1/*
2 * Copyright (c) 2003, 2019, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25#ifndef SHARE_SERVICES_THREADSERVICE_HPP
26#define SHARE_SERVICES_THREADSERVICE_HPP
27
28#include "classfile/javaClasses.hpp"
29#include "runtime/handles.hpp"
30#include "runtime/init.hpp"
31#include "runtime/jniHandles.hpp"
32#include "runtime/objectMonitor.hpp"
33#include "runtime/perfData.hpp"
34#include "runtime/safepoint.hpp"
35#include "runtime/thread.hpp"
36#include "runtime/threadSMR.hpp"
37#include "services/management.hpp"
38
39class OopClosure;
40class ThreadDumpResult;
41class ThreadStackTrace;
42class ThreadSnapshot;
43class StackFrameInfo;
44class ThreadConcurrentLocks;
45class DeadlockCycle;
46
47// VM monitoring and management support for the thread and
48// synchronization subsystem
49//
50// Thread contention monitoring is disabled by default.
51// When enabled, the VM will begin measuring the accumulated
52// elapsed time a thread blocked on synchronization.
53//
54class ThreadService : public AllStatic {
55private:
56 // These counters could be moved to Threads class
57 static PerfCounter* _total_threads_count;
58 static PerfVariable* _live_threads_count;
59 static PerfVariable* _peak_threads_count;
60 static PerfVariable* _daemon_threads_count;
61
62 // These 2 counters are like the above thread counts, but are
63 // atomically decremented in ThreadService::current_thread_exiting instead of
64 // ThreadService::remove_thread, so that the thread count is updated before
65 // Thread.join() returns.
66 static volatile int _atomic_threads_count;
67 static volatile int _atomic_daemon_threads_count;
68
69 static bool _thread_monitoring_contention_enabled;
70 static bool _thread_cpu_time_enabled;
71 static bool _thread_allocated_memory_enabled;
72
73 // Need to keep the list of thread dump result that
74 // keep references to Method* since thread dump can be
75 // requested by multiple threads concurrently.
76 static ThreadDumpResult* _threaddump_list;
77
78 static void decrement_thread_counts(JavaThread* jt, bool daemon);
79
80public:
81 static void init();
82 static void add_thread(JavaThread* thread, bool daemon);
83 static void remove_thread(JavaThread* thread, bool daemon);
84 static void current_thread_exiting(JavaThread* jt, bool daemon);
85
86 static bool set_thread_monitoring_contention(bool flag);
87 static bool is_thread_monitoring_contention() { return _thread_monitoring_contention_enabled; }
88
89 static bool set_thread_cpu_time_enabled(bool flag);
90 static bool is_thread_cpu_time_enabled() { return _thread_cpu_time_enabled; }
91
92 static bool set_thread_allocated_memory_enabled(bool flag);
93 static bool is_thread_allocated_memory_enabled() { return _thread_allocated_memory_enabled; }
94
95 static jlong get_total_thread_count() { return _total_threads_count->get_value(); }
96 static jlong get_peak_thread_count() { return _peak_threads_count->get_value(); }
97 static jlong get_live_thread_count() { return _atomic_threads_count; }
98 static jlong get_daemon_thread_count() { return _atomic_daemon_threads_count; }
99
100 // Support for thread dump
101 static void add_thread_dump(ThreadDumpResult* dump);
102 static void remove_thread_dump(ThreadDumpResult* dump);
103
104 static Handle get_current_contended_monitor(JavaThread* thread);
105
106 // This function is called by JVM_DumpThreads.
107 static Handle dump_stack_traces(GrowableArray<instanceHandle>* threads,
108 int num_threads, TRAPS);
109
110 static void reset_peak_thread_count();
111 static void reset_contention_count_stat(JavaThread* thread);
112 static void reset_contention_time_stat(JavaThread* thread);
113
114 static DeadlockCycle* find_deadlocks_at_safepoint(ThreadsList * t_list, bool object_monitors_only);
115
116 // GC support
117 static void oops_do(OopClosure* f);
118 static void metadata_do(void f(Metadata*));
119};
120
121// Per-thread Statistics for synchronization
122class ThreadStatistics : public CHeapObj<mtInternal> {
123private:
124 // The following contention statistics are only updated by
125 // the thread owning these statistics when contention occurs.
