1 /*
2 * Copyright (c) 2003, 2014, 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.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
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/atomic.inline.hpp"
33 #include "runtime/handles.inline.hpp"
34 #include "runtime/init.hpp"
35 #include "runtime/thread.hpp"
36 #include "runtime/vframe.hpp"
37 #include "runtime/thread.inline.hpp"
38 #include "runtime/vmThread.hpp"
39 #include "runtime/vm_operations.hpp"
40 #include "services/threadService.hpp"
41
42 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
43
44 // TODO: we need to define a naming convention for perf counters
45 // to distinguish counters for:
46 // - standard JSR174 use
47 // - Hotspot extension (public and committed)
48 // - Hotspot extension (private/internal and uncommitted)
49
50 // Default is disabled.
51 bool ThreadService::_thread_monitoring_contention_enabled = false;
52 bool ThreadService::_thread_cpu_time_enabled = false;
53 bool ThreadService::_thread_allocated_memory_enabled = false;
54
55 PerfCounter* ThreadService::_total_threads_count = NULL;
56 PerfVariable* ThreadService::_live_threads_count = NULL;
57 PerfVariable* ThreadService::_peak_threads_count = NULL;
58 PerfVariable* ThreadService::_daemon_threads_count = NULL;
59 volatile int ThreadService::_exiting_threads_count = 0;
60 volatile int ThreadService::_exiting_daemon_threads_count = 0;
61
62 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
63
64 static const int INITIAL_ARRAY_SIZE = 10;
65
66 void ThreadService::init() {
67 EXCEPTION_MARK;
68
69 // These counters are for java.lang.management API support.
70 // They are created even if -XX:-UsePerfData is set and in
71 // that case, they will be allocated on C heap.
72
73 _total_threads_count =
74 PerfDataManager::create_counter(JAVA_THREADS, "started",
75 PerfData::U_Events, CHECK);
76
77 _live_threads_count =
78 PerfDataManager::create_variable(JAVA_THREADS, "live",
79 PerfData::U_None, CHECK);
80
81 _peak_threads_count =
82 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
83 PerfData::U_None, CHECK);
84
85 _daemon_threads_count =
86 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
87 PerfData::U_None, CHECK);
88
89 if (os::is_thread_cpu_time_supported()) {
90 _thread_cpu_time_enabled = true;
91 }
92
93 _thread_allocated_memory_enabled = true; // Always on, so enable it
94 }
95
96 void ThreadService::reset_peak_thread_count() {
97 // Acquire the lock to update the peak thread count
98 // to synchronize with thread addition and removal.
99 MutexLockerEx mu(Threads_lock);
100 _peak_threads_count->set_value(get_live_thread_count());
101 }
102
103 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
104 // Do not count VM internal or JVMTI agent threads
105 if (thread->is_hidden_from_external_view() ||
106 thread->is_jvmti_agent_thread()) {
107 return;
108 }
109
110 _total_threads_count->inc();
111 _live_threads_count->inc();
112
113 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
114 _peak_threads_count->set_value(_live_threads_count->get_value());
115 }
116
117 if (daemon) {
118 _daemon_threads_count->inc();
119 }
120 }
121
122 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
123 Atomic::dec((jint*) &_exiting_threads_count);
124
125 if (thread->is_hidden_from_external_view() ||
126 thread->is_jvmti_agent_thread()) {
127 return;
128 }
129
130 _live_threads_count->set_value(_live_threads_count->get_value() - 1);
131
132 if (daemon) {
133 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
134 Atomic::dec((jint*) &_exiting_daemon_threads_count);
135 }
136 }
137
138 void ThreadService::current_thread_exiting(JavaThread* jt) {
139 assert(jt == JavaThread::current(), "Called by current thread");
140 Atomic::inc((jint*) &_exiting_threads_count);
141
142 oop threadObj = jt->threadObj();
143 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
144 Atomic::inc((jint*) &_exiting_daemon_threads_count);
145 }
146 }
147
148 // FIXME: JVMTI should call this function
149 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
150 assert(thread != NULL, "should be non-NULL");
151 assert(Threads_lock->owned_by_self(), "must grab Threads_lock or be at safepoint");
152
153 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
154
155 oop obj = NULL;
156 if (wait_obj != NULL) {
157 // thread is doing an Object.wait() call
158 obj = (oop) wait_obj->object();
159 assert(obj != NULL, "Object.wait() should have an object");
160 } else {
161 ObjectMonitor *enter_obj = thread->current_pending_monitor();
162 if (enter_obj != NULL) {
163 // thread is trying to enter() or raw_enter() an ObjectMonitor.
