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/handles.inline.hpp"
33 #include "runtime/init.hpp"
34 #include "runtime/thread.hpp"
35 #include "runtime/vframe.hpp"
36 #include "runtime/thread.inline.hpp"
37 #include "runtime/vmThread.hpp"
38 #include "runtime/vm_operations.hpp"
39 #include "services/threadService.hpp"
40
41 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
42
43 // TODO: we need to define a naming convention for perf counters
44 // to distinguish counters for:
45 // - standard JSR174 use
46 // - Hotspot extension (public and committed)
47 // - Hotspot extension (private/internal and uncommitted)
48
49 // Default is disabled.
50 bool ThreadService::_thread_monitoring_contention_enabled = false;
51 bool ThreadService::_thread_cpu_time_enabled = false;
52 bool ThreadService::_thread_allocated_memory_enabled = false;
53
54 PerfCounter* ThreadService::_total_threads_count = NULL;
55 PerfVariable* ThreadService::_live_threads_count = NULL;
56 PerfVariable* ThreadService::_peak_threads_count = NULL;
57 PerfVariable* ThreadService::_daemon_threads_count = NULL;
58 volatile int ThreadService::_exiting_threads_count = 0;
59 volatile int ThreadService::_exiting_daemon_threads_count = 0;
60
61 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
62
63 static const int INITIAL_ARRAY_SIZE = 10;
64
65 void ThreadService::init() {
66 EXCEPTION_MARK;
67
68 // These counters are for java.lang.management API support.
69 // They are created even if -XX:-UsePerfData is set and in
70 // that case, they will be allocated on C heap.
71
72 _total_threads_count =
73 PerfDataManager::create_counter(JAVA_THREADS, "started",
74 PerfData::U_Events, CHECK);
75
76 _live_threads_count =
77 PerfDataManager::create_variable(JAVA_THREADS, "live",
78 PerfData::U_None, CHECK);
79
80 _peak_threads_count =
81 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
82 PerfData::U_None, CHECK);
83
84 _daemon_threads_count =
85 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
86 PerfData::U_None, CHECK);
87
88 if (os::is_thread_cpu_time_supported()) {
89 _thread_cpu_time_enabled = true;
90 }
91
92 _thread_allocated_memory_enabled = true; // Always on, so enable it
93 }
94
95 void ThreadService::reset_peak_thread_count() {
96 // Acquire the lock to update the peak thread count
97 // to synchronize with thread addition and removal.
98 MutexLockerEx mu(Threads_lock);
99 _peak_threads_count->set_value(get_live_thread_count());
100 }
101
102 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
103 // Do not count VM internal or JVMTI agent threads
104 if (thread->is_hidden_from_external_view() ||
105 thread->is_jvmti_agent_thread()) {
106 return;
107 }
108
109 _total_threads_count->inc();
110 _live_threads_count->inc();
111
112 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
113 _peak_threads_count->set_value(_live_threads_count->get_value());
114 }
115
116 if (daemon) {
117 _daemon_threads_count->inc();
118 }
119 }
120
121 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
122 Atomic::dec((jint*) &_exiting_threads_count);
123
124 if (thread->is_hidden_from_external_view() ||
125 thread->is_jvmti_agent_thread()) {
126 return;
127 }
128
129 _live_threads_count->set_value(_live_threads_count->get_value() - 1);
130
131 if (daemon) {
132 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
133 Atomic::dec((jint*) &_exiting_daemon_threads_count);
134 }
135 }
136
137 void ThreadService::current_thread_exiting(JavaThread* jt) {
138 assert(jt == JavaThread::current(), "Called by current thread");
139 Atomic::inc((jint*) &_exiting_threads_count);
140
141 oop threadObj = jt->threadObj();
142 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
143 Atomic::inc((jint*) &_exiting_daemon_threads_count);
144 }
145 }
146
147 // FIXME: JVMTI should call this function
148 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
149 assert(thread != NULL, "should be non-NULL");
150 assert(Threads_lock->owned_by_self(), "must grab Threads_lock or be at safepoint");
151
152 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
153
154 oop obj = NULL;
155 if (wait_obj != NULL) {
156 // thread is doing an Object.wait() call
157 obj = (oop) wait_obj->object();
158 assert(obj != NULL, "Object.wait() should have an object");
159 } else {
160 ObjectMonitor *enter_obj = thread->current_pending_monitor();
161 if (enter_obj != NULL) {
162 // thread is trying to enter() or raw_enter() an ObjectMonitor.