126
127 jlong _contended_enter_count;
128 elapsedTimer _contended_enter_timer;
129 jlong _monitor_wait_count;
130 elapsedTimer _monitor_wait_timer;
131 jlong _sleep_count;
132 elapsedTimer _sleep_timer;
133
134
135 // These two reset flags are set to true when another thread
136 // requests to reset the statistics. The actual statistics
137 // are reset when the thread contention occurs and attempts
138 // to update the statistics.
139 bool _count_pending_reset;
140 bool _timer_pending_reset;
141
142 // Keep accurate times for potentially recursive class operations
143 int _perf_recursion_counts[6];
144 elapsedTimer _perf_timers[6];
145
146 // utility functions
147 void check_and_reset_count() {
148 if (!_count_pending_reset) return;
149 _contended_enter_count = 0;
150 _monitor_wait_count = 0;
151 _sleep_count = 0;
152 _count_pending_reset = 0;
153 }
154 void check_and_reset_timer() {
155 if (!_timer_pending_reset) return;
156 _contended_enter_timer.reset();
157 _monitor_wait_timer.reset();
158 _sleep_timer.reset();
159 _timer_pending_reset = 0;
160 }
161
162public:
163 ThreadStatistics();
164
165 jlong contended_enter_count() { return (_count_pending_reset ? 0 : _contended_enter_count); }
166 jlong contended_enter_ticks() { return (_timer_pending_reset ? 0 : _contended_enter_timer.active_ticks()); }
167 jlong monitor_wait_count() { return (_count_pending_reset ? 0 : _monitor_wait_count); }
168 jlong monitor_wait_ticks() { return (_timer_pending_reset ? 0 : _monitor_wait_timer.active_ticks()); }
169 jlong sleep_count() { return (_count_pending_reset ? 0 : _sleep_count); }
170 jlong sleep_ticks() { return (_timer_pending_reset ? 0 : _sleep_timer.active_ticks()); }
171
172 void monitor_wait() { check_and_reset_count(); _monitor_wait_count++; }
173 void monitor_wait_begin() { check_and_reset_timer(); _monitor_wait_timer.start(); }
174 void monitor_wait_end() { _monitor_wait_timer.stop(); check_and_reset_timer(); }
175
176 void thread_sleep() { check_and_reset_count(); _sleep_count++; }
177 void thread_sleep_begin() { check_and_reset_timer(); _sleep_timer.start(); }
178 void thread_sleep_end() { _sleep_timer.stop(); check_and_reset_timer(); }
179
180 void contended_enter() { check_and_reset_count(); _contended_enter_count++; }
181 void contended_enter_begin() { check_and_reset_timer(); _contended_enter_timer.start(); }
182 void contended_enter_end() { _contended_enter_timer.stop(); check_and_reset_timer(); }
183
184 void reset_count_stat() { _count_pending_reset = true; }
185 void reset_time_stat() { _timer_pending_reset = true; }
186
187 int* perf_recursion_counts_addr() { return _perf_recursion_counts; }
188 elapsedTimer* perf_timers_addr() { return _perf_timers; }
189};
190
191// Thread snapshot to represent the thread state and statistics
192class ThreadSnapshot : public CHeapObj<mtInternal> {
193private:
194 // This JavaThread* is protected by being stored in objects that are
195 // protected by a ThreadsListSetter (ThreadDumpResult).
196 JavaThread* _thread;
197 oop _threadObj;
198 java_lang_Thread::ThreadStatus _thread_status;
199
200 bool _is_ext_suspended;
201 bool _is_in_native;
202
203 jlong _contended_enter_ticks;
204 jlong _contended_enter_count;
205 jlong _monitor_wait_ticks;
206 jlong _monitor_wait_count;
207 jlong _sleep_ticks;
208 jlong _sleep_count;
209 oop _blocker_object;
210 oop _blocker_object_owner;
211
212 ThreadStackTrace* _stack_trace;
213 ThreadConcurrentLocks* _concurrent_locks;
214 ThreadSnapshot* _next;
215
216 // ThreadSnapshot instances should only be created via
217 // ThreadDumpResult::add_thread_snapshot.
