1 /* 2 * Copyright (c) 2003, 2013, 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 "oops/instanceKlass.hpp" 31 #include "oops/oop.inline.hpp" 32 #include "runtime/handles.inline.hpp" 33 #include "runtime/init.hpp" 34 #include "runtime/thread.hpp" 35 #include "runtime/vframe.hpp" 36 #include "runtime/vmThread.hpp" 37 #include "runtime/vm_operations.hpp" 38 #include "services/threadService.hpp" 39 40 // TODO: we need to define a naming convention for perf counters 41 // to distinguish counters for: 42 // - standard JSR174 use 43 // - Hotspot extension (public and committed) 44 // - Hotspot extension (private/internal and uncommitted) 45 46 // Default is disabled. 47 bool ThreadService::_thread_monitoring_contention_enabled = false; 48 bool ThreadService::_thread_cpu_time_enabled = false; 49 bool ThreadService::_thread_allocated_memory_enabled = false; 50 51 PerfCounter* ThreadService::_total_threads_count = NULL; 52 PerfVariable* ThreadService::_live_threads_count = NULL; 53 PerfVariable* ThreadService::_peak_threads_count = NULL; 54 PerfVariable* ThreadService::_daemon_threads_count = NULL; 55 volatile int ThreadService::_exiting_threads_count = 0; 56 volatile int ThreadService::_exiting_daemon_threads_count = 0; 57 58 ThreadDumpResult* ThreadService::_threaddump_list = NULL; 59 60 static const int INITIAL_ARRAY_SIZE = 10; 61 62 void ThreadService::init() { 63 EXCEPTION_MARK; 64 65 // These counters are for java.lang.management API support. 66 // They are created even if -XX:-UsePerfData is set and in 67 // that case, they will be allocated on C heap. 68 69 _total_threads_count = 70 PerfDataManager::create_counter(JAVA_THREADS, "started", 71 PerfData::U_Events, CHECK); 72 73 _live_threads_count = 74 PerfDataManager::create_variable(JAVA_THREADS, "live", 75 PerfData::U_None, CHECK); 76 77 _peak_threads_count = 78 PerfDataManager::create_variable(JAVA_THREADS, "livePeak", 79 PerfData::U_None, CHECK); 80 81 _daemon_threads_count = 82 PerfDataManager::create_variable(JAVA_THREADS, "daemon", 83 PerfData::U_None, CHECK); 84 85 if (os::is_thread_cpu_time_supported()) { 86 _thread_cpu_time_enabled = true; 87 } 88 89 _thread_allocated_memory_enabled = true; // Always on, so enable it 90 } 91 92 void ThreadService::reset_peak_thread_count() { 93 // Acquire the lock to update the peak thread count 94 // to synchronize with thread addition and removal. 95 MutexLockerEx mu(Threads_lock); 96 _peak_threads_count->set_value(get_live_thread_count()); 97 } 98 99 void ThreadService::add_thread(JavaThread* thread, bool daemon) { 100 // Do not count VM internal or JVMTI agent threads 101 if (thread->is_hidden_from_external_view() || 102 thread->is_jvmti_agent_thread()) { 103 return; 104 } 105 106 _total_threads_count->inc(); 107 _live_threads_count->inc(); 108 109 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) { 110 _peak_threads_count->set_value(_live_threads_count->get_value()); 111 } 112 113 if (daemon) { 114 _daemon_threads_count->inc(); 115 } 116 } 117 118 void ThreadService::remove_thread(JavaThread* thread, bool daemon) { 119 Atomic::dec((jint*) &_exiting_threads_count); 120 121 if (thread->is_hidden_from_external_view() || 122 thread->is_jvmti_agent_thread()) { 123 return; 124 } 125 126 _live_threads_count->set_value(_live_threads_count->get_value() - 1); 127 128 if (daemon) { 129 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1); 130 Atomic::dec((jint*) &_exiting_daemon_threads_count); 131 } 132 } 133 134 void ThreadService::current_thread_exiting(JavaThread* jt) { 135 assert(jt == JavaThread::current(), "Called by current thread"); 136 Atomic::inc((jint*) &_exiting_threads_count); 137 138 oop threadObj = jt->threadObj(); 139 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) { 140 Atomic::inc((jint*) &_exiting_daemon_threads_count); 141 } 142 } 143 144 // FIXME: JVMTI should call this function 145 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) { 146 assert(thread != NULL, "should be non-NULL"); 147 assert(Threads_lock->owned_by_self(), "must grab Threads_lock or be at safepoint"); 148 149 ObjectMonitor *wait_obj = thread->current_waiting_monitor(); 150 151 oop obj = NULL; 152 if (wait_obj != NULL) { 153 // thread is doing an Object.wait() call 154 obj = (oop) wait_obj->object(); 155 assert(obj != NULL, "Object.wait() should have an object"); 156 } else { 157 ObjectMonitor *enter_obj = thread->current_pending_monitor(); 158 if (enter_obj != NULL) { 159 // thread is trying to enter() or raw_enter() an ObjectMonitor. 