163 obj = (oop) enter_obj->object();
164 }
165 // If obj == NULL, then ObjectMonitor is raw which doesn't count.
166 }
167
168 Handle h(obj);
169 return h;
170 }
171
172 bool ThreadService::set_thread_monitoring_contention(bool flag) {
173 MutexLocker m(Management_lock);
174
175 bool prev = _thread_monitoring_contention_enabled;
176 _thread_monitoring_contention_enabled = flag;
177
178 return prev;
179 }
180
181 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
182 MutexLocker m(Management_lock);
183
184 bool prev = _thread_cpu_time_enabled;
185 _thread_cpu_time_enabled = flag;
186
187 return prev;
188 }
189
190 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
191 MutexLocker m(Management_lock);
192
193 bool prev = _thread_allocated_memory_enabled;
194 _thread_allocated_memory_enabled = flag;
195
196 return prev;
197 }
198
199 // GC support
200 void ThreadService::oops_do(OopClosure* f) {
201 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
202 dump->oops_do(f);
203 }
204 }
205
206 void ThreadService::metadata_do(void f(Metadata*)) {
207 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
208 dump->metadata_do(f);
209 }
210 }
211
212 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
213 MutexLocker ml(Management_lock);
214 if (_threaddump_list == NULL) {
215 _threaddump_list = dump;
216 } else {
217 dump->set_next(_threaddump_list);
218 _threaddump_list = dump;
219 }
220 }
221
222 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
223 MutexLocker ml(Management_lock);
224
225 ThreadDumpResult* prev = NULL;
226 bool found = false;
227 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
228 if (d == dump) {
229 if (prev == NULL) {
230 _threaddump_list = dump->next();
231 } else {
232 prev->set_next(dump->next());
233 }
234 found = true;
235 break;
236 }
237 }
238 assert(found, "The threaddump result to be removed must exist.");
239 }
240
241 // Dump stack trace of threads specified in the given threads array.
242 // Returns StackTraceElement[][] each element is the stack trace of a thread in
243 // the corresponding entry in the given threads array
244 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
245 int num_threads,
246 TRAPS) {
247 assert(num_threads > 0, "just checking");
248
249 ThreadDumpResult dump_result;
250 VM_ThreadDump op(&dump_result,
251 threads,
252 num_threads,
253 -1, /* entire stack */
254 false, /* with locked monitors */
255 false /* with locked synchronizers */);
256 VMThread::execute(&op);
257
258 // Allocate the resulting StackTraceElement[][] object
259
260 ResourceMark rm(THREAD);
261 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
262 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
263 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
264 objArrayHandle result_obj(THREAD, r);
265
266 int num_snapshots = dump_result.num_snapshots();
267 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
268 int i = 0;
269 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
270 ThreadStackTrace* stacktrace = ts->get_stack_trace();
271 if (stacktrace == NULL) {
272 // No stack trace
273 result_obj->obj_at_put(i, NULL);
274 } else {
275 // Construct an array of java/lang/StackTraceElement object
276 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
277 result_obj->obj_at_put(i, backtrace_h());
278 }
279 }
280
281 return result_obj;
282 }
283
284 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
285 ThreadStatistics* stat = thread->get_thread_stat();
286 if (stat != NULL) {
287 stat->reset_count_stat();
288 }
289 }
290
291 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
292 ThreadStatistics* stat = thread->get_thread_stat();
293 if (stat != NULL) {
294 stat->reset_time_stat();
295 }
296 }
297
298 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
299 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) {
300 // This code was modified from the original Threads::find_deadlocks code.
