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