.stw_random = os::random();
+ GVars.stw_cycle++;
}
void ObjectSynchronizer::deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
- ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged monitors
- ObjectMonitor * freeTailp = NULL;
+ ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors
+ ObjectMonitor* free_tail_p = NULL;
elapsedTimer timer;
if (log_is_enabled(Info, safepoint, cleanup) ||
@@ -1700,38 +1706,38 @@
timer.start();
}
- int deflated_count = deflate_monitor_list(thread->omInUseList_addr(), &freeHeadp, &freeTailp);
+ int deflated_count = deflate_monitor_list(thread->om_in_use_list_addr(), &free_head_p, &free_tail_p);
Thread::muxAcquire(&gListLock, "deflate_thread_local_monitors");
// Adjust counters
- counters->nInCirculation += thread->omInUseCount;
- thread->omInUseCount -= deflated_count;
- counters->nScavenged += deflated_count;
- counters->nInuse += thread->omInUseCount;
- counters->perThreadScavenged += deflated_count;
+ counters->n_in_circulation += thread->om_in_use_count;
+ thread->om_in_use_count -= deflated_count;
+ counters->n_scavenged += deflated_count;
+ counters->n_in_use += thread->om_in_use_count;
+ counters->per_thread_scavenged += deflated_count;
- // Move the scavenged monitors back to the global free list.
- if (freeHeadp != NULL) {
- guarantee(freeTailp != NULL && deflated_count > 0, "invariant");
- assert(freeTailp->FreeNext == NULL, "invariant");
+ if (free_head_p != NULL) {
+ // Move the deflated ObjectMonitors back to the global free list.
+ guarantee(free_tail_p != NULL && deflated_count > 0, "invariant");
+ assert(free_tail_p->_next_om == NULL, "invariant");
- // constant-time list splice - prepend scavenged segment to gFreeList
- freeTailp->FreeNext = gFreeList;
- gFreeList = freeHeadp;
+ // constant-time list splice - prepend scavenged segment to g_free_list
+ free_tail_p->_next_om = g_free_list;
+ g_free_list = free_head_p;
}
timer.stop();
- // Safepoint logging cares about cumulative perThreadTimes and
+ // Safepoint logging cares about cumulative per_thread_times and
// we'll capture most of the cost, but not the muxRelease() which
// should be cheap.
- counters->perThreadTimes += timer.seconds();
+ counters->per_thread_times += timer.seconds();
Thread::muxRelease(&gListLock);
LogStreamHandle(Debug, monitorinflation) lsh_debug;
LogStreamHandle(Info, monitorinflation) lsh_info;
- LogStream * ls = NULL;
+ LogStream* ls = NULL;
if (log_is_enabled(Debug, monitorinflation)) {
ls = &lsh_debug;
} else if (deflated_count != 0 && log_is_enabled(Info, monitorinflation)) {
@@ -1807,16 +1813,16 @@
return (u_char*)&GVars;
}
-u_char* ObjectSynchronizer::get_gvars_hcSequence_addr() {
- return (u_char*)&GVars.hcSequence;
+u_char* ObjectSynchronizer::get_gvars_hc_sequence_addr() {
+ return (u_char*)&GVars.hc_sequence;
}
size_t ObjectSynchronizer::get_gvars_size() {
return sizeof(SharedGlobals);
}
-u_char* ObjectSynchronizer::get_gvars_stwRandom_addr() {
- return (u_char*)&GVars.stwRandom;
+u_char* ObjectSynchronizer::get_gvars_stw_random_addr() {
+ return (u_char*)&GVars.stw_random;
}
void ObjectSynchronizer::audit_and_print_stats(bool on_exit) {
@@ -1825,7 +1831,7 @@
LogStreamHandle(Debug, monitorinflation) lsh_debug;
LogStreamHandle(Info, monitorinflation) lsh_info;
LogStreamHandle(Trace, monitorinflation) lsh_trace;
