1 /*
2 * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/heapInspection.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/instanceKlass.hpp"
32 #include "oops/objArrayOop.inline.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/atomic.hpp"
35 #include "runtime/handles.inline.hpp"
36 #include "runtime/init.hpp"
37 #include "runtime/objectMonitor.inline.hpp"
38 #include "runtime/thread.inline.hpp"
39 #include "runtime/threadSMR.inline.hpp"
40 #include "runtime/vframe.hpp"
41 #include "runtime/vmThread.hpp"
42 #include "runtime/vm_operations.hpp"
43 #include "services/threadService.hpp"
44
45 // TODO: we need to define a naming convention for perf counters
46 // to distinguish counters for:
47 // - standard JSR174 use
48 // - Hotspot extension (public and committed)
49 // - Hotspot extension (private/internal and uncommitted)
50
51 // Default is disabled.
52 bool ThreadService::_thread_monitoring_contention_enabled = false;
53 bool ThreadService::_thread_cpu_time_enabled = false;
54 bool ThreadService::_thread_allocated_memory_enabled = false;
55
56 PerfCounter* ThreadService::_total_threads_count = NULL;
57 PerfVariable* ThreadService::_live_threads_count = NULL;
58 PerfVariable* ThreadService::_peak_threads_count = NULL;
59 PerfVariable* ThreadService::_daemon_threads_count = NULL;
60 volatile int ThreadService::_exiting_threads_count = 0;
61 volatile int ThreadService::_exiting_daemon_threads_count = 0;
62
63 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
64
65 static const int INITIAL_ARRAY_SIZE = 10;
66
67 void ThreadService::init() {
68 EXCEPTION_MARK;
69
70 // These counters are for java.lang.management API support.
71 // They are created even if -XX:-UsePerfData is set and in
72 // that case, they will be allocated on C heap.
73
74 _total_threads_count =
75 PerfDataManager::create_counter(JAVA_THREADS, "started",
76 PerfData::U_Events, CHECK);
77
78 _live_threads_count =
79 PerfDataManager::create_variable(JAVA_THREADS, "live",
80 PerfData::U_None, CHECK);
81
82 _peak_threads_count =
83 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
84 PerfData::U_None, CHECK);
85
86 _daemon_threads_count =
87 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
88 PerfData::U_None, CHECK);
89
90 if (os::is_thread_cpu_time_supported()) {
91 _thread_cpu_time_enabled = true;
92 }
93
94 _thread_allocated_memory_enabled = true; // Always on, so enable it
95 }
96
97 void ThreadService::reset_peak_thread_count() {
98 // Acquire the lock to update the peak thread count
99 // to synchronize with thread addition and removal.
100 MutexLockerEx mu(Threads_lock);
101 _peak_threads_count->set_value(get_live_thread_count());
102 }
103
104 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
105 // Do not count VM internal or JVMTI agent threads
106 if (thread->is_hidden_from_external_view() ||
107 thread->is_jvmti_agent_thread()) {
108 return;
109 }
110
111 _total_threads_count->inc();
112 _live_threads_count->inc();
113
114 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
115 _peak_threads_count->set_value(_live_threads_count->get_value());
116 }
117
118 if (daemon) {
119 _daemon_threads_count->inc();
120 }
121 }
122
123 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
124 Atomic::dec(&_exiting_threads_count);
125 if (daemon) {
126 Atomic::dec(&_exiting_daemon_threads_count);
127 }
128
129 if (thread->is_hidden_from_external_view() ||
130 thread->is_jvmti_agent_thread()) {
131 return;
132 }
133
134 _live_threads_count->set_value(_live_threads_count->get_value() - 1);
135 if (daemon) {
136 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
137 }
138 }
139
140 void ThreadService::current_thread_exiting(JavaThread* jt) {
141 assert(jt == JavaThread::current(), "Called by current thread");
142 Atomic::inc(&_exiting_threads_count);
143
144 oop threadObj = jt->threadObj();
145 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
146 Atomic::inc(&_exiting_daemon_threads_count);
147 }
148 }
149
150 // FIXME: JVMTI should call this function
151 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
152 assert(thread != NULL, "should be non-NULL");
153 debug_only(Thread::check_for_dangling_thread_pointer(thread);)
154
155 ObjectMonitor *wait_obj = thread->current_waiting_monitor();
156
157 oop obj = NULL;
158 if (wait_obj != NULL) {
159 // thread is doing an Object.wait() call
160 obj = (oop) wait_obj->object();
161 assert(obj != NULL, "Object.wait() should have an object");
162 } else {
163 ObjectMonitor *enter_obj = thread->current_pending_monitor();
164 if (enter_obj != NULL) {
165 // thread is trying to enter() or raw_enter() an ObjectMonitor.
