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 if (waitingToLockMonitor->has_owner()) {
439 currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor);
440 if (currentThread == NULL) {
441 // This function is called at a safepoint so the JavaThread
442 // that owns waitingToLockMonitor should be findable, but
443 // if it is not findable, then the previous currentThread is
444 // blocked permanently. We record this as a deadlock.
445 num_deadlocks++;
446
447 cycle->set_deadlock(true);
448
449 // add this cycle to the deadlocks list
450 if (deadlocks == NULL) {
451 deadlocks = cycle;
452 } else {
453 last->set_next(cycle);
454 }
455 last = cycle;
456 cycle = new DeadlockCycle();
457 break;
458 }
459 }
460 } else {
461 if (concurrent_locks) {
462 if (waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
463 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
464 // This JavaThread (if there is one) is protected by the
465 // ThreadsListSetter in VM_FindDeadlocks::doit().
466 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
467 } else {
468 currentThread = NULL;
469 }
470 }
471 }
472
473 if (currentThread == NULL) {
474 // No dependency on another thread
475 break;
476 }
477 if (currentThread->depth_first_number() < 0) {
478 // First visit to this thread
479 currentThread->set_depth_first_number(globalDfn++);
480 } else if (currentThread->depth_first_number() < thisDfn) {
481 // Thread already visited, and not on a (new) cycle
482 break;
483 } else if (currentThread == previousThread) {
484 // Self-loop, ignore
485 break;
486 } else {
487 // We have a (new) cycle
488 num_deadlocks++;
489
490 cycle->set_deadlock(true);
491
492 // add this cycle to the deadlocks list
493 if (deadlocks == NULL) {
494 deadlocks = cycle;
495 } else {
496 last->set_next(cycle);
497 }
498 last = cycle;
499 cycle = new DeadlockCycle();
500 break;
501 }
502 previousThread = currentThread;
503 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
504 if (concurrent_locks) {
505 waitingToLockBlocker = currentThread->current_park_blocker();
506 }
507 }
508
509 }
510 delete cycle;
511 return deadlocks;
512 }
513
514 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
515
516 // Create a new ThreadDumpResult object and append to the list.
517 // If GC happens before this function returns, Method*
518 // in the stack trace will be visited.
519 ThreadService::add_thread_dump(this);
520 }
521
522 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
523 // Create a new ThreadDumpResult object and append to the list.
524 // If GC happens before this function returns, oops
525 // will be visited.
526 ThreadService::add_thread_dump(this);
527 }
528
529 ThreadDumpResult::~ThreadDumpResult() {
530 ThreadService::remove_thread_dump(this);
531
532 // free all the ThreadSnapshot objects created during
533 // the VM_ThreadDump operation
534 ThreadSnapshot* ts = _snapshots;
535 while (ts != NULL) {
536 ThreadSnapshot* p = ts;
537 ts = ts->next();
538 delete p;
539 }
540 }
541
542 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
543 ThreadSnapshot* ts = new ThreadSnapshot();
544 link_thread_snapshot(ts);
545 return ts;
546 }
547
548 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
549 ThreadSnapshot* ts = new ThreadSnapshot();
550 link_thread_snapshot(ts);
551 ts->initialize(t_list(), thread);
552 return ts;
553 }
554
555 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
556 assert(_num_threads == 0 || _num_snapshots < _num_threads,
557 "_num_snapshots must be less than _num_threads");
558 _num_snapshots++;
559 if (_snapshots == NULL) {
560 _snapshots = ts;
561 } else {
562 _last->set_next(ts);
563 }
564 _last = ts;
565 }
566
567 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
568 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
569 ts->metadata_do(f);
570 }
571 }
572
573 ThreadsList* ThreadDumpResult::t_list() {
574 return _setter.list();
575 }
576
577 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
578 _method = jvf->method();
579 _bci = jvf->bci();
580 _class_holder = OopHandle(_thread_service_storage, _method->method_holder()->klass_holder());
581 _locked_monitors = NULL;
582 if (with_lock_info) {
583 Thread* current_thread = Thread::current();
584 ResourceMark rm(current_thread);
585 HandleMark hm(current_thread);
586 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
587 int length = list->length();
588 if (length > 0) {
589 _locked_monitors = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(length, mtServiceability);
