1 /*
2 * Copyright (c) 2003, 2020, 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/objArrayKlass.hpp"
33 #include "oops/objArrayOop.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "prims/jvmtiRawMonitor.hpp"
36 #include "runtime/atomic.hpp"
37 #include "runtime/handles.inline.hpp"
38 #include "runtime/init.hpp"
39 #include "runtime/objectMonitor.inline.hpp"
40 #include "runtime/thread.inline.hpp"
41 #include "runtime/threadSMR.inline.hpp"
42 #include "runtime/vframe.hpp"
43 #include "runtime/vmThread.hpp"
44 #include "runtime/vmOperations.hpp"
45 #include "services/threadService.hpp"
46
47 // TODO: we need to define a naming convention for perf counters
48 // to distinguish counters for:
49 // - standard JSR174 use
50 // - Hotspot extension (public and committed)
51 // - Hotspot extension (private/internal and uncommitted)
52
53 // Default is disabled.
54 bool ThreadService::_thread_monitoring_contention_enabled = false;
55 bool ThreadService::_thread_cpu_time_enabled = false;
56 bool ThreadService::_thread_allocated_memory_enabled = false;
57
58 PerfCounter* ThreadService::_total_threads_count = NULL;
59 PerfVariable* ThreadService::_live_threads_count = NULL;
60 PerfVariable* ThreadService::_peak_threads_count = NULL;
61 PerfVariable* ThreadService::_daemon_threads_count = NULL;
62 volatile int ThreadService::_atomic_threads_count = 0;
63 volatile int ThreadService::_atomic_daemon_threads_count = 0;
64
65 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
66
67 static const int INITIAL_ARRAY_SIZE = 10;
68
69 void ThreadService::init() {
70 EXCEPTION_MARK;
71
72 // These counters are for java.lang.management API support.
73 // They are created even if -XX:-UsePerfData is set and in
74 // that case, they will be allocated on C heap.
75
76 _total_threads_count =
77 PerfDataManager::create_counter(JAVA_THREADS, "started",
78 PerfData::U_Events, CHECK);
79
80 _live_threads_count =
81 PerfDataManager::create_variable(JAVA_THREADS, "live",
82 PerfData::U_None, CHECK);
83
84 _peak_threads_count =
85 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
86 PerfData::U_None, CHECK);
87
88 _daemon_threads_count =
89 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
90 PerfData::U_None, CHECK);
91
92 if (os::is_thread_cpu_time_supported()) {
93 _thread_cpu_time_enabled = true;
94 }
95
96 _thread_allocated_memory_enabled = true; // Always on, so enable it
97 }
98
99 void ThreadService::reset_peak_thread_count() {
100 // Acquire the lock to update the peak thread count
101 // to synchronize with thread addition and removal.
102 MutexLocker mu(Threads_lock);
103 _peak_threads_count->set_value(get_live_thread_count());
104 }
105
106 static bool is_hidden_thread(JavaThread *thread) {
107 // hide VM internal or JVMTI agent threads
108 return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
109 }
110
111 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
112 assert(Threads_lock->owned_by_self(), "must have threads lock");
113
114 // Do not count hidden threads
115 if (is_hidden_thread(thread)) {
116 return;
117 }
118
119 _total_threads_count->inc();
120 _live_threads_count->inc();
121 Atomic::inc(&_atomic_threads_count);
122 int count = _atomic_threads_count;
123
124 if (count > _peak_threads_count->get_value()) {
125 _peak_threads_count->set_value(count);
126 }
127
128 if (daemon) {
129 _daemon_threads_count->inc();
130 Atomic::inc(&_atomic_daemon_threads_count);
131 }
132 }
133
134 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
135 Atomic::dec(&_atomic_threads_count);
136
137 if (daemon) {
138 Atomic::dec(&_atomic_daemon_threads_count);
139 }
140 }
141
142 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
143 assert(Threads_lock->owned_by_self(), "must have threads lock");
144
145 // Do not count hidden threads
146 if (is_hidden_thread(thread)) {
147 return;
148 }
149
150 assert(!thread->is_terminated(), "must not be terminated");
151 if (!thread->is_exiting()) {
152 // JavaThread::exit() skipped calling current_thread_exiting()
153 decrement_thread_counts(thread, daemon);
154 }
155
156 int daemon_count = _atomic_daemon_threads_count;
157 int count = _atomic_threads_count;
158
159 // Counts are incremented at the same time, but atomic counts are
160 // decremented earlier than perf counts.
