1 /*
2 * Copyright (c) 2003, 2016, 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 "memory/resourceArea.hpp"
31 #include "oops/instanceKlass.hpp"
32 #include "oops/objArrayOop.inline.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/atomic.inline.hpp"
35 #include "runtime/handles.inline.hpp"
36 #include "runtime/init.hpp"
37 #include "runtime/thread.hpp"
38 #include "runtime/vframe.hpp"
39 #include "runtime/thread.inline.hpp"
40 #include "runtime/vmThread.hpp"
41 #include "runtime/vm_operations.hpp"
42 #include "services/threadService.hpp"
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 Handle h(obj);
170 return h;
171 }
172
173 bool ThreadService::set_thread_monitoring_contention(bool flag) {
174 MutexLocker m(Management_lock);
175
176 bool prev = _thread_monitoring_contention_enabled;
177 _thread_monitoring_contention_enabled = flag;
178
179 return prev;
180 }
181
182 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
183 MutexLocker m(Management_lock);
184
185 bool prev = _thread_cpu_time_enabled;
186 _thread_cpu_time_enabled = flag;
187
188 return prev;
189 }
190
191 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
192 MutexLocker m(Management_lock);
193
194 bool prev = _thread_allocated_memory_enabled;
195 _thread_allocated_memory_enabled = flag;
196
197 return prev;
198 }
199
200 // GC support
201 void ThreadService::oops_do(OopClosure* f) {
202 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
203 dump->oops_do(f);
204 }
205 }
206
207 void ThreadService::metadata_do(void f(Metadata*)) {
208 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
209 dump->metadata_do(f);
210 }
211 }
212
213 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
214 MutexLocker ml(Management_lock);
215 if (_threaddump_list == NULL) {
216 _threaddump_list = dump;
217 } else {
218 dump->set_next(_threaddump_list);
219 _threaddump_list = dump;
220 }
221 }
222
223 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
224 MutexLocker ml(Management_lock);
225
226 ThreadDumpResult* prev = NULL;
227 bool found = false;
228 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
229 if (d == dump) {
230 if (prev == NULL) {
231 _threaddump_list = dump->next();
232 } else {
233 prev->set_next(dump->next());
234 }
235 found = true;
236 break;
237 }
238 }
239 assert(found, "The threaddump result to be removed must exist.");
240 }
241
242 // Dump stack trace of threads specified in the given threads array.
243 // Returns StackTraceElement[][] each element is the stack trace of a thread in
244 // the corresponding entry in the given threads array
245 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
246 int num_threads,
247 TRAPS) {
248 assert(num_threads > 0, "just checking");
249
250 ThreadDumpResult dump_result;
251 VM_ThreadDump op(&dump_result,
252 threads,
253 num_threads,
254 -1, /* entire stack */
255 false, /* with locked monitors */
256 false /* with locked synchronizers */);
257 VMThread::execute(&op);
258
259 // Allocate the resulting StackTraceElement[][] object
260
261 ResourceMark rm(THREAD);
262 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
263 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
264 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
265 objArrayHandle result_obj(THREAD, r);
266
267 int num_snapshots = dump_result.num_snapshots();
268 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
269 int i = 0;
270 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
271 ThreadStackTrace* stacktrace = ts->get_stack_trace();
272 if (stacktrace == NULL) {
273 // No stack trace
274 result_obj->obj_at_put(i, NULL);
275 } else {
276 // Construct an array of java/lang/StackTraceElement object
277 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
278 result_obj->obj_at_put(i, backtrace_h());
279 }
280 }
281
282 return result_obj;
283 }
284
285 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
286 ThreadStatistics* stat = thread->get_thread_stat();
287 if (stat != NULL) {
288 stat->reset_count_stat();
289 }
290 }
291
292 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
293 ThreadStatistics* stat = thread->get_thread_stat();
294 if (stat != NULL) {
295 stat->reset_time_stat();
296 }
297 }
298
299 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
300 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) {
301 // This code was modified from the original Threads::find_deadlocks code.