164 obj = (oop) enter_obj->object();
165 }
166 // If obj == NULL, then ObjectMonitor is raw which doesn't count.
167 }
168
169 obj = oopDesc::bs()->write_barrier(obj);
170 Handle h(obj);
171 return h;
172 }
173
174 bool ThreadService::set_thread_monitoring_contention(bool flag) {
175 MutexLocker m(Management_lock);
176
177 bool prev = _thread_monitoring_contention_enabled;
178 _thread_monitoring_contention_enabled = flag;
179
180 return prev;
181 }
182
183 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
184 MutexLocker m(Management_lock);
185
186 bool prev = _thread_cpu_time_enabled;
187 _thread_cpu_time_enabled = flag;
188
189 return prev;
190 }
191
192 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
193 MutexLocker m(Management_lock);
194
195 bool prev = _thread_allocated_memory_enabled;
196 _thread_allocated_memory_enabled = flag;
197
198 return prev;
199 }
200
201 // GC support
202 void ThreadService::oops_do(OopClosure* f) {
203 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
204 dump->oops_do(f);
205 }
206 }
207
208 void ThreadService::metadata_do(void f(Metadata*)) {
209 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
210 dump->metadata_do(f);
211 }
212 }
213
214 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
215 MutexLocker ml(Management_lock);
216 if (_threaddump_list == NULL) {
217 _threaddump_list = dump;
218 } else {
219 dump->set_next(_threaddump_list);
220 _threaddump_list = dump;
221 }
222 }
223
224 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
225 MutexLocker ml(Management_lock);
226
227 ThreadDumpResult* prev = NULL;
228 bool found = false;
229 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
230 if (d == dump) {
231 if (prev == NULL) {
232 _threaddump_list = dump->next();
233 } else {
234 prev->set_next(dump->next());
235 }
236 found = true;
237 break;
238 }
239 }
240 assert(found, "The threaddump result to be removed must exist.");
241 }
242
243 // Dump stack trace of threads specified in the given threads array.
244 // Returns StackTraceElement[][] each element is the stack trace of a thread in
245 // the corresponding entry in the given threads array
246 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
247 int num_threads,
248 TRAPS) {
249 assert(num_threads > 0, "just checking");
250
251 ThreadDumpResult dump_result;
252 VM_ThreadDump op(&dump_result,
253 threads,
254 num_threads,
255 -1, /* entire stack */
256 false, /* with locked monitors */
257 false /* with locked synchronizers */);
258 VMThread::execute(&op);
259
260 // Allocate the resulting StackTraceElement[][] object
261
262 ResourceMark rm(THREAD);
263 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
264 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
265 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
266 objArrayHandle result_obj(THREAD, r);
267
268 int num_snapshots = dump_result.num_snapshots();
269 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
270 int i = 0;
271 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
272 ThreadStackTrace* stacktrace = ts->get_stack_trace();
273 if (stacktrace == NULL) {
274 // No stack trace
275 result_obj->obj_at_put(i, NULL);
276 } else {
277 // Construct an array of java/lang/StackTraceElement object
278 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
279 result_obj->obj_at_put(i, backtrace_h());
280 }
281 }
282
283 return result_obj;
284 }
285
286 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
287 ThreadStatistics* stat = thread->get_thread_stat();
288 if (stat != NULL) {
289 stat->reset_count_stat();
290 }
291 }
292
293 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
294 ThreadStatistics* stat = thread->get_thread_stat();
295 if (stat != NULL) {
296 stat->reset_time_stat();
297 }
298 }
299
300 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
301 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) {
302 // This code was modified from the original Threads::find_deadlocks code.