160 obj = (oop) enter_obj->object(); 161 } 162 // If obj == NULL, then ObjectMonitor is raw which doesn't count. 163 } 164 165 Handle h(obj); 166 return h; 167 } 168 169 bool ThreadService::set_thread_monitoring_contention(bool flag) { 170 MutexLocker m(Management_lock); 171 172 bool prev = _thread_monitoring_contention_enabled; 173 _thread_monitoring_contention_enabled = flag; 174 175 return prev; 176 } 177 178 bool ThreadService::set_thread_cpu_time_enabled(bool flag) { 179 MutexLocker m(Management_lock); 180 181 bool prev = _thread_cpu_time_enabled; 182 _thread_cpu_time_enabled = flag; 183 184 return prev; 185 } 186 187 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) { 188 MutexLocker m(Management_lock); 189 190 bool prev = _thread_allocated_memory_enabled; 191 _thread_allocated_memory_enabled = flag; 192 193 return prev; 194 } 195 196 // GC support 197 void ThreadService::oops_do(OopClosure* f) { 198 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 199 dump->oops_do(f); 200 } 201 } 202 203 void ThreadService::metadata_do(void f(Metadata*)) { 204 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 205 dump->metadata_do(f); 206 } 207 } 208 209 void ThreadService::add_thread_dump(ThreadDumpResult* dump) { 210 MutexLocker ml(Management_lock); 211 if (_threaddump_list == NULL) { 212 _threaddump_list = dump; 213 } else { 214 dump->set_next(_threaddump_list); 215 _threaddump_list = dump; 216 } 217 } 218 219 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) { 220 MutexLocker ml(Management_lock); 221 222 ThreadDumpResult* prev = NULL; 223 bool found = false; 224 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) { 225 if (d == dump) { 226 if (prev == NULL) { 227 _threaddump_list = dump->next(); 228 } else { 229 prev->set_next(dump->next()); 230 } 231 found = true; 232 break; 233 } 234 } 235 assert(found, "The threaddump result to be removed must exist."); 236 } 237 238 // Dump stack trace of threads specified in the given threads array. 239 // Returns StackTraceElement[][] each element is the stack trace of a thread in 240 // the corresponding entry in the given threads array 241 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads, 242 int num_threads, 243 TRAPS) { 244 assert(num_threads > 0, "just checking"); 245 246 ThreadDumpResult dump_result; 247 VM_ThreadDump op(&dump_result, 248 threads, 249 num_threads, 250 -1, /* entire stack */ 251 false, /* with locked monitors */ 252 false /* with locked synchronizers */); 253 VMThread::execute(&op); 254 255 // Allocate the resulting StackTraceElement[][] object 256 257 ResourceMark rm(THREAD); 258 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH); 259 ObjArrayKlass* ik = ObjArrayKlass::cast(k); 260 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH); 261 objArrayHandle result_obj(THREAD, r); 262 263 int num_snapshots = dump_result.num_snapshots(); 264 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots"); 265 int i = 0; 266 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) { 267 ThreadStackTrace* stacktrace = ts->get_stack_trace(); 268 if (stacktrace == NULL) { 269 // No stack trace 270 result_obj->obj_at_put(i, NULL); 271 } else { 272 // Construct an array of java/lang/StackTraceElement object 273 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH); 274 result_obj->obj_at_put(i, backtrace_h()); 275 } 276 } 277 278 return result_obj; 279 } 280 281 void ThreadService::reset_contention_count_stat(JavaThread* thread) { 282 ThreadStatistics* stat = thread->get_thread_stat(); 283 if (stat != NULL) { 284 stat->reset_count_stat(); 285 } 286 } 287 288 void ThreadService::reset_contention_time_stat(JavaThread* thread) { 289 ThreadStatistics* stat = thread->get_thread_stat(); 290 if (stat != NULL) { 291 stat->reset_time_stat(); 292 } 293 } 294 295 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true 296 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) { 297 // This code was modified from the