302 int globalDfn = 0, thisDfn;
303 ObjectMonitor* waitingToLockMonitor = NULL;
304 oop waitingToLockBlocker = NULL;
305 bool blocked_on_monitor = false;
306 JavaThread *currentThread, *previousThread;
307 int num_deadlocks = 0;
308
309 for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) {
310 // Initialize the depth-first-number
311 p->set_depth_first_number(-1);
312 }
313
314 DeadlockCycle* deadlocks = NULL;
315 DeadlockCycle* last = NULL;
316 DeadlockCycle* cycle = new DeadlockCycle();
317 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
318 if (jt->depth_first_number() >= 0) {
319 // this thread was already visited
320 continue;
321 }
322
323 thisDfn = globalDfn;
324 jt->set_depth_first_number(globalDfn++);
325 previousThread = jt;
326 currentThread = jt;
327
328 cycle->reset();
329
330 // When there is a deadlock, all the monitors involved in the dependency
331 // cycle must be contended and heavyweight. So we only care about the
332 // heavyweight monitor a thread is waiting to lock.
333 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
334 if (concurrent_locks) {
335 waitingToLockBlocker = jt->current_park_blocker();
336 }
337 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
338 cycle->add_thread(currentThread);
339 if (waitingToLockMonitor != NULL) {
340 address currentOwner = (address)waitingToLockMonitor->owner();
341 if (currentOwner != NULL) {
342 currentThread = Threads::owning_thread_from_monitor_owner(
343 currentOwner,
344 false /* no locking needed */);
345 if (currentThread == NULL) {
346 // This function is called at a safepoint so the JavaThread
347 // that owns waitingToLockMonitor should be findable, but
348 // if it is not findable, then the previous currentThread is
349 // blocked permanently. We record this as a deadlock.
350 num_deadlocks++;
351
352 cycle->set_deadlock(true);
353
354 // add this cycle to the deadlocks list
355 if (deadlocks == NULL) {
356 deadlocks = cycle;
357 } else {
358 last->set_next(cycle);
359 }
360 last = cycle;
361 cycle = new DeadlockCycle();
362 break;
363 }
364 }
365 } else {
366 if (concurrent_locks) {
367 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
368 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
369 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
370 } else {
371 currentThread = NULL;
372 }
373 }
374 }
375
376 if (currentThread == NULL) {
377 // No dependency on another thread
378 break;
379 }
380 if (currentThread->depth_first_number() < 0) {
381 // First visit to this thread
382 currentThread->set_depth_first_number(globalDfn++);
383 } else if (currentThread->depth_first_number() < thisDfn) {
384 // Thread already visited, and not on a (new) cycle
385 break;
386 } else if (currentThread == previousThread) {
387 // Self-loop, ignore
388 break;
389 } else {
390 // We have a (new) cycle
391 num_deadlocks++;
392
393 cycle->set_deadlock(true);
394
395 // add this cycle to the deadlocks list
396 if (deadlocks == NULL) {
397 deadlocks = cycle;
398 } else {
399 last->set_next(cycle);
400 }
401 last = cycle;
402 cycle = new DeadlockCycle();
403 break;
404 }
405 previousThread = currentThread;
406 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
407 if (concurrent_locks) {
408 waitingToLockBlocker = currentThread->current_park_blocker();
409 }
410 }
411
412 }
413 delete cycle;
414 return deadlocks;
415 }
416
417 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
418
419 // Create a new ThreadDumpResult object and append to the list.
420 // If GC happens before this function returns, Method*
421 // in the stack trace will be visited.
422 ThreadService::add_thread_dump(this);
423 }
424
425 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
426 // Create a new ThreadDumpResult object and append to the list.
427 // If GC happens before this function returns, oops
428 // will be visited.
