1 /*
2 * Copyright (c) 2003, 2021, 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 "classfile/vmClasses.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "gc/shared/oopStorageSet.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/heapInspection.hpp"
32 #include "memory/oopFactory.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "memory/universe.hpp"
35 #include "oops/instanceKlass.hpp"
36 #include "oops/klass.inline.hpp"
37 #include "oops/objArrayKlass.hpp"
38 #include "oops/objArrayOop.inline.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "oops/oopHandle.inline.hpp"
41 #include "prims/jvmtiRawMonitor.hpp"
42 #include "runtime/atomic.hpp"
43 #include "runtime/handles.inline.hpp"
44 #include "runtime/init.hpp"
45 #include "runtime/objectMonitor.inline.hpp"
46 #include "runtime/thread.inline.hpp"
47 #include "runtime/threadSMR.inline.hpp"
48 #include "runtime/vframe.hpp"
49 #include "runtime/vmThread.hpp"
50 #include "runtime/vmOperations.hpp"
51 #include "services/threadService.hpp"
52
53 // TODO: we need to define a naming convention for perf counters
54 // to distinguish counters for:
55 // - standard JSR174 use
56 // - Hotspot extension (public and committed)
57 // - Hotspot extension (private/internal and uncommitted)
58
59 // Default is disabled.
60 bool ThreadService::_thread_monitoring_contention_enabled = false;
61 bool ThreadService::_thread_cpu_time_enabled = false;
62 bool ThreadService::_thread_allocated_memory_enabled = false;
63
64 PerfCounter* ThreadService::_total_threads_count = NULL;
65 PerfVariable* ThreadService::_live_threads_count = NULL;
66 PerfVariable* ThreadService::_peak_threads_count = NULL;
67 PerfVariable* ThreadService::_daemon_threads_count = NULL;
68 volatile int ThreadService::_atomic_threads_count = 0;
69 volatile int ThreadService::_atomic_daemon_threads_count = 0;
70
71 volatile jlong ThreadService::_exited_allocated_bytes = 0;
72
73 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
74
75 static const int INITIAL_ARRAY_SIZE = 10;
76
77 // OopStorage for thread stack sampling
78 static OopStorage* _thread_service_storage = NULL;
79
80 void ThreadService::init() {
81 EXCEPTION_MARK;
82
83 // These counters are for java.lang.management API support.
84 // They are created even if -XX:-UsePerfData is set and in
85 // that case, they will be allocated on C heap.
86
87 _total_threads_count =
88 PerfDataManager::create_counter(JAVA_THREADS, "started",
89 PerfData::U_Events, CHECK);
90
91 _live_threads_count =
92 PerfDataManager::create_variable(JAVA_THREADS, "live",
93 PerfData::U_None, CHECK);
94
95 _peak_threads_count =
96 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
97 PerfData::U_None, CHECK);
98
99 _daemon_threads_count =
100 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
101 PerfData::U_None, CHECK);
102
103 if (os::is_thread_cpu_time_supported()) {
104 _thread_cpu_time_enabled = true;
105 }
106
107 _thread_allocated_memory_enabled = true; // Always on, so enable it
108
109 // Initialize OopStorage for thread stack sampling walking
110 _thread_service_storage = OopStorageSet::create_strong("ThreadService OopStorage",
111 mtServiceability);
112 }
113
114 void ThreadService::reset_peak_thread_count() {
115 // Acquire the lock to update the peak thread count
116 // to synchronize with thread addition and removal.
