1 /* 2 * Copyright (c) 2003, 2010, 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/objectMonitor.inline.hpp" 34 #include "runtime/perfData.hpp" 35 #include "services/management.hpp" 36 #include "services/serviceUtil.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 69 // Need to keep the list of thread dump result that 70 // keep references to methodOop since thread dump can be 71 // requested by multiple threads concurrently. 72 static ThreadDumpResult* _threaddump_list; 73 74 public: 75 static void init(); 76 static void add_thread(JavaThread* thread, bool daemon); 77 static void remove_thread(JavaThread* thread, bool daemon); 78 static void current_thread_exiting(JavaThread* jt); 79 80 static bool set_thread_monitoring_contention(bool flag); 81 static bool is_thread_monitoring_contention() { return _thread_monitoring_contention_enabled; } 82 83 static bool set_thread_cpu_time_enabled(bool flag); 84 static bool is_thread_cpu_time_enabled() { return _thread_cpu_time_enabled; } 85 86 static jlong get_total_thread_count() { return _total_threads_count->get_value(); } 87 static jlong get_peak_thread_count() { return _peak_threads_count->get_value(); } 88 static jlong get_live_thread_count() { return _live_threads_count->get_value() - _exiting_threads_count; } 89 static jlong get_daemon_thread_count() { return _daemon_threads_count->get_value() - _exiting_daemon_threads_count; } 90 91 static int exiting_threads_count() { return _exiting_threads_count; } 92 static int exiting_daemon_threads_count() { return _exiting_daemon_threads_count; } 93 94 // Support for thread dump 95 static void add_thread_dump(ThreadDumpResult* dump); 96 static void remove_thread_dump(ThreadDumpResult* dump); 97 98 static Handle get_current_contended_monitor(JavaThread* thread); 99 100 // This function is called by JVM_DumpThreads. 101 static Handle dump_stack_traces(GrowableArray<instanceHandle>* threads, 102 int num_threads, TRAPS); 103 104 static void reset_peak_thread_count(); 105 static void reset_contention_count_stat(JavaThread* thread); 106 static void reset_contention_time_stat(JavaThread* thread); 107 108 static DeadlockCycle* find_deadlocks_at_safepoint(bool object_monitors_only); 109 110 // GC support 111 static void oops_do(OopClosure* f); 112 }; 113 114 // Per-thread Statistics for synchronization 115 class ThreadStatistics : public CHeapObj { 116 private: 117 // The following contention statistics are only updated by 118 // the thread owning these statistics when contention occurs. 119 120 jlong _contended_enter_count; 121 elapsedTimer _contended_enter_timer; 122 jlong _monitor_wait_count; 123 elapsedTimer _monitor_wait_timer; 124 jlong _sleep_count; 125 elapsedTimer _sleep_timer; 126 127 128 // These two reset flags are set to true when another thread 129 // requests to reset the statistics. The actual statistics 130 // are reset when the thread contention occurs and attempts 131 // to update the statistics. 132 bool _count_pending_reset; 133 bool _timer_pending_reset; 134 135 // Keep accurate times for potentially recursive class operations 136 int _perf_recursion_counts[6]; 137 elapsedTimer _perf_timers[6]; 138 139 // utility functions 140 void check_and_reset_count() { 141 if (!_count_pending_reset) return; 142 _contended_enter_count = 0; 143 _monitor_wait_count = 0; 144 _sleep_count = 0; 145 _count_pending_reset = 0; 146 } 147 void check_and_reset_timer() { 148 if (!_timer_pending_reset) return; 149 _contended_enter_timer.reset(); 150 _monitor_wait_timer.reset(); 151 _sleep_timer.reset(); 152 _timer_pending_reset = 0; 153 } 154 155 public: 156 ThreadStatistics(); 157 158 jlong contended_enter_count() { return (_count_pending_reset ? 