161 assert(_live_threads_count->get_value() > count,
162 "thread count mismatch %d : %d",
163 (int)_live_threads_count->get_value(), count);
164
165 _live_threads_count->dec(1);
166 if (daemon) {
167 assert(_daemon_threads_count->get_value() > daemon_count,
168 "thread count mismatch %d : %d",
169 (int)_daemon_threads_count->get_value(), daemon_count);
170
171 _daemon_threads_count->dec(1);
172 }
173
174 // Counts are incremented at the same time, but atomic counts are
175 // decremented earlier than perf counts.
176 assert(_daemon_threads_count->get_value() >= daemon_count,
177 "thread count mismatch %d : %d",
178 (int)_daemon_threads_count->get_value(), daemon_count);
179 assert(_live_threads_count->get_value() >= count,
180 "thread count mismatch %d : %d",
181 (int)_live_threads_count->get_value(), count);
182 assert(_live_threads_count->get_value() > 0 ||
183 (_live_threads_count->get_value() == 0 && count == 0 &&
184 _daemon_threads_count->get_value() == 0 && daemon_count == 0),
185 "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
186 (int)_live_threads_count->get_value(), count,
187 (int)_daemon_threads_count->get_value(), daemon_count);
188 assert(_daemon_threads_count->get_value() > 0 ||
189 (_daemon_threads_count->get_value() == 0 && daemon_count == 0),
190 "thread counts should reach 0 at the same time, daemon %d,%d",
191 (int)_daemon_threads_count->get_value(), daemon_count);
192 }
193
194 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
195 // Do not count hidden threads
196 if (is_hidden_thread(jt)) {
197 return;
198 }
199
200 assert(jt == JavaThread::current(), "Called by current thread");
201 assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
202
203 decrement_thread_counts(jt, daemon);
204 }
205
206 // FIXME: JVMTI should call this function
207 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
208 assert(thread != NULL, "should be non-NULL");
209 debug_only(Thread::check_for_dangling_thread_pointer(thread);)
210
211 // This function can be called on a target JavaThread that is not
212 // the caller and we are not at a safepoint. So it is possible for
213 // the waiting or pending condition to be over/stale and for the
214 // first stage of async deflation to clear the object field in
215 // the ObjectMonitor. It is also possible for the object to be
216 // inflated again and to be associated with a completely different
217 // ObjectMonitor by the time this object reference is processed
218 // by the caller.
219 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
220
221 oop obj = NULL;
222 if (wait_obj != NULL) {
223 // thread is doing an Object.wait() call
224 obj = (oop) wait_obj->object();
225 assert(AsyncDeflateIdleMonitors || obj != NULL, "Object.wait() should have an object");
226 } else {
227 ObjectMonitor *enter_obj = thread->current_pending_monitor();
228 if (enter_obj != NULL) {
229 // thread is trying to enter() an ObjectMonitor.