117 MutexLocker mu(Threads_lock);
118 _peak_threads_count->set_value(get_live_thread_count());
119 }
120
121 static bool is_hidden_thread(JavaThread *thread) {
122 // hide VM internal or JVMTI agent threads
123 return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
124 }
125
126 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
127 assert(Threads_lock->owned_by_self(), "must have threads lock");
128
129 // Do not count hidden threads
130 if (is_hidden_thread(thread)) {
131 return;
132 }
133
134 _total_threads_count->inc();
135 _live_threads_count->inc();
136 Atomic::inc(&_atomic_threads_count);
137 int count = _atomic_threads_count;
138
139 if (count > _peak_threads_count->get_value()) {
140 _peak_threads_count->set_value(count);
141 }
142
143 if (daemon) {
144 _daemon_threads_count->inc();
145 Atomic::inc(&_atomic_daemon_threads_count);
146 }
147 }
148
149 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
150 Atomic::dec(&_atomic_threads_count);
151
152 if (daemon) {
153 Atomic::dec(&_atomic_daemon_threads_count);
154 }
155 }
156
157 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
158 assert(Threads_lock->owned_by_self(), "must have threads lock");
159
160 // Include hidden thread allcations in exited_allocated_bytes
161 ThreadService::incr_exited_allocated_bytes(thread->cooked_allocated_bytes());
162
163 // Do not count hidden threads
164 if (is_hidden_thread(thread)) {
165 return;
166 }
167
168 assert(!thread->is_terminated(), "must not be terminated");
169 if (!thread->is_exiting()) {
170 // JavaThread::exit() skipped calling current_thread_exiting()
171 decrement_thread_counts(thread, daemon);
172 }
173
174 int daemon_count = _atomic_daemon_threads_count;
175 int count = _atomic_threads_count;
176
177 // Counts are incremented at the same time, but atomic counts are
178 // decremented earlier than perf counts.
179 assert(_live_threads_count->get_value() > count,
180 "thread count mismatch %d : %d",
181 (int)_live_threads_count->get_value(), count);
182
183 _live_threads_count->dec(1);
184 if (daemon) {
185 assert(_daemon_threads_count->get_value() > daemon_count,
186 "thread count mismatch %d : %d",
187 (int)_daemon_threads_count->get_value(), daemon_count);
188
189 _daemon_threads_count->dec(1);
190 }
191
192 // Counts are incremented at the same time, but atomic counts are
193 // decremented earlier than perf counts.
194 assert(_daemon_threads_count->get_value() >= daemon_count,
195 "thread count mismatch %d : %d",
196 (int)_daemon_threads_count->get_value(), daemon_count);
197 assert(_live_threads_count->get_value() >= count,
198 "thread count mismatch %d : %d",
199 (int)_live_threads_count->get_value(), count);
200 assert(_live_threads_count->get_value() > 0 ||
201 (_live_threads_count->get_value() == 0 && count == 0 &&
202 _daemon_threads_count->get_value() == 0 && daemon_count == 0),
203 "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
204 (int)_live_threads_count->get_value(), count,
205 (int)_daemon_threads_count->get_value(), daemon_count);
206 assert(_daemon_threads_count->get_value() > 0 ||
207 (_daemon_threads_count->get_value() == 0 && daemon_count == 0),
208 "thread counts should reach 0 at the same time, daemon %d,%d",
209 (int)_daemon_threads_count->get_value(), daemon_count);
210 }
211
212 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
213 // Do not count hidden threads
214 if (is_hidden_thread(jt)) {
215 return;
216 }
217
218 assert(jt == JavaThread::current(), "Called by current thread");
219 assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
220
221 decrement_thread_counts(jt, daemon);
222 }
223
224 // FIXME: JVMTI should call this function
225 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
226 assert(thread != NULL, "should be non-NULL");
227 debug_only(Thread::check_for_dangling_thread_pointer(thread);)
228
229 // This function can be called on a target JavaThread that is not
230 // the caller and we are not at a safepoint. So it is possible for
231 // the waiting or pending condition to be over/stale and for the
232 // first stage of async deflation to clear the object field in
233 // the ObjectMonitor. It is also possible for the object to be
234 // inflated again and to be associated with a completely different
235 // ObjectMonitor by the time this object reference is processed
236 // by the caller.
237 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
238
239 oop obj = NULL;
240 if (wait_obj != NULL) {
241 // thread is doing an Object.wait() call
242 obj = wait_obj->object();
243 } else {
244 ObjectMonitor *enter_obj = thread->current_pending_monitor();
245 if (enter_obj != NULL) {
246 // thread is trying to enter() an ObjectMonitor.