301 int globalDfn = 0, thisDfn;
302 ObjectMonitor* waitingToLockMonitor = NULL;
303 oop waitingToLockBlocker = NULL;
304 bool blocked_on_monitor = false;
305 JavaThread *currentThread, *previousThread;
306 int num_deadlocks = 0;
307
308 for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) {
309 // Initialize the depth-first-number
310 p->set_depth_first_number(-1);
311 }
312
313 DeadlockCycle* deadlocks = NULL;
314 DeadlockCycle* last = NULL;
315 DeadlockCycle* cycle = new DeadlockCycle();
316 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
317 if (jt->depth_first_number() >= 0) {
318 // this thread was already visited
319 continue;
320 }
321
322 thisDfn = globalDfn;
323 jt->set_depth_first_number(globalDfn++);
324 previousThread = jt;
325 currentThread = jt;
326
327 cycle->reset();
328
329 // When there is a deadlock, all the monitors involved in the dependency
330 // cycle must be contended and heavyweight. So we only care about the
331 // heavyweight monitor a thread is waiting to lock.
332 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
333 if (concurrent_locks) {
334 waitingToLockBlocker = jt->current_park_blocker();
335 }
336 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
337 cycle->add_thread(currentThread);
338 if (waitingToLockMonitor != NULL) {
339 address currentOwner = (address)waitingToLockMonitor->owner();
340 if (currentOwner != NULL) {
341 currentThread = Threads::owning_thread_from_monitor_owner(
342 currentOwner,
343 false /* no locking needed */);
344 if (currentThread == NULL) {
345 // This function is called at a safepoint so the JavaThread
346 // that owns waitingToLockMonitor should be findable, but
347 // if it is not findable, then the previous currentThread is
348 // blocked permanently. We record this as a deadlock.
349 num_deadlocks++;
350
351 cycle->set_deadlock(true);
352
353 // add this cycle to the deadlocks list
354 if (deadlocks == NULL) {
355 deadlocks = cycle;
356 } else {
357 last->set_next(cycle);
358 }
359 last = cycle;
360 cycle = new DeadlockCycle();
361 break;
362 }
363 }
364 } else {
365 if (concurrent_locks) {
366 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
367 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
368 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
369 } else {
370 currentThread = NULL;
371 }
372 }
373 }
374
375 if (currentThread == NULL) {
376 // No dependency on another thread
377 break;
378 }
379 if (currentThread->depth_first_number() < 0) {
380 // First visit to this thread
381 currentThread->set_depth_first_number(globalDfn++);
382 } else if (currentThread->depth_first_number() < thisDfn) {
383 // Thread already visited, and not on a (new) cycle
384 break;
385 } else if (currentThread == previousThread) {
386 // Self-loop, ignore
387 break;
388 } else {
389 // We have a (new) cycle
390 num_deadlocks++;
391
392 cycle->set_deadlock(true);
393
394 // add this cycle to the deadlocks list
395 if (deadlocks == NULL) {
396 deadlocks = cycle;
397 } else {
398 last->set_next(cycle);
399 }
400 last = cycle;
401 cycle = new DeadlockCycle();
402 break;
403 }
404 previousThread = currentThread;
405 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
406 if (concurrent_locks) {
407 waitingToLockBlocker = currentThread->current_park_blocker();
408 }
409 }
410
411 }
412 delete cycle;
413 return deadlocks;
414 }
415
416 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
417
418 // Create a new ThreadDumpResult object and append to the list.
419 // If GC happens before this function returns, Method*
420 // in the stack trace will be visited.
421 ThreadService::add_thread_dump(this);
422 }
423
424 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
425 // Create a new ThreadDumpResult object and append to the list.
426 // If GC happens before this function returns, oops
427 // will be visited.