original Threads::find_deadlocks code. 298 int globalDfn = 0, thisDfn; 299 ObjectMonitor* waitingToLockMonitor = NULL; 300 oop waitingToLockBlocker = NULL; 301 bool blocked_on_monitor = false; 302 JavaThread *currentThread, *previousThread; 303 int num_deadlocks = 0; 304 305 for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) { 306 // Initialize the depth-first-number 307 p->set_depth_first_number(-1); 308 } 309 310 DeadlockCycle* deadlocks = NULL; 311 DeadlockCycle* last = NULL; 312 DeadlockCycle* cycle = new DeadlockCycle(); 313 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) { 314 if (jt->depth_first_number() >= 0) { 315 // this thread was already visited 316 continue; 317 } 318 319 thisDfn = globalDfn; 320 jt->set_depth_first_number(globalDfn++); 321 previousThread = jt; 322 currentThread = jt; 323 324 cycle->reset(); 325 326 // When there is a deadlock, all the monitors involved in the dependency 327 // cycle must be contended and heavyweight. So we only care about the 328 // heavyweight monitor a thread is waiting to lock. 329 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor(); 330 if (concurrent_locks) { 331 waitingToLockBlocker = jt->current_park_blocker(); 332 } 333 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) { 334 cycle->add_thread(currentThread); 335 if (waitingToLockMonitor != NULL) { 336 address currentOwner = (address)waitingToLockMonitor->owner(); 337 if (currentOwner != NULL) { 338 currentThread = Threads::owning_thread_from_monitor_owner( 339 currentOwner, 340 false /* no locking needed */); 341 if (currentThread == NULL) { 342 // This function is called at a safepoint so the JavaThread 343 // that owns waitingToLockMonitor should be findable, but 344 // if it is not findable, then the previous currentThread is 345 // blocked permanently. We record this as a deadlock. 346 num_deadlocks++; 347 348 cycle->set_deadlock(true); 349 350 // add this cycle to the deadlocks list 351 if (deadlocks == NULL) { 352 deadlocks = cycle; 353 } else { 354 last->set_next(cycle); 355 } 356 last = cycle; 357 cycle = new DeadlockCycle(); 358 break; 359 } 360 } 361 } else { 362 if (concurrent_locks) { 363 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) { 364 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 365 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL; 366 } else { 367 currentThread = NULL; 368 } 369 } 370 } 371 372 if (currentThread == NULL) { 373 // No dependency on another thread 374 break; 375 } 376 if (currentThread->depth_first_number() < 0) { 377 // First visit to this thread 378 currentThread->set_depth_first_number(globalDfn++); 379 } else if (currentThread->depth_first_number() < thisDfn) { 380 // Thread already visited, and not on a (new) cycle 381 break; 382 } else if (currentThread == previousThread) { 383 // Self-loop, ignore 384 break; 385 } else { 386 // We have a (new) cycle 387 num_deadlocks++; 388 389 cycle->set_deadlock(true); 390 391 // add this cycle to the deadlocks list 392 if (deadlocks == NULL) { 393 deadlocks = cycle; 394 } else { 395 last->set_next(cycle); 396 } 397 last = cycle; 398 cycle = new DeadlockCycle(); 399 break; 400 } 401 previousThread = currentThread; 402 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); 403 if (concurrent_locks) { 404 waitingToLockBlocker = currentThread->current_park_blocker(); 405 } 406 } 407 408 } 409 delete cycle; 410 return deadlocks; 411 } 412 413 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) { 414 415 // Create a new ThreadDumpResult object and append to the list. 416 // If GC happens before this function returns, Method* 417 // in the stack trace will be visited. 418 ThreadService::add_thread_dump(this); 419 } 420 421 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) { 422 // Create a new ThreadDumpResult object and append to the list. 423 // If GC happens before this function returns, oops 424 // will be visited. 