247 obj = enter_obj->object();
248 }
249 }
250
251 Handle h(Thread::current(), obj);
252 return h;
253 }
254
255 bool ThreadService::set_thread_monitoring_contention(bool flag) {
256 MutexLocker m(Management_lock);
257
258 bool prev = _thread_monitoring_contention_enabled;
259 _thread_monitoring_contention_enabled = flag;
260
261 return prev;
262 }
263
264 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
265 MutexLocker m(Management_lock);
266
267 bool prev = _thread_cpu_time_enabled;
268 _thread_cpu_time_enabled = flag;
269
270 return prev;
271 }
272
273 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
274 MutexLocker m(Management_lock);
275
276 bool prev = _thread_allocated_memory_enabled;
277 _thread_allocated_memory_enabled = flag;
278
279 return prev;
280 }
281
282 void ThreadService::metadata_do(void f(Metadata*)) {
283 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
284 dump->metadata_do(f);
285 }
286 }
287
288 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
289 MutexLocker ml(Management_lock);
290 if (_threaddump_list == NULL) {
291 _threaddump_list = dump;
292 } else {
293 dump->set_next(_threaddump_list);
294 _threaddump_list = dump;
295 }
296 }
297
298 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
299 MutexLocker ml(Management_lock);
300
301 ThreadDumpResult* prev = NULL;
302 bool found = false;
303 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
304 if (d == dump) {
305 if (prev == NULL) {
306 _threaddump_list = dump->next();
307 } else {
308 prev->set_next(dump->next());
309 }
310 found = true;
311 break;
312 }
313 }
314 assert(found, "The threaddump result to be removed must exist.");
315 }
316
317 // Dump stack trace of threads specified in the given threads array.
318 // Returns StackTraceElement[][] each element is the stack trace of a thread in
319 // the corresponding entry in the given threads array
320 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
321 int num_threads,
322 TRAPS) {
323 assert(num_threads > 0, "just checking");
324
325 ThreadDumpResult dump_result;
326 VM_ThreadDump op(&dump_result,
327 threads,
328 num_threads,
329 -1, /* entire stack */
330 false, /* with locked monitors */
331 false /* with locked synchronizers */);
332 VMThread::execute(&op);
333
334 // Allocate the resulting StackTraceElement[][] object
335
336 ResourceMark rm(THREAD);
337 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
338 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
339 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
340 objArrayHandle result_obj(THREAD, r);
341
342 int num_snapshots = dump_result.num_snapshots();
343 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
344 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
345 int i = 0;
346 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
347 ThreadStackTrace* stacktrace = ts->get_stack_trace();
348 if (stacktrace == NULL) {
349 // No stack trace
350 result_obj->obj_at_put(i, NULL);
351 } else {
352 // Construct an array of java/lang/StackTraceElement object
353 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
354 result_obj->obj_at_put(i, backtrace_h());
355 }
356 }
357
358 return result_obj;
359 }
360
361 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
362 ThreadStatistics* stat = thread->get_thread_stat();
363 if (stat != NULL) {
364 stat->reset_count_stat();
365 }
366 }
367
368 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
369 ThreadStatistics* stat = thread->get_thread_stat();
370 if (stat != NULL) {
371 stat->reset_time_stat();
372 }
373 }
374
375 // Find deadlocks involving raw monitors, object monitors and concurrent locks
376 // if concurrent_locks is true.
377 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
378 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
379
380 // This code was modified from the original Threads::find_deadlocks code.
381 int globalDfn = 0, thisDfn;
382 ObjectMonitor* waitingToLockMonitor = NULL;
383 JvmtiRawMonitor* waitingToLockRawMonitor = NULL;
384 oop waitingToLockBlocker = NULL;
385 bool blocked_on_monitor = false;
386 JavaThread *currentThread, *previousThread;
387 int num_deadlocks = 0;
388
389 // Initialize the depth-first-number for each JavaThread.
390 JavaThreadIterator jti(t_list);
391 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
392 jt->set_depth_first_number(-1);
393 }
394
395 DeadlockCycle* deadlocks = NULL;
396 DeadlockCycle* last = NULL;
397 DeadlockCycle* cycle = new DeadlockCycle();
398 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
399 if (jt->depth_first_number() >= 0) {
400 // this thread was already visited
401 continue;
402 }
403
404 thisDfn = globalDfn;
405 jt->set_depth_first_number(globalDfn++);
406 previousThread = jt;
407 currentThread = jt;
408
409 cycle->reset();
410
411 // The ObjectMonitor* can't be async deflated since we are at a safepoint.