230 obj = (oop) enter_obj->object();
231 assert(AsyncDeflateIdleMonitors || obj != NULL, "ObjectMonitor should have an associated object!");
232 }
233 }
234
235 Handle h(Thread::current(), obj);
236 return h;
237 }
238
239 bool ThreadService::set_thread_monitoring_contention(bool flag) {
240 MutexLocker m(Management_lock);
241
242 bool prev = _thread_monitoring_contention_enabled;
243 _thread_monitoring_contention_enabled = flag;
244
245 return prev;
246 }
247
248 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
249 MutexLocker m(Management_lock);
250
251 bool prev = _thread_cpu_time_enabled;
252 _thread_cpu_time_enabled = flag;
253
254 return prev;
255 }
256
257 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
258 MutexLocker m(Management_lock);
259
260 bool prev = _thread_allocated_memory_enabled;
261 _thread_allocated_memory_enabled = flag;
262
263 return prev;
264 }
265
266 // GC support
267 void ThreadService::oops_do(OopClosure* f) {
268 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
269 dump->oops_do(f);
270 }
271 }
272
273 void ThreadService::metadata_do(void f(Metadata*)) {
274 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
275 dump->metadata_do(f);
276 }
277 }
278
279 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
280 MutexLocker ml(Management_lock);
281 if (_threaddump_list == NULL) {
282 _threaddump_list = dump;
283 } else {
284 dump->set_next(_threaddump_list);
285 _threaddump_list = dump;
286 }
287 }
288
289 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
290 MutexLocker ml(Management_lock);
291
292 ThreadDumpResult* prev = NULL;
293 bool found = false;
294 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
295 if (d == dump) {
296 if (prev == NULL) {
297 _threaddump_list = dump->next();
298 } else {
299 prev->set_next(dump->next());
300 }
301 found = true;
302 break;
303 }
304 }
305 assert(found, "The threaddump result to be removed must exist.");
306 }
307
308 // Dump stack trace of threads specified in the given threads array.
309 // Returns StackTraceElement[][] each element is the stack trace of a thread in
310 // the corresponding entry in the given threads array
311 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
312 int num_threads,
313 TRAPS) {
314 assert(num_threads > 0, "just checking");
315
316 ThreadDumpResult dump_result;
317 VM_ThreadDump op(&dump_result,
318 threads,
319 num_threads,
320 -1, /* entire stack */
321 false, /* with locked monitors */
322 false /* with locked synchronizers */);
323 VMThread::execute(&op);
324
325 // Allocate the resulting StackTraceElement[][] object
326
327 ResourceMark rm(THREAD);
328 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
329 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
330 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
331 objArrayHandle result_obj(THREAD, r);
332
333 int num_snapshots = dump_result.num_snapshots();
334 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
335 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
336 int i = 0;
337 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
338 ThreadStackTrace* stacktrace = ts->get_stack_trace();
339 if (stacktrace == NULL) {
340 // No stack trace
341 result_obj->obj_at_put(i, NULL);
342 } else {
343 // Construct an array of java/lang/StackTraceElement object
344 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
345 result_obj->obj_at_put(i, backtrace_h());
346 }
347 }
348
349 return result_obj;
350 }
351
352 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
353 ThreadStatistics* stat = thread->get_thread_stat();
354 if (stat != NULL) {
355 stat->reset_count_stat();
356 }
357 }
358
359 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
360 ThreadStatistics* stat = thread->get_thread_stat();
361 if (stat != NULL) {
362 stat->reset_time_stat();
363 }
364 }
365
366 // Find deadlocks involving raw monitors, object monitors and concurrent locks
367 // if concurrent_locks is true.
368 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
369 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
370
371 // This code was modified from the original Threads::find_deadlocks code.
372 int globalDfn = 0, thisDfn;
373 ObjectMonitor* waitingToLockMonitor = NULL;
374 JvmtiRawMonitor* waitingToLockRawMonitor = NULL;
375 oop waitingToLockBlocker = NULL;
376 bool blocked_on_monitor = false;
377 JavaThread *currentThread, *previousThread;
378 int num_deadlocks = 0;
379
380 // Initialize the depth-first-number for each JavaThread.
381 JavaThreadIterator jti(t_list);
382 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
383 jt->set_depth_first_number(-1);
384 }
385
386 DeadlockCycle* deadlocks = NULL;
387 DeadlockCycle* last = NULL;
388 DeadlockCycle* cycle = new DeadlockCycle();
389 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
390 if (jt->depth_first_number() >= 0) {
391 // this thread was already visited
392 continue;
393 }
394
395 thisDfn = globalDfn;
396 jt->set_depth_first_number(globalDfn++);
397 previousThread = jt;
398 currentThread = jt;
399
400 cycle->reset();
401
402 // The ObjectMonitor* can't be async deflated since we are at a safepoint.