428 ThreadService::add_thread_dump(this);
429 }
430
431 ThreadDumpResult::~ThreadDumpResult() {
432 ThreadService::remove_thread_dump(this);
433
434 // free all the ThreadSnapshot objects created during
435 // the VM_ThreadDump operation
436 ThreadSnapshot* ts = _snapshots;
437 while (ts != NULL) {
438 ThreadSnapshot* p = ts;
439 ts = ts->next();
440 delete p;
441 }
442 }
443
444
445 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
446 assert(_num_threads == 0 || _num_snapshots < _num_threads,
447 "_num_snapshots must be less than _num_threads");
448 _num_snapshots++;
449 if (_snapshots == NULL) {
450 _snapshots = ts;
451 } else {
452 _last->set_next(ts);
453 }
454 _last = ts;
455 }
456
457 void ThreadDumpResult::oops_do(OopClosure* f) {
458 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
459 ts->oops_do(f);
460 }
461 }
462
463 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
464 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
465 ts->metadata_do(f);
466 }
467 }
468
469 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
470 _method = jvf->method();
471 _bci = jvf->bci();
472 _class_holder = _method->method_holder()->klass_holder();
473 _locked_monitors = NULL;
474 if (with_lock_info) {
475 ResourceMark rm;
476 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
477 int length = list->length();
478 if (length > 0) {
479 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
480 for (int i = 0; i < length; i++) {
481 MonitorInfo* monitor = list->at(i);
482 assert(monitor->owner(), "This monitor must have an owning object");
483 _locked_monitors->append(monitor->owner());
484 }
485 }
486 }
487 }
488
489 void StackFrameInfo::oops_do(OopClosure* f) {
490 if (_locked_monitors != NULL) {
491 int length = _locked_monitors->length();
492 for (int i = 0; i < length; i++) {
493 f->do_oop((oop*) _locked_monitors->adr_at(i));
494 }
495 }
496 f->do_oop(&_class_holder);
497 }
498
499 void StackFrameInfo::metadata_do(void f(Metadata*)) {
500 f(_method);
501 }
502
503 void StackFrameInfo::print_on(outputStream* st) const {
504 ResourceMark rm;
505 java_lang_Throwable::print_stack_element(st, method(), bci());
506 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
507 for (int i = 0; i < len; i++) {
508 oop o = _locked_monitors->at(i);
509 InstanceKlass* ik = InstanceKlass::cast(o->klass());
510 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", (address)o, ik->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 && monitor->is_instance(), "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 if (JDK_Version::is_gte_jdk16x_version()) {
669 ResourceMark rm;
670
671 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE);
672
673 // Find all instances of AbstractOwnableSynchronizer
674 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(),
675 aos_objects);
676 // Build a map of thread to its owned AQS locks
677 build_map(aos_objects);
678 }
679 }
680
681
682 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
683 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
684 int length = aos_objects->length();
685 for (int i = 0; i < length; i++) {
686 oop o = aos_objects->at(i);
687 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
688 if (owner_thread_obj != NULL) {
689 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
690 assert(o->is_instance(), "Must be an instanceOop");
691 add_lock(thread, (instanceOop) o);
692 }
693 }
694 }
695
696 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
697 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
698 if (tcl != NULL) {
699 tcl->add_lock(o);
700 return;
701 }
702
703 // First owned lock found for this thread
704 tcl = new ThreadConcurrentLocks(thread);
705 tcl->add_lock(o);
706 if (_map == NULL) {
707 _map = tcl;
708 } else {
709 _last->set_next(tcl);
710 }
711 _last = tcl;
712 }
713
714 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
715 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
716 if (tcl->java_thread() == thread) {
717 return tcl;
718 }
719 }
720 return NULL;
721 }
722
723 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
724 st->print_cr(" Locked ownable synchronizers:");
725 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
726 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
