1 /*
2 * Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/heapInspection.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "oops/instanceKlass.hpp"
31 #include "oops/objArrayOop.inline.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/atomic.inline.hpp"
34 #include "runtime/handles.inline.hpp"
35 #include "runtime/init.hpp"
36 #include "runtime/thread.hpp"
37 #include "runtime/vframe.hpp"
38 #include "runtime/thread.inline.hpp"
39 #include "runtime/vmThread.hpp"
40 #include "runtime/vm_operations.hpp"
41 #include "services/threadService.hpp"
42
43 // TODO: we need to define a naming convention for perf counters
44 // to distinguish counters for:
45 // - standard JSR174 use
46 // - Hotspot extension (public and committed)
47 // - Hotspot extension (private/internal and uncommitted)
48
49 // Default is disabled.
50 bool ThreadService::_thread_monitoring_contention_enabled = false;
51 bool ThreadService::_thread_cpu_time_enabled = false;
52 bool ThreadService::_thread_allocated_memory_enabled = false;
53
54 PerfCounter* ThreadService::_total_threads_count = NULL;
55 PerfVariable* ThreadService::_live_threads_count = NULL;
56 PerfVariable* ThreadService::_peak_threads_count = NULL;
57 PerfVariable* ThreadService::_daemon_threads_count = NULL;
58 volatile int ThreadService::_exiting_threads_count = 0;
59 volatile int ThreadService::_exiting_daemon_threads_count = 0;
60
61 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
62
63 static const int INITIAL_ARRAY_SIZE = 10;
64
65 void ThreadService::init() {
66 EXCEPTION_MARK;
67
68 // These counters are for java.lang.management API support.
69 // They are created even if -XX:-UsePerfData is set and in
70 // that case, they will be allocated on C heap.
71
72 _total_threads_count =
73 PerfDataManager::create_counter(JAVA_THREADS, "started",
74 PerfData::U_Events, CHECK);
75
76 _live_threads_count =
77 PerfDataManager::create_variable(JAVA_THREADS, "live",
78 PerfData::U_None, CHECK);
79
80 _peak_threads_count =
81 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
82 PerfData::U_None, CHECK);
83
84 _daemon_threads_count =
85 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
86 PerfData::U_None, CHECK);
87
88 if (os::is_thread_cpu_time_supported()) {
89 _thread_cpu_time_enabled = true;
90 }
91
92 _thread_allocated_memory_enabled = true; // Always on, so enable it
93 }
94
95 void ThreadService::reset_peak_thread_count() {
96 // Acquire the lock to update the peak thread count
97 // to synchronize with thread addition and removal.
98 MutexLockerEx mu(Threads_lock);
99 _peak_threads_count->set_value(get_live_thread_count());
100 }
101
102 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
103 // Do not count VM internal or JVMTI agent threads
104 if (thread->is_hidden_from_external_view() ||
105 thread->is_jvmti_agent_thread()) {
106 return;
107 }
108
109 _total_threads_count->inc();
110 _live_threads_count->inc();
111
112 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
113 _peak_threads_count->set_value(_live_threads_count->get_value());
114 }
115
116 if (daemon) {
117 _daemon_threads_count->inc();
118 }
119 }
120
121 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
122 Atomic::dec((jint*) &_exiting_threads_count);
123
124 if (thread->is_hidden_from_external_view() ||
125 thread->is_jvmti_agent_thread()) {
126 return;
127 }
128
129 _live_threads_count->set_value(_live_threads_count->get_value() - 1);
130
131 if (daemon) {
132 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
133 Atomic::dec((jint*) &_exiting_daemon_threads_count);
134 }
135 }
136
137 void ThreadService::current_thread_exiting(JavaThread* jt) {
138 assert(jt == JavaThread::current(), "Called by current thread");
139 Atomic::inc((jint*) &_exiting_threads_count);
140
141 oop threadObj = jt->threadObj();
142 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
143 Atomic::inc((jint*) &_exiting_daemon_threads_count);
144 }
145 }
146
147 // FIXME: JVMTI should call this function
148 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
149 assert(thread != NULL, "should be non-NULL");
150 assert(Threads_lock->owned_by_self(), "must grab Threads_lock or be at safepoint");
151
152 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
153
154 oop obj = NULL;
155 if (wait_obj != NULL) {
156 // thread is doing an Object.wait() call
157 obj = (oop) wait_obj->object();
158 assert(obj != NULL, "Object.wait() should have an object");
159 } else {
160 ObjectMonitor *enter_obj = thread->current_pending_monitor();
161 if (enter_obj != NULL) {
162 // thread is trying to enter() or raw_enter() an ObjectMonitor.
