1 /* 2 * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 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 "memory/resourceArea.hpp" 31 #include "oops/instanceKlass.hpp" 32 #include "oops/objArrayKlass.hpp" 33 #include "oops/objArrayOop.inline.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "prims/jvmtiRawMonitor.hpp" 36 #include "runtime/atomic.hpp" 37 #include "runtime/handles.inline.hpp" 38 #include "runtime/init.hpp" 39 #include "runtime/objectMonitor.inline.hpp" 40 #include "runtime/thread.inline.hpp" 41 #include "runtime/threadSMR.inline.hpp" 42 #include "runtime/vframe.hpp" 43 #include "runtime/vmThread.hpp" 44 #include "runtime/vmOperations.hpp" 45 #include "services/threadService.hpp" 46 47 // TODO: we need to define a naming convention for perf counters 48 // to distinguish counters for: 49 // - standard JSR174 use 50 // - Hotspot extension (public and committed) 51 // - Hotspot extension (private/internal and uncommitted) 52 53 // Default is disabled. 54 bool ThreadService::_thread_monitoring_contention_enabled = false; 55 bool ThreadService::_thread_cpu_time_enabled = false; 56 bool ThreadService::_thread_allocated_memory_enabled = false; 57 58 PerfCounter* ThreadService::_total_threads_count = NULL; 59 PerfVariable* ThreadService::_live_threads_count = NULL; 60 PerfVariable* ThreadService::_peak_threads_count = NULL; 61 PerfVariable* ThreadService::_daemon_threads_count = NULL; 62 volatile int ThreadService::_atomic_threads_count = 0; 63 volatile int ThreadService::_atomic_daemon_threads_count = 0; 64 65 ThreadDumpResult* ThreadService::_threaddump_list = NULL; 66 67 static const int INITIAL_ARRAY_SIZE = 10; 68 69 void ThreadService::init() { 70 EXCEPTION_MARK; 71 72 // These counters are for java.lang.management API support. 73 // They are created even if -XX:-UsePerfData is set and in 74 // that case, they will be allocated on C heap. 75 76 _total_threads_count = 77 PerfDataManager::create_counter(JAVA_THREADS, "started", 78 PerfData::U_Events, CHECK); 79 80 _live_threads_count = 81 PerfDataManager::create_variable(JAVA_THREADS, "live", 82 PerfData::U_None, CHECK); 83 84 _peak_threads_count = 85 PerfDataManager::create_variable(JAVA_THREADS, "livePeak", 86 PerfData::U_None, CHECK); 87 88 _daemon_threads_count = 89 PerfDataManager::create_variable(JAVA_THREADS, "daemon", 90 PerfData::U_None, CHECK); 91 92 if (os::is_thread_cpu_time_supported()) { 93 _thread_cpu_time_enabled = true; 94 } 95 96 _thread_allocated_memory_enabled = true; // Always on, so enable it 97 } 98 99 void ThreadService::reset_peak_thread_count() { 100 // Acquire the lock to update the peak thread count 101 // to synchronize with thread addition and removal. 102 MutexLocker mu(Threads_lock); 103 _peak_threads_count->set_value(get_live_thread_count()); 104 } 105 106 static bool is_hidden_thread(JavaThread *thread) { 107 // hide VM internal or JVMTI agent threads 108 return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread(); 109 } 110 111 void ThreadService::add_thread(JavaThread* thread, bool daemon) { 112 assert(Threads_lock->owned_by_self(), "must have threads lock"); 113 114 // Do not count hidden threads 115 if (is_hidden_thread(thread)) { 116 return; 117 } 118 119 _total_threads_count->inc(); 120 _live_threads_count->inc(); 121 Atomic::inc(&_atomic_threads_count); 122 int count = _atomic_threads_count; 123 124 if (count > _peak_threads_count->get_value()) { 125 _peak_threads_count->set_value(count); 126 } 127 128 if (daemon) { 129 _daemon_threads_count->inc(); 130 Atomic::inc(&_atomic_daemon_threads_count); 131 } 132 } 133 134 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) { 135 Atomic::dec(&_atomic_threads_count); 136 137 if (daemon) { 138 Atomic::dec(&_atomic_daemon_threads_count); 139 } 140 } 141 142 void ThreadService::remove_thread(JavaThread* thread, bool daemon) { 143 assert(Threads_lock->owned_by_self(), "must have threads lock"); 144 145 // Do not count hidden threads 146 if (is_hidden_thread(thread)) { 147 return; 148 } 149 150 assert(!thread->is_terminated(), "must not be terminated"); 151 if (!thread->is_exiting()) { 152 // JavaThread::exit() skipped calling current_thread_exiting() 153 decrement_thread_counts(thread, daemon); 154 } 155 156 int daemon_count = _atomic_daemon_threads_count; 157 int count = _atomic_threads_count; 158 159 // Counts are incremented at the same time, but atomic counts are 160 // decremented earlier than perf counts. 