166 obj = (oop) enter_obj->object();
167 }
168 // If obj == NULL, then ObjectMonitor is raw which doesn't count.
169 }
170
171 Handle h(Thread::current(), obj);
172 return h;
173 }
174
175 bool ThreadService::set_thread_monitoring_contention(bool flag) {
176 MutexLocker m(Management_lock);
177
178 bool prev = _thread_monitoring_contention_enabled;
179 _thread_monitoring_contention_enabled = flag;
180
181 return prev;
182 }
183
184 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
185 MutexLocker m(Management_lock);
186
187 bool prev = _thread_cpu_time_enabled;
188 _thread_cpu_time_enabled = flag;
189
190 return prev;
191 }
192
193 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
194 MutexLocker m(Management_lock);
195
196 bool prev = _thread_allocated_memory_enabled;
197 _thread_allocated_memory_enabled = flag;
198
199 return prev;
200 }
201
202 // GC support
203 void ThreadService::oops_do(OopClosure* f) {
204 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
205 dump->oops_do(f);
206 }
207 }
208
209 void ThreadService::metadata_do(void f(Metadata*)) {
210 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
211 dump->metadata_do(f);
212 }
213 }
214
215 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
216 MutexLocker ml(Management_lock);
217 if (_threaddump_list == NULL) {
218 _threaddump_list = dump;
219 } else {
220 dump->set_next(_threaddump_list);
221 _threaddump_list = dump;
222 }
223 }
224
225 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
226 MutexLocker ml(Management_lock);
227
228 ThreadDumpResult* prev = NULL;
229 bool found = false;
230 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
231 if (d == dump) {
232 if (prev == NULL) {
233 _threaddump_list = dump->next();
234 } else {
235 prev->set_next(dump->next());
236 }
237 found = true;
238 break;
239 }
240 }
241 assert(found, "The threaddump result to be removed must exist.");
242 }
243
244 // Dump stack trace of threads specified in the given threads array.
245 // Returns StackTraceElement[][] each element is the stack trace of a thread in
246 // the corresponding entry in the given threads array
247 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
248 int num_threads,
249 TRAPS) {
250 assert(num_threads > 0, "just checking");
251
252 ThreadDumpResult dump_result;
253 VM_ThreadDump op(&dump_result,
254 threads,
255 num_threads,
256 -1, /* entire stack */
257 false, /* with locked monitors */
258 false /* with locked synchronizers */);
259 VMThread::execute(&op);
260
261 // Allocate the resulting StackTraceElement[][] object
262
263 ResourceMark rm(THREAD);
264 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
265 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
266 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
267 objArrayHandle result_obj(THREAD, r);
268
269 int num_snapshots = dump_result.num_snapshots();
270 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
271 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
272 int i = 0;
273 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
274 ThreadStackTrace* stacktrace = ts->get_stack_trace();
275 if (stacktrace == NULL) {
276 // No stack trace
277 result_obj->obj_at_put(i, NULL);
278 } else {
279 // Construct an array of java/lang/StackTraceElement object
280 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
281 result_obj->obj_at_put(i, backtrace_h());
282 }
283 }
284
285 return result_obj;
286 }
287
288 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
289 ThreadStatistics* stat = thread->get_thread_stat();
290 if (stat != NULL) {
291 stat->reset_count_stat();
292 }
293 }
294
295 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
296 ThreadStatistics* stat = thread->get_thread_stat();
297 if (stat != NULL) {
298 stat->reset_time_stat();
299 }
300 }
301
302 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
303 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
304 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
305
306 // This code was modified from the original Threads::find_deadlocks code.