- LogStream * ls = NULL;
+ LogStream* ls = NULL;
if (log_is_enabled(Trace, monitorinflation)) {
ls = &lsh_trace;
} else if (log_is_enabled(Debug, monitorinflation)) {
@@ -1841,26 +1847,26 @@
}
// Log counts for the global and per-thread monitor lists:
- int chkMonitorPopulation = log_monitor_list_counts(ls);
+ int chk_om_population = log_monitor_list_counts(ls);
int error_cnt = 0;
ls->print_cr("Checking global lists:");
- // Check gMonitorPopulation:
- if (gMonitorPopulation == chkMonitorPopulation) {
- ls->print_cr("gMonitorPopulation=%d equals chkMonitorPopulation=%d",
- gMonitorPopulation, chkMonitorPopulation);
+ // Check g_om_population:
+ if (g_om_population == chk_om_population) {
+ ls->print_cr("g_om_population=%d equals chk_om_population=%d",
+ g_om_population, chk_om_population);
} else {
- ls->print_cr("ERROR: gMonitorPopulation=%d is not equal to "
- "chkMonitorPopulation=%d", gMonitorPopulation,
- chkMonitorPopulation);
+ ls->print_cr("ERROR: g_om_population=%d is not equal to "
+ "chk_om_population=%d", g_om_population,
+ chk_om_population);
error_cnt++;
}
- // Check gOmInUseList and gOmInUseCount:
+ // Check g_om_in_use_list and g_om_in_use_count:
chk_global_in_use_list_and_count(ls, &error_cnt);
- // Check gFreeList and gMonitorFreeCount:
+ // Check g_free_list and g_om_free_count:
chk_global_free_list_and_count(ls, &error_cnt);
if (!on_exit) {
@@ -1870,10 +1876,10 @@
ls->print_cr("Checking per-thread lists:");
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
- // Check omInUseList and omInUseCount:
+ // Check om_in_use_list and om_in_use_count:
chk_per_thread_in_use_list_and_count(jt, ls, &error_cnt);
- // Check omFreeList and omFreeCount:
+ // Check om_free_list and om_free_count:
chk_per_thread_free_list_and_count(jt, ls, &error_cnt);
}
@@ -1897,7 +1903,7 @@
}
// Check a free monitor entry; log any errors.
-void ObjectSynchronizer::chk_free_entry(JavaThread * jt, ObjectMonitor * n,
+void ObjectSynchronizer::chk_free_entry(JavaThread* jt, ObjectMonitor* n,
outputStream * out, int *error_cnt_p) {
stringStream ss;
if (n->is_busy()) {
@@ -1942,18 +1948,18 @@
// Check the global free list and count; log the results of the checks.
void ObjectSynchronizer::chk_global_free_list_and_count(outputStream * out,
int *error_cnt_p) {
- int chkMonitorFreeCount = 0;
- for (ObjectMonitor * n = gFreeList; n != NULL; n = n->FreeNext) {
+ int chk_om_free_count = 0;
+ for (ObjectMonitor* n = g_free_list; n != NULL; n = n->_next_om) {
chk_free_entry(NULL /* jt */, n, out, error_cnt_p);
- chkMonitorFreeCount++;
+ chk_om_free_count++;
}
- if (gMonitorFreeCount == chkMonitorFreeCount) {
- out->print_cr("gMonitorFreeCount=%d equals chkMonitorFreeCount=%d",
- gMonitorFreeCount, chkMonitorFreeCount);
+ if (g_om_free_count == chk_om_free_count) {
+ out->print_cr("g_om_free_count=%d equals chk_om_free_count=%d",
+ g_om_free_count, chk_om_free_count);
} else {
- out->print_cr("ERROR: gMonitorFreeCount=%d is not equal to "
- "chkMonitorFreeCount=%d", gMonitorFreeCount,
- chkMonitorFreeCount);
+ out->print_cr("ERROR: g_om_free_count=%d is not equal to "
+ "chk_om_free_count=%d", g_om_free_count,
+ chk_om_free_count);
*error_cnt_p = *error_cnt_p + 1;
}
}
@@ -1961,23 +1967,23 @@
// Check the global in-use list and count; log the results of the checks.