590 for (int i = 0; i < length; i++) {
591 MonitorInfo* monitor = list->at(i);
592 assert(monitor->owner() != NULL, "This monitor must have an owning object");
593 _locked_monitors->append(OopHandle(_thread_service_storage, monitor->owner()));
594 }
595 }
596 }
597 }
598
599 StackFrameInfo::~StackFrameInfo() {
600 if (_locked_monitors != NULL) {
601 for (int i = 0; i < _locked_monitors->length(); i++) {
602 _locked_monitors->at(i).release(_thread_service_storage);
603 }
604 delete _locked_monitors;
605 }
606 _class_holder.release(_thread_service_storage);
607 }
608
609 void StackFrameInfo::metadata_do(void f(Metadata*)) {
610 f(_method);
611 }
612
613 void StackFrameInfo::print_on(outputStream* st) const {
614 ResourceMark rm;
615 java_lang_Throwable::print_stack_element(st, method(), bci());
616 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
617 for (int i = 0; i < len; i++) {
618 oop o = _locked_monitors->at(i).resolve();
619 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
620 }
621
622 }
623
624 // Iterate through monitor cache to find JNI locked monitors
625 class InflatedMonitorsClosure: public MonitorClosure {
626 private:
627 ThreadStackTrace* _stack_trace;
628 public:
629 InflatedMonitorsClosure(ThreadStackTrace* st) {
630 _stack_trace = st;
631 }
632 void do_monitor(ObjectMonitor* mid) {
633 oop object = mid->object();
634 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
635 _stack_trace->add_jni_locked_monitor(object);
636 }
637 }
638 };
639
640 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
641 _thread = t;
642 _frames = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, mtServiceability);
643 _depth = 0;
644 _with_locked_monitors = with_locked_monitors;
645 if (_with_locked_monitors) {
646 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability);
647 } else {
648 _jni_locked_monitors = NULL;
649 }
650 }
651
652 void ThreadStackTrace::add_jni_locked_monitor(oop object) {
653 _jni_locked_monitors->append(OopHandle(_thread_service_storage, object));
654 }
655
656 ThreadStackTrace::~ThreadStackTrace() {
657 for (int i = 0; i < _frames->length(); i++) {
658 delete _frames->at(i);
659 }
660 delete _frames;
661 if (_jni_locked_monitors != NULL) {
662 for (int i = 0; i < _jni_locked_monitors->length(); i++) {
663 _jni_locked_monitors->at(i).release(_thread_service_storage);
664 }
665 delete _jni_locked_monitors;
666 }
667 }
668
669 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
670 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
671
672 if (_thread->has_last_Java_frame()) {
673 RegisterMap reg_map(_thread);
674 vframe* start_vf = _thread->last_java_vframe(®_map);
675 int count = 0;
676 for (vframe* f = start_vf; f; f = f->sender() ) {
677 if (maxDepth >= 0 && count == maxDepth) {
678 // Skip frames if more than maxDepth
679 break;
680 }
681 if (f->is_java_frame()) {
682 javaVFrame* jvf = javaVFrame::cast(f);
683 add_stack_frame(jvf);
684 count++;
685 } else {
686 // Ignore non-Java frames
687 }
688 }
689 }
690
691 if (_with_locked_monitors) {
692 // Iterate inflated monitors and find monitors locked by this thread
693 // not found in the stack
694 InflatedMonitorsClosure imc(this);
695 ObjectSynchronizer::monitors_iterate(&imc, _thread);
696 }
697 }
698
699
700 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
701 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
702
703 bool found = false;
704 int num_frames = get_stack_depth();
705 for (int depth = 0; depth < num_frames; depth++) {
706 StackFrameInfo* frame = stack_frame_at(depth);
707 int len = frame->num_locked_monitors();
708 GrowableArray<OopHandle>* locked_monitors = frame->locked_monitors();
709 for (int j = 0; j < len; j++) {
710 oop monitor = locked_monitors->at(j).resolve();
711 assert(monitor != NULL, "must be a Java object");
712 if (monitor == object) {
713 found = true;
714 break;
715 }
716 }
717 }
718 return found;
719 }
720
721 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
722 InstanceKlass* ik = vmClasses::StackTraceElement_klass();
723 assert(ik != NULL, "must be loaded in 1.4+");
724
725 // Allocate an array of java/lang/StackTraceElement object
726 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
727 objArrayHandle backtrace(THREAD, ste);
728 for (int j = 0; j < _depth; j++) {
729 StackFrameInfo* frame = _frames->at(j);
730 methodHandle mh(THREAD, frame->method());
731 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