307 int globalDfn = 0, thisDfn;
308 ObjectMonitor* waitingToLockMonitor = NULL;
309 oop waitingToLockBlocker = NULL;
310 bool blocked_on_monitor = false;
311 JavaThread *currentThread, *previousThread;
312 int num_deadlocks = 0;
313
314 // Initialize the depth-first-number for each JavaThread.
315 JavaThreadIterator jti(t_list);
316 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
317 jt->set_depth_first_number(-1);
318 }
319
320 DeadlockCycle* deadlocks = NULL;
321 DeadlockCycle* last = NULL;
322 DeadlockCycle* cycle = new DeadlockCycle();
323 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
324 if (jt->depth_first_number() >= 0) {
325 // this thread was already visited
326 continue;
327 }
328
329 thisDfn = globalDfn;
330 jt->set_depth_first_number(globalDfn++);
331 previousThread = jt;
332 currentThread = jt;
333
334 cycle->reset();
335
336 // When there is a deadlock, all the monitors involved in the dependency
337 // cycle must be contended and heavyweight. So we only care about the
338 // heavyweight monitor a thread is waiting to lock.
339 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
340 if (concurrent_locks) {
341 waitingToLockBlocker = jt->current_park_blocker();
342 }
343 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
344 cycle->add_thread(currentThread);
345 if (waitingToLockMonitor != NULL) {
346 address currentOwner = (address)waitingToLockMonitor->owner();
347 if (currentOwner != NULL) {
348 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
349 currentOwner);
350 if (currentThread == NULL) {
351 // This function is called at a safepoint so the JavaThread
352 // that owns waitingToLockMonitor should be findable, but
353 // if it is not findable, then the previous currentThread is
354 // blocked permanently. We record this as a deadlock.
355 num_deadlocks++;
356
357 cycle->set_deadlock(true);
358
359 // add this cycle to the deadlocks list
360 if (deadlocks == NULL) {
361 deadlocks = cycle;
362 } else {
363 last->set_next(cycle);
364 }
365 last = cycle;
366 cycle = new DeadlockCycle();
367 break;
368 }
369 }
370 } else {
371 if (concurrent_locks) {
372 if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
373 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
374 // This JavaThread (if there is one) is protected by the
375 // ThreadsListSetter in VM_FindDeadlocks::doit().
376 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
377 } else {
378 currentThread = NULL;
379 }
380 }
381 }
382
383 if (currentThread == NULL) {
384 // No dependency on another thread
385 break;
386 }
387 if (currentThread->depth_first_number() < 0) {
388 // First visit to this thread
389 currentThread->set_depth_first_number(globalDfn++);
390 } else if (currentThread->depth_first_number() < thisDfn) {
391 // Thread already visited, and not on a (new) cycle
392 break;
393 } else if (currentThread == previousThread) {
394 // Self-loop, ignore
395 break;
396 } else {
397 // We have a (new) cycle
398 num_deadlocks++;
399
400 cycle->set_deadlock(true);
401
402 // add this cycle to the deadlocks list
403 if (deadlocks == NULL) {
404 deadlocks = cycle;
405 } else {
406 last->set_next(cycle);
407 }
408 last = cycle;
409 cycle = new DeadlockCycle();
410 break;
411 }
412 previousThread = currentThread;
413 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
414 if (concurrent_locks) {
415 waitingToLockBlocker = currentThread->current_park_blocker();
416 }
417 }
418
419 }
420 delete cycle;
421 return deadlocks;
422 }
423
424 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL), _setter() {
425
426 // Create a new ThreadDumpResult object and append to the list.
