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