1 /*
2 * Copyright (c) 2003, 2018, 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.hpp"
35 #include "runtime/handles.inline.hpp"
36 #include "runtime/init.hpp"
37 #include "runtime/objectMonitor.inline.hpp"
38 #include "runtime/thread.inline.hpp"
39 #include "runtime/threadSMR.inline.hpp"
40 #include "runtime/vframe.hpp"
41 #include "runtime/vmThread.hpp"
42 #include "runtime/vm_operations.hpp"
43 #include "services/threadService.hpp"
44
45 // TODO: we need to define a naming convention for perf counters
46 // to distinguish counters for:
47 // - standard JSR174 use
48 // - Hotspot extension (public and committed)
49 // - Hotspot extension (private/internal and uncommitted)
50
51 // Default is disabled.
52 bool ThreadService::_thread_monitoring_contention_enabled = false;
53 bool ThreadService::_thread_cpu_time_enabled = false;
54 bool ThreadService::_thread_allocated_memory_enabled = false;
55
56 PerfCounter* ThreadService::_total_threads_count = NULL;
57 PerfVariable* ThreadService::_live_threads_count = NULL;
58 PerfVariable* ThreadService::_peak_threads_count = NULL;
59 PerfVariable* ThreadService::_daemon_threads_count = NULL;
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 static bool is_hidden_thread(JavaThread *thread) {
103 // hide VM internal or JVMTI agent threads
104 return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
105 }
106
107 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
108 assert(Threads_lock->owned_by_self(), "must have threads lock");
109
110 // Do not count hidden threads
111 if (is_hidden_thread(thread)) {
112 return;
113 }
114
115 _total_threads_count->inc();
116 _live_threads_count->inc();
117
118 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
119 _peak_threads_count->set_value(_live_threads_count->get_value());
120 }
121
122 if (daemon) {
123 _daemon_threads_count->inc();
124 }
125 }
126
127 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
128 assert(Threads_lock->owned_by_self(), "must have threads lock");
129
130 _live_threads_count->dec(1);
131
132 if (daemon) {
133 _daemon_threads_count->dec(1);
134 }
135 }
136
137 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
138 assert(Threads_lock->owned_by_self(), "must have threads lock");
139
140 // Do not count hidden threads
141 if (is_hidden_thread(thread)) {
142 return;
143 }
144
145 assert(!thread->is_terminated(), "must not be terminated");
146 if (!thread->is_exiting()) {
147 // JavaThread::exit() skipped calling current_thread_exiting()
148 decrement_thread_counts(thread, daemon);
149 }
150
151 }
152
153 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
154 assert(Threads_lock->owned_by_self(), "must have threads lock");
155
156 // Do not count hidden threads
157 if (is_hidden_thread(jt)) {
158 return;
159 }
160
161 assert(jt == JavaThread::current(), "Called by current thread");
162 assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
163
164 decrement_thread_counts(jt, daemon);
165 }
166
167 // FIXME: JVMTI should call this function
168 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
169 assert(thread != NULL, "should be non-NULL");
170 debug_only(Thread::check_for_dangling_thread_pointer(thread);)
171
172 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
173
174 oop obj = NULL;
175 if (wait_obj != NULL) {
176 // thread is doing an Object.wait() call
177 obj = (oop) wait_obj->object();
178 assert(obj != NULL, "Object.wait() should have an object");
179 } else {
180 ObjectMonitor *enter_obj = thread->current_pending_monitor();
181 if (enter_obj != NULL) {
182 // thread is trying to enter() or raw_enter() an ObjectMonitor.
183 obj = (oop) enter_obj->object();
184 }
185 // If obj == NULL, then ObjectMonitor is raw which doesn't count.