427 // If GC happens before this function returns, Method*
428 // in the stack trace will be visited.
429 ThreadService::add_thread_dump(this);
430 }
431
432 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL), _setter() {
433 // Create a new ThreadDumpResult object and append to the list.
434 // If GC happens before this function returns, oops
435 // will be visited.
436 ThreadService::add_thread_dump(this);
437 }
438
439 ThreadDumpResult::~ThreadDumpResult() {
440 ThreadService::remove_thread_dump(this);
441
442 // free all the ThreadSnapshot objects created during
443 // the VM_ThreadDump operation
444 ThreadSnapshot* ts = _snapshots;
445 while (ts != NULL) {
446 ThreadSnapshot* p = ts;
447 ts = ts->next();
448 delete p;
449 }
450 }
451
452
453 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
454 assert(_num_threads == 0 || _num_snapshots < _num_threads,
455 "_num_snapshots must be less than _num_threads");
456 _num_snapshots++;
457 if (_snapshots == NULL) {
458 _snapshots = ts;
459 } else {
460 _last->set_next(ts);
461 }
462 _last = ts;
463 }
464
465 void ThreadDumpResult::oops_do(OopClosure* f) {
466 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
467 ts->oops_do(f);
468 }
469 }
470
471 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
472 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
473 ts->metadata_do(f);
474 }
475 }
476
477 ThreadsList* ThreadDumpResult::t_list() {
478 return _setter.list();
479 }
480
481 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
482 _method = jvf->method();
483 _bci = jvf->bci();
484 _class_holder = _method->method_holder()->klass_holder();
485 _locked_monitors = NULL;
486 if (with_lock_info) {
487 ResourceMark rm;
488 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
489 int length = list->length();
490 if (length > 0) {
491 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
492 for (int i = 0; i < length; i++) {
493 MonitorInfo* monitor = list->at(i);
494 assert(monitor->owner() != NULL, "This monitor must have an owning object");
495 _locked_monitors->append(monitor->owner());
496 }
497 }
498 }
499 }
500
501 void StackFrameInfo::oops_do(OopClosure* f) {
502 if (_locked_monitors != NULL) {
503 int length = _locked_monitors->length();
504 for (int i = 0; i < length; i++) {
505 f->do_oop((oop*) _locked_monitors->adr_at(i));
506 }
507 }
508 f->do_oop(&_class_holder);
509 }
510
511 void StackFrameInfo::metadata_do(void f(Metadata*)) {
512 f(_method);
513 }
514
515 void StackFrameInfo::print_on(outputStream* st) const {
516 ResourceMark rm;
517 java_lang_Throwable::print_stack_element(st, method(), bci());
518 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
519 for (int i = 0; i < len; i++) {
520 oop o = _locked_monitors->at(i);
521 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
522 }
523
524 }
525
526 // Iterate through monitor cache to find JNI locked monitors
527 class InflatedMonitorsClosure: public MonitorClosure {
528 private:
529 ThreadStackTrace* _stack_trace;
530 Thread* _thread;
531 public:
532 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
533 _thread = t;
534 _stack_trace = st;
535 }
536 void do_monitor(ObjectMonitor* mid) {
537 if (mid->owner() == _thread) {
538 oop object = (oop) mid->object();
539 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
540 _stack_trace->add_jni_locked_monitor(object);
541 }
542 }
543 }
544 };
545
546 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
547 _thread = t;
548 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
549 _depth = 0;
550 _with_locked_monitors = with_locked_monitors;
551 if (_with_locked_monitors) {
552 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
553 } else {
554 _jni_locked_monitors = NULL;
555 }
556 }
557
558 ThreadStackTrace::~ThreadStackTrace() {
559 for (int i = 0; i < _frames->length(); i++) {
560 delete _frames->at(i);
561 }
562 delete _frames;
563 if (_jni_locked_monitors != NULL) {
564 delete _jni_locked_monitors;
