/*
* Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/systemDictionary.hpp"
#include "memory/allocation.hpp"
#include "memory/heapInspection.hpp"
#include "memory/oopFactory.hpp"
#include "memory/resourceArea.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "prims/jvmtiRawMonitor.hpp"
#include "runtime/atomic.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/init.hpp"
#include "runtime/objectMonitor.inline.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threadSMR.inline.hpp"
#include "runtime/vframe.hpp"
#include "runtime/vmThread.hpp"
#include "runtime/vmOperations.hpp"
#include "services/threadService.hpp"
// TODO: we need to define a naming convention for perf counters
// to distinguish counters for:
// - standard JSR174 use
// - Hotspot extension (public and committed)
// - Hotspot extension (private/internal and uncommitted)
// Default is disabled.
bool ThreadService::_thread_monitoring_contention_enabled = false;
bool ThreadService::_thread_cpu_time_enabled = false;
bool ThreadService::_thread_allocated_memory_enabled = false;
PerfCounter* ThreadService::_total_threads_count = NULL;
PerfVariable* ThreadService::_live_threads_count = NULL;
PerfVariable* ThreadService::_peak_threads_count = NULL;
PerfVariable* ThreadService::_daemon_threads_count = NULL;
volatile int ThreadService::_atomic_threads_count = 0;
volatile int ThreadService::_atomic_daemon_threads_count = 0;
ThreadDumpResult* ThreadService::_threaddump_list = NULL;
static const int INITIAL_ARRAY_SIZE = 10;
void ThreadService::init() {
EXCEPTION_MARK;
// These counters are for java.lang.management API support.
// They are created even if -XX:-UsePerfData is set and in
// that case, they will be allocated on C heap.
_total_threads_count =
PerfDataManager::create_counter(JAVA_THREADS, "started",
PerfData::U_Events, CHECK);
_live_threads_count =
PerfDataManager::create_variable(JAVA_THREADS, "live",
PerfData::U_None, CHECK);
_peak_threads_count =
PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
PerfData::U_None, CHECK);
_daemon_threads_count =
PerfDataManager::create_variable(JAVA_THREADS, "daemon",
PerfData::U_None, CHECK);
if (os::is_thread_cpu_time_supported()) {
_thread_cpu_time_enabled = true;
}
_thread_allocated_memory_enabled = true; // Always on, so enable it
}
void ThreadService::reset_peak_thread_count() {
// Acquire the lock to update the peak thread count
// to synchronize with thread addition and removal.
MutexLocker mu(Threads_lock);
_peak_threads_count->set_value(get_live_thread_count());
}
static bool is_hidden_thread(JavaThread *thread) {
// hide VM internal or JVMTI agent threads
return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
}
void ThreadService::add_thread(JavaThread* thread, bool daemon) {
assert(Threads_lock->owned_by_self(), "must have threads lock");
// Do not count hidden threads
if (is_hidden_thread(thread)) {
return;
}
_total_threads_count->inc();
_live_threads_count->inc();
Atomic::inc(&_atomic_threads_count);
int count = _atomic_threads_count;
if (count > _peak_threads_count->get_value()) {
_peak_threads_count->set_value(count);
}
if (daemon) {
_daemon_threads_count->inc();
Atomic::inc(&_atomic_daemon_threads_count);
}
}
void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
Atomic::dec(&_atomic_threads_count);
if (daemon) {
Atomic::dec(&_atomic_daemon_threads_count);
}
}
void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
assert(Threads_lock->owned_by_self(), "must have threads lock");
// Do not count hidden threads
if (is_hidden_thread(thread)) {
return;
}
assert(!thread->is_terminated(), "must not be terminated");
if (!thread->is_exiting()) {
// JavaThread::exit() skipped calling current_thread_exiting()
decrement_thread_counts(thread, daemon);
}
int daemon_count = _atomic_daemon_threads_count;
int count = _atomic_threads_count;
// Counts are incremented at the same time, but atomic counts are
// decremented earlier than perf counts.