218 friend class ThreadDumpResult;
219 ThreadSnapshot() : _thread(NULL), _threadObj(NULL),
220 _blocker_object(NULL), _blocker_object_owner(NULL),
221 _stack_trace(NULL), _concurrent_locks(NULL), _next(NULL) {};
222 void initialize(ThreadsList * t_list, JavaThread* thread);
223
224public:
225 ~ThreadSnapshot();
226
227 java_lang_Thread::ThreadStatus thread_status() { return _thread_status; }
228
229 oop threadObj() const { return _threadObj; }
230
231 void set_next(ThreadSnapshot* n) { _next = n; }
232
233 bool is_ext_suspended() { return _is_ext_suspended; }
234 bool is_in_native() { return _is_in_native; }
235
236 jlong contended_enter_count() { return _contended_enter_count; }
237 jlong contended_enter_ticks() { return _contended_enter_ticks; }
238 jlong monitor_wait_count() { return _monitor_wait_count; }
239 jlong monitor_wait_ticks() { return _monitor_wait_ticks; }
240 jlong sleep_count() { return _sleep_count; }
241 jlong sleep_ticks() { return _sleep_ticks; }
242
243
244 oop blocker_object() { return _blocker_object; }
245 oop blocker_object_owner() { return _blocker_object_owner; }
246
247 ThreadSnapshot* next() const { return _next; }
248 ThreadStackTrace* get_stack_trace() { return _stack_trace; }
249 ThreadConcurrentLocks* get_concurrent_locks() { return _concurrent_locks; }
250
251 void dump_stack_at_safepoint(int max_depth, bool with_locked_monitors);
252 void set_concurrent_locks(ThreadConcurrentLocks* l) { _concurrent_locks = l; }
253 void oops_do(OopClosure* f);
254 void metadata_do(void f(Metadata*));
255};
256
257class ThreadStackTrace : public CHeapObj<mtInternal> {
258 private:
259 JavaThread* _thread;
260 int _depth; // number of stack frames added
261 bool _with_locked_monitors;
262 GrowableArray<StackFrameInfo*>* _frames;
263 GrowableArray<oop>* _jni_locked_monitors;
264
265 public:
266
267 ThreadStackTrace(JavaThread* thread, bool with_locked_monitors);
268 ~ThreadStackTrace();
269
270 JavaThread* thread() { return _thread; }
271 StackFrameInfo* stack_frame_at(int i) { return _frames->at(i); }
272 int get_stack_depth() { return _depth; }
273
274 void add_stack_frame(javaVFrame* jvf);
275 void dump_stack_at_safepoint(int max_depth);
276 Handle allocate_fill_stack_trace_element_array(TRAPS);
277 void oops_do(OopClosure* f);
278 void metadata_do(void f(Metadata*));
279 GrowableArray<oop>* jni_locked_monitors() { return _jni_locked_monitors; }
280 int num_jni_locked_monitors() { return (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); }
281
282 bool is_owned_monitor_on_stack(oop object);
283 void add_jni_locked_monitor(oop object) { _jni_locked_monitors->append(object); }
284};
285
286// StackFrameInfo for keeping Method* and bci during
287// stack walking for later construction of StackTraceElement[]
288// Java instances
289class StackFrameInfo : public CHeapObj<mtInternal> {
290 private:
291 Method* _method;
292 int _bci;
293 GrowableArray<oop>* _locked_monitors; // list of object monitors locked by this frame
294 // We need to save the mirrors in the backtrace to keep the class
295 // from being unloaded while we still have this stack trace.