186 }
187
188 Handle h(Thread::current(), obj);
189 return h;
190 }
191
192 bool ThreadService::set_thread_monitoring_contention(bool flag) {
193 MutexLocker m(Management_lock);
194
195 bool prev = _thread_monitoring_contention_enabled;
196 _thread_monitoring_contention_enabled = flag;
197
198 return prev;
199 }
200
201 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
202 MutexLocker m(Management_lock);
203
204 bool prev = _thread_cpu_time_enabled;
205 _thread_cpu_time_enabled = flag;
206
207 return prev;
208 }
209
210 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
211 MutexLocker m(Management_lock);
212
213 bool prev = _thread_allocated_memory_enabled;
214 _thread_allocated_memory_enabled = flag;
215
216 return prev;
217 }
218
219 // GC support
220 void ThreadService::oops_do(OopClosure* f) {
221 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
222 dump->oops_do(f);
223 }
224 }
225
226 void ThreadService::metadata_do(void f(Metadata*)) {
227 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
228 dump->metadata_do(f);
229 }
230 }
231
232 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
233 MutexLocker ml(Management_lock);
234 if (_threaddump_list == NULL) {
235 _threaddump_list = dump;
236 } else {
237 dump->set_next(_threaddump_list);
238 _threaddump_list = dump;
239 }
240 }
241
242 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
243 MutexLocker ml(Management_lock);
244
245 ThreadDumpResult* prev = NULL;
246 bool found = false;
247 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
248 if (d == dump) {
249 if (prev == NULL) {
250 _threaddump_list = dump->next();
251 } else {
252 prev->set_next(dump->next());
253 }
254 found = true;
255 break;
256 }
257 }
258 assert(found, "The threaddump result to be removed must exist.");
259 }
260
261 // Dump stack trace of threads specified in the given threads array.
262 // Returns StackTraceElement[][] each element is the stack trace of a thread in
263 // the corresponding entry in the given threads array
264 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
265 int num_threads,
266 TRAPS) {
267 assert(num_threads > 0, "just checking");
268
269 ThreadDumpResult dump_result;
270 VM_ThreadDump op(&dump_result,
271 threads,
272 num_threads,
273 -1, /* entire stack */
274 false, /* with locked monitors */
275 false /* with locked synchronizers */);
276 VMThread::execute(&op);
277
278 // Allocate the resulting StackTraceElement[][] object
279
280 ResourceMark rm(THREAD);
281 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
282 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
283 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
284 objArrayHandle result_obj(THREAD, r);
285
286 int num_snapshots = dump_result.num_snapshots();
287 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
288 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
289 int i = 0;
290 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
291 ThreadStackTrace* stacktrace = ts->get_stack_trace();
292 if (stacktrace == NULL) {
293 // No stack trace
294 result_obj->obj_at_put(i, NULL);
295 } else {
296 // Construct an array of java/lang/StackTraceElement object
297 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
298 result_obj->obj_at_put(i, backtrace_h());
299 }
300 }
301
302 return result_obj;
303 }
304
305 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
306 ThreadStatistics* stat = thread->get_thread_stat();
307 if (stat != NULL) {
308 stat->reset_count_stat();
309 }
310 }
311
312 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
313 ThreadStatistics* stat = thread->get_thread_stat();
314 if (stat != NULL) {
315 stat->reset_time_stat();
316 }
317 }
318
319 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
320 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
321 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
322
323 // This code was modified from the original Threads::find_deadlocks code.
324 int globalDfn = 0, thisDfn;
325 ObjectMonitor* waitingToLockMonitor = NULL;
326 oop waitingToLockBlocker = NULL;
327 bool blocked_on_monitor = false;
328 JavaThread *currentThread, *previousThread;
329 int num_deadlocks = 0;
330
331 // Initialize the depth-first-number for each JavaThread.
332 JavaThreadIterator jti(t_list);
333 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
334 jt->set_depth_first_number(-1);
335 }
336
337 DeadlockCycle* deadlocks = NULL;
338 DeadlockCycle* last = NULL;
339 DeadlockCycle* cycle = new DeadlockCycle();
340 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
341 if (jt->depth_first_number() >= 0) {
342 // this thread was already visited
343 continue;
344 }
345
346 thisDfn = globalDfn;
347 jt->set_depth_first_number(globalDfn++);
348 previousThread = jt;
349 currentThread = jt;
350
351 cycle->reset();
352
353 // When there is a deadlock, all the monitors involved in the dependency
354 // cycle must be contended and heavyweight. So we only care about the
355 // heavyweight monitor a thread is waiting to lock.
356 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
357 if (concurrent_locks) {
358 waitingToLockBlocker = jt->current_park_blocker();
359 }
360 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
361 cycle->add_thread(currentThread);
362 if (waitingToLockMonitor != NULL) {
363 address currentOwner = (address)waitingToLockMonitor->owner();
364 if (currentOwner != NULL) {
365 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
366 currentOwner);
367 if (currentThread == NULL) {
368 // This function is called at a safepoint so the JavaThread
369 // that owns waitingToLockMonitor should be findable, but
370 // if it is not findable, then the previous currentThread is
371 // blocked permanently. We record this as a deadlock.