163 obj = (oop) enter_obj->object();
164 }
165 // If obj == NULL, then ObjectMonitor is raw which doesn't count.
166 }
167
168 Handle h(obj);
169 return h;
170 }
171
172 bool ThreadService::set_thread_monitoring_contention(bool flag) {
173 MutexLocker m(Management_lock);
174
175 bool prev = _thread_monitoring_contention_enabled;
176 _thread_monitoring_contention_enabled = flag;
177
178 return prev;
179 }
180
181 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
182 MutexLocker m(Management_lock);
183
184 bool prev = _thread_cpu_time_enabled;
185 _thread_cpu_time_enabled = flag;
186
187 return prev;
188 }
189
190 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
191 MutexLocker m(Management_lock);
192
193 bool prev = _thread_allocated_memory_enabled;
194 _thread_allocated_memory_enabled = flag;
195
196 return prev;
197 }
198
199 // GC support
200 void ThreadService::oops_do(OopClosure* f) {
201 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
202 dump->oops_do(f);
203 }
204 }
205
206 void ThreadService::metadata_do(void f(Metadata*)) {
207 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
208 dump->metadata_do(f);
209 }
210 }
211
212 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
213 MutexLocker ml(Management_lock);
214 if (_threaddump_list == NULL) {
215 _threaddump_list = dump;
216 } else {
217 dump->set_next(_threaddump_list);
218 _threaddump_list = dump;
219 }
220 }
221
222 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
223 MutexLocker ml(Management_lock);
224
225 ThreadDumpResult* prev = NULL;
226 bool found = false;
227 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
228 if (d == dump) {
229 if (prev == NULL) {
230 _threaddump_list = dump->next();
231 } else {
232 prev->set_next(dump->next());
233 }
234 found = true;
235 break;
236 }
237 }
238 assert(found, "The threaddump result to be removed must exist.");
239 }
240
241 // Dump stack trace of threads specified in the given threads array.
242 // Returns StackTraceElement[][] each element is the stack trace of a thread in
243 // the corresponding entry in the given threads array
244 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
245 int num_threads,
246 TRAPS) {
247 assert(num_threads > 0, "just checking");
248
249 ThreadDumpResult dump_result;
250 VM_ThreadDump op(&dump_result,
251 threads,
252 num_threads,
253 -1, /* entire stack */
254 false, /* with locked monitors */
255 false /* with locked synchronizers */);
256 VMThread::execute(&op);
257
258 // Allocate the resulting StackTraceElement[][] object
259
260 ResourceMark rm(THREAD);
261 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
262 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
263 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
264 objArrayHandle result_obj(THREAD, r);
265
266 int num_snapshots = dump_result.num_snapshots();
267 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
268 int i = 0;
269 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
270 ThreadStackTrace* stacktrace = ts->get_stack_trace();
271 if (stacktrace == NULL) {
272 // No stack trace
273 result_obj->obj_at_put(i, NULL);
274 } else {
275 // Construct an array of java/lang/StackTraceElement object
276 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
277 result_obj->obj_at_put(i, backtrace_h());
278 }
279 }
280
281 return result_obj;
282 }
283
284 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
285 ThreadStatistics* stat = thread->get_thread_stat();
286 if (stat != NULL) {
287 stat->reset_count_stat();
288 }
289 }
290
291 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
292 ThreadStatistics* stat = thread->get_thread_stat();
293 if (stat != NULL) {
294 stat->reset_time_stat();
295 }
296 }
297
298 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
299 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) {
300 // This code was modified from the original Threads::find_deadlocks code.
