Mon, 17 Jun 2013 18:35:44 +0200
8016304: ThreadMXBean.getDeadlockedThreads reports bogus deadlocks on JDK 8
Reviewed-by: dcubed, mgronlun
1 /*
2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/heapInspection.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "oops/instanceKlass.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/handles.inline.hpp"
33 #include "runtime/init.hpp"
34 #include "runtime/thread.hpp"
35 #include "runtime/vframe.hpp"
36 #include "runtime/vmThread.hpp"
37 #include "runtime/vm_operations.hpp"
38 #include "services/threadService.hpp"
40 // TODO: we need to define a naming convention for perf counters
41 // to distinguish counters for:
42 // - standard JSR174 use
43 // - Hotspot extension (public and committed)
44 // - Hotspot extension (private/internal and uncommitted)
46 // Default is disabled.
47 bool ThreadService::_thread_monitoring_contention_enabled = false;
48 bool ThreadService::_thread_cpu_time_enabled = false;
49 bool ThreadService::_thread_allocated_memory_enabled = false;
51 PerfCounter* ThreadService::_total_threads_count = NULL;
52 PerfVariable* ThreadService::_live_threads_count = NULL;
53 PerfVariable* ThreadService::_peak_threads_count = NULL;
54 PerfVariable* ThreadService::_daemon_threads_count = NULL;
55 volatile int ThreadService::_exiting_threads_count = 0;
56 volatile int ThreadService::_exiting_daemon_threads_count = 0;
58 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
60 static const int INITIAL_ARRAY_SIZE = 10;
62 void ThreadService::init() {
63 EXCEPTION_MARK;
65 // These counters are for java.lang.management API support.
66 // They are created even if -XX:-UsePerfData is set and in
67 // that case, they will be allocated on C heap.
69 _total_threads_count =
70 PerfDataManager::create_counter(JAVA_THREADS, "started",
71 PerfData::U_Events, CHECK);
73 _live_threads_count =
74 PerfDataManager::create_variable(JAVA_THREADS, "live",
75 PerfData::U_None, CHECK);
77 _peak_threads_count =
78 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
79 PerfData::U_None, CHECK);
81 _daemon_threads_count =
82 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
83 PerfData::U_None, CHECK);
85 if (os::is_thread_cpu_time_supported()) {
86 _thread_cpu_time_enabled = true;
87 }
89 _thread_allocated_memory_enabled = true; // Always on, so enable it
90 }
92 void ThreadService::reset_peak_thread_count() {
93 // Acquire the lock to update the peak thread count
94 // to synchronize with thread addition and removal.
95 MutexLockerEx mu(Threads_lock);
96 _peak_threads_count->set_value(get_live_thread_count());
97 }
99 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
100 // Do not count VM internal or JVMTI agent threads
101 if (thread->is_hidden_from_external_view() ||
102 thread->is_jvmti_agent_thread()) {
103 return;
104 }
106 _total_threads_count->inc();
107 _live_threads_count->inc();
109 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
110 _peak_threads_count->set_value(_live_threads_count->get_value());
111 }
113 if (daemon) {
114 _daemon_threads_count->inc();
115 }
116 }
118 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
119 Atomic::dec((jint*) &_exiting_threads_count);
121 if (thread->is_hidden_from_external_view() ||
122 thread->is_jvmti_agent_thread()) {
123 return;
124 }
126 _live_threads_count->set_value(_live_threads_count->get_value() - 1);
128 if (daemon) {
129 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
130 Atomic::dec((jint*) &_exiting_daemon_threads_count);
131 }
132 }
134 void ThreadService::current_thread_exiting(JavaThread* jt) {
135 assert(jt == JavaThread::current(), "Called by current thread");
136 Atomic::inc((jint*) &_exiting_threads_count);
138 oop threadObj = jt->threadObj();
139 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
140 Atomic::inc((jint*) &_exiting_daemon_threads_count);
141 }
142 }
144 // FIXME: JVMTI should call this function
145 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
146 assert(thread != NULL, "should be non-NULL");
147 assert(Threads_lock->owned_by_self(), "must grab Threads_lock or be at safepoint");
149 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
151 oop obj = NULL;
152 if (wait_obj != NULL) {
153 // thread is doing an Object.wait() call
154 obj = (oop) wait_obj->object();
155 assert(obj != NULL, "Object.wait() should have an object");
156 } else {
157 ObjectMonitor *enter_obj = thread->current_pending_monitor();
158 if (enter_obj != NULL) {
159 // thread is trying to enter() or raw_enter() an ObjectMonitor.