403 // When there is a deadlock, all the monitors involved in the dependency
404 // cycle must be contended and heavyweight. So we only care about the
405 // heavyweight monitor a thread is waiting to lock.
406 waitingToLockMonitor = jt->current_pending_monitor();
407 // JVM TI raw monitors can also be involved in deadlocks, and we can be
408 // waiting to lock both a raw monitor and ObjectMonitor at the same time.
409 // It isn't clear how to make deadlock detection work correctly if that
410 // happens.
411 waitingToLockRawMonitor = jt->current_pending_raw_monitor();
412
413 if (concurrent_locks) {
414 waitingToLockBlocker = jt->current_park_blocker();
415 }
416
417 while (waitingToLockMonitor != NULL ||
418 waitingToLockRawMonitor != NULL ||
419 waitingToLockBlocker != NULL) {
420 cycle->add_thread(currentThread);
421 // Give preference to the raw monitor
422 if (waitingToLockRawMonitor != NULL) {
423 Thread* owner = waitingToLockRawMonitor->owner();
424 if (owner != NULL && // the raw monitor could be released at any time
425 owner->is_Java_thread()) {
426 // only JavaThreads can be reported here
427 currentThread = (JavaThread*) owner;
428 }
429 } else if (waitingToLockMonitor != NULL) {
430 address currentOwner = (address)waitingToLockMonitor->owner();
431 if (currentOwner != NULL) {
432 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
433 currentOwner);
434 if (currentThread == NULL) {
435 // This function is called at a safepoint so the JavaThread
436 // that owns waitingToLockMonitor should be findable, but
437 // if it is not findable, then the previous currentThread is
438 // blocked permanently. We record this as a deadlock.
439 num_deadlocks++;
440
441 cycle->set_deadlock(true);
442
443 // add this cycle to the deadlocks list
444 if (deadlocks == NULL) {
445 deadlocks = cycle;
446 } else {
447 last->set_next(cycle);
448 }
449 last = cycle;
450 cycle = new DeadlockCycle();
451 break;
452 }
453 }
454 } else {
455 if (concurrent_locks) {
456 if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
457 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
458 // This JavaThread (if there is one) is protected by the
459 // ThreadsListSetter in VM_FindDeadlocks::doit().
460 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
461 } else {
462 currentThread = NULL;
463 }
464 }
465 }
466
467 if (currentThread == NULL) {
468 // No dependency on another thread
469 break;
470 }
471 if (currentThread->depth_first_number() < 0) {
472 // First visit to this thread
473 currentThread->set_depth_first_number(globalDfn++);
474 } else if (currentThread->depth_first_number() < thisDfn) {
475 // Thread already visited, and not on a (new) cycle
476 break;
477 } else if (currentThread == previousThread) {
478 // Self-loop, ignore
479 break;
480 } else {
481 // We have a (new) cycle
482 num_deadlocks++;
483
484 cycle->set_deadlock(true);
485
486 // add this cycle to the deadlocks list
487 if (deadlocks == NULL) {
488 deadlocks = cycle;
489 } else {
490 last->set_next(cycle);
491 }
492 last = cycle;
493 cycle = new DeadlockCycle();
494 break;
495 }
496 previousThread = currentThread;
497 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
498 if (concurrent_locks) {
499 waitingToLockBlocker = currentThread->current_park_blocker();
500 }
501 }
502
503 }
504 delete cycle;
505 return deadlocks;
506 }
507
508 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
509
510 // Create a new ThreadDumpResult object and append to the list.
511 // If GC happens before this function returns, Method*
512 // in the stack trace will be visited.
513 ThreadService::add_thread_dump(this);
514 }
515
516 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
517 // Create a new ThreadDumpResult object and append to the list.
518 // If GC happens before this function returns, oops
519 // will be visited.