565 }
566 }
567
568 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
569 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
570
571 if (_thread->has_last_Java_frame()) {
572 RegisterMap reg_map(_thread);
573 vframe* start_vf = _thread->last_java_vframe(®_map);
574 int count = 0;
575 for (vframe* f = start_vf; f; f = f->sender() ) {
576 if (maxDepth >= 0 && count == maxDepth) {
577 // Skip frames if more than maxDepth
578 break;
579 }
580 if (f->is_java_frame()) {
581 javaVFrame* jvf = javaVFrame::cast(f);
582 add_stack_frame(jvf);
583 count++;
584 } else {
585 // Ignore non-Java frames
586 }
587 }
588 }
589
590 if (_with_locked_monitors) {
591 // Iterate inflated monitors and find monitors locked by this thread
592 // not found in the stack
593 InflatedMonitorsClosure imc(_thread, this);
594 ObjectSynchronizer::monitors_iterate(&imc);
595 }
596 }
597
598
599 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
600 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
601
602 bool found = false;
603 int num_frames = get_stack_depth();
604 for (int depth = 0; depth < num_frames; depth++) {
605 StackFrameInfo* frame = stack_frame_at(depth);
606 int len = frame->num_locked_monitors();
607 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
608 for (int j = 0; j < len; j++) {
609 oop monitor = locked_monitors->at(j);
610 assert(monitor != NULL, "must be a Java object");
611 if (oopDesc::equals(monitor, object)) {
612 found = true;
613 break;
614 }
615 }
616 }
617 return found;
618 }
619
620 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
621 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass();
622 assert(ik != NULL, "must be loaded in 1.4+");
623
624 // Allocate an array of java/lang/StackTraceElement object
625 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
626 objArrayHandle backtrace(THREAD, ste);
627 for (int j = 0; j < _depth; j++) {
628 StackFrameInfo* frame = _frames->at(j);
629 methodHandle mh(THREAD, frame->method());
630 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
631 backtrace->obj_at_put(j, element);
632 }
633 return backtrace;
634 }
635
636 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
637 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
638 _frames->append(frame);
639 _depth++;
640 }
641
642 void ThreadStackTrace::oops_do(OopClosure* f) {
643 int length = _frames->length();
644 for (int i = 0; i < length; i++) {
645 _frames->at(i)->oops_do(f);
646 }
647
648 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
649 for (int j = 0; j < length; j++) {
650 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
651 }
652 }
653
654 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
655 int length = _frames->length();
656 for (int i = 0; i < length; i++) {
657 _frames->at(i)->metadata_do(f);
658 }
659 }
660
661
662 ConcurrentLocksDump::~ConcurrentLocksDump() {
663 if (_retain_map_on_free) {
664 return;
665 }
666
667 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
668 ThreadConcurrentLocks* tcl = t;
669 t = t->next();
670 delete tcl;
671 }
672 }
673
674 void ConcurrentLocksDump::dump_at_safepoint() {
675 // dump all locked concurrent locks
676 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
677
678 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */);
679
680 // Find all instances of AbstractOwnableSynchronizer
681 HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
682 aos_objects);
683 // Build a map of thread to its owned AQS locks
684 build_map(aos_objects);
685
686 delete aos_objects;
687 }
688
689
690 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
691 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
692 int length = aos_objects->length();
693 for (int i = 0; i < length; i++) {
694 oop o = aos_objects->at(i);
695 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
696 if (owner_thread_obj != NULL) {
697 // See comments in ThreadConcurrentLocks to see how this
698 // JavaThread* is protected.