727 if (locks == NULL || locks->is_empty()) {
728 st->print_cr("\t- None");
729 st->cr();
730 return;
731 }
732
733 for (int i = 0; i < locks->length(); i++) {
734 instanceOop obj = locks->at(i);
735 InstanceKlass* ik = InstanceKlass::cast(obj->klass());
736 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", (address)obj, ik->external_name());
737 }
738 st->cr();
739 }
740
741 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
742 _thread = thread;
743 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
744 _next = NULL;
745 }
746
747 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
748 delete _owned_locks;
749 }
750
751 void ThreadConcurrentLocks::add_lock(instanceOop o) {
752 _owned_locks->append(o);
753 }
754
755 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
756 int length = _owned_locks->length();
757 for (int i = 0; i < length; i++) {
758 f->do_oop((oop*) _owned_locks->adr_at(i));
759 }
760 }
761
762 ThreadStatistics::ThreadStatistics() {
763 _contended_enter_count = 0;
764 _monitor_wait_count = 0;
765 _sleep_count = 0;
766 _count_pending_reset = false;
767 _timer_pending_reset = false;
768 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
769 }
770
771 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) {
772 _thread = thread;
773 _threadObj = thread->threadObj();
774 _stack_trace = NULL;
775 _concurrent_locks = NULL;
776 _next = NULL;
777
778 ThreadStatistics* stat = thread->get_thread_stat();
779 _contended_enter_ticks = stat->contended_enter_ticks();
780 _contended_enter_count = stat->contended_enter_count();
781 _monitor_wait_ticks = stat->monitor_wait_ticks();
782 _monitor_wait_count = stat->monitor_wait_count();
783 _sleep_ticks = stat->sleep_ticks();
784 _sleep_count = stat->sleep_count();
785
786 _blocker_object = NULL;
787 _blocker_object_owner = NULL;
788
789 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
790 _is_ext_suspended = thread->is_being_ext_suspended();
791 _is_in_native = (thread->thread_state() == _thread_in_native);
792
793 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
794 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
795 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
796
797 Handle obj = ThreadService::get_current_contended_monitor(thread);
798 if (obj() == NULL) {
799 // monitor no longer exists; thread is not blocked
800 _thread_status = java_lang_Thread::RUNNABLE;
801 } else {
802 _blocker_object = obj();
803 JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false);
804 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
805 || (owner != NULL && owner->is_attaching_via_jni())) {
806 // ownership information of the monitor is not available
807 // (may no longer be owned or releasing to some other thread)
808 // make this thread in RUNNABLE state.
809 // And when the owner thread is in attaching state, the java thread
810 // is not completely initialized. For example thread name and id
811 // and may not be set, so hide the attaching thread.
812 _thread_status = java_lang_Thread::RUNNABLE;
813 _blocker_object = NULL;
814 } else if (owner != NULL) {
815 _blocker_object_owner = owner->threadObj();
816 }
817 }
818 }
819
820 // Support for JSR-166 locks
821 if (JDK_Version::current().supports_thread_park_blocker() &&
822 (_thread_status == java_lang_Thread::PARKED ||
823 _thread_status == java_lang_Thread::PARKED_TIMED)) {
824
825 _blocker_object = thread->current_park_blocker();
826 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
827 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
828 }
829 }
830 }
831
832 ThreadSnapshot::~ThreadSnapshot() {
833 delete _stack_trace;
834 delete _concurrent_locks;
835 }
836
837 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
838 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
839 _stack_trace->dump_stack_at_safepoint(max_depth);
840 }
841
842
843 void ThreadSnapshot::oops_do(OopClosure* f) {
844 f->do_oop(&_threadObj);
845 f->do_oop(&_blocker_object);
846 f->do_oop(&_blocker_object_owner);
847 if (_stack_trace != NULL) {
848 _stack_trace->oops_do(f);
849 }
850 if (_concurrent_locks != NULL) {
851 _concurrent_locks->oops_do(f);
852 }
853 }
854
855 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