412 // When there is a deadlock, all the monitors involved in the dependency
413 // cycle must be contended and heavyweight. So we only care about the
414 // heavyweight monitor a thread is waiting to lock.
415 waitingToLockMonitor = jt->current_pending_monitor();
416 // JVM TI raw monitors can also be involved in deadlocks, and we can be
417 // waiting to lock both a raw monitor and ObjectMonitor at the same time.
418 // It isn't clear how to make deadlock detection work correctly if that
419 // happens.
420 waitingToLockRawMonitor = jt->current_pending_raw_monitor();
421
422 if (concurrent_locks) {
423 waitingToLockBlocker = jt->current_park_blocker();
424 }
425
426 while (waitingToLockMonitor != NULL ||
427 waitingToLockRawMonitor != NULL ||
428 waitingToLockBlocker != NULL) {
429 cycle->add_thread(currentThread);
430 // Give preference to the raw monitor
431 if (waitingToLockRawMonitor != NULL) {
432 Thread* owner = waitingToLockRawMonitor->owner();
433 if (owner != NULL && // the raw monitor could be released at any time
434 owner->is_Java_thread()) {
435 currentThread = owner->as_Java_thread();
436 }
437 } else if (waitingToLockMonitor != NULL) {
438 address currentOwner = (address)waitingToLockMonitor->owner();
439 if (currentOwner != NULL) {
440 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
441 currentOwner);
442 if (currentThread == NULL) {
443 // This function is called at a safepoint so the JavaThread
444 // that owns waitingToLockMonitor should be findable, but
445 // if it is not findable, then the previous currentThread is
446 // blocked permanently. We record this as a deadlock.
447 num_deadlocks++;
448
449 cycle->set_deadlock(true);
450
451 // add this cycle to the deadlocks list
452 if (deadlocks == NULL) {
453 deadlocks = cycle;
454 } else {
455 last->set_next(cycle);
456 }
457 last = cycle;
458 cycle = new DeadlockCycle();
459 break;
460 }
461 }
462 } else {
463 if (concurrent_locks) {
464 if (waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
465 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
466 // This JavaThread (if there is one) is protected by the
467 // ThreadsListSetter in VM_FindDeadlocks::doit().
468 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
469 } else {
470 currentThread = NULL;
471 }
472 }
473 }
474
475 if (currentThread == NULL) {
476 // No dependency on another thread
477 break;
478 }
479 if (currentThread->depth_first_number() < 0) {
480 // First visit to this thread
481 currentThread->set_depth_first_number(globalDfn++);
482 } else if (currentThread->depth_first_number() < thisDfn) {
483 // Thread already visited, and not on a (new) cycle
484 break;
485 } else if (currentThread == previousThread) {
486 // Self-loop, ignore
487 break;
488 } else {
489 // We have a (new) cycle
490 num_deadlocks++;
491
492 cycle->set_deadlock(true);
493
494 // add this cycle to the deadlocks list
495 if (deadlocks == NULL) {
496 deadlocks = cycle;
497 } else {
498 last->set_next(cycle);
499 }
500 last = cycle;
501 cycle = new DeadlockCycle();
502 break;
503 }
504 previousThread = currentThread;
505 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
506 if (concurrent_locks) {
507 waitingToLockBlocker = currentThread->current_park_blocker();
508 }
509 }
510
511 }
512 delete cycle;
513 return deadlocks;
514 }
515
516 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
517
518 // Create a new ThreadDumpResult object and append to the list.
519 // If GC happens before this function returns, Method*
520 // in the stack trace will be visited.
521 ThreadService::add_thread_dump(this);
522 }
523
524 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
525 // Create a new ThreadDumpResult object and append to the list.
526 // If GC happens before this function returns, oops
527 // will be visited.