699 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
700 assert(o->is_instance(), "Must be an instanceOop");
701 add_lock(thread, (instanceOop) o);
702 }
703 }
704 }
705
706 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
707 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
708 if (tcl != NULL) {
709 tcl->add_lock(o);
710 return;
711 }
712
713 // First owned lock found for this thread
714 tcl = new ThreadConcurrentLocks(thread);
715 tcl->add_lock(o);
716 if (_map == NULL) {
717 _map = tcl;
718 } else {
719 _last->set_next(tcl);
720 }
721 _last = tcl;
722 }
723
724 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
725 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
726 if (tcl->java_thread() == thread) {
727 return tcl;
728 }
729 }
730 return NULL;
731 }
732
733 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
734 st->print_cr(" Locked ownable synchronizers:");
735 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
736 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
737 if (locks == NULL || locks->is_empty()) {
738 st->print_cr("\t- None");
739 st->cr();
740 return;
741 }
742
743 for (int i = 0; i < locks->length(); i++) {
744 instanceOop obj = locks->at(i);
745 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
746 }
747 st->cr();
748 }
749
750 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
751 _thread = thread;
752 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
753 _next = NULL;
754 }
755
756 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
757 delete _owned_locks;
758 }
759
760 void ThreadConcurrentLocks::add_lock(instanceOop o) {
761 _owned_locks->append(o);
762 }
763
764 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
765 int length = _owned_locks->length();
766 for (int i = 0; i < length; i++) {
767 f->do_oop((oop*) _owned_locks->adr_at(i));
768 }
769 }
770
771 ThreadStatistics::ThreadStatistics() {
772 _contended_enter_count = 0;
773 _monitor_wait_count = 0;
774 _sleep_count = 0;
775 _count_pending_reset = false;
776 _timer_pending_reset = false;
777 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
778 }
779
780 ThreadSnapshot::ThreadSnapshot(ThreadsList * t_list, JavaThread* thread) {
781 _thread = thread;
782 _threadObj = thread->threadObj();
783 _stack_trace = NULL;
784 _concurrent_locks = NULL;
785 _next = NULL;
786
787 ThreadStatistics* stat = thread->get_thread_stat();
788 _contended_enter_ticks = stat->contended_enter_ticks();
789 _contended_enter_count = stat->contended_enter_count();
790 _monitor_wait_ticks = stat->monitor_wait_ticks();
791 _monitor_wait_count = stat->monitor_wait_count();
792 _sleep_ticks = stat->sleep_ticks();
793 _sleep_count = stat->sleep_count();
794
795 _blocker_object = NULL;
796 _blocker_object_owner = NULL;
797
798 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
799 _is_ext_suspended = thread->is_being_ext_suspended();
800 _is_in_native = (thread->thread_state() == _thread_in_native);
801
802 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
803 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
804 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
805
806 Handle obj = ThreadService::get_current_contended_monitor(thread);
807 if (obj() == NULL) {
808 // monitor no longer exists; thread is not blocked
809 _thread_status = java_lang_Thread::RUNNABLE;
810 } else {
811 _blocker_object = obj();
812 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
813 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
814 || (owner != NULL && owner->is_attaching_via_jni())) {
815 // ownership information of the monitor is not available
816 // (may no longer be owned or releasing to some other thread)
817 // make this thread in RUNNABLE state.
818 // And when the owner thread is in attaching state, the java thread
819 // is not completely initialized. For example thread name and id
820 // and may not be set, so hide the attaching thread.