372 num_deadlocks++;
373
374 cycle->set_deadlock(true);
375
376 // add this cycle to the deadlocks list
377 if (deadlocks == NULL) {
378 deadlocks = cycle;
379 } else {
380 last->set_next(cycle);
381 }
382 last = cycle;
383 cycle = new DeadlockCycle();
384 break;
385 }
386 }
387 } else {
388 if (concurrent_locks) {
389 if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
390 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
391 // This JavaThread (if there is one) is protected by the
392 // ThreadsListSetter in VM_FindDeadlocks::doit().
393 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
394 } else {
395 currentThread = NULL;
396 }
397 }
398 }
399
400 if (currentThread == NULL) {
401 // No dependency on another thread
402 break;
403 }
404 if (currentThread->depth_first_number() < 0) {
405 // First visit to this thread
406 currentThread->set_depth_first_number(globalDfn++);
407 } else if (currentThread->depth_first_number() < thisDfn) {
408 // Thread already visited, and not on a (new) cycle
409 break;
410 } else if (currentThread == previousThread) {
411 // Self-loop, ignore
412 break;
413 } else {
414 // We have a (new) cycle
415 num_deadlocks++;
416
417 cycle->set_deadlock(true);
418
419 // add this cycle to the deadlocks list
420 if (deadlocks == NULL) {
421 deadlocks = cycle;
422 } else {
423 last->set_next(cycle);
424 }
425 last = cycle;
426 cycle = new DeadlockCycle();
427 break;
428 }
429 previousThread = currentThread;
430 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
431 if (concurrent_locks) {
432 waitingToLockBlocker = currentThread->current_park_blocker();
433 }
434 }
435
436 }
437 delete cycle;
438 return deadlocks;
439 }
440
441 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
442
443 // Create a new ThreadDumpResult object and append to the list.
444 // If GC happens before this function returns, Method*
445 // in the stack trace will be visited.
446 ThreadService::add_thread_dump(this);
447 }
448
449 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
450 // Create a new ThreadDumpResult object and append to the list.
451 // If GC happens before this function returns, oops
452 // will be visited.
453 ThreadService::add_thread_dump(this);
454 }
455
456 ThreadDumpResult::~ThreadDumpResult() {
457 ThreadService::remove_thread_dump(this);
458
459 // free all the ThreadSnapshot objects created during
460 // the VM_ThreadDump operation
461 ThreadSnapshot* ts = _snapshots;
462 while (ts != NULL) {
463 ThreadSnapshot* p = ts;
464 ts = ts->next();
465 delete p;
466 }
467 }
468
469
470 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
471 assert(_num_threads == 0 || _num_snapshots < _num_threads,
472 "_num_snapshots must be less than _num_threads");
473 _num_snapshots++;
474 if (_snapshots == NULL) {
475 _snapshots = ts;
476 } else {
477 _last->set_next(ts);
478 }
479 _last = ts;
480 }
481
482 void ThreadDumpResult::oops_do(OopClosure* f) {
483 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
484 ts->oops_do(f);
485 }
486 }
487
488 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
489 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
490 ts->metadata_do(f);
491 }
492 }
493
494 ThreadsList* ThreadDumpResult::t_list() {
495 return _setter.list();
496 }
497
498 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
499 _method = jvf->method();
500 _bci = jvf->bci();
501 _class_holder = _method->method_holder()->klass_holder();
502 _locked_monitors = NULL;
503 if (with_lock_info) {
504 ResourceMark rm;
505 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
506 int length = list->length();
507 if (length > 0) {
508 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
509 for (int i = 0; i < length; i++) {
510 MonitorInfo* monitor = list->at(i);
511 assert(monitor->owner() != NULL, "This monitor must have an owning object");
512 _locked_monitors->append(monitor->owner());
513 }
514 }
515 }
516 }
517
518 void StackFrameInfo::oops_do(OopClosure* f) {
519 if (_locked_monitors != NULL) {
520 int length = _locked_monitors->length();
521 for (int i = 0; i < length; i++) {
522 f->do_oop((oop*) _locked_monitors->adr_at(i));
523 }
524 }
525 f->do_oop(&_class_holder);
526 }
527
528 void StackFrameInfo::metadata_do(void f(Metadata*)) {
529 f(_method);
530 }
531
532 void StackFrameInfo::print_on(outputStream* st) const {
533 ResourceMark rm;
534 java_lang_Throwable::print_stack_element(st, method(), bci());
535 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
536 for (int i = 0; i < len; i++) {
537 oop o = _locked_monitors->at(i);
538 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
539 }
540
541 }
542
543 // Iterate through monitor cache to find JNI locked monitors
544 class InflatedMonitorsClosure: public MonitorClosure {
545 private:
546 ThreadStackTrace* _stack_trace;
547 Thread* _thread;
548 public:
549 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
550 _thread = t;
551 _stack_trace = st;
552 }
553 void do_monitor(ObjectMonitor* mid) {
554 if (mid->owner() == _thread) {
555 oop object = (oop) mid->object();
556 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
557 _stack_trace->add_jni_locked_monitor(object);
558 }
559 }
560 }
561 };
562
563 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
564 _thread = t;
565 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
566 _depth = 0;
567 _with_locked_monitors = with_locked_monitors;
568 if (_with_locked_monitors) {
569 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
570 } else {
571 _jni_locked_monitors = NULL;
572 }
573 }
574
575 ThreadStackTrace::~ThreadStackTrace() {
576 for (int i = 0; i < _frames->length(); i++) {
577 delete _frames->at(i);
578 }
579 delete _frames;
580 if (_jni_locked_monitors != NULL) {
581 delete _jni_locked_monitors;
582 }
583 }
584
585 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
586 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
587
588 if (_thread->has_last_Java_frame()) {
589 RegisterMap reg_map(_thread);
590 vframe* start_vf = _thread->last_java_vframe(®_map);
591 int count = 0;
592 for (vframe* f = start_vf; f; f = f->sender() ) {
593 if (maxDepth >= 0 && count == maxDepth) {
594 // Skip frames if more than maxDepth
595 break;
596 }
597 if (f->is_java_frame()) {
598 javaVFrame* jvf = javaVFrame::cast(f);
599 add_stack_frame(jvf);
600 count++;
601 } else {
602 // Ignore non-Java frames
603 }
604 }
605 }
606
607 if (_with_locked_monitors) {
608 // Iterate inflated monitors and find monitors locked by this thread
609 // not found in the stack
610 InflatedMonitorsClosure imc(_thread, this);
611 ObjectSynchronizer::monitors_iterate(&imc);
612 }
613 }
614
615
616 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
617 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
618
619 bool found = false;
620 int num_frames = get_stack_depth();
621 for (int depth = 0; depth < num_frames; depth++) {
622 StackFrameInfo* frame = stack_frame_at(depth);
623 int len = frame->num_locked_monitors();
624 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
625 for (int j = 0; j < len; j++) {
626 oop monitor = locked_monitors->at(j);
627 assert(monitor != NULL, "must be a Java object");
628 if (oopDesc::equals(monitor, object)) {
629 found = true;
630 break;
631 }
632 }
633 }
634 return found;
635 }
636
637 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
638 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass();
639 assert(ik != NULL, "must be loaded in 1.4+");
640
641 // Allocate an array of java/lang/StackTraceElement object
642 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
643 objArrayHandle backtrace(THREAD, ste);
644 for (int j = 0; j < _depth; j++) {
645 StackFrameInfo* frame = _frames->at(j);
646 methodHandle mh(THREAD, frame->method());
647 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
648 backtrace->obj_at_put(j, element);
649 }
650 return backtrace;
651 }
652
653 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
654 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
655 _frames->append(frame);
656 _depth++;
657 }
658
659 void ThreadStackTrace::oops_do(OopClosure* f) {
660 int length = _frames->length();
661 for (int i = 0; i < length; i++) {
662 _frames->at(i)->oops_do(f);
663 }
664
665 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
666 for (int j = 0; j < length; j++) {
667 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
668 }
669 }
670
671 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
672 int length = _frames->length();
673 for (int i = 0; i < length; i++) {
674 _frames->at(i)->metadata_do(f);
675 }
676 }
677
678
679 ConcurrentLocksDump::~ConcurrentLocksDump() {
680 if (_retain_map_on_free) {
681 return;
682 }
683
684 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
685 ThreadConcurrentLocks* tcl = t;
686 t = t->next();
687 delete tcl;
688 }
689 }
690
691 void ConcurrentLocksDump::dump_at_safepoint() {
692 // dump all locked concurrent locks
693 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
694
695 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */);
696
697 // Find all instances of AbstractOwnableSynchronizer
698 HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
699 aos_objects);
700 // Build a map of thread to its owned AQS locks
701 build_map(aos_objects);
702
703 delete aos_objects;
704 }
705
706
707 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
708 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
709 int length = aos_objects->length();
710 for (int i = 0; i < length; i++) {
711 oop o = aos_objects->at(i);
712 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
713 if (owner_thread_obj != NULL) {
714 // See comments in ThreadConcurrentLocks to see how this
715 // JavaThread* is protected.