429 ThreadService::add_thread_dump(this);
430 }
431
432 ThreadDumpResult::~ThreadDumpResult() {
433 ThreadService::remove_thread_dump(this);
434
435 // free all the ThreadSnapshot objects created during
436 // the VM_ThreadDump operation
437 ThreadSnapshot* ts = _snapshots;
438 while (ts != NULL) {
439 ThreadSnapshot* p = ts;
440 ts = ts->next();
441 delete p;
442 }
443 }
444
445
446 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
447 assert(_num_threads == 0 || _num_snapshots < _num_threads,
448 "_num_snapshots must be less than _num_threads");
449 _num_snapshots++;
450 if (_snapshots == NULL) {
451 _snapshots = ts;
452 } else {
453 _last->set_next(ts);
454 }
455 _last = ts;
456 }
457
458 void ThreadDumpResult::oops_do(OopClosure* f) {
459 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
460 ts->oops_do(f);
461 }
462 }
463
464 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
465 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
466 ts->metadata_do(f);
467 }
468 }
469
470 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
471 _method = jvf->method();
472 _bci = jvf->bci();
473 _class_holder = _method->method_holder()->klass_holder();
474 _locked_monitors = NULL;
475 if (with_lock_info) {
476 ResourceMark rm;
477 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
478 int length = list->length();
479 if (length > 0) {
480 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
481 for (int i = 0; i < length; i++) {
482 MonitorInfo* monitor = list->at(i);
483 assert(monitor->owner(), "This monitor must have an owning object");
484 _locked_monitors->append(monitor->owner());
485 }
486 }
487 }
488 }
489
490 void StackFrameInfo::oops_do(OopClosure* f) {
491 if (_locked_monitors != NULL) {
492 int length = _locked_monitors->length();
493 for (int i = 0; i < length; i++) {
494 f->do_oop((oop*) _locked_monitors->adr_at(i));
495 }
496 }
497 f->do_oop(&_class_holder);
498 }
499
500 void StackFrameInfo::metadata_do(void f(Metadata*)) {
501 f(_method);
502 }
503
504 void StackFrameInfo::print_on(outputStream* st) const {
505 ResourceMark rm;
506 java_lang_Throwable::print_stack_element(st, method(), bci());
507 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
508 for (int i = 0; i < len; i++) {
509 oop o = _locked_monitors->at(i);
510 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
511 }
512
513 }
514
515 // Iterate through monitor cache to find JNI locked monitors
516 class InflatedMonitorsClosure: public MonitorClosure {
517 private:
518 ThreadStackTrace* _stack_trace;
519 Thread* _thread;
520 public:
521 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
522 _thread = t;
523 _stack_trace = st;
524 }
525 void do_monitor(ObjectMonitor* mid) {
526 if (mid->owner() == _thread) {
527 oop object = (oop) mid->object();
528 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
529 _stack_trace->add_jni_locked_monitor(object);
530 }
531 }
532 }
533 };
534
535 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
536 _thread = t;
537 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
538 _depth = 0;
539 _with_locked_monitors = with_locked_monitors;
540 if (_with_locked_monitors) {
541 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
542 } else {
543 _jni_locked_monitors = NULL;
544 }
545 }
546
547 ThreadStackTrace::~ThreadStackTrace() {
548 for (int i = 0; i < _frames->length(); i++) {
549 delete _frames->at(i);
550 }
551 delete _frames;
552 if (_jni_locked_monitors != NULL) {
553 delete _jni_locked_monitors;
554 }
555 }
556
557 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
558 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
559
560 if (_thread->has_last_Java_frame()) {
561 RegisterMap reg_map(_thread);
562 vframe* start_vf = _thread->last_java_vframe(®_map);
563 int count = 0;
564 for (vframe* f = start_vf; f; f = f->sender() ) {
565 if (f->is_java_frame()) {
566 javaVFrame* jvf = javaVFrame::cast(f);
567 add_stack_frame(jvf);
568 count++;
569 } else {
570 // Ignore non-Java frames
571 }
572 if (maxDepth > 0 && count == maxDepth) {
573 // Skip frames if more than maxDepth
574 break;
575 }
576 }
577 }
578
579 if (_with_locked_monitors) {