303 int globalDfn = 0, thisDfn;
304 ObjectMonitor* waitingToLockMonitor = NULL;
305 oop waitingToLockBlocker = NULL;
306 bool blocked_on_monitor = false;
307 JavaThread *currentThread, *previousThread;
308 int num_deadlocks = 0;
309
310 for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) {
311 // Initialize the depth-first-number
312 p->set_depth_first_number(-1);
313 }
314
315 DeadlockCycle* deadlocks = NULL;
316 DeadlockCycle* last = NULL;
317 DeadlockCycle* cycle = new DeadlockCycle();
318 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
319 if (jt->depth_first_number() >= 0) {
320 // this thread was already visited
321 continue;
322 }
323
324 thisDfn = globalDfn;
325 jt->set_depth_first_number(globalDfn++);
326 previousThread = jt;
327 currentThread = jt;
328
329 cycle->reset();
330
331 // When there is a deadlock, all the monitors involved in the dependency
332 // cycle must be contended and heavyweight. So we only care about the
333 // heavyweight monitor a thread is waiting to lock.
334 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
335 if (concurrent_locks) {
336 waitingToLockBlocker = jt->current_park_blocker();
337 }
338 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
339 cycle->add_thread(currentThread);
340 if (waitingToLockMonitor != NULL) {
341 address currentOwner = (address)waitingToLockMonitor->owner();
342 if (currentOwner != NULL) {
343 currentThread = Threads::owning_thread_from_monitor_owner(
344 currentOwner,
345 false /* no locking needed */);
346 if (currentThread == NULL) {
347 // This function is called at a safepoint so the JavaThread
348 // that owns waitingToLockMonitor should be findable, but
349 // if it is not findable, then the previous currentThread is
350 // blocked permanently. We record this as a deadlock.
351 num_deadlocks++;
352
353 cycle->set_deadlock(true);
354
355 // add this cycle to the deadlocks list
356 if (deadlocks == NULL) {
357 deadlocks = cycle;
358 } else {
359 last->set_next(cycle);
360 }
361 last = cycle;
362 cycle = new DeadlockCycle();
363 break;
364 }
365 }
366 } else {
367 if (concurrent_locks) {
368 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
369 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
370 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
371 } else {
372 currentThread = NULL;
373 }
374 }
375 }
376
377 if (currentThread == NULL) {
378 // No dependency on another thread
379 break;
380 }
381 if (currentThread->depth_first_number() < 0) {
382 // First visit to this thread
383 currentThread->set_depth_first_number(globalDfn++);
384 } else if (currentThread->depth_first_number() < thisDfn) {
385 // Thread already visited, and not on a (new) cycle
386 break;
387 } else if (currentThread == previousThread) {
388 // Self-loop, ignore
389 break;
390 } else {
391 // We have a (new) cycle
392 num_deadlocks++;
393
394 cycle->set_deadlock(true);
395
396 // add this cycle to the deadlocks list
397 if (deadlocks == NULL) {
398 deadlocks = cycle;
399 } else {
400 last->set_next(cycle);
401 }
402 last = cycle;
403 cycle = new DeadlockCycle();
404 break;
405 }
406 previousThread = currentThread;
407 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
408 if (concurrent_locks) {
409 waitingToLockBlocker = currentThread->current_park_blocker();
410 }
411 }
412
413 }
414 delete cycle;
415 return deadlocks;
416 }
417
418 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
419
420 // Create a new ThreadDumpResult object and append to the list.
421 // If GC happens before this function returns, Method*
422 // in the stack trace will be visited.
423 ThreadService::add_thread_dump(this);
424 }
425
426 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
427 // Create a new ThreadDumpResult object and append to the list.
428 // If GC happens before this function returns, oops
429 // will be visited.