161 assert(_live_threads_count->get_value() > count, 162 "thread count mismatch %d : %d", 163 (int)_live_threads_count->get_value(), count); 164 165 _live_threads_count->dec(1); 166 if (daemon) { 167 assert(_daemon_threads_count->get_value() > daemon_count, 168 "thread count mismatch %d : %d", 169 (int)_daemon_threads_count->get_value(), daemon_count); 170 171 _daemon_threads_count->dec(1); 172 } 173 174 // Counts are incremented at the same time, but atomic counts are 175 // decremented earlier than perf counts. 176 assert(_daemon_threads_count->get_value() >= daemon_count, 177 "thread count mismatch %d : %d", 178 (int)_daemon_threads_count->get_value(), daemon_count); 179 assert(_live_threads_count->get_value() >= count, 180 "thread count mismatch %d : %d", 181 (int)_live_threads_count->get_value(), count); 182 assert(_live_threads_count->get_value() > 0 || 183 (_live_threads_count->get_value() == 0 && count == 0 && 184 _daemon_threads_count->get_value() == 0 && daemon_count == 0), 185 "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d", 186 (int)_live_threads_count->get_value(), count, 187 (int)_daemon_threads_count->get_value(), daemon_count); 188 assert(_daemon_threads_count->get_value() > 0 || 189 (_daemon_threads_count->get_value() == 0 && daemon_count == 0), 190 "thread counts should reach 0 at the same time, daemon %d,%d", 191 (int)_daemon_threads_count->get_value(), daemon_count); 192 } 193 194 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) { 195 // Do not count hidden threads 196 if (is_hidden_thread(jt)) { 197 return; 198 } 199 200 assert(jt == JavaThread::current(), "Called by current thread"); 201 assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting"); 202 203 decrement_thread_counts(jt, daemon); 204 } 205 206 // FIXME: JVMTI should call this function 207 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) { 208 assert(thread != NULL, "should be non-NULL"); 209 debug_only(Thread::check_for_dangling_thread_pointer(thread);) 210 211 ObjectMonitor *wait_obj = thread->current_waiting_monitor(); 212 213 oop obj = NULL; 214 if (wait_obj != NULL) { 215 // thread is doing an Object.wait() call 216 obj = (oop) wait_obj->object(); 217 assert(obj != NULL, "Object.wait() should have an object"); 218 } else { 219 ObjectMonitor *enter_obj = thread->current_pending_monitor(); 220 if (enter_obj != NULL) { 221 // thread is trying to enter() an ObjectMonitor. 222 obj = (oop) enter_obj->object(); 223 assert(obj != NULL, "ObjectMonitor should have an associated object!"); 224 } 225 } 226 227 Handle h(Thread::current(), obj); 228 return h; 229 } 230 231 bool ThreadService::set_thread_monitoring_contention(bool flag) { 232 MutexLocker m(Management_lock); 233 234 bool prev = _thread_monitoring_contention_enabled; 235 _thread_monitoring_contention_enabled = flag; 236 237 return prev; 238 } 239 240 bool ThreadService::set_thread_cpu_time_enabled(bool flag) { 241 MutexLocker m(Management_lock); 242 243 bool prev = _thread_cpu_time_enabled; 244 _thread_cpu_time_enabled = flag; 245 246 return prev; 247 } 248 249 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) { 250 MutexLocker m(Management_lock); 251 252 bool prev = _thread_allocated_memory_enabled; 253 _thread_allocated_memory_enabled = flag; 254 255 return prev; 256 } 257 258 // GC support 259 void ThreadService::oops_do(OopClosure* f) { 260 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 261 dump->oops_do(f); 262 } 263 } 264 265 void ThreadService::metadata_do(void f(Metadata*)) { 266 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 267 dump->metadata_do(f); 268 } 269 } 270 271 void ThreadService::add_thread_dump(ThreadDumpResult* dump) { 272 MutexLocker ml(Management_lock); 273 if (_threaddump_list == NULL) { 274 _threaddump_list = dump; 275 } else { 276 dump->set_next(_threaddump_list); 277 _threaddump_list = dump; 278 } 279 } 280 281 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) { 282 MutexLocker ml(Management_lock); 283 284 ThreadDumpResult* prev = NULL; 285 bool found = false; 286 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) { 287 if (d == dump) { 288 if (prev == NULL) { 289 _threaddump_list = dump->next(); 290 } else { 291 prev->set_next(dump->next()); 292 } 293 found = true; 294 break; 295 } 296 } 297 assert(found, "The threaddump result to be removed must exist."); 298 } 299 300 // Dump stack trace of threads specified in the given threads array. 301 // Returns StackTraceElement[][] each element is the stack trace of a thread in 302 // the corresponding entry in the given threads array 303 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads, 304 int num_threads, 305 TRAPS) { 306 assert(num_threads > 0, "just checking"); 307 308 ThreadDumpResult dump_result; 309 VM_ThreadDump op(&dump_result, 310 threads, 311 num_threads, 312 -1, /* entire stack */ 313 false, /* with locked monitors */ 314 false /* with locked synchronizers */); 315 VMThread::execute(&op); 316 317 // Allocate the resulting StackTraceElement[][] object 318 319 ResourceMark rm(THREAD); 320 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH); 321 ObjArrayKlass* ik = ObjArrayKlass::cast(k); 322 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH); 323 objArrayHandle result_obj(THREAD, r); 324 325 int num_snapshots = dump_result.num_snapshots(); 326 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots"); 327 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot"); 328 int i = 0; 329 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) { 330 ThreadStackTrace* stacktrace = ts->get_stack_trace(); 331 if (stacktrace == NULL) { 332 // No stack trace 333 result_obj->obj_at_put(i, NULL); 334 } else { 335 // Construct an array of java/lang/StackTraceElement object 336 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH); 337 result_obj->obj_at_put(i, backtrace_h()); 338 } 339 } 340 341 return result_obj; 342 } 343 344 void ThreadService::reset_contention_count_stat(JavaThread* thread) { 345 ThreadStatistics* stat = thread->get_thread_stat(); 346 if (stat != NULL) { 347 stat->reset_count_stat(); 348 } 349 } 350 351 void ThreadService::reset_contention_time_stat(JavaThread* thread) { 352 ThreadStatistics* stat = thread->get_thread_stat(); 353 if (stat != NULL) { 354 stat->reset_time_stat(); 355 } 356 } 357 358 // Find deadlocks involving raw monitors, object monitors and concurrent locks 359 // if concurrent_locks is true. 360 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) { 361 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 362 363 // This code was modified from the original Threads::find_deadlocks code. 364 int globalDfn = 0, thisDfn; 365 ObjectMonitor* waitingToLockMonitor = NULL; 366 JvmtiRawMonitor* waitingToLockRawMonitor = NULL; 367 oop waitingToLockBlocker = NULL; 368 bool blocked_on_monitor = false; 369 JavaThread *currentThread, *previousThread; 370 int num_deadlocks = 0; 371 372 // Initialize the depth-first-number for each JavaThread. 373 JavaThreadIterator jti(t_list); 374 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 375 jt->set_depth_first_number(-1); 376 } 377 378 DeadlockCycle* deadlocks = NULL; 379 DeadlockCycle* last = NULL; 380 DeadlockCycle* cycle = new DeadlockCycle(); 381 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 382 if (jt->depth_first_number() >= 0) { 383 // this thread was already visited 384 continue; 385 } 386 387 thisDfn = globalDfn; 388 jt->set_depth_first_number(globalDfn++); 389 previousThread = jt; 390 currentThread = jt; 391 392 cycle->reset(); 393 394 // When there is a deadlock, all the monitors involved in the dependency 395 // cycle must be contended and heavyweight. So we only care about the 396 // heavyweight monitor a thread is waiting to lock. 397 waitingToLockMonitor = jt->current_pending_monitor(); 398 // JVM TI raw monitors can also be involved in deadlocks, and we can be 399 // waiting to lock both a raw monitor and ObjectMonitor at the same time. 400 // It isn't clear how to make deadlock detection work correctly if that 401 // happens. 