580 // Iterate inflated monitors and find monitors locked by this thread
581 // not found in the stack
582 InflatedMonitorsClosure imc(_thread, this);
583 ObjectSynchronizer::monitors_iterate(&imc);
584 }
585 }
586
587
588 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
589 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
590
591 bool found = false;
592 int num_frames = get_stack_depth();
593 for (int depth = 0; depth < num_frames; depth++) {
594 StackFrameInfo* frame = stack_frame_at(depth);
595 int len = frame->num_locked_monitors();
596 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
597 for (int j = 0; j < len; j++) {
598 oop monitor = locked_monitors->at(j);
599 assert(monitor != NULL, "must be a Java object");
600 if (monitor == object) {
601 found = true;
602 break;
603 }
604 }
605 }
606 return found;
607 }
608
609 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
610 Klass* k = SystemDictionary::StackTraceElement_klass();
611 assert(k != NULL, "must be loaded in 1.4+");
612 instanceKlassHandle ik(THREAD, k);
613
614 // Allocate an array of java/lang/StackTraceElement object
615 objArrayOop ste = oopFactory::new_objArray(ik(), _depth, CHECK_NH);
616 objArrayHandle backtrace(THREAD, ste);
617 for (int j = 0; j < _depth; j++) {
618 StackFrameInfo* frame = _frames->at(j);
619 methodHandle mh(THREAD, frame->method());
620 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
621 backtrace->obj_at_put(j, element);
622 }
623 return backtrace;
624 }
625
626 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
627 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
628 _frames->append(frame);
629 _depth++;
630 }
631
632 void ThreadStackTrace::oops_do(OopClosure* f) {
633 int length = _frames->length();
634 for (int i = 0; i < length; i++) {
635 _frames->at(i)->oops_do(f);
636 }
637
638 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
639 for (int j = 0; j < length; j++) {
640 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
641 }
642 }
643
644 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
645 int length = _frames->length();
646 for (int i = 0; i < length; i++) {
647 _frames->at(i)->metadata_do(f);
648 }
649 }
650
651
652 ConcurrentLocksDump::~ConcurrentLocksDump() {
653 if (_retain_map_on_free) {
654 return;
655 }
656
657 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
658 ThreadConcurrentLocks* tcl = t;
659 t = t->next();
660 delete tcl;
661 }
662 }
663
664 void ConcurrentLocksDump::dump_at_safepoint() {
665 // dump all locked concurrent locks
666 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
667
668 ResourceMark rm;
669
670 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE);
671
672 // Find all instances of AbstractOwnableSynchronizer
673 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(),
674 aos_objects);
675 // Build a map of thread to its owned AQS locks
676 build_map(aos_objects);
677 }
678
679
680 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
681 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
682 int length = aos_objects->length();
683 for (int i = 0; i < length; i++) {
684 oop o = aos_objects->at(i);
685 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
686 if (owner_thread_obj != NULL) {
687 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
688 assert(o->is_instance(), "Must be an instanceOop");
689 add_lock(thread, (instanceOop) o);
690 }
691 }
692 }
693
694 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
695 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
696 if (tcl != NULL) {
697 tcl->add_lock(o);
698 return;
699 }
700
701 // First owned lock found for this thread
702 tcl = new ThreadConcurrentLocks(thread);
703 tcl->add_lock(o);
704 if (_map == NULL) {
705 _map = tcl;
706 } else {
707 _last->set_next(tcl);
708 }
709 _last = tcl;
710 }
711
712 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
713 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
714 if (tcl->java_thread() == thread) {
715 return tcl;
716 }
717 }
718 return NULL;
719 }
720
721 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
722 st->print_cr(" Locked ownable synchronizers:");
723 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