301 int globalDfn = 0, thisDfn;
302 ObjectMonitor* waitingToLockMonitor = NULL;
303 oop waitingToLockBlocker = NULL;
304 bool blocked_on_monitor = false;
305 JavaThread *currentThread, *previousThread;
306 int num_deadlocks = 0;
307
308 for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) {
309 // Initialize the depth-first-number
310 p->set_depth_first_number(-1);
311 }
312
313 DeadlockCycle* deadlocks = NULL;
314 DeadlockCycle* last = NULL;
315 DeadlockCycle* cycle = new DeadlockCycle();
316 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
317 if (jt->depth_first_number() >= 0) {
318 // this thread was already visited
319 continue;
320 }
321
322 thisDfn = globalDfn;
323 jt->set_depth_first_number(globalDfn++);
324 previousThread = jt;
325 currentThread = jt;
326
327 cycle->reset();
328
329 // When there is a deadlock, all the monitors involved in the dependency
330 // cycle must be contended and heavyweight. So we only care about the
331 // heavyweight monitor a thread is waiting to lock.
332 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
333 if (concurrent_locks) {
334 waitingToLockBlocker = jt->current_park_blocker();
335 }
336 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
337 cycle->add_thread(currentThread);
338 if (waitingToLockMonitor != NULL) {
339 address currentOwner = (address)waitingToLockMonitor->owner();
340 if (currentOwner != NULL) {
341 currentThread = Threads::owning_thread_from_monitor_owner(
342 currentOwner,
343 false /* no locking needed */);
344 if (currentThread == NULL) {
345 // This function is called at a safepoint so the JavaThread
346 // that owns waitingToLockMonitor should be findable, but
347 // if it is not findable, then the previous currentThread is
348 // blocked permanently. We record this as a deadlock.
349 num_deadlocks++;
350
351 cycle->set_deadlock(true);
352
353 // add this cycle to the deadlocks list
354 if (deadlocks == NULL) {
355 deadlocks = cycle;
356 } else {
357 last->set_next(cycle);
358 }
359 last = cycle;
360 cycle = new DeadlockCycle();
361 break;
362 }
363 }
364 } else {
365 if (concurrent_locks) {
366 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
367 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
368 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
369 } else {
370 currentThread = NULL;
371 }
372 }
373 }
374
375 if (currentThread == NULL) {
376 // No dependency on another thread
377 break;
378 }
379 if (currentThread->depth_first_number() < 0) {
380 // First visit to this thread
381 currentThread->set_depth_first_number(globalDfn++);
382 } else if (currentThread->depth_first_number() < thisDfn) {
383 // Thread already visited, and not on a (new) cycle
384 break;
385 } else if (currentThread == previousThread) {
386 // Self-loop, ignore
387 break;
388 } else {
389 // We have a (new) cycle
390 num_deadlocks++;
391
392 cycle->set_deadlock(true);
393
394 // add this cycle to the deadlocks list
395 if (deadlocks == NULL) {
396 deadlocks = cycle;
397 } else {
398 last->set_next(cycle);
399 }
400 last = cycle;
401 cycle = new DeadlockCycle();
402 break;
403 }
404 previousThread = currentThread;
405 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
406 if (concurrent_locks) {
407 waitingToLockBlocker = currentThread->current_park_blocker();
408 }
409 }
410
411 }
412 delete cycle;
413 return deadlocks;
414 }
415
416 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
417
418 // Create a new ThreadDumpResult object and append to the list.
419 // If GC happens before this function returns, Method*
420 // in the stack trace will be visited.