402 waitingToLockRawMonitor = jt->current_pending_raw_monitor(); 403 404 if (concurrent_locks) { 405 waitingToLockBlocker = jt->current_park_blocker(); 406 } 407 408 while (waitingToLockMonitor != NULL || 409 waitingToLockRawMonitor != NULL || 410 waitingToLockBlocker != NULL) { 411 cycle->add_thread(currentThread); 412 // Give preference to the raw monitor 413 if (waitingToLockRawMonitor != NULL) { 414 Thread* owner = waitingToLockRawMonitor->owner(); 415 if (owner != NULL && // the raw monitor could be released at any time 416 owner->is_Java_thread()) { 417 // only JavaThreads can be reported here 418 currentThread = (JavaThread*) owner; 419 } 420 } else if (waitingToLockMonitor != NULL) { 421 address currentOwner = (address)waitingToLockMonitor->owner(); 422 if (currentOwner != NULL) { 423 currentThread = Threads::owning_thread_from_monitor_owner(t_list, 424 currentOwner); 425 if (currentThread == NULL) { 426 // This function is called at a safepoint so the JavaThread 427 // that owns waitingToLockMonitor should be findable, but 428 // if it is not findable, then the previous currentThread is 429 // blocked permanently. We record this as a deadlock. 430 num_deadlocks++; 431 432 cycle->set_deadlock(true); 433 434 // add this cycle to the deadlocks list 435 if (deadlocks == NULL) { 436 deadlocks = cycle; 437 } else { 438 last->set_next(cycle); 439 } 440 last = cycle; 441 cycle = new DeadlockCycle(); 442 break; 443 } 444 } 445 } else { 446 if (concurrent_locks) { 447 if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { 448 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 449 // This JavaThread (if there is one) is protected by the 450 // ThreadsListSetter in VM_FindDeadlocks::doit(). 451 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL; 452 } else { 453 currentThread = NULL; 454 } 455 } 456 } 457 458 if (currentThread == NULL) { 459 // No dependency on another thread 460 break; 461 } 462 if (currentThread->depth_first_number() < 0) { 463 // First visit to this thread 464 currentThread->set_depth_first_number(globalDfn++); 465 } else if (currentThread->depth_first_number() < thisDfn) { 466 // Thread already visited, and not on a (new) cycle 467 break; 468 } else if (currentThread == previousThread) { 469 // Self-loop, ignore 470 break; 471 } else { 472 // We have a (new) cycle 473 num_deadlocks++; 474 475 cycle->set_deadlock(true); 476 477 // add this cycle to the deadlocks list 478 if (deadlocks == NULL) { 479 deadlocks = cycle; 480 } else { 481 last->set_next(cycle); 482 } 483 last = cycle; 484 cycle = new DeadlockCycle(); 485 break; 486 } 487 previousThread = currentThread; 488 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); 489 if (concurrent_locks) { 490 waitingToLockBlocker = currentThread->current_park_blocker(); 491 } 492 } 493 494 } 495 delete cycle; 496 return deadlocks; 497 } 498 499 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() { 500 501 // Create a new ThreadDumpResult object and append to the list. 502 // If GC happens before this function returns, Method* 503 // in the stack trace will be visited. 504 ThreadService::add_thread_dump(this); 505 } 506 507 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() { 508 // Create a new ThreadDumpResult object and append to the list. 509 // If GC happens before this function returns, oops 510 // will be visited. 511 ThreadService::add_thread_dump(this); 512 } 513 514 ThreadDumpResult::~ThreadDumpResult() { 515 ThreadService::remove_thread_dump(this); 516 517 // free all the ThreadSnapshot objects created during 518 // the VM_ThreadDump operation 519 ThreadSnapshot* ts = _snapshots; 520 while (ts != NULL) { 521 ThreadSnapshot* p = ts; 522 ts = ts->next(); 523 delete p; 524 } 525 } 526 527 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() { 528 ThreadSnapshot* ts = new ThreadSnapshot(); 529 link_thread_snapshot(ts); 530 return ts; 531 } 532 533 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) { 534 // Note: it is very important that the ThreadSnapshot* gets linked before 535 // ThreadSnapshot::initialize gets called. This is to ensure that 536 // ThreadSnapshot::oops_do can get called prior to the field 537 // ThreadSnapshot::_threadObj being assigned a value (to prevent a dangling 538 // oop). 