assert(_live_threads_count->get_value() > count,
"thread count mismatch %d : %d",
(int)_live_threads_count->get_value(), count);
_live_threads_count->dec(1);
if (daemon) {
assert(_daemon_threads_count->get_value() > daemon_count,
"thread count mismatch %d : %d",
(int)_daemon_threads_count->get_value(), daemon_count);
_daemon_threads_count->dec(1);
}
// Counts are incremented at the same time, but atomic counts are
// decremented earlier than perf counts.
assert(_daemon_threads_count->get_value() >= daemon_count,
"thread count mismatch %d : %d",
(int)_daemon_threads_count->get_value(), daemon_count);
assert(_live_threads_count->get_value() >= count,
"thread count mismatch %d : %d",
(int)_live_threads_count->get_value(), count);
assert(_live_threads_count->get_value() > 0 ||
(_live_threads_count->get_value() == 0 && count == 0 &&
_daemon_threads_count->get_value() == 0 && daemon_count == 0),
"thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
(int)_live_threads_count->get_value(), count,
(int)_daemon_threads_count->get_value(), daemon_count);
assert(_daemon_threads_count->get_value() > 0 ||
(_daemon_threads_count->get_value() == 0 && daemon_count == 0),
"thread counts should reach 0 at the same time, daemon %d,%d",
(int)_daemon_threads_count->get_value(), daemon_count);
}
void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
// Do not count hidden threads
if (is_hidden_thread(jt)) {
return;
}
assert(jt == JavaThread::current(), "Called by current thread");
assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
decrement_thread_counts(jt, daemon);
}
// FIXME: JVMTI should call this function
Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
assert(thread != NULL, "should be non-NULL");
debug_only(Thread::check_for_dangling_thread_pointer(thread);)
ObjectMonitor *wait_obj = thread->current_waiting_monitor();
oop obj = NULL;
if (wait_obj != NULL) {
// thread is doing an Object.wait() call
obj = (oop) wait_obj->object();
assert(obj != NULL, "Object.wait() should have an object");
} else {
ObjectMonitor *enter_obj = thread->current_pending_monitor();
if (enter_obj != NULL) {
// thread is trying to enter() an ObjectMonitor.
obj = (oop) enter_obj->object();
assert(obj != NULL, "ObjectMonitor should have an associated object!");
}
}
Handle h(Thread::current(), obj);
return h;
}
bool ThreadService::set_thread_monitoring_contention(bool flag) {
MutexLocker m(Management_lock);
bool prev = _thread_monitoring_contention_enabled;
_thread_monitoring_contention_enabled = flag;
return prev;
}
bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
MutexLocker m(Management_lock);
bool prev = _thread_cpu_time_enabled;
_thread_cpu_time_enabled = flag;
return prev;
}
bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
MutexLocker m(Management_lock);
bool prev = _thread_allocated_memory_enabled;
_thread_allocated_memory_enabled = flag;
return prev;
}
// GC support
void ThreadService::oops_do(OopClosure* f) {
for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
dump->oops_do(f);
}
}
void ThreadService::metadata_do(void f(Metadata*)) {
for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
dump->metadata_do(f);
}
}
void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
MutexLocker ml(Management_lock);
if (_threaddump_list == NULL) {
_threaddump_list = dump;
} else {
dump->set_next(_threaddump_list);
_threaddump_list = dump;
}
}
void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
MutexLocker ml(Management_lock);
ThreadDumpResult* prev = NULL;
bool found = false;
for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
if (d == dump) {
if (prev == NULL) {
_threaddump_list = dump->next();
} else {
prev->set_next(dump->next());
}
found = true;
break;
}
}
assert(found, "The threaddump result to be removed must exist.");
}
// Dump stack trace of threads specified in the given threads array.