421 ThreadService::add_thread_dump(this);
422 }
423
424 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
425 // Create a new ThreadDumpResult object and append to the list.
426 // If GC happens before this function returns, oops
427 // will be visited.
428 ThreadService::add_thread_dump(this);
429 }
430
431 ThreadDumpResult::~ThreadDumpResult() {
432 ThreadService::remove_thread_dump(this);
433
434 // free all the ThreadSnapshot objects created during
435 // the VM_ThreadDump operation
436 ThreadSnapshot* ts = _snapshots;
437 while (ts != NULL) {
438 ThreadSnapshot* p = ts;
439 ts = ts->next();
440 delete p;
441 }
442 }
443
444
445 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
446 assert(_num_threads == 0 || _num_snapshots < _num_threads,
447 "_num_snapshots must be less than _num_threads");
448 _num_snapshots++;
449 if (_snapshots == NULL) {
450 _snapshots = ts;
451 } else {
452 _last->set_next(ts);
453 }
454 _last = ts;
455 }
456
457 void ThreadDumpResult::oops_do(OopClosure* f) {
458 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
459 ts->oops_do(f);
460 }
461 }
462
463 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
464 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
465 ts->metadata_do(f);
466 }
467 }
468
469 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
470 _method = jvf->method();
471 _bci = jvf->bci();
472 _class_holder = _method->method_holder()->klass_holder();
473 _locked_monitors = NULL;
474 if (with_lock_info) {
475 ResourceMark rm;
476 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
477 int length = list->length();
478 if (length > 0) {
479 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
480 for (int i = 0; i < length; i++) {
481 MonitorInfo* monitor = list->at(i);
482 assert(monitor->owner(), "This monitor must have an owning object");
483 _locked_monitors->append(monitor->owner());
484 }
485 }
486 }
487 }
488
489 void StackFrameInfo::oops_do(OopClosure* f) {
490 if (_locked_monitors != NULL) {
491 int length = _locked_monitors->length();
492 for (int i = 0; i < length; i++) {
493 f->do_oop((oop*) _locked_monitors->adr_at(i));
494 }
495 }
496 f->do_oop(&_class_holder);
497 }
498
499 void StackFrameInfo::metadata_do(void f(Metadata*)) {
500 f(_method);
501 }
502
503 void StackFrameInfo::print_on(outputStream* st) const {
504 ResourceMark rm;
505 java_lang_Throwable::print_stack_element(st, method(), bci());
506 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
507 for (int i = 0; i < len; i++) {
508 oop o = _locked_monitors->at(i);
509 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
510 }
511
512 }
513
514 // Iterate through monitor cache to find JNI locked monitors
515 class InflatedMonitorsClosure: public MonitorClosure {
516 private:
517 ThreadStackTrace* _stack_trace;
518 Thread* _thread;
519 public:
520 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
521 _thread = t;
522 _stack_trace = st;
523 }
524 void do_monitor(ObjectMonitor* mid) {
525 if (mid->owner() == _thread) {
526 oop object = (oop) mid->object();
527 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
528 _stack_trace->add_jni_locked_monitor(object);
529 }
530 }
531 }
532 };
533
534 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
535 _thread = t;
536 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
537 _depth = 0;
538 _with_locked_monitors = with_locked_monitors;
539 if (_with_locked_monitors) {
540 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
541 } else {
542 _jni_locked_monitors = NULL;
543 }
544 }
545
546 ThreadStackTrace::~ThreadStackTrace() {
547 for (int i = 0; i < _frames->length(); i++) {
548 delete _frames->at(i);
549 }
550 delete _frames;
551 if (_jni_locked_monitors != NULL) {
552 delete _jni_locked_monitors;
553 }
554 }
555
556 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