160 obj = (oop) enter_obj->object();
161 }
162 // If obj == NULL, then ObjectMonitor is raw which doesn't count.
163 }
165 Handle h(obj);
166 return h;
167 }
169 bool ThreadService::set_thread_monitoring_contention(bool flag) {
170 MutexLocker m(Management_lock);
172 bool prev = _thread_monitoring_contention_enabled;
173 _thread_monitoring_contention_enabled = flag;
175 return prev;
176 }
178 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
179 MutexLocker m(Management_lock);
181 bool prev = _thread_cpu_time_enabled;
182 _thread_cpu_time_enabled = flag;
184 return prev;
185 }
187 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
188 MutexLocker m(Management_lock);
190 bool prev = _thread_allocated_memory_enabled;
191 _thread_allocated_memory_enabled = flag;
193 return prev;
194 }
196 // GC support
197 void ThreadService::oops_do(OopClosure* f) {
198 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
199 dump->oops_do(f);
200 }
201 }
203 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
204 MutexLocker ml(Management_lock);
205 if (_threaddump_list == NULL) {
206 _threaddump_list = dump;
207 } else {
208 dump->set_next(_threaddump_list);
209 _threaddump_list = dump;
210 }
211 }
213 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
214 MutexLocker ml(Management_lock);
216 ThreadDumpResult* prev = NULL;
217 bool found = false;
218 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
219 if (d == dump) {
220 if (prev == NULL) {
221 _threaddump_list = dump->next();
222 } else {
223 prev->set_next(dump->next());
224 }
225 found = true;
226 break;
227 }
228 }
229 assert(found, "The threaddump result to be removed must exist.");
230 }
232 // Dump stack trace of threads specified in the given threads array.
233 // Returns StackTraceElement[][] each element is the stack trace of a thread in
234 // the corresponding entry in the given threads array
235 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
236 int num_threads,
237 TRAPS) {
238 assert(num_threads > 0, "just checking");
240 ThreadDumpResult dump_result;
241 VM_ThreadDump op(&dump_result,
242 threads,
243 num_threads,
244 -1, /* entire stack */
245 false, /* with locked monitors */
246 false /* with locked synchronizers */);
247 VMThread::execute(&op);
249 // Allocate the resulting StackTraceElement[][] object
251 ResourceMark rm(THREAD);
252 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
253 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
254 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
255 objArrayHandle result_obj(THREAD, r);
257 int num_snapshots = dump_result.num_snapshots();
258 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
259 int i = 0;
260 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
261 ThreadStackTrace* stacktrace = ts->get_stack_trace();
262 if (stacktrace == NULL) {
263 // No stack trace
264 result_obj->obj_at_put(i, NULL);
265 } else {
266 // Construct an array of java/lang/StackTraceElement object
267 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
268 result_obj->obj_at_put(i, backtrace_h());
269 }
270 }
272 return result_obj;
273 }
275 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
276 ThreadStatistics* stat = thread->get_thread_stat();
277 if (stat != NULL) {
278 stat->reset_count_stat();
279 }
280 }
282 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
283 ThreadStatistics* stat = thread->get_thread_stat();
284 if (stat != NULL) {
285 stat->reset_time_stat();
286 }
287 }
289 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
290 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) {
291 // This code was modified from the original Threads::find_deadlocks code.
292 int globalDfn = 0, thisDfn;
293 ObjectMonitor* waitingToLockMonitor = NULL;
294 oop waitingToLockBlocker = NULL;
295 bool blocked_on_monitor = false;
296 JavaThread *currentThread, *previousThread;
297 int num_deadlocks = 0;
299 for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) {
300 // Initialize the depth-first-number
301 p->set_depth_first_number(-1);
302 }
304 DeadlockCycle* deadlocks = NULL;
305 DeadlockCycle* last = NULL;
306 DeadlockCycle* cycle = new DeadlockCycle();
307 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
308 if (jt->depth_first_number() >= 0) {
309 // this thread was already visited
310 continue;
311 }
313 thisDfn = globalDfn;
314 jt->set_depth_first_number(globalDfn++);
315 previousThread = jt;
316 currentThread = jt;
318 cycle->reset();
320 // When there is a deadlock, all the monitors involved in the dependency
321 // cycle must be contended and heavyweight. So we only care about the
322 // heavyweight monitor a thread is waiting to lock.