528 ThreadService::add_thread_dump(this);
529 }
530
531 ThreadDumpResult::~ThreadDumpResult() {
532 ThreadService::remove_thread_dump(this);
533
534 // free all the ThreadSnapshot objects created during
535 // the VM_ThreadDump operation
536 ThreadSnapshot* ts = _snapshots;
537 while (ts != NULL) {
538 ThreadSnapshot* p = ts;
539 ts = ts->next();
540 delete p;
541 }
542 }
543
544 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
545 ThreadSnapshot* ts = new ThreadSnapshot();
546 link_thread_snapshot(ts);
547 return ts;
548 }
549
550 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
551 ThreadSnapshot* ts = new ThreadSnapshot();
552 link_thread_snapshot(ts);
553 ts->initialize(t_list(), thread);
554 return ts;
555 }
556
557 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
558 assert(_num_threads == 0 || _num_snapshots < _num_threads,
559 "_num_snapshots must be less than _num_threads");
560 _num_snapshots++;
561 if (_snapshots == NULL) {
562 _snapshots = ts;
563 } else {
564 _last->set_next(ts);
565 }
566 _last = ts;
567 }
568
569 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
570 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
571 ts->metadata_do(f);
572 }
573 }
574
575 ThreadsList* ThreadDumpResult::t_list() {
576 return _setter.list();
577 }
578
579 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
580 _method = jvf->method();
581 _bci = jvf->bci();
582 _class_holder = OopHandle(_thread_service_storage, _method->method_holder()->klass_holder());
583 _locked_monitors = NULL;
584 if (with_lock_info) {
585 Thread* current_thread = Thread::current();
586 ResourceMark rm(current_thread);
587 HandleMark hm(current_thread);
588 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
589 int length = list->length();
590 if (length > 0) {
591 _locked_monitors = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(length, mtServiceability);
592 for (int i = 0; i < length; i++) {
593 MonitorInfo* monitor = list->at(i);
594 assert(monitor->owner() != NULL, "This monitor must have an owning object");
595 _locked_monitors->append(OopHandle(_thread_service_storage, monitor->owner()));
596 }
597 }
598 }
599 }
600
601 StackFrameInfo::~StackFrameInfo() {
602 if (_locked_monitors != NULL) {
603 for (int i = 0; i < _locked_monitors->length(); i++) {
604 _locked_monitors->at(i).release(_thread_service_storage);
605 }
606 delete _locked_monitors;
607 }
608 _class_holder.release(_thread_service_storage);
609 }
610
611 void StackFrameInfo::metadata_do(void f(Metadata*)) {
612 f(_method);
613 }
614
615 void StackFrameInfo::print_on(outputStream* st) const {
616 ResourceMark rm;
617 java_lang_Throwable::print_stack_element(st, method(), bci());
618 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
619 for (int i = 0; i < len; i++) {
620 oop o = _locked_monitors->at(i).resolve();
621 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
622 }
623
624 }
625
626 // Iterate through monitor cache to find JNI locked monitors
627 class InflatedMonitorsClosure: public MonitorClosure {
628 private:
629 ThreadStackTrace* _stack_trace;
630 public:
631 InflatedMonitorsClosure(ThreadStackTrace* st) {
632 _stack_trace = st;
633 }
634 void do_monitor(ObjectMonitor* mid) {
635 oop object = mid->object();
636 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
637 _stack_trace->add_jni_locked_monitor(object);
638 }
639 }
640 };
641
642 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
643 _thread = t;
644 _frames = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, mtServiceability);
645 _depth = 0;
646 _with_locked_monitors = with_locked_monitors;
647 if (_with_locked_monitors) {
648 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability);
649 } else {
650 _jni_locked_monitors = NULL;
651 }
652 }
653
654 void ThreadStackTrace::add_jni_locked_monitor(oop object) {
655 _jni_locked_monitors->append(OopHandle(_thread_service_storage, object));
656 }
657
658 ThreadStackTrace::~ThreadStackTrace() {