520 ThreadService::add_thread_dump(this);
521 }
522
523 ThreadDumpResult::~ThreadDumpResult() {
524 ThreadService::remove_thread_dump(this);
525
526 // free all the ThreadSnapshot objects created during
527 // the VM_ThreadDump operation
528 ThreadSnapshot* ts = _snapshots;
529 while (ts != NULL) {
530 ThreadSnapshot* p = ts;
531 ts = ts->next();
532 delete p;
533 }
534 }
535
536 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
537 ThreadSnapshot* ts = new ThreadSnapshot();
538 link_thread_snapshot(ts);
539 return ts;
540 }
541
542 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
543 // Note: it is very important that the ThreadSnapshot* gets linked before
544 // ThreadSnapshot::initialize gets called. This is to ensure that
545 // ThreadSnapshot::oops_do can get called prior to the field
546 // ThreadSnapshot::_threadObj being assigned a value (to prevent a dangling
547 // oop).
548 ThreadSnapshot* ts = new ThreadSnapshot();
549 link_thread_snapshot(ts);
550 ts->initialize(t_list(), thread);
551 return ts;
552 }
553
554 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
555 assert(_num_threads == 0 || _num_snapshots < _num_threads,
556 "_num_snapshots must be less than _num_threads");
557 _num_snapshots++;
558 if (_snapshots == NULL) {
559 _snapshots = ts;
560 } else {
561 _last->set_next(ts);
562 }
563 _last = ts;
564 }
565
566 void ThreadDumpResult::oops_do(OopClosure* f) {
567 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
568 ts->oops_do(f);
569 }
570 }
571
572 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
573 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
574 ts->metadata_do(f);
575 }
576 }
577
578 ThreadsList* ThreadDumpResult::t_list() {
579 return _setter.list();
580 }
581
582 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
583 _method = jvf->method();
584 _bci = jvf->bci();
585 _class_holder = _method->method_holder()->klass_holder();
586 _locked_monitors = NULL;
587 if (with_lock_info) {
588 ResourceMark rm;
589 HandleMark hm;
590 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
591 int length = list->length();
592 if (length > 0) {
593 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
594 for (int i = 0; i < length; i++) {
595 MonitorInfo* monitor = list->at(i);
596 assert(monitor->owner() != NULL, "This monitor must have an owning object");
597 _locked_monitors->append(monitor->owner());
598 }
599 }
600 }
601 }
602
603 void StackFrameInfo::oops_do(OopClosure* f) {
604 if (_locked_monitors != NULL) {
605 int length = _locked_monitors->length();
606 for (int i = 0; i < length; i++) {
607 f->do_oop((oop*) _locked_monitors->adr_at(i));
608 }
609 }
610 f->do_oop(&_class_holder);
611 }
612
613 void StackFrameInfo::metadata_do(void f(Metadata*)) {
614 f(_method);
615 }
616
617 void StackFrameInfo::print_on(outputStream* st) const {
618 ResourceMark rm;
619 java_lang_Throwable::print_stack_element(st, method(), bci());
620 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
621 for (int i = 0; i < len; i++) {
622 oop o = _locked_monitors->at(i);
623 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
624 }
625
626 }
627
628 // Iterate through monitor cache to find JNI locked monitors
629 class InflatedMonitorsClosure: public MonitorClosure {
630 private:
631 ThreadStackTrace* _stack_trace;
632 Thread* _thread;
633 public:
634 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
635 _thread = t;
636 _stack_trace = st;
637 }
638 void do_monitor(ObjectMonitor* mid) {
639 if (mid->owner() == _thread) {
640 oop object = (oop) mid->object();
641 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
642 _stack_trace->add_jni_locked_monitor(object);
643 }
644 }
645 }
646 };
647
648 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
649 _thread = t;
650 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
651 _depth = 0;
652 _with_locked_monitors = with_locked_monitors;
653 if (_with_locked_monitors) {
654 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
655 } else {
656 _jni_locked_monitors = NULL;
657 }
658 }
659
660 ThreadStackTrace::~ThreadStackTrace() {