732 backtrace->obj_at_put(j, element);
733 }
734 return backtrace;
735 }
736
737 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
738 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
739 _frames->append(frame);
740 _depth++;
741 }
742
743 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
744 int length = _frames->length();
745 for (int i = 0; i < length; i++) {
746 _frames->at(i)->metadata_do(f);
747 }
748 }
749
750
751 ConcurrentLocksDump::~ConcurrentLocksDump() {
752 if (_retain_map_on_free) {
753 return;
754 }
755
756 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
757 ThreadConcurrentLocks* tcl = t;
758 t = t->next();
759 delete tcl;
760 }
761 }
762
763 void ConcurrentLocksDump::dump_at_safepoint() {
764 // dump all locked concurrent locks
765 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
766
767 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<oop>(INITIAL_ARRAY_SIZE, mtServiceability);
768
769 // Find all instances of AbstractOwnableSynchronizer
770 HeapInspection::find_instances_at_safepoint(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
771 aos_objects);
772 // Build a map of thread to its owned AQS locks
773 build_map(aos_objects);
774
775 delete aos_objects;
776 }
777
778
779 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
780 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
781 int length = aos_objects->length();
782 for (int i = 0; i < length; i++) {
783 oop o = aos_objects->at(i);
784 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
785 if (owner_thread_obj != NULL) {
786 // See comments in ThreadConcurrentLocks to see how this
787 // JavaThread* is protected.
788 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
789 assert(o->is_instance(), "Must be an instanceOop");
790 add_lock(thread, (instanceOop) o);
791 }
792 }
793 }
794
795 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
796 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
797 if (tcl != NULL) {
798 tcl->add_lock(o);
799 return;
800 }
801
802 // First owned lock found for this thread
803 tcl = new ThreadConcurrentLocks(thread);
804 tcl->add_lock(o);
805 if (_map == NULL) {
806 _map = tcl;
807 } else {
808 _last->set_next(tcl);
809 }
810 _last = tcl;
811 }
812
813 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
814 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
815 if (tcl->java_thread() == thread) {
816 return tcl;
817 }
818 }
819 return NULL;
820 }
821
822 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
823 st->print_cr(" Locked ownable synchronizers:");
824 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
825 GrowableArray<OopHandle>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
826 if (locks == NULL || locks->is_empty()) {
827 st->print_cr("\t- None");
828 st->cr();
829 return;
830 }
831
832 for (int i = 0; i < locks->length(); i++) {
833 oop obj = locks->at(i).resolve();
834 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
835 }
836 st->cr();
837 }
838
839 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
840 _thread = thread;
841 _owned_locks = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability);
842 _next = NULL;
843 }
844
845 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
846 for (int i = 0; i < _owned_locks->length(); i++) {
847 _owned_locks->at(i).release(_thread_service_storage);
848 }
849 delete _owned_locks;
850 }
851
852 void ThreadConcurrentLocks::add_lock(instanceOop o) {
853 _owned_locks->append(OopHandle(_thread_service_storage, o));
854 }
855
856 ThreadStatistics::ThreadStatistics() {
857 _contended_enter_count = 0;
858 _monitor_wait_count = 0;
859 _sleep_count = 0;
860 _count_pending_reset = false;
861 _timer_pending_reset = false;
862 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
863 }
864
865 oop ThreadSnapshot::threadObj() const { return _threadObj.resolve(); }
866
867 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
868 _thread = thread;
869 oop threadObj = thread->threadObj();
870 _threadObj = OopHandle(_thread_service_storage, threadObj);
871
872 ThreadStatistics* stat = thread->get_thread_stat();
873 _contended_enter_ticks = stat->contended_enter_ticks();
874 _contended_enter_count = stat->contended_enter_count();
875 _monitor_wait_ticks = stat->monitor_wait_ticks();
876 _monitor_wait_count = stat->monitor_wait_count();
877 _sleep_ticks = stat->sleep_ticks();
878 _sleep_count = stat->sleep_count();
879
880 // If thread is still attaching then threadObj will be NULL.