425 ThreadService::add_thread_dump(this); 426 } 427 428 ThreadDumpResult::~ThreadDumpResult() { 429 ThreadService::remove_thread_dump(this); 430 431 // free all the ThreadSnapshot objects created during 432 // the VM_ThreadDump operation 433 ThreadSnapshot* ts = _snapshots; 434 while (ts != NULL) { 435 ThreadSnapshot* p = ts; 436 ts = ts->next(); 437 delete p; 438 } 439 } 440 441 442 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) { 443 assert(_num_threads == 0 || _num_snapshots < _num_threads, 444 "_num_snapshots must be less than _num_threads"); 445 _num_snapshots++; 446 if (_snapshots == NULL) { 447 _snapshots = ts; 448 } else { 449 _last->set_next(ts); 450 } 451 _last = ts; 452 } 453 454 void ThreadDumpResult::oops_do(OopClosure* f) { 455 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 456 ts->oops_do(f); 457 } 458 } 459 460 void ThreadDumpResult::metadata_do(void f(Metadata*)) { 461 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 462 ts->metadata_do(f); 463 } 464 } 465 466 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) { 467 _method = jvf->method(); 468 _bci = jvf->bci(); 469 _class_holder = _method->method_holder()->klass_holder(); 470 _locked_monitors = NULL; 471 if (with_lock_info) { 472 ResourceMark rm; 473 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors(); 474 int length = list->length(); 475 if (length > 0) { 476 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true); 477 for (int i = 0; i < length; i++) { 478 MonitorInfo* monitor = list->at(i); 479 assert(monitor->owner(), "This monitor must have an owning object"); 480 _locked_monitors->append(monitor->owner()); 481 } 482 } 483 } 484 } 485 486 void StackFrameInfo::oops_do(OopClosure* f) { 487 if (_locked_monitors != NULL) { 488 int length = _locked_monitors->length(); 489 for (int i = 0; i < length; i++) { 490 f->do_oop((oop*) _locked_monitors->adr_at(i)); 491 } 492 } 493 f->do_oop(&_class_holder); 494 } 495 496 void StackFrameInfo::metadata_do(void f(Metadata*)) { 497 f(_method); 498 } 499 500 void StackFrameInfo::print_on(outputStream* st) const { 501 ResourceMark rm; 502 java_lang_Throwable::print_stack_element(st, method(), bci()); 503 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0); 504 for (int i = 0; i < len; i++) { 505 oop o = _locked_monitors->at(i); 506 InstanceKlass* ik = InstanceKlass::cast(o->klass()); 507 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", (address)o, ik->external_name()); 508 } 509 510 } 511 512 // Iterate through monitor cache to find JNI locked monitors 513 class InflatedMonitorsClosure: public MonitorClosure { 514 private: 515 ThreadStackTrace* _stack_trace; 516 Thread* _thread; 517 public: 518 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) { 519 _thread = t; 520 _stack_trace = st; 521 } 522 void do_monitor(ObjectMonitor* mid) { 523 if (mid->owner() == _thread) { 524 oop object = (oop) mid->object(); 525 if (!_stack_trace->is_owned_monitor_on_stack(object)) { 526 _stack_trace->add_jni_locked_monitor(object); 527 } 528 } 529 } 530 }; 531 532 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) { 533 _thread = t; 534 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true); 535 _depth = 0; 536 _with_locked_monitors = with_locked_monitors; 537 if (_with_locked_monitors) { 538 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true); 539 } else { 540 _jni_locked_monitors = NULL; 541 } 542 } 543 544 ThreadStackTrace::~ThreadStackTrace() { 545 for (int i = 0; i < _frames->length(); i++) { 546 delete _frames->at(i); 547 } 548 delete _frames; 549 if (_jni_locked_monitors != NULL) { 550 delete _jni_locked_monitors; 551 } 552 } 553 554 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) { 555 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 556 557 if (_thread->has_last_Java_frame()) { 558 RegisterMap reg_map(_thread); 559 vframe* start_vf = _thread->last_java_vframe(®_map); 560 int count = 0; 561 for (vframe* f = start_vf; f; f = f->sender() ) { 562 if (f->is_java_frame()) { 563 javaVFrame* jvf = javaVFrame::cast(f); 564 add_stack_frame(jvf); 565 count++; 566 } else { 567 // Ignore non-Java frames 568 } 569 if (maxDepth > 0 && count == maxDepth) { 570 // Skip frames if more than maxDepth 571 break; 572 } 573 } 574 } 575 576 if (_with_locked_monitors) { 577 // Iterate inflated monitors and find monitors locked by this thread 578 // not found in the stack 579 InflatedMonitorsClosure imc(_thread, this); 580 ObjectSynchronizer::monitors_iterate(&imc); 581 } 582 } 583 584 585 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) { 