// Returns StackTraceElement[][] each element is the stack trace of a thread in
// the corresponding entry in the given threads array
Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
int num_threads,
TRAPS) {
assert(num_threads > 0, "just checking");
ThreadDumpResult dump_result;
VM_ThreadDump op(&dump_result,
threads,
num_threads,
-1, /* entire stack */
false, /* with locked monitors */
false /* with locked synchronizers */);
VMThread::execute(&op);
// Allocate the resulting StackTraceElement[][] object
ResourceMark rm(THREAD);
Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
ObjArrayKlass* ik = ObjArrayKlass::cast(k);
objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
objArrayHandle result_obj(THREAD, r);
int num_snapshots = dump_result.num_snapshots();
assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
int i = 0;
for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
ThreadStackTrace* stacktrace = ts->get_stack_trace();
if (stacktrace == NULL) {
// No stack trace
result_obj->obj_at_put(i, NULL);
} else {
// Construct an array of java/lang/StackTraceElement object
Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
result_obj->obj_at_put(i, backtrace_h());
}
}
return result_obj;
}
void ThreadService::reset_contention_count_stat(JavaThread* thread) {
ThreadStatistics* stat = thread->get_thread_stat();
if (stat != NULL) {
stat->reset_count_stat();
}
}
void ThreadService::reset_contention_time_stat(JavaThread* thread) {
ThreadStatistics* stat = thread->get_thread_stat();
if (stat != NULL) {
stat->reset_time_stat();
}
}
// Find deadlocks involving raw monitors, object monitors and concurrent locks
// if concurrent_locks is true.
DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
// This code was modified from the original Threads::find_deadlocks code.
int globalDfn = 0, thisDfn;
ObjectMonitor* waitingToLockMonitor = NULL;
JvmtiRawMonitor* waitingToLockRawMonitor = NULL;
oop waitingToLockBlocker = NULL;
bool blocked_on_monitor = false;
JavaThread *currentThread, *previousThread;
int num_deadlocks = 0;
// Initialize the depth-first-number for each JavaThread.
JavaThreadIterator jti(t_list);
for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
jt->set_depth_first_number(-1);
}
DeadlockCycle* deadlocks = NULL;
DeadlockCycle* last = NULL;
DeadlockCycle* cycle = new DeadlockCycle();
for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
if (jt->depth_first_number() >= 0) {
// this thread was already visited
continue;
}
thisDfn = globalDfn;
jt->set_depth_first_number(globalDfn++);
previousThread = jt;
currentThread = jt;
cycle->reset();
// When there is a deadlock, all the monitors involved in the dependency
// cycle must be contended and heavyweight. So we only care about the
// heavyweight monitor a thread is waiting to lock.
waitingToLockMonitor = jt->current_pending_monitor();
// JVM TI raw monitors can also be involved in deadlocks, and we can be
// waiting to lock both a raw monitor and ObjectMonitor at the same time.
// It isn't clear how to make deadlock detection work correctly if that
// happens.
waitingToLockRawMonitor = jt->current_pending_raw_monitor();
if (concurrent_locks) {
waitingToLockBlocker = jt->current_park_blocker();
}
while (waitingToLockMonitor != NULL ||
waitingToLockRawMonitor != NULL ||
waitingToLockBlocker != NULL) {
cycle->add_thread(currentThread);
// Give preference to the raw monitor
if (waitingToLockRawMonitor != NULL) {
Thread* owner = waitingToLockRawMonitor->owner();
if (owner != NULL && // the raw monitor could be released at any time
owner->is_Java_thread()) {
// only JavaThreads can be reported here
currentThread = (JavaThread*) owner;
}
} else if (waitingToLockMonitor != NULL) {
address currentOwner = (address)waitingToLockMonitor->owner();
if (currentOwner != NULL) {
currentThread = Threads::owning_thread_from_monitor_owner(t_list,
currentOwner);
if (currentThread == NULL) {
// This function is called at a safepoint so the JavaThread
// that owns waitingToLockMonitor should be findable, but
// if it is not findable, then the previous currentThread is
// blocked permanently. We record this as a deadlock.