430 ThreadService::add_thread_dump(this);
431 }
432
433 ThreadDumpResult::~ThreadDumpResult() {
434 ThreadService::remove_thread_dump(this);
435
436 // free all the ThreadSnapshot objects created during
437 // the VM_ThreadDump operation
438 ThreadSnapshot* ts = _snapshots;
439 while (ts != NULL) {
440 ThreadSnapshot* p = ts;
441 ts = ts->next();
442 delete p;
443 }
444 }
445
446
447 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
448 assert(_num_threads == 0 || _num_snapshots < _num_threads,
449 "_num_snapshots must be less than _num_threads");
450 _num_snapshots++;
451 if (_snapshots == NULL) {
452 _snapshots = ts;
453 } else {
454 _last->set_next(ts);
455 }
456 _last = ts;
457 }
458
459 void ThreadDumpResult::oops_do(OopClosure* f) {
460 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
461 ts->oops_do(f);
462 }
463 }
464
465 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
466 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
467 ts->metadata_do(f);
468 }
469 }
470
471 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
472 _method = jvf->method();
473 _bci = jvf->bci();
474 _class_holder = _method->method_holder()->klass_holder();
475 _locked_monitors = NULL;
476 if (with_lock_info) {
477 ResourceMark rm;
478 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
479 int length = list->length();
480 if (length > 0) {
481 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
482 for (int i = 0; i < length; i++) {
483 MonitorInfo* monitor = list->at(i);
484 assert(monitor->owner(), "This monitor must have an owning object");
485 _locked_monitors->append(monitor->owner());
486 }
487 }
488 }
489 }
490
491 void StackFrameInfo::oops_do(OopClosure* f) {
492 if (_locked_monitors != NULL) {
493 int length = _locked_monitors->length();
494 for (int i = 0; i < length; i++) {
495 f->do_oop((oop*) _locked_monitors->adr_at(i));
496 }
497 }
498 f->do_oop(&_class_holder);
499 }
500
501 void StackFrameInfo::metadata_do(void f(Metadata*)) {
502 f(_method);
503 }
504
505 void StackFrameInfo::print_on(outputStream* st) const {
506 ResourceMark rm;
507 java_lang_Throwable::print_stack_element(st, method(), bci());
508 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
509 for (int i = 0; i < len; i++) {
510 oop o = _locked_monitors->at(i);
511 InstanceKlass* ik = InstanceKlass::cast(o->klass());
512 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", (address)o, ik->external_name());
513 }
514
515 }
516
517 // Iterate through monitor cache to find JNI locked monitors
518 class InflatedMonitorsClosure: public MonitorClosure {
519 private:
520 ThreadStackTrace* _stack_trace;
521 Thread* _thread;
522 public:
523 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
524 _thread = t;
525 _stack_trace = st;
526 }
527 void do_monitor(ObjectMonitor* mid) {
528 if (mid->owner() == _thread) {
529 oop object = (oop) mid->object();
530 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
531 _stack_trace->add_jni_locked_monitor(object);
532 }
533 }
534 }
535 };
536
537 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
538 _thread = t;
539 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
540 _depth = 0;
541 _with_locked_monitors = with_locked_monitors;
542 if (_with_locked_monitors) {
543 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
544 } else {
545 _jni_locked_monitors = NULL;
546 }
547 }
548
549 ThreadStackTrace::~ThreadStackTrace() {
550 for (int i = 0; i < _frames->length(); i++) {
551 delete _frames->at(i);
552 }
553 delete _frames;
554 if (_jni_locked_monitors != NULL) {
555 delete _jni_locked_monitors;
556 }
557 }
558
559 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
560 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
561
562 if (_thread->has_last_Java_frame()) {
563 RegisterMap reg_map(_thread);
564 vframe* start_vf = _thread->last_java_vframe(®_map);
565 int count = 0;
566 for (vframe* f = start_vf; f; f = f->sender() ) {
567 if (f->is_java_frame()) {
568 javaVFrame* jvf = javaVFrame::cast(f);
569 add_stack_frame(jvf);
570 count++;
571 } else {
572 // Ignore non-Java frames
573 }
574 if (maxDepth > 0 && count == maxDepth) {
575 // Skip frames if more than maxDepth
576 break;
577 }
578 }
579 }
580
581 if (_with_locked_monitors) {