void ObjectSynchronizer::chk_global_in_use_list_and_count(outputStream * out,
int *error_cnt_p) {
- int chkOmInUseCount = 0;
- for (ObjectMonitor * n = gOmInUseList; n != NULL; n = n->FreeNext) {
+ int chk_om_in_use_count = 0;
+ for (ObjectMonitor* n = g_om_in_use_list; n != NULL; n = n->_next_om) {
chk_in_use_entry(NULL /* jt */, n, out, error_cnt_p);
- chkOmInUseCount++;
+ chk_om_in_use_count++;
}
- if (gOmInUseCount == chkOmInUseCount) {
- out->print_cr("gOmInUseCount=%d equals chkOmInUseCount=%d", gOmInUseCount,
- chkOmInUseCount);
+ if (g_om_in_use_count == chk_om_in_use_count) {
+ out->print_cr("g_om_in_use_count=%d equals chk_om_in_use_count=%d", g_om_in_use_count,
+ chk_om_in_use_count);
} else {
- out->print_cr("ERROR: gOmInUseCount=%d is not equal to chkOmInUseCount=%d",
- gOmInUseCount, chkOmInUseCount);
+ out->print_cr("ERROR: g_om_in_use_count=%d is not equal to chk_om_in_use_count=%d",
+ g_om_in_use_count, chk_om_in_use_count);
*error_cnt_p = *error_cnt_p + 1;
}
}
// Check an in-use monitor entry; log any errors.
-void ObjectSynchronizer::chk_in_use_entry(JavaThread * jt, ObjectMonitor * n,
+void ObjectSynchronizer::chk_in_use_entry(JavaThread* jt, ObjectMonitor* n,
outputStream * out, int *error_cnt_p) {
if (n->header().value() == 0) {
if (jt != NULL) {
@@ -2017,7 +2023,7 @@
}
*error_cnt_p = *error_cnt_p + 1;
}
- ObjectMonitor * const obj_mon = mark.monitor();
+ ObjectMonitor* const obj_mon = mark.monitor();
if (n != obj_mon) {
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
@@ -2039,18 +2045,18 @@
void ObjectSynchronizer::chk_per_thread_free_list_and_count(JavaThread *jt,
outputStream * out,
int *error_cnt_p) {
- int chkOmFreeCount = 0;
- for (ObjectMonitor * n = jt->omFreeList; n != NULL; n = n->FreeNext) {
+ int chk_om_free_count = 0;
+ for (ObjectMonitor* n = jt->om_free_list; n != NULL; n = n->_next_om) {
chk_free_entry(jt, n, out, error_cnt_p);
- chkOmFreeCount++;
+ chk_om_free_count++;
}
- if (jt->omFreeCount == chkOmFreeCount) {
- out->print_cr("jt=" INTPTR_FORMAT ": omFreeCount=%d equals "
- "chkOmFreeCount=%d", p2i(jt), jt->omFreeCount, chkOmFreeCount);
+ if (jt->om_free_count == chk_om_free_count) {
+ out->print_cr("jt=" INTPTR_FORMAT ": om_free_count=%d equals "
+ "chk_om_free_count=%d", p2i(jt), jt->om_free_count, chk_om_free_count);
} else {
- out->print_cr("ERROR: jt=" INTPTR_FORMAT ": omFreeCount=%d is not "
- "equal to chkOmFreeCount=%d", p2i(jt), jt->omFreeCount,
- chkOmFreeCount);
+ out->print_cr("ERROR: jt=" INTPTR_FORMAT ": om_free_count=%d is not "
+ "equal to chk_om_free_count=%d", p2i(jt), jt->om_free_count,
+ chk_om_free_count);
*error_cnt_p = *error_cnt_p + 1;
}
}
@@ -2059,19 +2065,19 @@
void ObjectSynchronizer::chk_per_thread_in_use_list_and_count(JavaThread *jt,
outputStream * out,
int *error_cnt_p) {
- int chkOmInUseCount = 0;
- for (ObjectMonitor * n = jt->omInUseList; n != NULL; n = n->FreeNext) {
+ int chk_om_in_use_count = 0;
+ for (ObjectMonitor* n = jt->om_in_use_list; n != NULL; n = n->_next_om) {
chk_in_use_entry(jt, n, out, error_cnt_p);
- chkOmInUseCount++;
+ chk_om_in_use_count++;
}
- if (jt->omInUseCount == chkOmInUseCount) {
- out->print_cr("jt=" INTPTR_FORMAT ": omInUseCount=%d equals "
- "chkOmInUseCount=%d", p2i(jt), jt->omInUseCount,
- chkOmInUseCount);
+ if (jt->om_in_use_count == chk_om_in_use_count) {
+ out->print_cr("jt=" INTPTR_FORMAT ": om_in_use_count=%d equals "