539 ThreadSnapshot* ts = new ThreadSnapshot(); 540 link_thread_snapshot(ts); 541 ts->initialize(t_list(), thread); 542 return ts; 543 } 544 545 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) { 546 assert(_num_threads == 0 || _num_snapshots < _num_threads, 547 "_num_snapshots must be less than _num_threads"); 548 _num_snapshots++; 549 if (_snapshots == NULL) { 550 _snapshots = ts; 551 } else { 552 _last->set_next(ts); 553 } 554 _last = ts; 555 } 556 557 void ThreadDumpResult::oops_do(OopClosure* f) { 558 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 559 ts->oops_do(f); 560 } 561 } 562 563 void ThreadDumpResult::metadata_do(void f(Metadata*)) { 564 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 565 ts->metadata_do(f); 566 } 567 } 568 569 ThreadsList* ThreadDumpResult::t_list() { 570 return _setter.list(); 571 } 572 573 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) { 574 _method = jvf->method(); 575 _bci = jvf->bci(); 576 _class_holder = _method->method_holder()->klass_holder(); 577 _locked_monitors = NULL; 578 if (with_lock_info) { 579 ResourceMark rm; 580 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors(); 581 int length = list->length(); 582 if (length > 0) { 583 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true); 584 for (int i = 0; i < length; i++) { 585 MonitorInfo* monitor = list->at(i); 586 assert(monitor->owner() != NULL, "This monitor must have an owning object"); 587 _locked_monitors->append(monitor->owner()); 588 } 589 } 590 } 591 } 592 593 void StackFrameInfo::oops_do(OopClosure* f) { 594 if (_locked_monitors != NULL) { 595 int length = _locked_monitors->length(); 596 for (int i = 0; i < length; i++) { 597 f->do_oop((oop*) _locked_monitors->adr_at(i)); 598 } 599 } 600 f->do_oop(&_class_holder); 601 } 602 603 void StackFrameInfo::metadata_do(void f(Metadata*)) { 604 f(_method); 605 } 606 607 void StackFrameInfo::print_on(outputStream* st) const { 608 ResourceMark rm; 609 java_lang_Throwable::print_stack_element(st, method(), bci()); 610 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0); 611 for (int i = 0; i < len; i++) { 612 oop o = _locked_monitors->at(i); 613 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name()); 614 } 615 616 } 617 618 // Iterate through monitor cache to find JNI locked monitors 619 class InflatedMonitorsClosure: public MonitorClosure { 620 private: 621 ThreadStackTrace* _stack_trace; 622 Thread* _thread; 623 public: 624 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) { 625 _thread = t; 626 _stack_trace = st; 627 } 628 void do_monitor(ObjectMonitor* mid) { 629 if (mid->owner() == _thread) { 630 oop object = (oop) mid->object(); 631 if (!_stack_trace->is_owned_monitor_on_stack(object)) { 632 _stack_trace->add_jni_locked_monitor(object); 633 } 634 } 635 } 636 }; 637 638 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) { 639 _thread = t; 640 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true); 641 _depth = 0; 642 _with_locked_monitors = with_locked_monitors; 643 if (_with_locked_monitors) { 644 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true); 645 } else { 646 _jni_locked_monitors = NULL; 647 } 648 } 649 650 ThreadStackTrace::~ThreadStackTrace() { 651 for (int i = 0; i < _frames->length(); i++) { 652 delete _frames->at(i); 653 } 654 delete _frames; 655 if (_jni_locked_monitors != NULL) { 656 delete _jni_locked_monitors; 657 } 658 } 659 660 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) { 661 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 662 663 if (_thread->has_last_Java_frame()) { 664 RegisterMap reg_map(_thread); 665 vframe* start_vf = _thread->last_java_vframe(®_map); 666 int count = 0; 667 for (vframe* f = start_vf; f; f = f->sender() ) { 668 if (maxDepth >= 0 && count == maxDepth) { 669 // Skip