582 // Iterate inflated monitors and find monitors locked by this thread
583 // not found in the stack
584 InflatedMonitorsClosure imc(_thread, this);
585 ObjectSynchronizer::monitors_iterate(&imc);
586 }
587 }
588
589
590 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
591 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
592
593 object = oopDesc::bs()->write_barrier(object);
594
595 bool found = false;
596 int num_frames = get_stack_depth();
597 for (int depth = 0; depth < num_frames; depth++) {
598 StackFrameInfo* frame = stack_frame_at(depth);
599 int len = frame->num_locked_monitors();
600 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
601 for (int j = 0; j < len; j++) {
602 oop monitor = locked_monitors->at(j);
603 monitor = oopDesc::bs()->write_barrier(monitor);
604 assert(monitor != NULL, "must be a Java object");
605 if (monitor == object) {
606 found = true;
607 break;
608 }
609 }
610 }
611 return found;
612 }
613
614 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
615 Klass* k = SystemDictionary::StackTraceElement_klass();
616 assert(k != NULL, "must be loaded in 1.4+");
617 instanceKlassHandle ik(THREAD, k);
618
619 // Allocate an array of java/lang/StackTraceElement object
620 objArrayOop ste = oopFactory::new_objArray(ik(), _depth, CHECK_NH);
621 objArrayHandle backtrace(THREAD, ste);
622 for (int j = 0; j < _depth; j++) {
623 StackFrameInfo* frame = _frames->at(j);
624 methodHandle mh(THREAD, frame->method());
625 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
626 backtrace->obj_at_put(j, element);
627 }
628 return backtrace;
629 }
630
631 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
632 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
633 _frames->append(frame);
634 _depth++;
635 }
636
637 void ThreadStackTrace::oops_do(OopClosure* f) {
638 int length = _frames->length();
639 for (int i = 0; i < length; i++) {
640 _frames->at(i)->oops_do(f);
641 }
642
643 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
644 for (int j = 0; j < length; j++) {
645 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
646 }
647 }
648
649 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
650 int length = _frames->length();
651 for (int i = 0; i < length; i++) {
652 _frames->at(i)->metadata_do(f);
653 }
654 }
655
656
657 ConcurrentLocksDump::~ConcurrentLocksDump() {
658 if (_retain_map_on_free) {
659 return;
660 }
661
662 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
663 ThreadConcurrentLocks* tcl = t;
664 t = t->next();
665 delete tcl;
666 }
667 }
668
669 void ConcurrentLocksDump::dump_at_safepoint() {
670 // dump all locked concurrent locks
671 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
672
673 ResourceMark rm;
674
675 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE);
676
677 // Find all instances of AbstractOwnableSynchronizer
678 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(),
679 aos_objects);
680 // Build a map of thread to its owned AQS locks
681 build_map(aos_objects);
682 }
683
684
685 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
686 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
687 int length = aos_objects->length();
688 for (int i = 0; i < length; i++) {
689 oop o = aos_objects->at(i);
690 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
691 if (owner_thread_obj != NULL) {
692 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
693 assert(o->is_instance(), "Must be an instanceOop");
694 add_lock(thread, (instanceOop) o);
695 }
696 }
697 }
698
699 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
700 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
701 if (tcl != NULL) {
702 tcl->add_lock(o);
703 return;
704 }
705
706 // First owned lock found for this thread
707 tcl = new ThreadConcurrentLocks(thread);
708 tcl->add_lock(o);
709 if (_map == NULL) {
710 _map = tcl;
711 } else {
712 _last->set_next(tcl);
713 }
714 _last = tcl;
715 }
716
717 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
718 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
719 if (tcl->java_thread() == thread) {
720 return tcl;
721 }
722 }
723 return NULL;
724 }
725
726 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
727 st->print_cr(" Locked ownable synchronizers:");
728 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