323 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
324 if (concurrent_locks) {
325 waitingToLockBlocker = jt->current_park_blocker();
326 }
327 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
328 cycle->add_thread(currentThread);
329 if (waitingToLockMonitor != NULL) {
330 address currentOwner = (address)waitingToLockMonitor->owner();
331 if (currentOwner != NULL) {
332 currentThread = Threads::owning_thread_from_monitor_owner(
333 currentOwner,
334 false /* no locking needed */);
335 if (currentThread == NULL) {
336 // This function is called at a safepoint so the JavaThread
337 // that owns waitingToLockMonitor should be findable, but
338 // if it is not findable, then the previous currentThread is
339 // blocked permanently. We record this as a deadlock.
340 num_deadlocks++;
342 cycle->set_deadlock(true);
344 // add this cycle to the deadlocks list
345 if (deadlocks == NULL) {
346 deadlocks = cycle;
347 } else {
348 last->set_next(cycle);
349 }
350 last = cycle;
351 cycle = new DeadlockCycle();
352 break;
353 }
354 }
355 } else {
356 if (concurrent_locks) {
357 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
358 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
359 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
360 } else {
361 currentThread = NULL;
362 }
363 }
364 }
366 if (currentThread == NULL) {
367 // No dependency on another thread
368 break;
369 }
370 if (currentThread->depth_first_number() < 0) {
371 // First visit to this thread
372 currentThread->set_depth_first_number(globalDfn++);
373 } else if (currentThread->depth_first_number() < thisDfn) {
374 // Thread already visited, and not on a (new) cycle
375 break;
376 } else if (currentThread == previousThread) {
377 // Self-loop, ignore
378 break;
379 } else {
380 // We have a (new) cycle
381 num_deadlocks++;
383 cycle->set_deadlock(true);
385 // add this cycle to the deadlocks list
386 if (deadlocks == NULL) {
387 deadlocks = cycle;
388 } else {
389 last->set_next(cycle);
390 }
391 last = cycle;
392 cycle = new DeadlockCycle();
393 break;
394 }
395 previousThread = currentThread;
396 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
397 if (concurrent_locks) {
398 waitingToLockBlocker = currentThread->current_park_blocker();
399 }
400 }
402 }
403 delete cycle;
404 return deadlocks;
405 }
407 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
409 // Create a new ThreadDumpResult object and append to the list.
410 // If GC happens before this function returns, Method*
411 // in the stack trace will be visited.
412 ThreadService::add_thread_dump(this);
413 }
415 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
416 // Create a new ThreadDumpResult object and append to the list.
417 // If GC happens before this function returns, oops
418 // will be visited.
419 ThreadService::add_thread_dump(this);
420 }
422 ThreadDumpResult::~ThreadDumpResult() {
423 ThreadService::remove_thread_dump(this);
425 // free all the ThreadSnapshot objects created during
426 // the VM_ThreadDump operation
427 ThreadSnapshot* ts = _snapshots;
428 while (ts != NULL) {
429 ThreadSnapshot* p = ts;
430 ts = ts->next();
431 delete p;
432 }
433 }
436 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
437 assert(_num_threads == 0 || _num_snapshots < _num_threads,
438 "_num_snapshots must be less than _num_threads");
439 _num_snapshots++;
440 if (_snapshots == NULL) {
441 _snapshots = ts;
442 } else {
443 _last->set_next(ts);
444 }
445 _last = ts;
446 }
448 void ThreadDumpResult::oops_do(OopClosure* f) {
449 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
450 ts->oops_do(f);
451 }
452 }
454 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
455 _method = jvf->method();
456 _bci = jvf->bci();
457 _locked_monitors = NULL;
458 if (with_lock_info) {
459 ResourceMark rm;
460 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
461 int length = list->length();
462 if (length > 0) {
463 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
464 for (int i = 0; i < length; i++) {
465 MonitorInfo* monitor = list->at(i);
466 assert(monitor->owner(), "This monitor must have an owning object");
467 _locked_monitors->append(monitor->owner());
468 }
469 }
470 }
471 }
473 void StackFrameInfo::oops_do(OopClosure* f) {
474 if (_locked_monitors != NULL) {
475 int length = _locked_monitors->length();
476 for (int i = 0; i < length; i++) {
477 f->do_oop((oop*) _locked_monitors->adr_at(i));
478 }
479 }
480 }
482 void StackFrameInfo::print_on(outputStream* st) const {
483 ResourceMark rm;