716 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
717 assert(o->is_instance(), "Must be an instanceOop");
718 add_lock(thread, (instanceOop) o);
719 }
720 }
721 }
722
723 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
724 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
725 if (tcl != NULL) {
726 tcl->add_lock(o);
727 return;
728 }
729
730 // First owned lock found for this thread
731 tcl = new ThreadConcurrentLocks(thread);
732 tcl->add_lock(o);
733 if (_map == NULL) {
734 _map = tcl;
735 } else {
736 _last->set_next(tcl);
737 }
738 _last = tcl;
739 }
740
741 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
742 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
743 if (tcl->java_thread() == thread) {
744 return tcl;
745 }
746 }
747 return NULL;
748 }
749
750 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
751 st->print_cr(" Locked ownable synchronizers:");
752 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
753 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
754 if (locks == NULL || locks->is_empty()) {
755 st->print_cr("\t- None");
756 st->cr();
757 return;
758 }
759
760 for (int i = 0; i < locks->length(); i++) {
761 instanceOop obj = locks->at(i);
762 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
763 }
764 st->cr();
765 }
766
767 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
768 _thread = thread;
769 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
770 _next = NULL;
771 }
772
773 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
774 delete _owned_locks;
775 }
776
777 void ThreadConcurrentLocks::add_lock(instanceOop o) {
778 _owned_locks->append(o);
779 }
780
781 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
782 int length = _owned_locks->length();
783 for (int i = 0; i < length; i++) {
784 f->do_oop((oop*) _owned_locks->adr_at(i));
785 }
786 }
787
788 ThreadStatistics::ThreadStatistics() {
789 _contended_enter_count = 0;
790 _monitor_wait_count = 0;
791 _sleep_count = 0;
792 _count_pending_reset = false;
793 _timer_pending_reset = false;
794 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
795 }
796
797 ThreadSnapshot::ThreadSnapshot(ThreadsList * t_list, JavaThread* thread) {
798 _thread = thread;
799 _threadObj = thread->threadObj();
800 _stack_trace = NULL;
801 _concurrent_locks = NULL;
802 _next = NULL;
803
804 ThreadStatistics* stat = thread->get_thread_stat();
805 _contended_enter_ticks = stat->contended_enter_ticks();
806 _contended_enter_count = stat->contended_enter_count();
807 _monitor_wait_ticks = stat->monitor_wait_ticks();
808 _monitor_wait_count = stat->monitor_wait_count();
809 _sleep_ticks = stat->sleep_ticks();
810 _sleep_count = stat->sleep_count();
811
812 _blocker_object = NULL;
813 _blocker_object_owner = NULL;
814
815 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
816 _is_ext_suspended = thread->is_being_ext_suspended();
817 _is_in_native = (thread->thread_state() == _thread_in_native);
818
819 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
820 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
821 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
822
823 Handle obj = ThreadService::get_current_contended_monitor(thread);
824 if (obj() == NULL) {
825 // monitor no longer exists; thread is not blocked
826 _thread_status = java_lang_Thread::RUNNABLE;
827 } else {
828 _blocker_object = obj();
829 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
830 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
831 || (owner != NULL && owner->is_attaching_via_jni())) {
832 // ownership information of the monitor is not available
833 // (may no longer be owned or releasing to some other thread)
834 // make this thread in RUNNABLE state.
835 // And when the owner thread is in attaching state, the java thread
836 // is not completely initialized. For example thread name and id
837 // and may not be set, so hide the attaching thread.