729 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
730 if (locks == NULL || locks->is_empty()) {
731 st->print_cr("\t- None");
732 st->cr();
733 return;
734 }
735
736 for (int i = 0; i < locks->length(); i++) {
737 instanceOop obj = locks->at(i);
738 InstanceKlass* ik = InstanceKlass::cast(obj->klass());
739 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", (address)obj, ik->external_name());
740 }
741 st->cr();
742 }
743
744 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
745 _thread = thread;
746 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
747 _next = NULL;
748 }
749
750 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
751 delete _owned_locks;
752 }
753
754 void ThreadConcurrentLocks::add_lock(instanceOop o) {
755 _owned_locks->append(o);
756 }
757
758 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
759 int length = _owned_locks->length();
760 for (int i = 0; i < length; i++) {
761 f->do_oop((oop*) _owned_locks->adr_at(i));
762 }
763 }
764
765 ThreadStatistics::ThreadStatistics() {
766 _contended_enter_count = 0;
767 _monitor_wait_count = 0;
768 _sleep_count = 0;
769 _count_pending_reset = false;
770 _timer_pending_reset = false;
771 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
772 }
773
774 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) {
775 _thread = thread;
776 _threadObj = thread->threadObj();
777 _stack_trace = NULL;
778 _concurrent_locks = NULL;
779 _next = NULL;
780
781 ThreadStatistics* stat = thread->get_thread_stat();
782 _contended_enter_ticks = stat->contended_enter_ticks();
783 _contended_enter_count = stat->contended_enter_count();
784 _monitor_wait_ticks = stat->monitor_wait_ticks();
785 _monitor_wait_count = stat->monitor_wait_count();
786 _sleep_ticks = stat->sleep_ticks();
787 _sleep_count = stat->sleep_count();
788
789 _blocker_object = NULL;
790 _blocker_object_owner = NULL;
791
792 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
793 _is_ext_suspended = thread->is_being_ext_suspended();
794 _is_in_native = (thread->thread_state() == _thread_in_native);
795
796 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
797 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
798 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
799
800 Handle obj = ThreadService::get_current_contended_monitor(thread);
801 if (obj() == NULL) {
802 // monitor no longer exists; thread is not blocked
803 _thread_status = java_lang_Thread::RUNNABLE;
804 } else {
805 _blocker_object = obj();
806 JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false);
807 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
808 || (owner != NULL && owner->is_attaching_via_jni())) {
809 // ownership information of the monitor is not available
810 // (may no longer be owned or releasing to some other thread)
811 // make this thread in RUNNABLE state.
812 // And when the owner thread is in attaching state, the java thread
813 // is not completely initialized. For example thread name and id
814 // and may not be set, so hide the attaching thread.
815 _thread_status = java_lang_Thread::RUNNABLE;
816 _blocker_object = NULL;
817 } else if (owner != NULL) {
818 _blocker_object_owner = owner->threadObj();
819 }
820 }
821 }
822
823 // Support for JSR-166 locks
824 if (JDK_Version::current().supports_thread_park_blocker() &&
825 (_thread_status == java_lang_Thread::PARKED ||
826 _thread_status == java_lang_Thread::PARKED_TIMED)) {
827
828 _blocker_object = thread->current_park_blocker();
829 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
830 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
831 }
832 }
833 }
834
835 ThreadSnapshot::~ThreadSnapshot() {
836 delete _stack_trace;
837 delete _concurrent_locks;
838 }
839
840 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
841 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
842 _stack_trace->dump_stack_at_safepoint(max_depth);
843 }
844
845
846 void ThreadSnapshot::oops_do(OopClosure* f) {
847 f->do_oop(&_threadObj);
848 f->do_oop(&_blocker_object);
849 f->do_oop(&_blocker_object_owner);
850 if (_stack_trace != NULL) {
851 _stack_trace->oops_do(f);
852 }
853 if (_concurrent_locks != NULL) {
854 _concurrent_locks->oops_do(f);
855 }
856 }
857
858 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