484 java_lang_Throwable::print_stack_element(st, method(), bci());
485 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
486 for (int i = 0; i < len; i++) {
487 oop o = _locked_monitors->at(i);
488 InstanceKlass* ik = InstanceKlass::cast(o->klass());
489 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", (address)o, ik->external_name());
490 }
492 }
494 // Iterate through monitor cache to find JNI locked monitors
495 class InflatedMonitorsClosure: public MonitorClosure {
496 private:
497 ThreadStackTrace* _stack_trace;
498 Thread* _thread;
499 public:
500 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
501 _thread = t;
502 _stack_trace = st;
503 }
504 void do_monitor(ObjectMonitor* mid) {
505 if (mid->owner() == _thread) {
506 oop object = (oop) mid->object();
507 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
508 _stack_trace->add_jni_locked_monitor(object);
509 }
510 }
511 }
512 };
514 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
515 _thread = t;
516 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
517 _depth = 0;
518 _with_locked_monitors = with_locked_monitors;
519 if (_with_locked_monitors) {
520 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
521 } else {
522 _jni_locked_monitors = NULL;
523 }
524 }
526 ThreadStackTrace::~ThreadStackTrace() {
527 for (int i = 0; i < _frames->length(); i++) {
528 delete _frames->at(i);
529 }
530 delete _frames;
531 if (_jni_locked_monitors != NULL) {
532 delete _jni_locked_monitors;
533 }
534 }
536 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
537 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
539 if (_thread->has_last_Java_frame()) {
540 RegisterMap reg_map(_thread);
541 vframe* start_vf = _thread->last_java_vframe(®_map);
542 int count = 0;
543 for (vframe* f = start_vf; f; f = f->sender() ) {
544 if (f->is_java_frame()) {
545 javaVFrame* jvf = javaVFrame::cast(f);
546 add_stack_frame(jvf);
547 count++;
548 } else {
549 // Ignore non-Java frames
550 }
551 if (maxDepth > 0 && count == maxDepth) {
552 // Skip frames if more than maxDepth
553 break;
554 }
555 }
556 }
558 if (_with_locked_monitors) {
559 // Iterate inflated monitors and find monitors locked by this thread
560 // not found in the stack
561 InflatedMonitorsClosure imc(_thread, this);
562 ObjectSynchronizer::monitors_iterate(&imc);
563 }
564 }
567 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
568 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
570 bool found = false;
571 int num_frames = get_stack_depth();
572 for (int depth = 0; depth < num_frames; depth++) {
573 StackFrameInfo* frame = stack_frame_at(depth);
574 int len = frame->num_locked_monitors();
575 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
576 for (int j = 0; j < len; j++) {
577 oop monitor = locked_monitors->at(j);
578 assert(monitor != NULL && monitor->is_instance(), "must be a Java object");
579 if (monitor == object) {
580 found = true;
581 break;
582 }
583 }
584 }
585 return found;
586 }
588 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
589 Klass* k = SystemDictionary::StackTraceElement_klass();
590 assert(k != NULL, "must be loaded in 1.4+");
591 instanceKlassHandle ik(THREAD, k);
593 // Allocate an array of java/lang/StackTraceElement object
594 objArrayOop ste = oopFactory::new_objArray(ik(), _depth, CHECK_NH);
595 objArrayHandle backtrace(THREAD, ste);
596 for (int j = 0; j < _depth; j++) {
597 StackFrameInfo* frame = _frames->at(j);
598 methodHandle mh(THREAD, frame->method());
599 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
600 backtrace->obj_at_put(j, element);
601 }
602 return backtrace;
603 }
605 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
606 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
607 _frames->append(frame);
608 _depth++;
609 }
611 void ThreadStackTrace::oops_do(OopClosure* f) {
612 int length = _frames->length();
613 for (int i = 0; i < length; i++) {
614 _frames->at(i)->oops_do(f);
615 }
617 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
618 for (int j = 0; j < length; j++) {
619 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
620 }
621 }
623 ConcurrentLocksDump::~ConcurrentLocksDump() {
624 if (_retain_map_on_free) {
625 return;
626 }
628 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
629 ThreadConcurrentLocks* tcl = t;
630 t = t->next();
631 delete tcl;
632 }
633 }
635 void ConcurrentLocksDump::dump_at_safepoint() {
636 // dump all locked concurrent locks
637 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
639 if (JDK_Version::is_gte_jdk16x_version()) {
640 ResourceMark rm;