661 for (int i = 0; i < _frames->length(); i++) {
662 delete _frames->at(i);
663 }
664 delete _frames;
665 if (_jni_locked_monitors != NULL) {
666 delete _jni_locked_monitors;
667 }
668 }
669
670 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
671 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
672
673 if (_thread->has_last_Java_frame()) {
674 RegisterMap reg_map(_thread);
675 vframe* start_vf = _thread->last_java_vframe(®_map);
676 int count = 0;
677 for (vframe* f = start_vf; f; f = f->sender() ) {
678 if (maxDepth >= 0 && count == maxDepth) {
679 // Skip frames if more than maxDepth
680 break;
681 }
682 if (f->is_java_frame()) {
683 javaVFrame* jvf = javaVFrame::cast(f);
684 add_stack_frame(jvf);
685 count++;
686 } else {
687 // Ignore non-Java frames
688 }
689 }
690 }
691
692 if (_with_locked_monitors) {
693 // Iterate inflated monitors and find monitors locked by this thread
694 // not found in the stack
695 InflatedMonitorsClosure imc(_thread, this);
696 ObjectSynchronizer::monitors_iterate(&imc);
697 }
698 }
699
700
701 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
702 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
703
704 bool found = false;
705 int num_frames = get_stack_depth();
706 for (int depth = 0; depth < num_frames; depth++) {
707 StackFrameInfo* frame = stack_frame_at(depth);
708 int len = frame->num_locked_monitors();
709 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
710 for (int j = 0; j < len; j++) {
711 oop monitor = locked_monitors->at(j);
712 assert(monitor != NULL, "must be a Java object");
713 if (monitor == object) {
714 found = true;
715 break;
716 }
717 }
718 }
719 return found;
720 }
721
722 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
723 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass();
724 assert(ik != NULL, "must be loaded in 1.4+");
725
726 // Allocate an array of java/lang/StackTraceElement object
727 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
728 objArrayHandle backtrace(THREAD, ste);
729 for (int j = 0; j < _depth; j++) {
730 StackFrameInfo* frame = _frames->at(j);
731 methodHandle mh(THREAD, frame->method());
732 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
733 backtrace->obj_at_put(j, element);
734 }
735 return backtrace;
736 }
737
738 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
739 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
740 _frames->append(frame);
741 _depth++;
742 }
743
744 void ThreadStackTrace::oops_do(OopClosure* f) {
745 int length = _frames->length();
746 for (int i = 0; i < length; i++) {
747 _frames->at(i)->oops_do(f);
748 }
749
750 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
751 for (int j = 0; j < length; j++) {
752 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
753 }
754 }
755
756 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
757 int length = _frames->length();
758 for (int i = 0; i < length; i++) {
759 _frames->at(i)->metadata_do(f);
760 }
761 }
762
763
764 ConcurrentLocksDump::~ConcurrentLocksDump() {
765 if (_retain_map_on_free) {
766 return;
767 }
768
769 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
770 ThreadConcurrentLocks* tcl = t;
771 t = t->next();
772 delete tcl;
773 }
774 }
775
776 void ConcurrentLocksDump::dump_at_safepoint() {
777 // dump all locked concurrent locks
778 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
779
780 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */);
781
782 // Find all instances of AbstractOwnableSynchronizer
783 HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
784 aos_objects);
785 // Build a map of thread to its owned AQS locks
786 build_map(aos_objects);
787
788 delete aos_objects;
789 }
790
791
792 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
793 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
794 int length = aos_objects->length();
795 for (int i = 0; i < length; i++) {
796 oop o = aos_objects->at(i);
797 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
798 if (owner_thread_obj != NULL) {
799 // See comments in ThreadConcurrentLocks to see how this
800 // JavaThread* is protected.