659 for (int i = 0; i < _frames->length(); i++) {
660 delete _frames->at(i);
661 }
662 delete _frames;
663 if (_jni_locked_monitors != NULL) {
664 for (int i = 0; i < _jni_locked_monitors->length(); i++) {
665 _jni_locked_monitors->at(i).release(_thread_service_storage);
666 }
667 delete _jni_locked_monitors;
668 }
669 }
670
671 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
672 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
673
674 if (_thread->has_last_Java_frame()) {
675 RegisterMap reg_map(_thread);
676 vframe* start_vf = _thread->last_java_vframe(®_map);
677 int count = 0;
678 for (vframe* f = start_vf; f; f = f->sender() ) {
679 if (maxDepth >= 0 && count == maxDepth) {
680 // Skip frames if more than maxDepth
681 break;
682 }
683 if (f->is_java_frame()) {
684 javaVFrame* jvf = javaVFrame::cast(f);
685 add_stack_frame(jvf);
686 count++;
687 } else {
688 // Ignore non-Java frames
689 }
690 }
691 }
692
693 if (_with_locked_monitors) {
694 // Iterate inflated monitors and find monitors locked by this thread
695 // not found in the stack
696 InflatedMonitorsClosure imc(this);
697 ObjectSynchronizer::monitors_iterate(&imc, _thread);
698 }
699 }
700
701
702 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
703 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
704
705 bool found = false;
706 int num_frames = get_stack_depth();
707 for (int depth = 0; depth < num_frames; depth++) {
708 StackFrameInfo* frame = stack_frame_at(depth);
709 int len = frame->num_locked_monitors();
710 GrowableArray<OopHandle>* locked_monitors = frame->locked_monitors();
711 for (int j = 0; j < len; j++) {
712 oop monitor = locked_monitors->at(j).resolve();
713 assert(monitor != NULL, "must be a Java object");
714 if (monitor == object) {
715 found = true;
716 break;
717 }
718 }
719 }
720 return found;
721 }
722
723 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
724 InstanceKlass* ik = vmClasses::StackTraceElement_klass();
725 assert(ik != NULL, "must be loaded in 1.4+");
726
727 // Allocate an array of java/lang/StackTraceElement object
728 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
729 objArrayHandle backtrace(THREAD, ste);
730 for (int j = 0; j < _depth; j++) {
731 StackFrameInfo* frame = _frames->at(j);
732 methodHandle mh(THREAD, frame->method());
733 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
734 backtrace->obj_at_put(j, element);
735 }
736 return backtrace;
737 }
738
739 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
740 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
741 _frames->append(frame);
742 _depth++;
743 }
744
745 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
746 int length = _frames->length();
747 for (int i = 0; i < length; i++) {
748 _frames->at(i)->metadata_do(f);
749 }
750 }
751
752
753 ConcurrentLocksDump::~ConcurrentLocksDump() {
754 if (_retain_map_on_free) {
755 return;
756 }
757
758 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
759 ThreadConcurrentLocks* tcl = t;
760 t = t->next();
761 delete tcl;
762 }
763 }
764
765 void ConcurrentLocksDump::dump_at_safepoint() {
766 // dump all locked concurrent locks
767 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
768
769 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<oop>(INITIAL_ARRAY_SIZE, mtServiceability);
770
771 // Find all instances of AbstractOwnableSynchronizer
772 HeapInspection::find_instances_at_safepoint(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
773 aos_objects);
774 // Build a map of thread to its owned AQS locks
775 build_map(aos_objects);
776
777 delete aos_objects;
778 }
779
780
781 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
782 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
783 int length = aos_objects->length();
784 for (int i = 0; i < length; i++) {
785 oop o = aos_objects->at(i);
786 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
787 if (owner_thread_obj != NULL) {
788 // See comments in ThreadConcurrentLocks to see how this
789 // JavaThread* is protected.