586 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 587 588 bool found = false; 589 int num_frames = get_stack_depth(); 590 for (int depth = 0; depth < num_frames; depth++) { 591 StackFrameInfo* frame = stack_frame_at(depth); 592 int len = frame->num_locked_monitors(); 593 GrowableArray<oop>* locked_monitors = frame->locked_monitors(); 594 for (int j = 0; j < len; j++) { 595 oop monitor = locked_monitors->at(j); 596 assert(monitor != NULL && monitor->is_instance(), "must be a Java object"); 597 if (monitor == object) { 598 found = true; 599 break; 600 } 601 } 602 } 603 return found; 604 } 605 606 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) { 607 Klass* k = SystemDictionary::StackTraceElement_klass(); 608 assert(k != NULL, "must be loaded in 1.4+"); 609 instanceKlassHandle ik(THREAD, k); 610 611 // Allocate an array of java/lang/StackTraceElement object 612 objArrayOop ste = oopFactory::new_objArray(ik(), _depth, CHECK_NH); 613 objArrayHandle backtrace(THREAD, ste); 614 for (int j = 0; j < _depth; j++) { 615 StackFrameInfo* frame = _frames->at(j); 616 methodHandle mh(THREAD, frame->method()); 617 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH); 618 backtrace->obj_at_put(j, element); 619 } 620 return backtrace; 621 } 622 623 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) { 624 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors); 625 _frames->append(frame); 626 _depth++; 627 } 628 629 void ThreadStackTrace::oops_do(OopClosure* f) { 630 int length = _frames->length(); 631 for (int i = 0; i < length; i++) { 632 _frames->at(i)->oops_do(f); 633 } 634 635 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); 636 for (int j = 0; j < length; j++) { 637 f->do_oop((oop*) _jni_locked_monitors->adr_at(j)); 638 } 639 } 640 641 void ThreadStackTrace::metadata_do(void f(Metadata*)) { 642 int length = _frames->length(); 643 for (int i = 0; i < length; i++) { 644 _frames->at(i)->metadata_do(f); 645 } 646 } 647 648 649 ConcurrentLocksDump::~ConcurrentLocksDump() { 650 if (_retain_map_on_free) { 651 return; 652 } 653 654 for (ThreadConcurrentLocks* t = _map; t != NULL;) { 655 ThreadConcurrentLocks* tcl = t; 656 t = t->next(); 657 delete tcl; 658 } 659 } 660 661 void ConcurrentLocksDump::dump_at_safepoint() { 662 // dump all locked concurrent locks 663 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 664 665 if (JDK_Version::is_gte_jdk16x_version()) { 666 ResourceMark rm; 667 668 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE); 669 670 // Find all instances of AbstractOwnableSynchronizer 671 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(), 672 aos_objects); 673 // Build a map of thread to its owned AQS locks 674 build_map(aos_objects); 675 } 676 } 677 678 679 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer 680 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) { 681 int length = aos_objects->length(); 682 for (int i = 0; i < length; i++) { 683 oop o = aos_objects->at(i); 684 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o); 685 if (owner_thread_obj != NULL) { 686 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj); 687 assert(o->is_instance(), "Must be an instanceOop"); 688 add_lock(thread, (instanceOop) o); 689 } 690 } 691 } 692 693 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) { 694 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread); 695 if (tcl != NULL) { 696 tcl->add_lock(o); 697 return; 698 } 699 700 // First owned lock found for this thread 701 tcl = new ThreadConcurrentLocks(thread); 702 tcl->add_lock(o); 703 if (_map == NULL) { 704 _map = tcl; 705 } else { 706 _last->set_next(tcl); 707 } 708 _last = tcl; 709 } 710 711 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) { 712 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) { 713 if (tcl->java_thread() == thread) { 714 return tcl; 715 } 716 } 717 return NULL; 718 } 719 720 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) { 721 st->print_cr(" Locked ownable synchronizers:"); 722 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t); 723 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL); 724 if (locks == NULL || locks->is_empty()) { 725 st->print_cr("\t- None"); 726 st->cr(); 727 return; 