296 oop _class_holder;
297
298 public:
299
300 StackFrameInfo(javaVFrame* jvf, bool with_locked_monitors);
301 ~StackFrameInfo() {
302 if (_locked_monitors != NULL) {
303 delete _locked_monitors;
304 }
305 };
306 Method* method() const { return _method; }
307 int bci() const { return _bci; }
308 void oops_do(OopClosure* f);
309 void metadata_do(void f(Metadata*));
310
311 int num_locked_monitors() { return (_locked_monitors != NULL ? _locked_monitors->length() : 0); }
312 GrowableArray<oop>* locked_monitors() { return _locked_monitors; }
313
314 void print_on(outputStream* st) const;
315};
316
317class ThreadConcurrentLocks : public CHeapObj<mtInternal> {
318private:
319 GrowableArray<instanceOop>* _owned_locks;
320 ThreadConcurrentLocks* _next;
321 // This JavaThread* is protected in one of two different ways
322 // depending on the usage of the ThreadConcurrentLocks object:
323 // 1) by being stored in objects that are only allocated and used at a
324 // safepoint (ConcurrentLocksDump), or 2) by being stored in objects
325 // that are protected by a ThreadsListSetter (ThreadSnapshot inside
326 // ThreadDumpResult).
327 JavaThread* _thread;
328 public:
329 ThreadConcurrentLocks(JavaThread* thread);
330 ~ThreadConcurrentLocks();
331
332 void add_lock(instanceOop o);
333 void set_next(ThreadConcurrentLocks* n) { _next = n; }
334 ThreadConcurrentLocks* next() { return _next; }
335 JavaThread* java_thread() { return _thread; }
336 GrowableArray<instanceOop>* owned_locks() { return _owned_locks; }
337 void oops_do(OopClosure* f);
338};
339
340class ConcurrentLocksDump : public StackObj {
341 private:
342 ThreadConcurrentLocks* _map;
343 ThreadConcurrentLocks* _last; // Last ThreadConcurrentLocks in the map
344 bool _retain_map_on_free;
345
346 void build_map(GrowableArray<oop>* aos_objects);
347 void add_lock(JavaThread* thread, instanceOop o);
348
349 public:
350 ConcurrentLocksDump(bool retain_map_on_free) : _map(NULL), _last(NULL), _retain_map_on_free(retain_map_on_free) {
351 assert(SafepointSynchronize::is_at_safepoint(), "Must be constructed at a safepoint.");
352 };
353 ConcurrentLocksDump() : _map(NULL), _last(NULL), _retain_map_on_free(false) {
354 assert(SafepointSynchronize::is_at_safepoint(), "Must be constructed at a safepoint.");
355 };
356 ~ConcurrentLocksDump();
357
358 void dump_at_safepoint();
359 ThreadConcurrentLocks* thread_concurrent_locks(JavaThread* thread);
360 void print_locks_on(JavaThread* t, outputStream* st);
361};
362
363class ThreadDumpResult : public StackObj {
364 private:
365 int _num_threads;
366 int _num_snapshots;
367 ThreadSnapshot* _snapshots;
368 ThreadSnapshot* _last;
369 ThreadDumpResult* _next;
370 ThreadsListSetter _setter; // Helper to set hazard ptr in the originating thread
371 // which protects the JavaThreads in _snapshots.