557 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
558
559 if (_thread->has_last_Java_frame()) {
560 RegisterMap reg_map(_thread);
561 vframe* start_vf = _thread->last_java_vframe(®_map);
562 int count = 0;
563 for (vframe* f = start_vf; f; f = f->sender() ) {
564 if (f->is_java_frame()) {
565 javaVFrame* jvf = javaVFrame::cast(f);
566 add_stack_frame(jvf);
567 count++;
568 } else {
569 // Ignore non-Java frames
570 }
571 if (maxDepth > 0 && count == maxDepth) {
572 // Skip frames if more than maxDepth
573 break;
574 }
575 }
576 }
577
578 if (_with_locked_monitors) {
579 // Iterate inflated monitors and find monitors locked by this thread
580 // not found in the stack
581 InflatedMonitorsClosure imc(_thread, this);
582 ObjectSynchronizer::monitors_iterate(&imc);
583 }
584 }
585
586
587 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
588 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
589
590 bool found = false;
591 int num_frames = get_stack_depth();
592 for (int depth = 0; depth < num_frames; depth++) {
593 StackFrameInfo* frame = stack_frame_at(depth);
594 int len = frame->num_locked_monitors();
595 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
596 for (int j = 0; j < len; j++) {
597 oop monitor = locked_monitors->at(j);
598 assert(monitor != NULL, "must be a Java object");
599 if (monitor == object) {
600 found = true;
601 break;
602 }
603 }
604 }
605 return found;
606 }
607
608 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
609 Klass* k = SystemDictionary::StackTraceElement_klass();
610 assert(k != NULL, "must be loaded in 1.4+");
611 instanceKlassHandle ik(THREAD, k);
612
613 // Allocate an array of java/lang/StackTraceElement object
614 objArrayOop ste = oopFactory::new_objArray(ik(), _depth, CHECK_NH);
615 objArrayHandle backtrace(THREAD, ste);
616 for (int j = 0; j < _depth; j++) {
617 StackFrameInfo* frame = _frames->at(j);
618 methodHandle mh(THREAD, frame->method());
619 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
620 backtrace->obj_at_put(j, element);
621 }
622 return backtrace;
623 }
624
625 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
626 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
627 _frames->append(frame);
628 _depth++;
629 }
630
631 void ThreadStackTrace::oops_do(OopClosure* f) {
632 int length = _frames->length();
633 for (int i = 0; i < length; i++) {
634 _frames->at(i)->oops_do(f);
635 }
636
637 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
638 for (int j = 0; j < length; j++) {
639 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
640 }
641 }
642
643 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
644 int length = _frames->length();
645 for (int i = 0; i < length; i++) {
646 _frames->at(i)->metadata_do(f);
647 }
648 }
649
650
651 ConcurrentLocksDump::~ConcurrentLocksDump() {
652 if (_retain_map_on_free) {
653 return;
654 }
655
656 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
657 ThreadConcurrentLocks* tcl = t;
658 t = t->next();
659 delete tcl;
660 }
661 }
662
663 void ConcurrentLocksDump::dump_at_safepoint() {
664 // dump all locked concurrent locks
665 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
666
667 ResourceMark rm;
668
669 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE);
670
671 // Find all instances of AbstractOwnableSynchronizer
672 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(),
673 aos_objects);
674 // Build a map of thread to its owned AQS locks
675 build_map(aos_objects);
676 }
677
678
679 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
680 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
681 int length = aos_objects->length();
682 for (int i = 0; i < length; i++) {
683 oop o = aos_objects->at(i);
684 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
685 if (owner_thread_obj != NULL) {
686 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