+ "chk_om_in_use_count=%d", p2i(jt), jt->om_in_use_count,
+ chk_om_in_use_count);
} else {
- out->print_cr("ERROR: jt=" INTPTR_FORMAT ": omInUseCount=%d is not "
- "equal to chkOmInUseCount=%d", p2i(jt), jt->omInUseCount,
- chkOmInUseCount);
+ out->print_cr("ERROR: jt=" INTPTR_FORMAT ": om_in_use_count=%d is not "
+ "equal to chk_om_in_use_count=%d", p2i(jt), jt->om_in_use_count,
+ chk_om_in_use_count);
*error_cnt_p = *error_cnt_p + 1;
}
}
@@ -2087,13 +2093,13 @@
}
stringStream ss;
- if (gOmInUseCount > 0) {
+ if (g_om_in_use_count > 0) {
out->print_cr("In-use global monitor info:");
out->print_cr("(B -> is_busy, H -> has hash code, L -> lock status)");
out->print_cr("%18s %s %18s %18s",
"monitor", "BHL", "object", "object type");
out->print_cr("================== === ================== ==================");
- for (ObjectMonitor * n = gOmInUseList; n != NULL; n = n->FreeNext) {
+ for (ObjectMonitor* n = g_om_in_use_list; n != NULL; n = n->_next_om) {
const oop obj = (oop) n->object();
const markWord mark = n->header();
ResourceMark rm;
@@ -2118,7 +2124,7 @@
"jt", "monitor", "BHL", "object", "object type");
out->print_cr("================== ================== === ================== ==================");
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
- for (ObjectMonitor * n = jt->omInUseList; n != NULL; n = n->FreeNext) {
+ for (ObjectMonitor* n = jt->om_in_use_list; n != NULL; n = n->_next_om) {
const oop obj = (oop) n->object();
const markWord mark = n->header();
ResourceMark rm;
@@ -2140,13 +2146,13 @@
// Log counts for the global and per-thread monitor lists and return
// the population count.
int ObjectSynchronizer::log_monitor_list_counts(outputStream * out) {
- int popCount = 0;
+ int pop_count = 0;
out->print_cr("%18s %10s %10s %10s",
"Global Lists:", "InUse", "Free", "Total");
out->print_cr("================== ========== ========== ==========");
out->print_cr("%18s %10d %10d %10d", "",
- gOmInUseCount, gMonitorFreeCount, gMonitorPopulation);
- popCount += gOmInUseCount + gMonitorFreeCount;
+ g_om_in_use_count, g_om_free_count, g_om_population);
+ pop_count += g_om_in_use_count + g_om_free_count;
out->print_cr("%18s %10s %10s %10s",
"Per-Thread Lists:", "InUse", "Free", "Provision");
@@ -2154,10 +2160,10 @@
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
out->print_cr(INTPTR_FORMAT " %10d %10d %10d", p2i(jt),
- jt->omInUseCount, jt->omFreeCount, jt->omFreeProvision);
- popCount += jt->omInUseCount + jt->omFreeCount;
+ jt->om_in_use_count, jt->om_free_count, jt->om_free_provision);
+ pop_count += jt->om_in_use_count + jt->om_free_count;
}
- return popCount;
+ return pop_count;
}
#ifndef PRODUCT
@@ -2167,17 +2173,17 @@
// the list of extant blocks without taking a lock.
int ObjectSynchronizer::verify_objmon_isinpool(ObjectMonitor *monitor) {
- PaddedEnd<ObjectMonitor> * block = OrderAccess::load_acquire(&gBlockList);
+ PaddedObjectMonitor* block = OrderAccess::load_acquire(&g_block_list);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
if (monitor > &block[0] && monitor < &block[_BLOCKSIZE]) {
address mon = (address)monitor;
address blk = (address)block;
size_t diff = mon - blk;
- assert((diff % sizeof(PaddedEnd<ObjectMonitor>)) == 0, "must be aligned");
+ assert((diff % sizeof(PaddedObjectMonitor)) == 0, "must be aligned");
return 1;
}
- block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
+ block = (PaddedObjectMonitor*)block->_next_om;
}
return 0;
}