642 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE);
644 // Find all instances of AbstractOwnableSynchronizer
645 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(),
646 aos_objects);
647 // Build a map of thread to its owned AQS locks
648 build_map(aos_objects);
649 }
650 }
653 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
654 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
655 int length = aos_objects->length();
656 for (int i = 0; i < length; i++) {
657 oop o = aos_objects->at(i);
658 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
659 if (owner_thread_obj != NULL) {
660 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
661 assert(o->is_instance(), "Must be an instanceOop");
662 add_lock(thread, (instanceOop) o);
663 }
664 }
665 }
667 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
668 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
669 if (tcl != NULL) {
670 tcl->add_lock(o);
671 return;
672 }
674 // First owned lock found for this thread
675 tcl = new ThreadConcurrentLocks(thread);
676 tcl->add_lock(o);
677 if (_map == NULL) {
678 _map = tcl;
679 } else {
680 _last->set_next(tcl);
681 }
682 _last = tcl;
683 }
685 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
686 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
687 if (tcl->java_thread() == thread) {
688 return tcl;
689 }
690 }
691 return NULL;
692 }
694 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
695 st->print_cr(" Locked ownable synchronizers:");
696 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
697 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
698 if (locks == NULL || locks->is_empty()) {
699 st->print_cr("\t- None");
700 st->cr();
701 return;
702 }
704 for (int i = 0; i < locks->length(); i++) {
705 instanceOop obj = locks->at(i);
706 InstanceKlass* ik = InstanceKlass::cast(obj->klass());
707 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", (address)obj, ik->external_name());
708 }
709 st->cr();
710 }
712 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
713 _thread = thread;
714 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
715 _next = NULL;
716 }
718 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
719 delete _owned_locks;
720 }
722 void ThreadConcurrentLocks::add_lock(instanceOop o) {
723 _owned_locks->append(o);
724 }
726 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
727 int length = _owned_locks->length();
728 for (int i = 0; i < length; i++) {
729 f->do_oop((oop*) _owned_locks->adr_at(i));
730 }
731 }
733 ThreadStatistics::ThreadStatistics() {
734 _contended_enter_count = 0;
735 _monitor_wait_count = 0;
736 _sleep_count = 0;
737 _count_pending_reset = false;
738 _timer_pending_reset = false;
739 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
740 }
742 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) {
743 _thread = thread;
744 _threadObj = thread->threadObj();
745 _stack_trace = NULL;
746 _concurrent_locks = NULL;
747 _next = NULL;
749 ThreadStatistics* stat = thread->get_thread_stat();
750 _contended_enter_ticks = stat->contended_enter_ticks();
751 _contended_enter_count = stat->contended_enter_count();
752 _monitor_wait_ticks = stat->monitor_wait_ticks();
753 _monitor_wait_count = stat->monitor_wait_count();
754 _sleep_ticks = stat->sleep_ticks();
755 _sleep_count = stat->sleep_count();
757 _blocker_object = NULL;
758 _blocker_object_owner = NULL;
760 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
761 _is_ext_suspended = thread->is_being_ext_suspended();
762 _is_in_native = (thread->thread_state() == _thread_in_native);
764 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
765 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
766 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
768 Handle obj = ThreadService::get_current_contended_monitor(thread);
769 if (obj() == NULL) {
770 // monitor no longer exists; thread is not blocked
771 _thread_status = java_lang_Thread::RUNNABLE;
772 } else {
773 _blocker_object = obj();
774 JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false);
775 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
776 || (owner != NULL && owner->is_attaching_via_jni())) {
777 // ownership information of the monitor is not available
778 // (may no longer be owned or releasing to some other thread)
779 // make this thread in RUNNABLE state.
780 // And when the owner thread is in attaching state, the java thread
781 // is not completely initialized. For example thread name and id
782 // and may not be set, so hide the attaching thread.