728 } 729 730 for (int i = 0; i < locks->length(); i++) { 731 instanceOop obj = locks->at(i); 732 InstanceKlass* ik = InstanceKlass::cast(obj->klass()); 733 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", (address)obj, ik->external_name()); 734 } 735 st->cr(); 736 } 737 738 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) { 739 _thread = thread; 740 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true); 741 _next = NULL; 742 } 743 744 ThreadConcurrentLocks::~ThreadConcurrentLocks() { 745 delete _owned_locks; 746 } 747 748 void ThreadConcurrentLocks::add_lock(instanceOop o) { 749 _owned_locks->append(o); 750 } 751 752 void ThreadConcurrentLocks::oops_do(OopClosure* f) { 753 int length = _owned_locks->length(); 754 for (int i = 0; i < length; i++) { 755 f->do_oop((oop*) _owned_locks->adr_at(i)); 756 } 757 } 758 759 ThreadStatistics::ThreadStatistics() { 760 _contended_enter_count = 0; 761 _monitor_wait_count = 0; 762 _sleep_count = 0; 763 _count_pending_reset = false; 764 _timer_pending_reset = false; 765 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts)); 766 } 767 768 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) { 769 _thread = thread; 770 _threadObj = thread->threadObj(); 771 _stack_trace = NULL; 772 _concurrent_locks = NULL; 773 _next = NULL; 774 775 ThreadStatistics* stat = thread->get_thread_stat(); 776 _contended_enter_ticks = stat->contended_enter_ticks(); 777 _contended_enter_count = stat->contended_enter_count(); 778 _monitor_wait_ticks = stat->monitor_wait_ticks(); 779 _monitor_wait_count = stat->monitor_wait_count(); 780 _sleep_ticks = stat->sleep_ticks(); 781 _sleep_count = stat->sleep_count(); 782 783 _blocker_object = NULL; 784 _blocker_object_owner = NULL; 785 786 _thread_status = java_lang_Thread::get_thread_status(_threadObj); 787 _is_ext_suspended = thread->is_being_ext_suspended(); 788 _is_in_native = (thread->thread_state() == _thread_in_native); 789 790 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER || 791 _thread_status == java_lang_Thread::IN_OBJECT_WAIT || 792 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) { 793 794 Handle obj = ThreadService::get_current_contended_monitor(thread); 795 if (obj() == NULL) { 796 // monitor no longer exists; thread is not blocked 797 _thread_status = java_lang_Thread::RUNNABLE; 798 } else { 799 _blocker_object = obj(); 800 JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false); 801 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER) 802 || (owner != NULL && owner->is_attaching_via_jni())) { 803 // ownership information of the monitor is not available 804 // (may no longer be owned or releasing to some other thread) 805 // make this thread in RUNNABLE state. 806 // And when the owner thread is in attaching state, the java thread 807 // is not completely initialized. For example thread name and id 808 // and may not be set, so hide the attaching thread. 809 _thread_status = java_lang_Thread::RUNNABLE; 810 _blocker_object = NULL; 811 } else if (owner != NULL) { 812 _blocker_object_owner = owner->threadObj(); 813 } 814 } 815 } 816 817 // Support for JSR-166 locks 818 if (JDK_Version::current().supports_thread_park_blocker() && 819 (_thread_status == java_lang_Thread::PARKED || 820 _thread_status == java_lang_Thread::PARKED_TIMED)) { 821 822 _blocker_object = thread->current_park_blocker(); 823 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) { 824 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object); 825 } 826 } 827 } 828 829 ThreadSnapshot::~ThreadSnapshot() { 830 delete _stack_trace; 831 delete _concurrent_locks; 832 } 833 834 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) { 835 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors); 836 _stack_trace->dump_stack_at_safepoint(max_depth); 837 } 838 839 840 void ThreadSnapshot::oops_do(OopClosure* f) { 841 f->do_oop(&_threadObj); 842 f->do_oop(&_blocker_object); 843 f->do_oop(&_blocker_object_owner); 844 if (_stack_trace != NULL) { 845 _stack_trace->oops_do(f); 846 } 847 if (_concurrent_locks != NULL) { 848 _concurrent_locks->oops_do(f); 849 } 850 } 851 852 void ThreadSnapshot::metadata_do(void f(Metadata*)) { 853 if (_stack_trace != NULL) { 854 _stack_trace->metadata_do(f); 