num_deadlocks++;
cycle->set_deadlock(true);
// add this cycle to the deadlocks list
if (deadlocks == NULL) {
deadlocks = cycle;
} else {
last->set_next(cycle);
}
last = cycle;
cycle = new DeadlockCycle();
break;
}
}
} else {
if (concurrent_locks) {
if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
// This JavaThread (if there is one) is protected by the
// ThreadsListSetter in VM_FindDeadlocks::doit().
currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
} else {
currentThread = NULL;
}
}
}
if (currentThread == NULL) {
// No dependency on another thread
break;
}
if (currentThread->depth_first_number() < 0) {
// First visit to this thread
currentThread->set_depth_first_number(globalDfn++);
} else if (currentThread->depth_first_number() < thisDfn) {
// Thread already visited, and not on a (new) cycle
break;
} else if (currentThread == previousThread) {
// Self-loop, ignore
break;
} else {
// We have a (new) cycle
num_deadlocks++;
cycle->set_deadlock(true);
// add this cycle to the deadlocks list
if (deadlocks == NULL) {
deadlocks = cycle;
} else {
last->set_next(cycle);
}
last = cycle;
cycle = new DeadlockCycle();
break;
}
previousThread = currentThread;
waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
if (concurrent_locks) {
waitingToLockBlocker = currentThread->current_park_blocker();
}
}
}
delete cycle;
return deadlocks;
}
ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
// Create a new ThreadDumpResult object and append to the list.
// If GC happens before this function returns, Method*
// in the stack trace will be visited.
ThreadService::add_thread_dump(this);
}
ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
// Create a new ThreadDumpResult object and append to the list.
// If GC happens before this function returns, oops
// will be visited.
ThreadService::add_thread_dump(this);
}
ThreadDumpResult::~ThreadDumpResult() {
ThreadService::remove_thread_dump(this);
// free all the ThreadSnapshot objects created during
// the VM_ThreadDump operation
ThreadSnapshot* ts = _snapshots;
while (ts != NULL) {
ThreadSnapshot* p = ts;
ts = ts->next();
delete p;
}
}
ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
ThreadSnapshot* ts = new ThreadSnapshot();
link_thread_snapshot(ts);
return ts;
}
ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
// Note: it is very important that the ThreadSnapshot* gets linked before
// ThreadSnapshot::initialize gets called. This is to ensure that
// ThreadSnapshot::oops_do can get called prior to the field
// ThreadSnapshot::_threadObj being assigned a value (to prevent a dangling
// oop).
ThreadSnapshot* ts = new ThreadSnapshot();
link_thread_snapshot(ts);
ts->initialize(t_list(), thread);
return ts;
}
void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
assert(_num_threads == 0 || _num_snapshots < _num_threads,
"_num_snapshots must be less than _num_threads");
_num_snapshots++;
if (_snapshots == NULL) {
_snapshots = ts;
} else {
_last->set_next(ts);
}
_last = ts;
}
void ThreadDumpResult::oops_do(OopClosure* f) {
for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
ts->oops_do(f);
}
}
void ThreadDumpResult::metadata_do(void f(Metadata*)) {
for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
ts->metadata_do(f);
}
}
ThreadsList* ThreadDumpResult::t_list() {
return _setter.list();
}
StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
_method = jvf->method();
_bci = jvf->bci();
_class_holder = _method->method_holder()->klass_holder();
_locked_monitors = NULL;
if (with_lock_info) {
ResourceMark rm;
GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
int length = list->length();
if (length > 0) {
_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
for (int i = 0; i < length; i++) {
MonitorInfo* monitor = list->at(i);
assert(monitor->owner() != NULL, "This monitor must have an owning object");
_locked_monitors->append(monitor->owner());
}
}
}
}
void StackFrameInfo::oops_do(OopClosure* f) {
if (_locked_monitors != NULL) {
int length = _locked_monitors->length();
for (int i = 0; i < length; i++) {
f->do_oop((oop*) _locked_monitors->adr_at(i));
}
}
f->do_oop(&_class_holder);
}
void StackFrameInfo::metadata_do(void f(Metadata*)) {
f(_method);
}
void StackFrameInfo::print_on(outputStream* st) const {
ResourceMark rm;
java_lang_Throwable::print_stack_element(st, method(), bci());
int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
