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