881 _thread_status = threadObj == NULL ? JavaThreadStatus::NEW
882 : java_lang_Thread::get_thread_status(threadObj);
883
884 _is_suspended = thread->is_suspended();
885 _is_in_native = (thread->thread_state() == _thread_in_native);
886
887 Handle obj = ThreadService::get_current_contended_monitor(thread);
888
889 oop blocker_object = NULL;
890 oop blocker_object_owner = NULL;
891
892 if (_thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER ||
893 _thread_status == JavaThreadStatus::IN_OBJECT_WAIT ||
894 _thread_status == JavaThreadStatus::IN_OBJECT_WAIT_TIMED) {
895
896 if (obj() == NULL) {
897 // monitor no longer exists; thread is not blocked
898 _thread_status = JavaThreadStatus::RUNNABLE;
899 } else {
900 blocker_object = obj();
901 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
902 if ((owner == NULL && _thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER)
903 || (owner != NULL && owner->is_attaching_via_jni())) {
904 // ownership information of the monitor is not available
905 // (may no longer be owned or releasing to some other thread)
906 // make this thread in RUNNABLE state.
907 // And when the owner thread is in attaching state, the java thread
908 // is not completely initialized. For example thread name and id
909 // and may not be set, so hide the attaching thread.
910 _thread_status = JavaThreadStatus::RUNNABLE;
911 blocker_object = NULL;
912 } else if (owner != NULL) {
913 blocker_object_owner = owner->threadObj();
914 }
915 }
916 }
917
918 // Support for JSR-166 locks
919 if (_thread_status == JavaThreadStatus::PARKED || _thread_status == JavaThreadStatus::PARKED_TIMED) {
920 blocker_object = thread->current_park_blocker();
921 if (blocker_object != NULL && blocker_object->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
922 blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(blocker_object);
923 }
924 }
925
926 if (blocker_object != NULL) {
927 _blocker_object = OopHandle(_thread_service_storage, blocker_object);
928 }
929 if (blocker_object_owner != NULL) {
930 _blocker_object_owner = OopHandle(_thread_service_storage, blocker_object_owner);
931 }
932 }
933
934 oop ThreadSnapshot::blocker_object() const { return _blocker_object.resolve(); }
935 oop ThreadSnapshot::blocker_object_owner() const { return _blocker_object_owner.resolve(); }
936
937 ThreadSnapshot::~ThreadSnapshot() {
938 _blocker_object.release(_thread_service_storage);
939 _blocker_object_owner.release(_thread_service_storage);
940 _threadObj.release(_thread_service_storage);
941
942 delete _stack_trace;
943 delete _concurrent_locks;
944 }
945
946 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
947 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
948 _stack_trace->dump_stack_at_safepoint(max_depth);
949 }
950
951
952 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
953 if (_stack_trace != NULL) {
954 _stack_trace->metadata_do(f);
955 }
956 }
957
958
959 DeadlockCycle::DeadlockCycle() {
960 _is_deadlock = false;
961 _threads = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, mtServiceability);
962 _next = NULL;
963 }
964
965 DeadlockCycle::~DeadlockCycle() {
966 delete _threads;
967 }
968
969 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
970 st->cr();
971 st->print_cr("Found one Java-level deadlock:");
972 st->print("=============================");
973
974 JavaThread* currentThread;
975 JvmtiRawMonitor* waitingToLockRawMonitor;
976 oop waitingToLockBlocker;
977 int len = _threads->length();
978 for (int i = 0; i < len; i++) {
979 currentThread = _threads->at(i);
980 // The ObjectMonitor* can't be async deflated since we are at a safepoint.