for (int i = 0; i < len; i++) {
oop o = _locked_monitors->at(i);
st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
}
}
// Iterate through monitor cache to find JNI locked monitors
class InflatedMonitorsClosure: public MonitorClosure {
private:
ThreadStackTrace* _stack_trace;
Thread* _thread;
public:
InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
_thread = t;
_stack_trace = st;
}
void do_monitor(ObjectMonitor* mid) {
if (mid->owner() == _thread) {
oop object = (oop) mid->object();
if (!_stack_trace->is_owned_monitor_on_stack(object)) {
_stack_trace->add_jni_locked_monitor(object);
}
}
}
};
ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
_thread = t;
_frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
_depth = 0;
_with_locked_monitors = with_locked_monitors;
if (_with_locked_monitors) {
_jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
} else {
_jni_locked_monitors = NULL;
}
}
ThreadStackTrace::~ThreadStackTrace() {
for (int i = 0; i < _frames->length(); i++) {
delete _frames->at(i);
}
delete _frames;
if (_jni_locked_monitors != NULL) {
delete _jni_locked_monitors;
}
}
void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
if (_thread->has_last_Java_frame()) {
RegisterMap reg_map(_thread);
vframe* start_vf = _thread->last_java_vframe(®_map);
int count = 0;
for (vframe* f = start_vf; f; f = f->sender() ) {
if (maxDepth >= 0 && count == maxDepth) {
// Skip frames if more than maxDepth
break;
}
if (f->is_java_frame()) {
javaVFrame* jvf = javaVFrame::cast(f);
add_stack_frame(jvf);
count++;
} else {
// Ignore non-Java frames
}
}
}
if (_with_locked_monitors) {
// Iterate inflated monitors and find monitors locked by this thread
// not found in the stack
InflatedMonitorsClosure imc(_thread, this);
ObjectSynchronizer::monitors_iterate(&imc);
}
}
bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
bool found = false;
int num_frames = get_stack_depth();
for (int depth = 0; depth < num_frames; depth++) {
StackFrameInfo* frame = stack_frame_at(depth);
int len = frame->num_locked_monitors();
GrowableArray<oop>* locked_monitors = frame->locked_monitors();
for (int j = 0; j < len; j++) {
oop monitor = locked_monitors->at(j);
assert(monitor != NULL, "must be a Java object");
if (monitor == object) {
found = true;
break;
}
}
}
return found;
}
Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
InstanceKlass* ik = SystemDictionary::StackTraceElement_klass();
assert(ik != NULL, "must be loaded in 1.4+");
// Allocate an array of java/lang/StackTraceElement object
objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
objArrayHandle backtrace(THREAD, ste);
for (int j = 0; j < _depth; j++) {
StackFrameInfo* frame = _frames->at(j);
methodHandle mh(THREAD, frame->method());
oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
backtrace->obj_at_put(j, element);
}
return backtrace;
}
void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
_frames->append(frame);
_depth++;
}
void ThreadStackTrace::oops_do(OopClosure* f) {
int length = _frames->length();
for (int i = 0; i < length; i++) {
_frames->at(i)->oops_do(f);
}
length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
for (int j = 0; j < length; j++) {
f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
}
}
void ThreadStackTrace::metadata_do(void f(Metadata*)) {
int length = _frames->length();
for (int i = 0; i < length; i++) {
_frames->at(i)->metadata_do(f);
}
}
ConcurrentLocksDump::~ConcurrentLocksDump() {
if (_retain_map_on_free) {
return;
}
for (ThreadConcurrentLocks* t = _map; t != NULL;) {
ThreadConcurrentLocks* tcl = t;
t = t->next();
delete tcl;
}
}
void ConcurrentLocksDump::dump_at_safepoint() {
// dump all locked concurrent locks
assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */);
// Find all instances of AbstractOwnableSynchronizer
HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
aos_objects);
// Build a map of thread to its owned AQS locks
build_map(aos_objects);
delete aos_objects;
}
// build a map of JavaThread to all its owned AbstractOwnableSynchronizer
void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
int length = aos_objects->length();
for (int i = 0; i < length; i++) {
oop o = aos_objects->at(i);
oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
if (owner_thread_obj != NULL) {
// See comments in ThreadConcurrentLocks to see how this
// JavaThread* is protected.
JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
assert(o->is_instance(), "Must be an instanceOop");
add_lock(thread, (instanceOop) o);
}
}
}
void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
if (tcl != NULL) {
tcl->add_lock(o);
return;
}
// First owned lock found for this thread
tcl = new ThreadConcurrentLocks(thread);
tcl->add_lock(o);
if (_map == NULL) {
_map = tcl;
} else {
_last->set_next(tcl);
}
_last = tcl;
}
ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
if (tcl->java_thread() == thread) {
return tcl;
}
}
return NULL;
}
void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
st->print_cr(" Locked ownable synchronizers:");
ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
if (locks == NULL || locks->is_empty()) {
st->print_cr("\t- None");
st->cr();
return;
}
for (int i = 0; i < locks->length(); i++) {
instanceOop obj = locks->at(i);
st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
}
st->cr();
}
ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
_thread = thread;
_owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
_next = NULL;
}
ThreadConcurrentLocks::~ThreadConcurrentLocks() {
delete _owned_locks;
}
void ThreadConcurrentLocks::add_lock(instanceOop o) {
_owned_locks->append(o);
}
void ThreadConcurrentLocks::oops_do(OopClosure* f) {
int length = _owned_locks->length();
for (int i = 0; i < length; i++) {
f->do_oop((oop*) _owned_locks->adr_at(i));
}
}
ThreadStatistics::ThreadStatistics() {
_contended_enter_count = 0;
_monitor_wait_count = 0;
_sleep_count = 0;
_count_pending_reset = false;
_timer_pending_reset = false;
memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
}
void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
_thread = thread;
_threadObj = thread->threadObj();
ThreadStatistics* stat = thread->get_thread_stat();
_contended_enter_ticks = stat->contended_enter_ticks();
_contended_enter_count = stat->contended_enter_count();
_monitor_wait_ticks = stat->monitor_wait_ticks();
_monitor_wait_count = stat->monitor_wait_count();
_sleep_ticks = stat->sleep_ticks();
_sleep_count = stat->sleep_count();
_thread_status = java_lang_Thread::get_thread_status(_threadObj);
_is_ext_suspended = thread->is_being_ext_suspended();
_is_in_native = (thread->thread_state() == _thread_in_native);
if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
_thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
_thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
Handle obj = ThreadService::get_current_contended_monitor(thread);
if (obj() == NULL) {
// monitor no longer exists; thread is not blocked
_thread_status = java_lang_Thread::RUNNABLE;
} else {
_blocker_object = obj();
JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
|| (owner != NULL && owner->is_attaching_via_jni())) {
// ownership information of the monitor is not available
// (may no longer be owned or releasing to some other thread)
// make this thread in RUNNABLE state.
// And when the owner thread is in attaching state, the java thread
// is not completely initialized. For example thread name and id
// and may not be set, so hide the attaching thread.