783 _thread_status = java_lang_Thread::RUNNABLE;
784 _blocker_object = NULL;
785 } else if (owner != NULL) {
786 _blocker_object_owner = owner->threadObj();
787 }
788 }
789 }
791 // Support for JSR-166 locks
792 if (JDK_Version::current().supports_thread_park_blocker() &&
793 (_thread_status == java_lang_Thread::PARKED ||
794 _thread_status == java_lang_Thread::PARKED_TIMED)) {
796 _blocker_object = thread->current_park_blocker();
797 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
798 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
799 }
800 }
801 }
803 ThreadSnapshot::~ThreadSnapshot() {
804 delete _stack_trace;
805 delete _concurrent_locks;
806 }
808 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
809 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
810 _stack_trace->dump_stack_at_safepoint(max_depth);
811 }
814 void ThreadSnapshot::oops_do(OopClosure* f) {
815 f->do_oop(&_threadObj);
816 f->do_oop(&_blocker_object);
817 f->do_oop(&_blocker_object_owner);
818 if (_stack_trace != NULL) {
819 _stack_trace->oops_do(f);
820 }
821 if (_concurrent_locks != NULL) {
822 _concurrent_locks->oops_do(f);
823 }
824 }
826 DeadlockCycle::DeadlockCycle() {
827 _is_deadlock = false;
828 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
829 _next = NULL;
830 }
832 DeadlockCycle::~DeadlockCycle() {
833 delete _threads;
834 }
836 void DeadlockCycle::print_on(outputStream* st) const {
837 st->cr();
838 st->print_cr("Found one Java-level deadlock:");
839 st->print("=============================");
841 JavaThread* currentThread;
842 ObjectMonitor* waitingToLockMonitor;
843 oop waitingToLockBlocker;
844 int len = _threads->length();
845 for (int i = 0; i < len; i++) {
846 currentThread = _threads->at(i);
847 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
848 waitingToLockBlocker = currentThread->current_park_blocker();
849 st->cr();
850 st->print_cr("\"%s\":", currentThread->get_thread_name());
851 const char* owner_desc = ",\n which is held by";
852 if (waitingToLockMonitor != NULL) {
853 st->print(" waiting to lock monitor " INTPTR_FORMAT, waitingToLockMonitor);
854 oop obj = (oop)waitingToLockMonitor->object();
855 if (obj != NULL) {
856 st->print(" (object "INTPTR_FORMAT ", a %s)", (address)obj,
857 (InstanceKlass::cast(obj->klass()))->external_name());
859 if (!currentThread->current_pending_monitor_is_from_java()) {
860 owner_desc = "\n in JNI, which is held by";
861 }
862 } else {
863 // No Java object associated - a JVMTI raw monitor
864 owner_desc = " (JVMTI raw monitor),\n which is held by";
865 }
866 currentThread = Threads::owning_thread_from_monitor_owner(
867 (address)waitingToLockMonitor->owner(),
868 false /* no locking needed */);
869 if (currentThread == NULL) {
870 // The deadlock was detected at a safepoint so the JavaThread
871 // that owns waitingToLockMonitor should be findable, but
872 // if it is not findable, then the previous currentThread is
873 // blocked permanently.
874 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
875 (address)waitingToLockMonitor->owner());
876 continue;
877 }
878 } else {
879 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
880 (address)waitingToLockBlocker,
881 (InstanceKlass::cast(waitingToLockBlocker->klass()))->external_name());
882 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()),
883 "Must be an AbstractOwnableSynchronizer");
884 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
885 currentThread = java_lang_Thread::thread(ownerObj);
886 }
887 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
888 }
890 st->cr();
891 st->cr();
893 // Print stack traces
894 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
895 JavaMonitorsInStackTrace = true;
896 st->print_cr("Java stack information for the threads listed above:");
897 st->print_cr("===================================================");
898 for (int j = 0; j < len; j++) {
899 currentThread = _threads->at(j);
900 st->print_cr("\"%s\":", currentThread->get_thread_name());
901 currentThread->print_stack_on(st);
902 }
903 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
904 }
906 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
907 bool include_jvmti_agent_threads,
908 bool include_jni_attaching_threads) {
909 assert(cur_thread == Thread::current(), "Check current thread");
911 int init_size = ThreadService::get_live_thread_count();
912 _threads_array = new GrowableArray<instanceHandle>(init_size);
914 MutexLockerEx ml(Threads_lock);
916 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
917 // skips JavaThreads in the process of exiting
918 // and also skips VM internal JavaThreads
919 // Threads in _thread_new or _thread_new_trans state are included.
920 // i.e. threads have been started but not yet running.
921 if (jt->threadObj() == NULL ||
922 jt->is_exiting() ||
923 !java_lang_Thread::is_alive(jt->threadObj()) ||
924 jt->is_hidden_from_external_view()) {
925 continue;
926 }
928 // skip agent threads
929 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
930 continue;
931 }
933 // skip jni threads in the process of attaching
934 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
935 continue;
936 }
938 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
939 _threads_array->append(h);
940 }
941 }