687 assert(o->is_instance(), "Must be an instanceOop");
688 add_lock(thread, (instanceOop) o);
689 }
690 }
691 }
692
693 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
694 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
695 if (tcl != NULL) {
696 tcl->add_lock(o);
697 return;
698 }
699
700 // First owned lock found for this thread
701 tcl = new ThreadConcurrentLocks(thread);
702 tcl->add_lock(o);
703 if (_map == NULL) {
704 _map = tcl;
705 } else {
706 _last->set_next(tcl);
707 }
708 _last = tcl;
709 }
710
711 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
712 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
713 if (tcl->java_thread() == thread) {
714 return tcl;
715 }
716 }
717 return NULL;
718 }
719
720 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
721 st->print_cr(" Locked ownable synchronizers:");
722 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
723 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
724 if (locks == NULL || locks->is_empty()) {
725 st->print_cr("\t- None");
726 st->cr();
727 return;
728 }
729
730 for (int i = 0; i < locks->length(); i++) {
731 instanceOop obj = locks->at(i);
732 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
733 }
734 st->cr();
735 }
736
737 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
738 _thread = thread;
739 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
740 _next = NULL;
741 }
742
743 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
744 delete _owned_locks;
745 }
746
747 void ThreadConcurrentLocks::add_lock(instanceOop o) {
748 _owned_locks->append(o);
749 }
750
751 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
752 int length = _owned_locks->length();
753 for (int i = 0; i < length; i++) {
754 f->do_oop((oop*) _owned_locks->adr_at(i));
755 }
756 }
757
758 ThreadStatistics::ThreadStatistics() {
759 _contended_enter_count = 0;
760 _monitor_wait_count = 0;
761 _sleep_count = 0;
762 _count_pending_reset = false;
763 _timer_pending_reset = false;
764 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
765 }
766
767 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) {
768 _thread = thread;
769 _threadObj = thread->threadObj();
770 _stack_trace = NULL;
771 _concurrent_locks = NULL;
772 _next = NULL;
773
774 ThreadStatistics* stat = thread->get_thread_stat();
775 _contended_enter_ticks = stat->contended_enter_ticks();
776 _contended_enter_count = stat->contended_enter_count();
777 _monitor_wait_ticks = stat->monitor_wait_ticks();
778 _monitor_wait_count = stat->monitor_wait_count();
779 _sleep_ticks = stat->sleep_ticks();
780 _sleep_count = stat->sleep_count();
781
782 _blocker_object = NULL;
783 _blocker_object_owner = NULL;
784
785 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
786 _is_ext_suspended = thread->is_being_ext_suspended();
787 _is_in_native = (thread->thread_state() == _thread_in_native);
788
789 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
790 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
791 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
792
793 Handle obj = ThreadService::get_current_contended_monitor(thread);
794 if (obj() == NULL) {
795 // monitor no longer exists; thread is not blocked
796 _thread_status = java_lang_Thread::RUNNABLE;
797 } else {
798 _blocker_object = obj();
799 JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false);
800 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
801 || (owner != NULL && owner->is_attaching_via_jni())) {
802 // ownership information of the monitor is not available
803 // (may no longer be owned or releasing to some other thread)
804 // make this thread in RUNNABLE state.
805 // And when the owner thread is in attaching state, the java thread
806 // is not completely initialized. For example thread name and id
807 // and may not be set, so hide the attaching thread.