_thread_status = java_lang_Thread::RUNNABLE;
_blocker_object = NULL;
} else if (owner != NULL) {
_blocker_object_owner = owner->threadObj();
}
}
}
// Support for JSR-166 locks
if (_thread_status == java_lang_Thread::PARKED || _thread_status == java_lang_Thread::PARKED_TIMED) {
_blocker_object = thread->current_park_blocker();
if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
_blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
}
}
}
ThreadSnapshot::~ThreadSnapshot() {
delete _stack_trace;
delete _concurrent_locks;
}
void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
_stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
_stack_trace->dump_stack_at_safepoint(max_depth);
}
void ThreadSnapshot::oops_do(OopClosure* f) {
f->do_oop(&_threadObj);
f->do_oop(&_blocker_object);
f->do_oop(&_blocker_object_owner);
if (_stack_trace != NULL) {
_stack_trace->oops_do(f);
}
if (_concurrent_locks != NULL) {
_concurrent_locks->oops_do(f);
}
}
void ThreadSnapshot::metadata_do(void f(Metadata*)) {
if (_stack_trace != NULL) {
_stack_trace->metadata_do(f);
}
}
DeadlockCycle::DeadlockCycle() {
_is_deadlock = false;
_threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
_next = NULL;
}
DeadlockCycle::~DeadlockCycle() {
delete _threads;
}
void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
st->cr();
st->print_cr("Found one Java-level deadlock:");
st->print("=============================");
JavaThread* currentThread;
ObjectMonitor* waitingToLockMonitor;
JvmtiRawMonitor* waitingToLockRawMonitor;
oop waitingToLockBlocker;
int len = _threads->length();
for (int i = 0; i < len; i++) {
currentThread = _threads->at(i);
waitingToLockMonitor = currentThread->current_pending_monitor();
waitingToLockRawMonitor = currentThread->current_pending_raw_monitor();
waitingToLockBlocker = currentThread->current_park_blocker();
st->cr();
st->print_cr("\"%s\":", currentThread->get_thread_name());
const char* owner_desc = ",\n which is held by";
// Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor
// sets the current pending monitor, it is possible to then see a pending raw monitor as well.
if (waitingToLockRawMonitor != NULL) {
st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor));
Thread* owner = waitingToLockRawMonitor->owner();
// Could be NULL as the raw monitor could be released at any time if held by non-JavaThread
if (owner != NULL) {
if (owner->is_Java_thread()) {
currentThread = (JavaThread*) owner;
st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
} else {
st->print_cr(",\n which has now been released");
}
} else {
st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner));
}
}
if (waitingToLockMonitor != NULL) {
st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
oop obj = (oop)waitingToLockMonitor->object();
st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
obj->klass()->external_name());
if (!currentThread->current_pending_monitor_is_from_java()) {
owner_desc = "\n in JNI, which is held by";
}
currentThread = Threads::owning_thread_from_monitor_owner(t_list,
(address)waitingToLockMonitor->owner());
if (currentThread == NULL) {
// The deadlock was detected at a safepoint so the JavaThread
// that owns waitingToLockMonitor should be findable, but
// if it is not findable, then the previous currentThread is
// blocked permanently.
st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
p2i(waitingToLockMonitor->owner()));
continue;
}
} else {
st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
p2i(waitingToLockBlocker),
waitingToLockBlocker->klass()->external_name());
assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
"Must be an AbstractOwnableSynchronizer");
oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
currentThread = java_lang_Thread::thread(ownerObj);
assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
}
st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
}
st->cr();
// Print stack traces
bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
JavaMonitorsInStackTrace = true;
st->print_cr("Java stack information for the threads listed above:");
st->print_cr("===================================================");
for (int j = 0; j < len; j++) {
currentThread = _threads->at(j);
st->print_cr("\"%s\":", currentThread->get_thread_name());
currentThread->print_stack_on(st);
}
JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
}
ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
bool include_jvmti_agent_threads,
bool include_jni_attaching_threads) {
assert(cur_thread == Thread::current(), "Check current thread");
int init_size = ThreadService::get_live_thread_count();
_threads_array = new GrowableArray<instanceHandle>(init_size);
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
// skips JavaThreads in the process of exiting
// and also skips VM internal JavaThreads
// Threads in _thread_new or _thread_new_trans state are included.
// i.e. threads have been started but not yet running.
if (jt->threadObj() == NULL ||
jt->is_exiting() ||
!java_lang_Thread::is_alive(jt->threadObj()) ||
jt->is_hidden_from_external_view()) {
continue;
}
// skip agent threads
if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
continue;
}
// skip jni threads in the process of attaching
if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
continue;
}
instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
_threads_array->append(h);
}
}