724 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
725 if (locks == NULL || locks->is_empty()) {
726 st->print_cr("\t- None");
727 st->cr();
728 return;
729 }
730
731 for (int i = 0; i < locks->length(); i++) {
732 instanceOop obj = locks->at(i);
733 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
734 }
735 st->cr();
736 }
737
738 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
739 _thread = thread;
740 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
741 _next = NULL;
742 }
743
744 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
745 delete _owned_locks;
746 }
747
748 void ThreadConcurrentLocks::add_lock(instanceOop o) {
749 _owned_locks->append(o);
750 }
751
752 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
753 int length = _owned_locks->length();
754 for (int i = 0; i < length; i++) {
755 f->do_oop((oop*) _owned_locks->adr_at(i));
756 }
757 }
758
759 ThreadStatistics::ThreadStatistics() {
760 _contended_enter_count = 0;
761 _monitor_wait_count = 0;
762 _sleep_count = 0;
763 _count_pending_reset = false;
764 _timer_pending_reset = false;
765 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
766 }
767
768 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) {
769 _thread = thread;
770 _threadObj = thread->threadObj();
771 _stack_trace = NULL;
772 _concurrent_locks = NULL;
773 _next = NULL;
774
775 ThreadStatistics* stat = thread->get_thread_stat();
776 _contended_enter_ticks = stat->contended_enter_ticks();
777 _contended_enter_count = stat->contended_enter_count();
778 _monitor_wait_ticks = stat->monitor_wait_ticks();
779 _monitor_wait_count = stat->monitor_wait_count();
780 _sleep_ticks = stat->sleep_ticks();
781 _sleep_count = stat->sleep_count();
782
783 _blocker_object = NULL;
784 _blocker_object_owner = NULL;
785
786 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
787 _is_ext_suspended = thread->is_being_ext_suspended();
788 _is_in_native = (thread->thread_state() == _thread_in_native);
789
790 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
791 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
792 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
793
794 Handle obj = ThreadService::get_current_contended_monitor(thread);
795 if (obj() == NULL) {
796 // monitor no longer exists; thread is not blocked
797 _thread_status = java_lang_Thread::RUNNABLE;
798 } else {
799 _blocker_object = obj();
800 JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false);
801 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
802 || (owner != NULL && owner->is_attaching_via_jni())) {
803 // ownership information of the monitor is not available
804 // (may no longer be owned or releasing to some other thread)
805 // make this thread in RUNNABLE state.
806 // And when the owner thread is in attaching state, the java thread
807 // is not completely initialized. For example thread name and id
808 // and may not be set, so hide the attaching thread.
809 _thread_status = java_lang_Thread::RUNNABLE;
810 _blocker_object = NULL;
811 } else if (owner != NULL) {
812 _blocker_object_owner = owner->threadObj();
813 }
814 }
815 }
816
817 // Support for JSR-166 locks
818 if (JDK_Version::current().supports_thread_park_blocker() &&
819 (_thread_status == java_lang_Thread::PARKED ||
820 _thread_status == java_lang_Thread::PARKED_TIMED)) {
821
822 _blocker_object = thread->current_park_blocker();
823 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
824 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
825 }
826 }
827 }
828
829 ThreadSnapshot::~ThreadSnapshot() {
830 delete _stack_trace;
831 delete _concurrent_locks;
832 }
833
834 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
835 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
836 _stack_trace->dump_stack_at_safepoint(max_depth);
837 }
838
839
840 void ThreadSnapshot::oops_do(OopClosure* f) {
841 f->do_oop(&_threadObj);
842 f->do_oop(&_blocker_object);
843 f->do_oop(&_blocker_object_owner);
844 if (_stack_trace != NULL) {
845 _stack_trace->oops_do(f);
846 }
847 if (_concurrent_locks != NULL) {
848 _concurrent_locks->oops_do(f);
849 }
850 }
851
852 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