372
373 void link_thread_snapshot(ThreadSnapshot* ts);
374
375 public:
376 ThreadDumpResult();
377 ThreadDumpResult(int num_threads);
378 ~ThreadDumpResult();
379
380 ThreadSnapshot* add_thread_snapshot();
381 ThreadSnapshot* add_thread_snapshot(JavaThread* thread);
382
383 void set_next(ThreadDumpResult* next) { _next = next; }
384 ThreadDumpResult* next() { return _next; }
385 int num_threads() { return _num_threads; }
386 int num_snapshots() { return _num_snapshots; }
387 ThreadSnapshot* snapshots() { return _snapshots; }
388 void set_t_list() { _setter.set(); }
389 ThreadsList* t_list();
390 bool t_list_has_been_set() { return _setter.is_set(); }
391 void oops_do(OopClosure* f);
392 void metadata_do(void f(Metadata*));
393};
394
395class DeadlockCycle : public CHeapObj<mtInternal> {
396 private:
397 bool _is_deadlock;
398 GrowableArray<JavaThread*>* _threads;
399 DeadlockCycle* _next;
400 public:
401 DeadlockCycle();
402 ~DeadlockCycle();
403
404 DeadlockCycle* next() { return _next; }
405 void set_next(DeadlockCycle* d) { _next = d; }
406 void add_thread(JavaThread* t) { _threads->append(t); }
407 void reset() { _is_deadlock = false; _threads->clear(); }
408 void set_deadlock(bool value) { _is_deadlock = value; }
409 bool is_deadlock() { return _is_deadlock; }
410 int num_threads() { return _threads->length(); }
411 GrowableArray<JavaThread*>* threads() { return _threads; }
412 void print_on_with(ThreadsList * t_list, outputStream* st) const;
413};
414
415// Utility class to get list of java threads.
416class ThreadsListEnumerator : public StackObj {
417private:
418 GrowableArray<instanceHandle>* _threads_array;
419public:
420 ThreadsListEnumerator(Thread* cur_thread,
421 bool include_jvmti_agent_threads = false,
422 bool include_jni_attaching_threads = true);
423 int num_threads() { return _threads_array->length(); }
424 instanceHandle get_threadObj(int index) { return _threads_array->at(index); }
425};
426
427
428// abstract utility class to set new thread states, and restore previous after the block exits
429class JavaThreadStatusChanger : public StackObj {
430 private:
431 java_lang_Thread::ThreadStatus _old_state;
432 JavaThread* _java_thread;
433 bool _is_alive;
434
435 void save_old_state(JavaThread* java_thread) {
436 _java_thread = java_thread;
437 _is_alive = is_alive(java_thread);
438 if (is_alive()) {
439 _old_state = java_lang_Thread::get_thread_status(_java_thread->threadObj());
440 }
441 }
442
443 public:
444 static void set_thread_status(JavaThread* java_thread,
445 java_lang_Thread::ThreadStatus state) {
446 java_lang_Thread::set_thread_status(java_thread->threadObj(), state);
447 }
448
449 void set_thread_status(java_lang_Thread::ThreadStatus state) {
450 if (is_alive()) {
451 set_thread_status(_java_thread, state);
452 }
453 }
454
455 JavaThreadStatusChanger(JavaThread* java_thread,
456 java_lang_Thread::ThreadStatus state) : _old_state(java_lang_Thread::NEW) {
457 save_old_state(java_thread);
458 set_thread_status(state);
459 }
460
461 JavaThreadStatusChanger(JavaThread* java_thread) : _old_state(java_lang_Thread::NEW) {
462 save_old_state(java_thread);
463 }
464
465 ~JavaThreadStatusChanger() {
466 set_thread_status(_old_state);
467 }
468
469 static bool is_alive(JavaThread* java_thread) {
470 return java_thread != NULL && java_thread->threadObj() != NULL;
471 }
472
473 bool is_alive() {
474 return _is_alive;
475 }
476};
477
478// Change status to waiting on an object (timed or indefinite)
479class JavaThreadInObjectWaitState : public JavaThreadStatusChanger {
480 private:
481 ThreadStatistics* _stat;
482 bool _active;
483
484 public:
485 JavaThreadInObjectWaitState(JavaThread *java_thread, bool timed) :
486 JavaThreadStatusChanger(java_thread,
487 timed ? java_lang_Thread::IN_OBJECT_WAIT_TIMED : java_lang_Thread::IN_OBJECT_WAIT) {
488 if (is_alive()) {
489 _stat = java_thread->get_thread_stat();