801 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
802 assert(o->is_instance(), "Must be an instanceOop");
803 add_lock(thread, (instanceOop) o);
804 }
805 }
806 }
807
808 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
809 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
810 if (tcl != NULL) {
811 tcl->add_lock(o);
812 return;
813 }
814
815 // First owned lock found for this thread
816 tcl = new ThreadConcurrentLocks(thread);
817 tcl->add_lock(o);
818 if (_map == NULL) {
819 _map = tcl;
820 } else {
821 _last->set_next(tcl);
822 }
823 _last = tcl;
824 }
825
826 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
827 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
828 if (tcl->java_thread() == thread) {
829 return tcl;
830 }
831 }
832 return NULL;
833 }
834
835 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
836 st->print_cr(" Locked ownable synchronizers:");
837 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
838 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
839 if (locks == NULL || locks->is_empty()) {
840 st->print_cr("\t- None");
841 st->cr();
842 return;
843 }
844
845 for (int i = 0; i < locks->length(); i++) {
846 instanceOop obj = locks->at(i);
847 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
848 }
849 st->cr();
850 }
851
852 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
853 _thread = thread;
854 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
855 _next = NULL;
856 }
857
858 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
859 delete _owned_locks;
860 }
861
862 void ThreadConcurrentLocks::add_lock(instanceOop o) {
863 _owned_locks->append(o);
864 }
865
866 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
867 int length = _owned_locks->length();
868 for (int i = 0; i < length; i++) {
869 f->do_oop((oop*) _owned_locks->adr_at(i));
870 }
871 }
872
873 ThreadStatistics::ThreadStatistics() {
874 _contended_enter_count = 0;
875 _monitor_wait_count = 0;
876 _sleep_count = 0;
877 _count_pending_reset = false;
878 _timer_pending_reset = false;
879 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
880 }
881
882 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
883 _thread = thread;
884 _threadObj = thread->threadObj();
885
886 ThreadStatistics* stat = thread->get_thread_stat();
887 _contended_enter_ticks = stat->contended_enter_ticks();
888 _contended_enter_count = stat->contended_enter_count();
889 _monitor_wait_ticks = stat->monitor_wait_ticks();
890 _monitor_wait_count = stat->monitor_wait_count();
891 _sleep_ticks = stat->sleep_ticks();
892 _sleep_count = stat->sleep_count();
893
894 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
895 _is_ext_suspended = thread->is_being_ext_suspended();
896 _is_in_native = (thread->thread_state() == _thread_in_native);
897
898 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
899 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
900 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
901
902 Handle obj = ThreadService::get_current_contended_monitor(thread);
903 if (obj() == NULL) {
904 // monitor no longer exists; thread is not blocked
905 _thread_status = java_lang_Thread::RUNNABLE;
906 } else {
907 _blocker_object = obj();
908 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
909 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
910 || (owner != NULL && owner->is_attaching_via_jni())) {
911 // ownership information of the monitor is not available
912 // (may no longer be owned or releasing to some other thread)
913 // make this thread in RUNNABLE state.
914 // And when the owner thread is in attaching state, the java thread
915 // is not completely initialized. For example thread name and id
916 // and may not be set, so hide the attaching thread.
917 _thread_status = java_lang_Thread::RUNNABLE;
918 _blocker_object = NULL;
919 } else if (owner != NULL) {
920 _blocker_object_owner = owner->threadObj();
921 }
922 }
923 }
924
925 // Support for JSR-166 locks
926 if (_thread_status == java_lang_Thread::PARKED || _thread_status == java_lang_Thread::PARKED_TIMED) {
927 _blocker_object = thread->current_park_blocker();
928 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
929 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
930 }
931 }
932 }
933
934 ThreadSnapshot::~ThreadSnapshot() {
935 delete _stack_trace;
936 delete _concurrent_locks;
937 }
938
939 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
940 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
941 _stack_trace->dump_stack_at_safepoint(max_depth);
942 }
943
944
945 void ThreadSnapshot::oops_do(OopClosure* f) {
946 f->do_oop(&_threadObj);
947 f->do_oop(&_blocker_object);
948 f->do_oop(&_blocker_object_owner);
949 if (_stack_trace != NULL) {
950 _stack_trace->oops_do(f);
951 }
952 if (_concurrent_locks != NULL) {
953 _concurrent_locks->oops_do(f);
954 }
955 }
956
957 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
958 if (_stack_trace != NULL) {
959 _stack_trace->metadata_do(f);
960 }
961 }
962
963
964 DeadlockCycle::DeadlockCycle() {
965 _is_deadlock = false;
966 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
967 _next = NULL;
968 }
969
970 DeadlockCycle::~DeadlockCycle() {
971 delete _threads;
972 }
973
974 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
975 st->cr();
976 st->print_cr("Found one Java-level deadlock:");
977 st->print("=============================");
978
979 JavaThread* currentThread;
980 JvmtiRawMonitor* waitingToLockRawMonitor;
981 oop waitingToLockBlocker;
982 int len = _threads->length();
983 for (int i = 0; i < len; i++) {
984 currentThread = _threads->at(i);
985 // The ObjectMonitor* can't be async deflated since we are at a safepoint.