853 if (_stack_trace != NULL) {
854 _stack_trace->metadata_do(f);
855 }
856 }
857
858
859 DeadlockCycle::DeadlockCycle() {
860 _is_deadlock = false;
861 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
862 _next = NULL;
863 }
864
865 DeadlockCycle::~DeadlockCycle() {
866 delete _threads;
867 }
868
869 void DeadlockCycle::print_on(outputStream* st) const {
870 st->cr();
871 st->print_cr("Found one Java-level deadlock:");
872 st->print("=============================");
873
874 JavaThread* currentThread;
875 ObjectMonitor* waitingToLockMonitor;
876 oop waitingToLockBlocker;
877 int len = _threads->length();
878 for (int i = 0; i < len; i++) {
879 currentThread = _threads->at(i);
880 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
881 waitingToLockBlocker = currentThread->current_park_blocker();
882 st->cr();
883 st->print_cr("\"%s\":", currentThread->get_thread_name());
884 const char* owner_desc = ",\n which is held by";
885 if (waitingToLockMonitor != NULL) {
886 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
887 oop obj = (oop)waitingToLockMonitor->object();
888 if (obj != NULL) {
889 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
890 obj->klass()->external_name());
891
892 if (!currentThread->current_pending_monitor_is_from_java()) {
893 owner_desc = "\n in JNI, which is held by";
894 }
895 } else {
896 // No Java object associated - a JVMTI raw monitor
897 owner_desc = " (JVMTI raw monitor),\n which is held by";
898 }
899 currentThread = Threads::owning_thread_from_monitor_owner(
900 (address)waitingToLockMonitor->owner(),
901 false /* no locking needed */);
902 if (currentThread == NULL) {
903 // The deadlock was detected at a safepoint so the JavaThread
904 // that owns waitingToLockMonitor should be findable, but
905 // if it is not findable, then the previous currentThread is
906 // blocked permanently.
907 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
908 p2i(waitingToLockMonitor->owner()));
909 continue;
910 }
911 } else {
912 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
913 p2i(waitingToLockBlocker),
914 waitingToLockBlocker->klass()->external_name());
915 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()),
916 "Must be an AbstractOwnableSynchronizer");
917 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
918 currentThread = java_lang_Thread::thread(ownerObj);
919 }
920 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
921 }
922
923 st->cr();
924 st->cr();
925
926 // Print stack traces
927 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
928 JavaMonitorsInStackTrace = true;
929 st->print_cr("Java stack information for the threads listed above:");
930 st->print_cr("===================================================");
931 for (int j = 0; j < len; j++) {
932 currentThread = _threads->at(j);
933 st->print_cr("\"%s\":", currentThread->get_thread_name());
934 currentThread->print_stack_on(st);
935 }
936 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
937 }
938
939 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
940 bool include_jvmti_agent_threads,
941 bool include_jni_attaching_threads) {
942 assert(cur_thread == Thread::current(), "Check current thread");
943
944 int init_size = ThreadService::get_live_thread_count();
945 _threads_array = new GrowableArray<instanceHandle>(init_size);
946
947 MutexLockerEx ml(Threads_lock);
948
949 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
950 // skips JavaThreads in the process of exiting
951 // and also skips VM internal JavaThreads
952 // Threads in _thread_new or _thread_new_trans state are included.
953 // i.e. threads have been started but not yet running.
954 if (jt->threadObj() == NULL ||
955 jt->is_exiting() ||
956 !java_lang_Thread::is_alive(jt->threadObj()) ||
957 jt->is_hidden_from_external_view()) {
958 continue;
959 }
960
961 // skip agent threads
962 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
963 continue;
964 }
965
966 // skip jni threads in the process of attaching
967 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
968 continue;
969 }
970
971 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
972 _threads_array->append(h);
973 }
974 }