490 _active = ThreadService::is_thread_monitoring_contention();
491 _stat->monitor_wait();
492 if (_active) {
493 _stat->monitor_wait_begin();
494 }
495 } else {
496 _active = false;
497 }
498 }
499
500 ~JavaThreadInObjectWaitState() {
501 if (_active) {
502 _stat->monitor_wait_end();
503 }
504 }
505};
506
507// Change status to parked (timed or indefinite)
508class JavaThreadParkedState : public JavaThreadStatusChanger {
509 private:
510 ThreadStatistics* _stat;
511 bool _active;
512
513 public:
514 JavaThreadParkedState(JavaThread *java_thread, bool timed) :
515 JavaThreadStatusChanger(java_thread,
516 timed ? java_lang_Thread::PARKED_TIMED : java_lang_Thread::PARKED) {
517 if (is_alive()) {
518 _stat = java_thread->get_thread_stat();
519 _active = ThreadService::is_thread_monitoring_contention();
520 _stat->monitor_wait();
521 if (_active) {
522 _stat->monitor_wait_begin();
523 }
524 } else {
525 _active = false;
526 }
527 }
528
529 ~JavaThreadParkedState() {
530 if (_active) {
531 _stat->monitor_wait_end();
532 }
533 }
534};
535
536// Change status to blocked on (re-)entering a synchronization block
537class JavaThreadBlockedOnMonitorEnterState : public JavaThreadStatusChanger {
538 private:
539 ThreadStatistics* _stat;
540 bool _active;
541
542 static bool contended_enter_begin(JavaThread *java_thread) {
543 set_thread_status(java_thread, java_lang_Thread::BLOCKED_ON_MONITOR_ENTER);
544 ThreadStatistics* stat = java_thread->get_thread_stat();
545 stat->contended_enter();
546 bool active = ThreadService::is_thread_monitoring_contention();
547 if (active) {
548 stat->contended_enter_begin();
549 }
550 return active;
551 }
552
553 public:
554 // java_thread is waiting thread being blocked on monitor reenter.
555 // Current thread is the notifying thread which holds the monitor.
556 static bool wait_reenter_begin(JavaThread *java_thread, ObjectMonitor *obj_m) {
557 assert((java_thread != NULL), "Java thread should not be null here");
558 bool active = false;
559 if (is_alive(java_thread)) {
560 active = contended_enter_begin(java_thread);
561 }
562 return active;
563 }
564
565 static void wait_reenter_end(JavaThread *java_thread, bool active) {
566 if (active) {
567 java_thread->get_thread_stat()->contended_enter_end();
568 }
569 set_thread_status(java_thread, java_lang_Thread::RUNNABLE);
570 }
571
572 JavaThreadBlockedOnMonitorEnterState(JavaThread *java_thread, ObjectMonitor *obj_m) :
573 JavaThreadStatusChanger(java_thread), _stat(NULL), _active(false) {
574 assert((java_thread != NULL), "Java thread should not be null here");
575 // Change thread status and collect contended enter stats for monitor contended
576 // enter done for external java world objects and it is contended. All other cases
577 // like for vm internal objects and for external objects which are not contended
578 // thread status is not changed and contended enter stat is not collected.
579 _active = false;
580 if (is_alive() && obj_m->contentions() > 0) {
581 _stat = java_thread->get_thread_stat();
582 _active = contended_enter_begin(java_thread);
583 }
584 }
585
586 ~JavaThreadBlockedOnMonitorEnterState() {
587 if (_active) {
588 _stat->contended_enter_end();
589 }
590 }
591};
592
593// Change status to sleeping
594class JavaThreadSleepState : public JavaThreadStatusChanger {
595 private:
596 ThreadStatistics* _stat;
597 bool _active;
598 public:
599 JavaThreadSleepState(JavaThread *java_thread) :
600 JavaThreadStatusChanger(java_thread, java_lang_Thread::SLEEPING) {
601 if (is_alive()) {
602 _stat = java_thread->get_thread_stat();
603 _active = ThreadService::is_thread_monitoring_contention();
604 _stat->thread_sleep();
605 if (_active) {
606 _stat->thread_sleep_begin();
607 }
608 } else {
609 _active = false;
610 }
611 }
612
613 ~JavaThreadSleepState() {
614 if (_active) {
615 _stat->thread_sleep_end();
616 }
617 }
618};
619
620#endif // SHARE_SERVICES_THREADSERVICE_HPP
621