986 ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor();
987 waitingToLockRawMonitor = currentThread->current_pending_raw_monitor();
988 waitingToLockBlocker = currentThread->current_park_blocker();
989 st->cr();
990 st->print_cr("\"%s\":", currentThread->get_thread_name());
991 const char* owner_desc = ",\n which is held by";
992
993 // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor
994 // sets the current pending monitor, it is possible to then see a pending raw monitor as well.
995 if (waitingToLockRawMonitor != NULL) {
996 st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor));
997 Thread* owner = waitingToLockRawMonitor->owner();
998 // Could be NULL as the raw monitor could be released at any time if held by non-JavaThread
999 if (owner != NULL) {
1000 if (owner->is_Java_thread()) {
1001 currentThread = (JavaThread*) owner;
1002 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
1003 } else {
1004 st->print_cr(",\n which has now been released");
1005 }
1006 } else {
1007 st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner));
1008 }
1009 }
1010
1011 if (waitingToLockMonitor != NULL) {
1012 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
1013 oop obj = (oop)waitingToLockMonitor->object();
1014 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
1015 obj->klass()->external_name());
1016
1017 if (!currentThread->current_pending_monitor_is_from_java()) {
1018 owner_desc = "\n in JNI, which is held by";
1019 }
1020 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
1021 (address)waitingToLockMonitor->owner());
1022 if (currentThread == NULL) {
1023 // The deadlock was detected at a safepoint so the JavaThread
1024 // that owns waitingToLockMonitor should be findable, but
1025 // if it is not findable, then the previous currentThread is
1026 // blocked permanently.
1027 st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
1028 p2i(waitingToLockMonitor->owner()));
1029 continue;
1030 }
1031 } else {
1032 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
1033 p2i(waitingToLockBlocker),
1034 waitingToLockBlocker->klass()->external_name());
1035 assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
1036 "Must be an AbstractOwnableSynchronizer");
1037 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
1038 currentThread = java_lang_Thread::thread(ownerObj);
1039 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
1040 }
1041 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
1042 }
1043
1044 st->cr();
1045
1046 // Print stack traces
1047 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
1048 JavaMonitorsInStackTrace = true;
1049 st->print_cr("Java stack information for the threads listed above:");
1050 st->print_cr("===================================================");
1051 for (int j = 0; j < len; j++) {
1052 currentThread = _threads->at(j);
1053 st->print_cr("\"%s\":", currentThread->get_thread_name());
1054 currentThread->print_stack_on(st);
1055 }
1056 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
1057 }
1058
1059 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
1060 bool include_jvmti_agent_threads,
1061 bool include_jni_attaching_threads) {
1062 assert(cur_thread == Thread::current(), "Check current thread");
1063
1064 int init_size = ThreadService::get_live_thread_count();
1065 _threads_array = new GrowableArray<instanceHandle>(init_size);
1066
1067 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
1068 // skips JavaThreads in the process of exiting
1069 // and also skips VM internal JavaThreads
1070 // Threads in _thread_new or _thread_new_trans state are included.
1071 // i.e. threads have been started but not yet running.
1072 if (jt->threadObj() == NULL ||
1073 jt->is_exiting() ||
1074 !java_lang_Thread::is_alive(jt->threadObj()) ||
1075 jt->is_hidden_from_external_view()) {
1076 continue;
1077 }
1078
1079 // skip agent threads
1080 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
1081 continue;
1082 }
1083
1084 // skip jni threads in the process of attaching
1085 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
1086 continue;
1087 }
1088
1089 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
1090 _threads_array->append(h);
1091 }
1092 }