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