856 if (_stack_trace != NULL) {
857 _stack_trace->metadata_do(f);
858 }
859 }
860
861
862 DeadlockCycle::DeadlockCycle() {
863 _is_deadlock = false;
864 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
865 _next = NULL;
866 }
867
868 DeadlockCycle::~DeadlockCycle() {
869 delete _threads;
870 }
871
872 void DeadlockCycle::print_on(outputStream* st) const {
873 st->cr();
874 st->print_cr("Found one Java-level deadlock:");
875 st->print("=============================");
876
877 JavaThread* currentThread;
878 ObjectMonitor* waitingToLockMonitor;
879 oop waitingToLockBlocker;
880 int len = _threads->length();
881 for (int i = 0; i < len; i++) {
882 currentThread = _threads->at(i);
883 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
884 waitingToLockBlocker = currentThread->current_park_blocker();
885 st->cr();
886 st->print_cr("\"%s\":", currentThread->get_thread_name());
887 const char* owner_desc = ",\n which is held by";
888 if (waitingToLockMonitor != NULL) {
889 st->print(" waiting to lock monitor " INTPTR_FORMAT, waitingToLockMonitor);
890 oop obj = (oop)waitingToLockMonitor->object();
891 if (obj != NULL) {
892 st->print(" (object "INTPTR_FORMAT ", a %s)", (address)obj,
893 (InstanceKlass::cast(obj->klass()))->external_name());
894
895 if (!currentThread->current_pending_monitor_is_from_java()) {
896 owner_desc = "\n in JNI, which is held by";
897 }
898 } else {
899 // No Java object associated - a JVMTI raw monitor
900 owner_desc = " (JVMTI raw monitor),\n which is held by";
901 }
902 currentThread = Threads::owning_thread_from_monitor_owner(
903 (address)waitingToLockMonitor->owner(),
904 false /* no locking needed */);
905 if (currentThread == NULL) {
906 // The deadlock was detected at a safepoint so the JavaThread
907 // that owns waitingToLockMonitor should be findable, but
908 // if it is not findable, then the previous currentThread is
909 // blocked permanently.
910 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
911 (address)waitingToLockMonitor->owner());
912 continue;
913 }
914 } else {
915 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
916 (address)waitingToLockBlocker,
917 (InstanceKlass::cast(waitingToLockBlocker->klass()))->external_name());
918 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()),
919 "Must be an AbstractOwnableSynchronizer");
920 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
921 currentThread = java_lang_Thread::thread(ownerObj);
922 }
923 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
924 }
925
926 st->cr();
927 st->cr();
928
929 // Print stack traces
930 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
931 JavaMonitorsInStackTrace = true;
932 st->print_cr("Java stack information for the threads listed above:");
933 st->print_cr("===================================================");
934 for (int j = 0; j < len; j++) {
935 currentThread = _threads->at(j);
936 st->print_cr("\"%s\":", currentThread->get_thread_name());
937 currentThread->print_stack_on(st);
938 }
939 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
940 }
941
942 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
943 bool include_jvmti_agent_threads,
944 bool include_jni_attaching_threads) {
945 assert(cur_thread == Thread::current(), "Check current thread");
946
947 int init_size = ThreadService::get_live_thread_count();
948 _threads_array = new GrowableArray<instanceHandle>(init_size);
949
950 MutexLockerEx ml(Threads_lock);
951
952 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
953 // skips JavaThreads in the process of exiting
954 // and also skips VM internal JavaThreads
955 // Threads in _thread_new or _thread_new_trans state are included.
956 // i.e. threads have been started but not yet running.
957 if (jt->threadObj() == NULL ||
958 jt->is_exiting() ||
959 !java_lang_Thread::is_alive(jt->threadObj()) ||
960 jt->is_hidden_from_external_view()) {
961 continue;
962 }
963
964 // skip agent threads
965 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
966 continue;
967 }
968
969 // skip jni threads in the process of attaching
970 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
971 continue;
972 }
973
974 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
975 _threads_array->append(h);
976 }
977 }