frames if more than maxDepth 670 break; 671 } 672 if (f->is_java_frame()) { 673 javaVFrame* jvf = javaVFrame::cast(f); 674 add_stack_frame(jvf); 675 count++; 676 } else { 677 // Ignore non-Java frames 678 } 679 } 680 } 681 682 if (_with_locked_monitors) { 683 // Iterate inflated monitors and find monitors locked by this thread 684 // not found in the stack 685 InflatedMonitorsClosure imc(_thread, this); 686 ObjectSynchronizer::monitors_iterate(&imc); 687 } 688 } 689 690 691 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) { 692 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 693 694 bool found = false; 695 int num_frames = get_stack_depth(); 696 for (int depth = 0; depth < num_frames; depth++) { 697 StackFrameInfo* frame = stack_frame_at(depth); 698 int len = frame->num_locked_monitors(); 699 GrowableArray<oop>* locked_monitors = frame->locked_monitors(); 700 for (int j = 0; j < len; j++) { 701 oop monitor = locked_monitors->at(j); 702 assert(monitor != NULL, "must be a Java object"); 703 if (monitor == object) { 704 found = true; 705 break; 706 } 707 } 708 } 709 return found; 710 } 711 712 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) { 713 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass(); 714 assert(ik != NULL, "must be loaded in 1.4+"); 715 716 // Allocate an array of java/lang/StackTraceElement object 717 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH); 718 objArrayHandle backtrace(THREAD, ste); 719 for (int j = 0; j < _depth; j++) { 720 StackFrameInfo* frame = _frames->at(j); 721 methodHandle mh(THREAD, frame->method()); 722 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH); 723 backtrace->obj_at_put(j, element); 724 } 725 return backtrace; 726 } 727 728 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) { 729 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors); 730 _frames->append(frame); 731 _depth++; 732 } 733 734 void ThreadStackTrace::oops_do(OopClosure* f) { 735 int length = _frames->length(); 736 for (int i = 0; i < length; i++) { 737 _frames->at(i)->oops_do(f); 738 } 739 740 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); 741 for (int j = 0; j < length; j++) { 742 f->do_oop((oop*) _jni_locked_monitors->adr_at(j)); 743 } 744 } 745 746 void ThreadStackTrace::metadata_do(void f(Metadata*)) { 747 int length = _frames->length(); 748 for (int i = 0; i < length; i++) { 749 _frames->at(i)->metadata_do(f); 750 } 751 } 752 753 754 ConcurrentLocksDump::~ConcurrentLocksDump() { 755 if (_retain_map_on_free) { 756 return; 757 } 758 759 for (ThreadConcurrentLocks* t = _map; t != NULL;) { 760 ThreadConcurrentLocks* tcl = t; 761 t = t->next(); 762 delete tcl; 763 } 764 } 765 766 void ConcurrentLocksDump::dump_at_safepoint() { 767 // dump all locked concurrent locks 768 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 769 770 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */); 771 772 // Find all instances of AbstractOwnableSynchronizer 773 HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(), 774 aos_objects); 775 // Build a map of thread to its owned AQS locks 776 build_map(aos_objects); 777 778 delete aos_objects; 779 } 780 781 782 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer 783 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) { 784 int length = aos_objects->length(); 785 for (int i = 0; i < length; i++) { 786 oop o = aos_objects->at(i); 787 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o); 788 if (owner_thread_obj != NULL) { 789 // See comments in ThreadConcurrentLocks to see how this 790 // JavaThread* is protected. 