859 if (_stack_trace != NULL) {
860 _stack_trace->metadata_do(f);
861 }
862 }
863
864
865 DeadlockCycle::DeadlockCycle() {
866 _is_deadlock = false;
867 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
868 _next = NULL;
869 }
870
871 DeadlockCycle::~DeadlockCycle() {
872 delete _threads;
873 }
874
875 void DeadlockCycle::print_on(outputStream* st) const {
876 st->cr();
877 st->print_cr("Found one Java-level deadlock:");
878 st->print("=============================");
879
880 JavaThread* currentThread;
881 ObjectMonitor* waitingToLockMonitor;
882 oop waitingToLockBlocker;
883 int len = _threads->length();
884 for (int i = 0; i < len; i++) {
885 currentThread = _threads->at(i);
886 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
887 waitingToLockBlocker = currentThread->current_park_blocker();
888 st->cr();
889 st->print_cr("\"%s\":", currentThread->get_thread_name());
890 const char* owner_desc = ",\n which is held by";
891 if (waitingToLockMonitor != NULL) {
892 st->print(" waiting to lock monitor " INTPTR_FORMAT, waitingToLockMonitor);
893 oop obj = (oop)waitingToLockMonitor->object();
894 if (obj != NULL) {
895 st->print(" (object " INTPTR_FORMAT ", a %s)", (address)obj,
896 (InstanceKlass::cast(obj->klass()))->external_name());
897
898 if (!currentThread->current_pending_monitor_is_from_java()) {
899 owner_desc = "\n in JNI, which is held by";
900 }
901 } else {
902 // No Java object associated - a JVMTI raw monitor
903 owner_desc = " (JVMTI raw monitor),\n which is held by";
904 }
905 currentThread = Threads::owning_thread_from_monitor_owner(
906 (address)waitingToLockMonitor->owner(),
907 false /* no locking needed */);
908 if (currentThread == NULL) {
909 // The deadlock was detected at a safepoint so the JavaThread
910 // that owns waitingToLockMonitor should be findable, but
911 // if it is not findable, then the previous currentThread is
912 // blocked permanently.
913 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
914 (address)waitingToLockMonitor->owner());
915 continue;
916 }
917 } else {
918 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
919 (address)waitingToLockBlocker,
920 (InstanceKlass::cast(waitingToLockBlocker->klass()))->external_name());
921 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()),
922 "Must be an AbstractOwnableSynchronizer");
923 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
924 currentThread = java_lang_Thread::thread(ownerObj);
925 }
926 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
927 }
928
929 st->cr();
930 st->cr();
931
932 // Print stack traces
933 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
934 JavaMonitorsInStackTrace = true;
935 st->print_cr("Java stack information for the threads listed above:");
936 st->print_cr("===================================================");
937 for (int j = 0; j < len; j++) {
938 currentThread = _threads->at(j);
939 st->print_cr("\"%s\":", currentThread->get_thread_name());
940 currentThread->print_stack_on(st);
941 }
942 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
943 }
944
945 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
946 bool include_jvmti_agent_threads,
947 bool include_jni_attaching_threads) {
948 assert(cur_thread == Thread::current(), "Check current thread");
949
950 int init_size = ThreadService::get_live_thread_count();
951 _threads_array = new GrowableArray<instanceHandle>(init_size);
952
953 MutexLockerEx ml(Threads_lock);
954
955 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
956 // skips JavaThreads in the process of exiting
957 // and also skips VM internal JavaThreads
958 // Threads in _thread_new or _thread_new_trans state are included.
959 // i.e. threads have been started but not yet running.
960 if (jt->threadObj() == NULL ||
961 jt->is_exiting() ||
962 !java_lang_Thread::is_alive(jt->threadObj()) ||
963 jt->is_hidden_from_external_view()) {
964 continue;
965 }
966
967 // skip agent threads
968 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
969 continue;
970 }
971
972 // skip jni threads in the process of attaching
973 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
974 continue;
975 }
976
977 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
978 _threads_array->append(h);
979 }
980 }