808 _thread_status = java_lang_Thread::RUNNABLE;
809 _blocker_object = NULL;
810 } else if (owner != NULL) {
811 _blocker_object_owner = owner->threadObj();
812 }
813 }
814 }
815
816 // Support for JSR-166 locks
817 if (JDK_Version::current().supports_thread_park_blocker() &&
818 (_thread_status == java_lang_Thread::PARKED ||
819 _thread_status == java_lang_Thread::PARKED_TIMED)) {
820
821 _blocker_object = thread->current_park_blocker();
822 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
823 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
824 }
825 }
826 }
827
828 ThreadSnapshot::~ThreadSnapshot() {
829 delete _stack_trace;
830 delete _concurrent_locks;
831 }
832
833 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
834 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
835 _stack_trace->dump_stack_at_safepoint(max_depth);
836 }
837
838
839 void ThreadSnapshot::oops_do(OopClosure* f) {
840 f->do_oop(&_threadObj);
841 f->do_oop(&_blocker_object);
842 f->do_oop(&_blocker_object_owner);
843 if (_stack_trace != NULL) {
844 _stack_trace->oops_do(f);
845 }
846 if (_concurrent_locks != NULL) {
847 _concurrent_locks->oops_do(f);
848 }
849 }
850
851 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
852 if (_stack_trace != NULL) {
853 _stack_trace->metadata_do(f);
854 }
855 }
856
857
858 DeadlockCycle::DeadlockCycle() {
859 _is_deadlock = false;
860 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
861 _next = NULL;
862 }
863
864 DeadlockCycle::~DeadlockCycle() {
865 delete _threads;
866 }
867
868 void DeadlockCycle::print_on(outputStream* st) const {
869 st->cr();
870 st->print_cr("Found one Java-level deadlock:");
871 st->print("=============================");
872
873 JavaThread* currentThread;
874 ObjectMonitor* waitingToLockMonitor;
875 oop waitingToLockBlocker;
876 int len = _threads->length();
877 for (int i = 0; i < len; i++) {
878 currentThread = _threads->at(i);
879 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
880 waitingToLockBlocker = currentThread->current_park_blocker();
881 st->cr();
882 st->print_cr("\"%s\":", currentThread->get_thread_name());
883 const char* owner_desc = ",\n which is held by";
884 if (waitingToLockMonitor != NULL) {
885 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
886 oop obj = (oop)waitingToLockMonitor->object();
887 if (obj != NULL) {
888 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
889 obj->klass()->external_name());
890
891 if (!currentThread->current_pending_monitor_is_from_java()) {
892 owner_desc = "\n in JNI, which is held by";
893 }
894 } else {
895 // No Java object associated - a JVMTI raw monitor
896 owner_desc = " (JVMTI raw monitor),\n which is held by";
897 }
898 currentThread = Threads::owning_thread_from_monitor_owner(
899 (address)waitingToLockMonitor->owner(),
900 false /* no locking needed */);
901 if (currentThread == NULL) {
902 // The deadlock was detected at a safepoint so the JavaThread
903 // that owns waitingToLockMonitor should be findable, but
904 // if it is not findable, then the previous currentThread is
905 // blocked permanently.
906 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
907 p2i(waitingToLockMonitor->owner()));
908 continue;
909 }
910 } else {
911 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
912 p2i(waitingToLockBlocker),
913 waitingToLockBlocker->klass()->external_name());
914 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()),
915 "Must be an AbstractOwnableSynchronizer");
916 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
917 currentThread = java_lang_Thread::thread(ownerObj);
918 }
919 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
920 }
921
922 st->cr();
923 st->cr();
924
925 // Print stack traces
926 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
927 JavaMonitorsInStackTrace = true;
928 st->print_cr("Java stack information for the threads listed above:");
929 st->print_cr("===================================================");
930 for (int j = 0; j < len; j++) {
931 currentThread = _threads->at(j);
932 st->print_cr("\"%s\":", currentThread->get_thread_name());
933 currentThread->print_stack_on(st);
934 }
935 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
936 }
937
938 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
939 bool include_jvmti_agent_threads,
940 bool include_jni_attaching_threads) {
941 assert(cur_thread == Thread::current(), "Check current thread");
942
943 int init_size = ThreadService::get_live_thread_count();
944 _threads_array = new GrowableArray<instanceHandle>(init_size);
945
946 MutexLockerEx ml(Threads_lock);
947
948 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
949 // skips JavaThreads in the process of exiting
950 // and also skips VM internal JavaThreads
951 // Threads in _thread_new or _thread_new_trans state are included.
952 // i.e. threads have been started but not yet running.
953 if (jt->threadObj() == NULL ||
954 jt->is_exiting() ||
955 !java_lang_Thread::is_alive(jt->threadObj()) ||
956 jt->is_hidden_from_external_view()) {
957 continue;
958 }
959
960 // skip agent threads
961 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
962 continue;
963 }
964
965 // skip jni threads in the process of attaching
966 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
967 continue;
968 }
969
970 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
971 _threads_array->append(h);
972 }
973 }