838 _thread_status = java_lang_Thread::RUNNABLE;
839 _blocker_object = NULL;
840 } else if (owner != NULL) {
841 _blocker_object_owner = owner->threadObj();
842 }
843 }
844 }
845
846 // Support for JSR-166 locks
847 if (JDK_Version::current().supports_thread_park_blocker() &&
848 (_thread_status == java_lang_Thread::PARKED ||
849 _thread_status == java_lang_Thread::PARKED_TIMED)) {
850
851 _blocker_object = thread->current_park_blocker();
852 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
853 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
854 }
855 }
856 }
857
858 ThreadSnapshot::~ThreadSnapshot() {
859 delete _stack_trace;
860 delete _concurrent_locks;
861 }
862
863 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
864 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
865 _stack_trace->dump_stack_at_safepoint(max_depth);
866 }
867
868
869 void ThreadSnapshot::oops_do(OopClosure* f) {
870 f->do_oop(&_threadObj);
871 f->do_oop(&_blocker_object);
872 f->do_oop(&_blocker_object_owner);
873 if (_stack_trace != NULL) {
874 _stack_trace->oops_do(f);
875 }
876 if (_concurrent_locks != NULL) {
877 _concurrent_locks->oops_do(f);
878 }
879 }
880
881 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
882 if (_stack_trace != NULL) {
883 _stack_trace->metadata_do(f);
884 }
885 }
886
887
888 DeadlockCycle::DeadlockCycle() {
889 _is_deadlock = false;
890 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
891 _next = NULL;
892 }
893
894 DeadlockCycle::~DeadlockCycle() {
895 delete _threads;
896 }
897
898 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
899 st->cr();
900 st->print_cr("Found one Java-level deadlock:");
901 st->print("=============================");
902
903 JavaThread* currentThread;
904 ObjectMonitor* waitingToLockMonitor;
905 oop waitingToLockBlocker;
906 int len = _threads->length();
907 for (int i = 0; i < len; i++) {
908 currentThread = _threads->at(i);
909 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
910 waitingToLockBlocker = currentThread->current_park_blocker();
911 st->cr();
912 st->print_cr("\"%s\":", currentThread->get_thread_name());
913 const char* owner_desc = ",\n which is held by";
914 if (waitingToLockMonitor != NULL) {
915 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
916 oop obj = (oop)waitingToLockMonitor->object();
917 if (obj != NULL) {
918 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
919 obj->klass()->external_name());
920
921 if (!currentThread->current_pending_monitor_is_from_java()) {
922 owner_desc = "\n in JNI, which is held by";
923 }
924 } else {
925 // No Java object associated - a JVMTI raw monitor
926 owner_desc = " (JVMTI raw monitor),\n which is held by";
927 }
928 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
929 (address)waitingToLockMonitor->owner());
930 if (currentThread == NULL) {
931 // The deadlock was detected at a safepoint so the JavaThread
932 // that owns waitingToLockMonitor should be findable, but
933 // if it is not findable, then the previous currentThread is
934 // blocked permanently.
935 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
936 p2i(waitingToLockMonitor->owner()));
937 continue;
938 }
939 } else {
940 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
941 p2i(waitingToLockBlocker),
942 waitingToLockBlocker->klass()->external_name());
943 assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
944 "Must be an AbstractOwnableSynchronizer");
945 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
946 currentThread = java_lang_Thread::thread(ownerObj);
947 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
948 }
949 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
950 }
951
952 st->cr();
953 st->cr();
954
955 // Print stack traces
956 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
957 JavaMonitorsInStackTrace = true;
958 st->print_cr("Java stack information for the threads listed above:");
959 st->print_cr("===================================================");
960 for (int j = 0; j < len; j++) {
961 currentThread = _threads->at(j);
962 st->print_cr("\"%s\":", currentThread->get_thread_name());
963 currentThread->print_stack_on(st);
964 }
965 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
966 }
967
968 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
969 bool include_jvmti_agent_threads,
970 bool include_jni_attaching_threads) {
971 assert(cur_thread == Thread::current(), "Check current thread");
972
973 int init_size = ThreadService::get_live_thread_count();
974 _threads_array = new GrowableArray<instanceHandle>(init_size);
975
976 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
977 // skips JavaThreads in the process of exiting
978 // and also skips VM internal JavaThreads
979 // Threads in _thread_new or _thread_new_trans state are included.
980 // i.e. threads have been started but not yet running.
981 if (jt->threadObj() == NULL ||
982 jt->is_exiting() ||
983 !java_lang_Thread::is_alive(jt->threadObj()) ||
984 jt->is_hidden_from_external_view()) {
985 continue;
986 }
987
988 // skip agent threads
989 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
990 continue;
991 }
992
993 // skip jni threads in the process of attaching
994 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
995 continue;
996 }
997
998 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
999 _threads_array->append(h);
1000 }
1001 }