855 } 856 } 857 858 859 DeadlockCycle::DeadlockCycle() { 860 _is_deadlock = false; 861 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true); 862 _next = NULL; 863 } 864 865 DeadlockCycle::~DeadlockCycle() { 866 delete _threads; 867 } 868 869 void DeadlockCycle::print_on(outputStream* st) const { 870 st->cr(); 871 st->print_cr("Found one Java-level deadlock:"); 872 st->print("============================="); 873 874 JavaThread* currentThread; 875 ObjectMonitor* waitingToLockMonitor; 876 oop waitingToLockBlocker; 877 int len = _threads->length(); 878 for (int i = 0; i < len; i++) { 879 currentThread = _threads->at(i); 880 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); 881 waitingToLockBlocker = currentThread->current_park_blocker(); 882 st->cr(); 883 st->print_cr("\"%s\":", currentThread->get_thread_name()); 884 const char* owner_desc = ",\n which is held by"; 885 if (waitingToLockMonitor != NULL) { 886 st->print(" waiting to lock monitor " INTPTR_FORMAT, waitingToLockMonitor); 887 oop obj = (oop)waitingToLockMonitor->object(); 888 if (obj != NULL) { 889 st->print(" (object "INTPTR_FORMAT ", a %s)", (address)obj, 890 (InstanceKlass::cast(obj->klass()))->external_name()); 891 892 if (!currentThread->current_pending_monitor_is_from_java()) { 893 owner_desc = "\n in JNI, which is held by"; 894 } 895 } else { 896 // No Java object associated - a JVMTI raw monitor 897 owner_desc = " (JVMTI raw monitor),\n which is held by"; 898 } 899 currentThread = Threads::owning_thread_from_monitor_owner( 900 (address)waitingToLockMonitor->owner(), 901 false /* no locking needed */); 902 if (currentThread == NULL) { 903 // The deadlock was detected at a safepoint so the JavaThread 904 // that owns waitingToLockMonitor should be findable, but 905 // if it is not findable, then the previous currentThread is 906 // blocked permanently. 907 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc, 908 (address)waitingToLockMonitor->owner()); 909 continue; 910 } 911 } else { 912 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)", 913 (address)waitingToLockBlocker, 914 (InstanceKlass::cast(waitingToLockBlocker->klass()))->external_name()); 915 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()), 916 "Must be an AbstractOwnableSynchronizer"); 917 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 918 currentThread = java_lang_Thread::thread(ownerObj); 919 } 920 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 921 } 922 923 st->cr(); 924 st->cr(); 925 926 // Print stack traces 927 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace; 928 JavaMonitorsInStackTrace = true; 929 st->print_cr("Java stack information for the threads listed above:"); 930 st->print_cr("==================================================="); 931 for (int j = 0; j < len; j++) { 932 currentThread = _threads->at(j); 933 st->print_cr("\"%s\":", currentThread->get_thread_name()); 934 currentThread->print_stack_on(st); 935 } 936 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace; 937 } 938 939 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread, 940 bool include_jvmti_agent_threads, 941 bool include_jni_attaching_threads) { 942 assert(cur_thread == Thread::current(), "Check current thread"); 943 944 int init_size = ThreadService::get_live_thread_count(); 945 _threads_array = new GrowableArray<instanceHandle>(init_size); 946 947 MutexLockerEx ml(Threads_lock); 948 949 for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) { 950 // skips JavaThreads in the process of exiting 951 // and also skips VM internal JavaThreads 952 // Threads in _thread_new or _thread_new_trans state are included. 953 // i.e. threads have been started but not yet running. 954 if (jt->threadObj() == NULL || 955 jt->is_exiting() || 956 !java_lang_Thread::is_alive(jt->threadObj()) || 957 jt->is_hidden_from_external_view()) { 958 continue; 959 } 960 961 // skip agent threads 962 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) { 963 continue; 964 } 965 966 // skip jni threads in the process of attaching 967 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) { 968 continue; 969 } 970 971 instanceHandle h(cur_thread, (instanceOop) jt->threadObj()); 972 _threads_array->append(h); 973 } 974 }