821 _thread_status = java_lang_Thread::RUNNABLE;
822 _blocker_object = NULL;
823 } else if (owner != NULL) {
824 _blocker_object_owner = owner->threadObj();
825 }
826 }
827 }
828
829 // Support for JSR-166 locks
830 if (JDK_Version::current().supports_thread_park_blocker() &&
831 (_thread_status == java_lang_Thread::PARKED ||
832 _thread_status == java_lang_Thread::PARKED_TIMED)) {
833
834 _blocker_object = thread->current_park_blocker();
835 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
836 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
837 }
838 }
839 }
840
841 ThreadSnapshot::~ThreadSnapshot() {
842 delete _stack_trace;
843 delete _concurrent_locks;
844 }
845
846 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
847 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
848 _stack_trace->dump_stack_at_safepoint(max_depth);
849 }
850
851
852 void ThreadSnapshot::oops_do(OopClosure* f) {
853 f->do_oop(&_threadObj);
854 f->do_oop(&_blocker_object);
855 f->do_oop(&_blocker_object_owner);
856 if (_stack_trace != NULL) {
857 _stack_trace->oops_do(f);
858 }
859 if (_concurrent_locks != NULL) {
860 _concurrent_locks->oops_do(f);
861 }
862 }
863
864 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
865 if (_stack_trace != NULL) {
866 _stack_trace->metadata_do(f);
867 }
868 }
869
870
871 DeadlockCycle::DeadlockCycle() {
872 _is_deadlock = false;
873 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
874 _next = NULL;
875 }
876
877 DeadlockCycle::~DeadlockCycle() {
878 delete _threads;
879 }
880
881 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
882 st->cr();
883 st->print_cr("Found one Java-level deadlock:");
884 st->print("=============================");
885
886 JavaThread* currentThread;
887 ObjectMonitor* waitingToLockMonitor;
888 oop waitingToLockBlocker;
889 int len = _threads->length();
890 for (int i = 0; i < len; i++) {
891 currentThread = _threads->at(i);
892 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
893 waitingToLockBlocker = currentThread->current_park_blocker();
894 st->cr();
895 st->print_cr("\"%s\":", currentThread->get_thread_name());
896 const char* owner_desc = ",\n which is held by";
897 if (waitingToLockMonitor != NULL) {
898 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
899 oop obj = (oop)waitingToLockMonitor->object();
900 if (obj != NULL) {
901 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
902 obj->klass()->external_name());
903
904 if (!currentThread->current_pending_monitor_is_from_java()) {
905 owner_desc = "\n in JNI, which is held by";
906 }
907 } else {
908 // No Java object associated - a JVMTI raw monitor
909 owner_desc = " (JVMTI raw monitor),\n which is held by";
910 }
911 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
912 (address)waitingToLockMonitor->owner());
913 if (currentThread == NULL) {
914 // The deadlock was detected at a safepoint so the JavaThread
915 // that owns waitingToLockMonitor should be findable, but
916 // if it is not findable, then the previous currentThread is
917 // blocked permanently.
918 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
919 p2i(waitingToLockMonitor->owner()));
920 continue;
921 }
922 } else {
923 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
924 p2i(waitingToLockBlocker),
925 waitingToLockBlocker->klass()->external_name());
926 assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
927 "Must be an AbstractOwnableSynchronizer");
928 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
929 currentThread = java_lang_Thread::thread(ownerObj);
930 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
931 }
932 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
933 }
934
935 st->cr();
936 st->cr();
937
938 // Print stack traces
939 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
940 JavaMonitorsInStackTrace = true;
941 st->print_cr("Java stack information for the threads listed above:");
942 st->print_cr("===================================================");
943 for (int j = 0; j < len; j++) {
944 currentThread = _threads->at(j);
945 st->print_cr("\"%s\":", currentThread->get_thread_name());
946 currentThread->print_stack_on(st);
947 }
948 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
949 }
950
951 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
952 bool include_jvmti_agent_threads,
953 bool include_jni_attaching_threads) {
954 assert(cur_thread == Thread::current(), "Check current thread");
955
956 int init_size = ThreadService::get_live_thread_count();
957 _threads_array = new GrowableArray<instanceHandle>(init_size);
958
959 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
960 // skips JavaThreads in the process of exiting
961 // and also skips VM internal JavaThreads
962 // Threads in _thread_new or _thread_new_trans state are included.
963 // i.e. threads have been started but not yet running.
964 if (jt->threadObj() == NULL ||
965 jt->is_exiting() ||
966 !java_lang_Thread::is_alive(jt->threadObj()) ||
967 jt->is_hidden_from_external_view()) {
968 continue;
969 }
970
971 // skip agent threads
972 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
973 continue;
974 }
975
976 // skip jni threads in the process of attaching
977 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
978 continue;
979 }
980
981 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
982 _threads_array->append(h);
983 }
984 }