0 : _contended_enter_count); } 159 jlong contended_enter_ticks() { return (_timer_pending_reset ? 0 : _contended_enter_timer.active_ticks()); } 160 jlong monitor_wait_count() { return (_count_pending_reset ? 0 : _monitor_wait_count); } 161 jlong monitor_wait_ticks() { return (_timer_pending_reset ? 0 : _monitor_wait_timer.active_ticks()); } 162 jlong sleep_count() { return (_count_pending_reset ? 0 : _sleep_count); } 163 jlong sleep_ticks() { return (_timer_pending_reset ? 0 : _sleep_timer.active_ticks()); } 164 165 void monitor_wait() { check_and_reset_count(); _monitor_wait_count++; } 166 void monitor_wait_begin() { check_and_reset_timer(); _monitor_wait_timer.start(); } 167 void monitor_wait_end() { _monitor_wait_timer.stop(); check_and_reset_timer(); } 168 169 void thread_sleep() { check_and_reset_count(); _sleep_count++; } 170 void thread_sleep_begin() { check_and_reset_timer(); _sleep_timer.start(); } 171 void thread_sleep_end() { _sleep_timer.stop(); check_and_reset_timer(); } 172 173 void contended_enter() { check_and_reset_count(); _contended_enter_count++; } 174 void contended_enter_begin() { check_and_reset_timer(); _contended_enter_timer.start(); } 175 void contended_enter_end() { _contended_enter_timer.stop(); check_and_reset_timer(); } 176 177 void reset_count_stat() { _count_pending_reset = true; } 178 void reset_time_stat() { _timer_pending_reset = true; } 179 180 int* perf_recursion_counts_addr() { return _perf_recursion_counts; } 181 elapsedTimer* perf_timers_addr() { return _perf_timers; } 182 }; 183 184 // Thread snapshot to represent the thread state and statistics 185 class ThreadSnapshot : public CHeapObj { 186 private: 187 JavaThread* _thread; 188 oop _threadObj; 189 java_lang_Thread::ThreadStatus _thread_status; 190 191 bool _is_ext_suspended; 192 bool _is_in_native; 193 194 jlong _contended_enter_ticks; 195 jlong _contended_enter_count; 196 jlong _monitor_wait_ticks; 197 jlong _monitor_wait_count; 198 jlong _sleep_ticks; 199 jlong _sleep_count; 200 oop _blocker_object; 201 oop _blocker_object_owner; 202 203 ThreadStackTrace* _stack_trace; 204 ThreadConcurrentLocks* _concurrent_locks; 205 ThreadSnapshot* _next; 206 207 public: 208 // Dummy snapshot 209 ThreadSnapshot() : _thread(NULL), _threadObj(NULL), _stack_trace(NULL), _concurrent_locks(NULL), _next(NULL), 210 _blocker_object(NULL), _blocker_object_owner(NULL) {}; 211 ThreadSnapshot(JavaThread* thread); 212 ~ThreadSnapshot(); 213 214 java_lang_Thread::ThreadStatus thread_status() { return _thread_status; } 215 216 oop threadObj() const { return _threadObj; } 217 218 void set_next(ThreadSnapshot* n) { _next = n; } 219 220 bool is_ext_suspended() { return _is_ext_suspended; } 221 bool is_in_native() { return _is_in_native; } 222 223 jlong contended_enter_count() { return _contended_enter_count; } 224 jlong contended_enter_ticks() { return _contended_enter_ticks; } 225 jlong monitor_wait_count() { return _monitor_wait_count; } 226 jlong monitor_wait_ticks() { return _monitor_wait_ticks; } 227 jlong sleep_count() { return _sleep_count; } 228 jlong sleep_ticks() { return _sleep_ticks; } 229 230 231 oop blocker_object() { return _blocker_object; } 232 oop blocker_object_owner() { return _blocker_object_owner; } 233 234 ThreadSnapshot* next() const { return _next; } 235 ThreadStackTrace* get_stack_trace() { return _stack_trace; } 236 ThreadConcurrentLocks* get_concurrent_locks() { return _concurrent_locks; } 237 238 void dump_stack_at_safepoint(int max_depth, bool with_locked_monitors); 239 void set_concurrent_locks(ThreadConcurrentLocks* l) { _concurrent_locks = l; } 240 void