790 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
791 assert(o->is_instance(), "Must be an instanceOop");
792 add_lock(thread, (instanceOop) o);
793 }
794 }
795 }
796
797 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
798 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
799 if (tcl != NULL) {
800 tcl->add_lock(o);
801 return;
802 }
803
804 // First owned lock found for this thread
805 tcl = new ThreadConcurrentLocks(thread);
806 tcl->add_lock(o);
807 if (_map == NULL) {
808 _map = tcl;
809 } else {
810 _last->set_next(tcl);
811 }
812 _last = tcl;
813 }
814
815 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
816 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
817 if (tcl->java_thread() == thread) {
818 return tcl;
819 }
820 }
821 return NULL;
822 }
823
824 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
825 st->print_cr(" Locked ownable synchronizers:");
826 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
827 GrowableArray<OopHandle>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
828 if (locks == NULL || locks->is_empty()) {
829 st->print_cr("\t- None");
830 st->cr();
831 return;
832 }
833
834 for (int i = 0; i < locks->length(); i++) {
835 oop obj = locks->at(i).resolve();
836 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
837 }
838 st->cr();
839 }
840
841 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
842 _thread = thread;
843 _owned_locks = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability);
844 _next = NULL;
845 }
846
847 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
848 for (int i = 0; i < _owned_locks->length(); i++) {
849 _owned_locks->at(i).release(_thread_service_storage);
850 }
851 delete _owned_locks;
852 }
853
854 void ThreadConcurrentLocks::add_lock(instanceOop o) {
855 _owned_locks->append(OopHandle(_thread_service_storage, o));
856 }
857
858 ThreadStatistics::ThreadStatistics() {
859 _contended_enter_count = 0;
860 _monitor_wait_count = 0;
861 _sleep_count = 0;
862 _count_pending_reset = false;
863 _timer_pending_reset = false;
864 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
865 }
866
867 oop ThreadSnapshot::threadObj() const { return _threadObj.resolve(); }
868
869 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
870 _thread = thread;
871 oop threadObj = thread->threadObj();
872 _threadObj = OopHandle(_thread_service_storage, threadObj);
873
874 ThreadStatistics* stat = thread->get_thread_stat();
875 _contended_enter_ticks = stat->contended_enter_ticks();
876 _contended_enter_count = stat->contended_enter_count();
877 _monitor_wait_ticks = stat->monitor_wait_ticks();
878 _monitor_wait_count = stat->monitor_wait_count();
879 _sleep_ticks = stat->sleep_ticks();
880 _sleep_count = stat->sleep_count();
881
882 // If thread is still attaching then threadObj will be NULL.
883 _thread_status = threadObj == NULL ? JavaThreadStatus::NEW
884 : java_lang_Thread::get_thread_status(threadObj);
885
886 _is_suspended = thread->is_suspended();
887 _is_in_native = (thread->thread_state() == _thread_in_native);
888
889 Handle obj = ThreadService::get_current_contended_monitor(thread);
890
891 oop blocker_object = NULL;
892 oop blocker_object_owner = NULL;
893
894 if (_thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER ||
895 _thread_status == JavaThreadStatus::IN_OBJECT_WAIT ||
896 _thread_status == JavaThreadStatus::IN_OBJECT_WAIT_TIMED) {
897
898 if (obj() == NULL) {
899 // monitor no longer exists; thread is not blocked
900 _thread_status = JavaThreadStatus::RUNNABLE;
901 } else {
902 blocker_object = obj();
903 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
904 if ((owner == NULL && _thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER)
905 || (owner != NULL && owner->is_attaching_via_jni())) {
906 // ownership information of the monitor is not available
907 // (may no longer be owned or releasing to some other thread)
908 // make this thread in RUNNABLE state.
909 // And when the owner thread is in attaching state, the java thread
910 // is not completely initialized. For example thread name and id
911 // and may not be set, so hide the attaching thread.
912 _thread_status = JavaThreadStatus::RUNNABLE;
913 blocker_object = NULL;
914 } else if (owner != NULL) {
915 blocker_object_owner = owner->threadObj();
916 }
917 }
918 }
919
920 // Support for JSR-166 locks
921 if (_thread_status == JavaThreadStatus::PARKED || _thread_status == JavaThreadStatus::PARKED_TIMED) {
922 blocker_object = thread->current_park_blocker();
923 if (blocker_object != NULL && blocker_object->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
924 blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(blocker_object);
925 }
926 }
927
928 if (blocker_object != NULL) {
929 _blocker_object = OopHandle(_thread_service_storage, blocker_object);
930 }
931 if (blocker_object_owner != NULL) {
932 _blocker_object_owner = OopHandle(_thread_service_storage, blocker_object_owner);
933 }
934 }
935
936 oop ThreadSnapshot::blocker_object() const { return _blocker_object.resolve(); }
937 oop ThreadSnapshot::blocker_object_owner() const { return _blocker_object_owner.resolve(); }
938
939 ThreadSnapshot::~ThreadSnapshot() {
940 _blocker_object.release(_thread_service_storage);
941 _blocker_object_owner.release(_thread_service_storage);
942 _threadObj.release(_thread_service_storage);
943
944 delete _stack_trace;
945 delete _concurrent_locks;
946 }
947
948 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
949 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
950 _stack_trace->dump_stack_at_safepoint(max_depth);
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 = owner->as_Java_thread();
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 = 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(vmClasses::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 }