981 ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor();
982 waitingToLockRawMonitor = currentThread->current_pending_raw_monitor();
983 waitingToLockBlocker = currentThread->current_park_blocker();
984 st->cr();
985 st->print_cr("\"%s\":", currentThread->get_thread_name());
986 const char* owner_desc = ",\n which is held by";
987
988 // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor
989 // sets the current pending monitor, it is possible to then see a pending raw monitor as well.
990 if (waitingToLockRawMonitor != NULL) {
991 st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor));
992 Thread* owner = waitingToLockRawMonitor->owner();
993 // Could be NULL as the raw monitor could be released at any time if held by non-JavaThread
994 if (owner != NULL) {
995 if (owner->is_Java_thread()) {
996 currentThread = owner->as_Java_thread();
997 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
998 } else {
999 st->print_cr(",\n which has now been released");
1000 }
1001 } else {
1002 st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner));
1003 }
1004 }
1005
1006 if (waitingToLockMonitor != NULL) {
1007 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
1008 oop obj = waitingToLockMonitor->object();
1009 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
1010 obj->klass()->external_name());
1011
1012 if (!currentThread->current_pending_monitor_is_from_java()) {
1013 owner_desc = "\n in JNI, which is held by";
1014 }
1015 currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor);
1016 if (currentThread == NULL) {
1017 // The deadlock was detected at a safepoint so the JavaThread
1018 // that owns waitingToLockMonitor should be findable, but
1019 // if it is not findable, then the previous currentThread is
1020 // blocked permanently.
1021 st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
1022 p2i(waitingToLockMonitor->owner()));
1023 continue;
1024 }
1025 } else {
1026 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
1027 p2i(waitingToLockBlocker),
1028 waitingToLockBlocker->klass()->external_name());
1029 assert(waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
1030 "Must be an AbstractOwnableSynchronizer");
1031 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
1032 currentThread = java_lang_Thread::thread(ownerObj);
1033 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
1034 }
1035 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
1036 }
1037
1038 st->cr();
1039
1040 // Print stack traces
1041 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
1042 JavaMonitorsInStackTrace = true;
1043 st->print_cr("Java stack information for the threads listed above:");
1044 st->print_cr("===================================================");
1045 for (int j = 0; j < len; j++) {
1046 currentThread = _threads->at(j);
1047 st->print_cr("\"%s\":", currentThread->get_thread_name());
1048 currentThread->print_stack_on(st);
1049 }
1050 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
1051 }
1052
1053 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
1054 bool include_jvmti_agent_threads,
1055 bool include_jni_attaching_threads) {
1056 assert(cur_thread == Thread::current(), "Check current thread");
1057
1058 int init_size = ThreadService::get_live_thread_count();
1059 _threads_array = new GrowableArray<instanceHandle>(init_size);
1060
1061 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
1062 // skips JavaThreads in the process of exiting
1063 // and also skips VM internal JavaThreads
1064 // Threads in _thread_new or _thread_new_trans state are included.
1065 // i.e. threads have been started but not yet running.
1066 if (jt->threadObj() == NULL ||
1067 jt->is_exiting() ||
1068 !java_lang_Thread::is_alive(jt->threadObj()) ||
1069 jt->is_hidden_from_external_view()) {
1070 continue;
1071 }
1072
1073 // skip agent threads
1074 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
1075 continue;
1076 }
1077
1078 // skip jni threads in the process of attaching
1079 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
1080 continue;
1081 }
1082
1083 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
1084 _threads_array->append(h);
1085 }
1086 }