oops_do(OopClosure* f); 241 }; 242 243 class ThreadStackTrace : public CHeapObj { 244 private: 245 JavaThread* _thread; 246 int _depth; // number of stack frames added 247 bool _with_locked_monitors; 248 GrowableArray<StackFrameInfo*>* _frames; 249 GrowableArray<oop>* _jni_locked_monitors; 250 251 public: 252 253 ThreadStackTrace(JavaThread* thread, bool with_locked_monitors); 254 ~ThreadStackTrace(); 255 256 JavaThread* thread() { return _thread; } 257 StackFrameInfo* stack_frame_at(int i) { return _frames->at(i); } 258 int get_stack_depth() { return _depth; } 259 260 void add_stack_frame(javaVFrame* jvf); 261 void dump_stack_at_safepoint(int max_depth); 262 Handle allocate_fill_stack_trace_element_array(TRAPS); 263 void oops_do(OopClosure* f); 264 GrowableArray<oop>* jni_locked_monitors() { return _jni_locked_monitors; } 265 int num_jni_locked_monitors() { return (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); } 266 267 bool is_owned_monitor_on_stack(oop object); 268 void add_jni_locked_monitor(oop object) { _jni_locked_monitors->append(object); } 269 }; 270 271 // StackFrameInfo for keeping methodOop and bci during 272 // stack walking for later construction of StackTraceElement[] 273 // Java instances 274 class StackFrameInfo : public CHeapObj { 275 private: 276 methodOop _method; 277 int _bci; 278 GrowableArray<oop>* _locked_monitors; // list of object monitors locked by this frame 279 280 public: 281 282 StackFrameInfo(javaVFrame* jvf, bool with_locked_monitors); 283 ~StackFrameInfo() { 284 if (_locked_monitors != NULL) { 285 delete _locked_monitors; 286 } 287 }; 288 methodOop method() const { return _method; } 289 int bci() const { return _bci; } 290 void oops_do(OopClosure* f); 291 292 int num_locked_monitors() { return (_locked_monitors != NULL ? _locked_monitors->length() : 0); } 293 GrowableArray<oop>* locked_monitors() { return _locked_monitors; } 294 295 void print_on(outputStream* st) const; 296 }; 297 298 class ThreadConcurrentLocks : public CHeapObj { 299 private: 300 GrowableArray<instanceOop>* _owned_locks; 301 ThreadConcurrentLocks* _next; 302 JavaThread* _thread; 303 public: 304 ThreadConcurrentLocks(JavaThread* thread); 305 ~ThreadConcurrentLocks(); 306 307 void add_lock(instanceOop o); 308 void set_next(ThreadConcurrentLocks* n) { _next = n; } 309 ThreadConcurrentLocks* next() { return _next; } 310 JavaThread* java_thread() { return _thread; } 311 GrowableArray<instanceOop>* owned_locks() { return _owned_locks; } 312 void oops_do(OopClosure* f); 313 }; 314 315 class ConcurrentLocksDump : public StackObj { 316 private: 317 ThreadConcurrentLocks* _map; 318 ThreadConcurrentLocks* _last; // Last ThreadConcurrentLocks in the map 319 bool _retain_map_on_free; 320 321 void build_map(GrowableArray<oop>* aos_objects); 322 void add_lock(JavaThread* thread, instanceOop o); 323 324 public: 325 ConcurrentLocksDump(bool retain_map_on_free) : _map(NULL), _last(NULL), _retain_map_on_free(retain_map_on_free) {}; 326 ConcurrentLocksDump() : _map(NULL), _last(NULL), _retain_map_on_free(false) {}; 327 ~ConcurrentLocksDump(); 328 329 void dump_at_safepoint(); 330 ThreadConcurrentLocks* thread_concurrent_locks(JavaThread* thread); 331 void print_locks_on(JavaThread* t, outputStream* st); 332 }; 333 334 class ThreadDumpResult : public StackObj { 335 private: 336 int _num_threads; 337 int _num_snapshots; 338 ThreadSnapshot* _snapshots; 339 ThreadSnapshot* _last; 340 ThreadDumpResult* _next; 341 public: 342 ThreadDumpResult(); 343 ThreadDumpResult(int num_threads); 344 ~ThreadDumpResult(); 345 346 void add_thread_snapshot(ThreadSnapshot* ts); 347 void set_next(ThreadDumpResult* next) { _next = next; } 348 ThreadDumpResult* next() { return _next; } 349 int num_threads() { return _num_threads; } 350 int num_snapshots() { return _num_snapshots; } 351 ThreadSnapshot* snapshots() { return _snapshots; } 352 void oops_do(OopClosure* f); 353 }; 354 355 class DeadlockCycle : public CHeapObj { 356 private: 357 bool _is_deadlock; 358 GrowableArray<JavaThread*>* _threads; 359 DeadlockCycle* _next; 360 public: 361 DeadlockCycle(); 362 ~DeadlockCycle(); 363 364 DeadlockCycle* next() { return _next; } 365 void set_next(DeadlockCycle* d) { _next = d; } 366 void add_thread(JavaThread* t) { _threads->append(t); } 367 void reset() { _is_deadlock = false; _threads->clear(); } 368 void set_deadlock(bool value) { _is_deadlock = value; } 369 bool is_deadlock() { return _is_deadlock; } 370 int num_threads() { return _threads->length(); } 371 GrowableArray<JavaThread*>* threads() { return _threads; } 372 void print_on(outputStream* st) const; 373 }; 374 375 // Utility class to get list of java threads. 376 class ThreadsListEnumerator : public StackObj { 377 private: 378 GrowableArray<instanceHandle>* _threads_array; 379 public: 380 ThreadsListEnumerator(Thread* cur_thread, 381 bool include_jvmti_agent_threads = false, 382 bool include_jni_attaching_threads = true); 383 int num_threads() { return _threads_array->length(); } 384 instanceHandle get_threadObj(int index) { return _threads_array->at(index); } 385 }; 386 387 388 // abstract utility class to set new thread states, and restore previous after the block exits 389 class JavaThreadStatusChanger : public StackObj { 390 private: 391 java_lang_Thread::ThreadStatus _old_state; 392 JavaThread* _java_thread; 393 bool _is_alive; 394 395 void save_old_state(JavaThread* java_thread) { 396 _java_thread = java_thread; 397 _is_alive = is_alive(java_thread); 398 if (is_alive()) { 399 _old_state = java_lang_Thread::get_thread_status(_java_thread->threadObj()); 400 } 401 } 402 403 public: 404 static void set_thread_status(JavaThread* java_thread, 405 java_lang_Thread::ThreadStatus state) { 406 java_lang_Thread::set_thread_status(java_thread->threadObj(), state); 407 } 408 409 void set_thread_status(java_lang_Thread::ThreadStatus state) { 410 if (is_alive()) { 411 set_thread_status(_java_thread, state); 412 } 413 } 414 415 JavaThreadStatusChanger(JavaThread* java_thread, 416 java_lang_Thread::ThreadStatus state) { 417 save_old_state(java_thread); 418 set_thread_status(state); 419 } 420 421 JavaThreadStatusChanger(JavaThread* java_thread) { 422 save_old_state(java_thread); 423 } 424 425 ~JavaThreadStatusChanger() { 426 set_thread_status(_old_state); 427 } 428 429 static bool is_alive(JavaThread* java_thread) { 430 return java_thread != NULL && java_thread->threadObj() != NULL; 431 } 432 433 bool is_alive() { 434 return _is_alive; 435 } 436 }; 437 438 // Change status to waiting on an object (timed or indefinite) 439 class JavaThreadInObjectWaitState : public JavaThreadStatusChanger { 440 private: 441 ThreadStatistics* _stat; 442 bool _active; 443 444 public: 445 JavaThreadInObjectWaitState(JavaThread *java_thread, bool timed) : 446 JavaThreadStatusChanger(java_thread, 447 timed ? java_lang_Thread::IN_OBJECT_WAIT_TIMED : java_lang_Thread::IN_OBJECT_WAIT) { 448 if (is_alive()) { 449 _stat = java_thread->get_thread_stat(); 450 _active = ThreadService::is_thread_monitoring_contention(); 451 _stat->monitor_wait(); 452 if (_active) { 453 _stat->monitor_wait_begin(); 454 } 455 } else { 456 _active = false; 457 } 458 } 459 460 ~JavaThreadInObjectWaitState() { 461 if (_active) { 462 _stat->monitor_wait_end(); 463 } 464 } 465 }; 466 467 // Change status to parked (timed