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