or indefinite) 468 class JavaThreadParkedState : public JavaThreadStatusChanger { 469 private: 470 ThreadStatistics* _stat; 471 bool _active; 472 473 public: 474 JavaThreadParkedState(JavaThread *java_thread, bool timed) : 475 JavaThreadStatusChanger(java_thread, 476 timed ? java_lang_Thread::PARKED_TIMED : java_lang_Thread::PARKED) { 477 if (is_alive()) { 478 _stat = java_thread->get_thread_stat(); 479 _active = ThreadService::is_thread_monitoring_contention(); 480 _stat->monitor_wait(); 481 if (_active) { 482 _stat->monitor_wait_begin(); 483 } 484 } else { 485 _active = false; 486 } 487 } 488 489 ~JavaThreadParkedState() { 490 if (_active) { 491 _stat->monitor_wait_end(); 492 } 493 } 494 }; 495 496 // Change status to blocked on (re-)entering a synchronization block 497 class JavaThreadBlockedOnMonitorEnterState : public JavaThreadStatusChanger { 498 private: 499 ThreadStatistics* _stat; 500 bool _active; 501 502 static bool contended_enter_begin(JavaThread *java_thread) { 503 set_thread_status(java_thread, java_lang_Thread::BLOCKED_ON_MONITOR_ENTER); 504 ThreadStatistics* stat = java_thread->get_thread_stat(); 505 stat->contended_enter(); 506 bool active = ThreadService::is_thread_monitoring_contention(); 507 if (active) { 508 stat->contended_enter_begin(); 509 } 510 return active; 511 } 512 513 public: 514 // java_thread is waiting thread being blocked on monitor reenter. 515 // Current thread is the notifying thread which holds the monitor. 516 static bool wait_reenter_begin(JavaThread *java_thread, ObjectMonitor *obj_m) { 517 assert((java_thread != NULL), "Java thread should not be null here"); 518 bool active = false; 519 if (is_alive(java_thread) && ServiceUtil::visible_oop((oop)obj_m->object())) { 520 active = contended_enter_begin(java_thread); 521 } 522 return active; 523 } 524 525 static void wait_reenter_end(JavaThread *java_thread, bool active) { 526 if (active) { 527 java_thread->get_thread_stat()->contended_enter_end(); 528 } 529 set_thread_status(java_thread, java_lang_Thread::RUNNABLE); 530 } 531 532 JavaThreadBlockedOnMonitorEnterState(JavaThread *java_thread, ObjectMonitor *obj_m) : 533 JavaThreadStatusChanger(java_thread) { 534 assert((java_thread != NULL), "Java thread should not be null here"); 535 // Change thread status and collect contended enter stats for monitor contended 536 // enter done for external java world objects and it is contended. All other cases 537 // like for vm internal objects and for external objects which are not contended 538 // thread status is not changed and contended enter stat is not collected. 539 _active = false; 540 if (is_alive() && ServiceUtil::visible_oop((oop)obj_m->object()) && obj_m->contentions() > 0) { 541 _stat = java_thread->get_thread_stat(); 542 _active = contended_enter_begin(java_thread); 543 } 544 } 545 546 ~JavaThreadBlockedOnMonitorEnterState() { 547 if (_active) { 548 _stat->contended_enter_end(); 549 } 550 } 551 }; 552 553 // Change status to sleeping 554 class JavaThreadSleepState : public JavaThreadStatusChanger { 555 private: 556 ThreadStatistics* _stat; 557 bool _active; 558 public: 559 JavaThreadSleepState(JavaThread *java_thread) : 560 JavaThreadStatusChanger(java_thread, java_lang_Thread::SLEEPING) { 561 if (is_alive()) { 562 _stat = java_thread->get_thread_stat(); 563 _active = ThreadService::is_thread_monitoring_contention(); 564 _stat->thread_sleep(); 565 if (_active) { 566 _stat->thread_sleep_begin(); 567 } 568 } else { 569 _active = false; 570 } 571 } 572 573 ~JavaThreadSleepState() { 574 if (_active) { 575 _stat->thread_sleep_end(); 576 } 577 } 578 }; 579 580 #endif // SHARE_VM_SERVICES_THREADSERVICE_HPP