791 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj); 792 assert(o->is_instance(), "Must be an instanceOop"); 793 add_lock(thread, (instanceOop) o); 794 } 795 } 796 } 797 798 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) { 799 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread); 800 if (tcl != NULL) { 801 tcl->add_lock(o); 802 return; 803 } 804 805 // First owned lock found for this thread 806 tcl = new ThreadConcurrentLocks(thread); 807 tcl->add_lock(o); 808 if (_map == NULL) { 809 _map = tcl; 810 } else { 811 _last->set_next(tcl); 812 } 813 _last = tcl; 814 } 815 816 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) { 817 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) { 818 if (tcl->java_thread() == thread) { 819 return tcl; 820 } 821 } 822 return NULL; 823 } 824 825 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) { 826 st->print_cr(" Locked ownable synchronizers:"); 827 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t); 828 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL); 829 if (locks == NULL || locks->is_empty()) { 830 st->print_cr("\t- None"); 831 st->cr(); 832 return; 833 } 834 835 for (int i = 0; i < locks->length(); i++) { 836 instanceOop obj = locks->at(i); 837 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name()); 838 } 839 st->cr(); 840 } 841 842 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) { 843 _thread = thread; 844 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true); 845 _next = NULL; 846 } 847 848 ThreadConcurrentLocks::~ThreadConcurrentLocks() { 849 delete _owned_locks; 850 } 851 852 void ThreadConcurrentLocks::add_lock(instanceOop o) { 853 _owned_locks->append(o); 854 } 855 856 void ThreadConcurrentLocks::oops_do(OopClosure* f) { 857 int length = _owned_locks->length(); 858 for (int i = 0; i < length; i++) { 859 f->do_oop((oop*) _owned_locks->adr_at(i)); 860 } 861 } 862 863 ThreadStatistics::ThreadStatistics() { 864 _contended_enter_count = 0; 865 _monitor_wait_count = 0; 866 _sleep_count = 0; 867 _count_pending_reset = false; 868 _timer_pending_reset = false; 869 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts)); 870 } 871 872 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) { 873 _thread = thread; 874 _threadObj = thread->threadObj(); 875 876 ThreadStatistics* stat = thread->get_thread_stat(); 877 _contended_enter_ticks = stat->contended_enter_ticks(); 878 _contended_enter_count = stat->contended_enter_count(); 879 _monitor_wait_ticks = stat->monitor_wait_ticks(); 880 _monitor_wait_count = stat->monitor_wait_count(); 881 _sleep_ticks = stat->sleep_ticks(); 882 _sleep_count = stat->sleep_count(); 883 884 _thread_status = java_lang_Thread::get_thread_status(_threadObj); 885 _is_ext_suspended = thread->is_being_ext_suspended(); 886 _is_in_native = (thread->thread_state() == _thread_in_native); 887 888 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER || 889 _thread_status == java_lang_Thread::IN_OBJECT_WAIT || 890 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) { 891 892 Handle obj = ThreadService::get_current_contended_monitor(thread); 893 if (obj() == NULL) { 894 // monitor no longer exists; thread is not blocked 895 _thread_status = java_lang_Thread::RUNNABLE; 896 } else { 897 _blocker_object = obj(); 898 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj); 899 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER) 900 || (owner != NULL && owner->is_attaching_via_jni())) { 901 // ownership information of the monitor is not available 902 // (may no longer be owned or releasing to some other thread) 903 // make this thread in RUNNABLE state. 904 // And when the owner thread is in attaching state, the java thread 905 // is not completely initialized. For example thread name and id 906 // and may not be set, so hide the attaching thread. 907 _thread_status = java_lang_Thread::RUNNABLE; 908 _blocker_object = NULL; 909 } else if (owner != NULL) { 910 _blocker_object_owner = owner->threadObj(); 911 } 912 } 913 } 914 915 // Support for JSR-166 locks 916 if (_thread_status == java_lang_Thread::PARKED || _thread_status == java_lang_Thread::PARKED_TIMED) { 917 _blocker_object = thread->current_park_blocker(); 918 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { 919 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object); 920 } 921 } 922 } 923 924 ThreadSnapshot::~ThreadSnapshot() { 925 delete _stack_trace; 926 delete _concurrent_locks; 927 } 928 929 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) { 930 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors); 931 _stack_trace->dump_stack_at_safepoint(max_depth); 932 } 933 934 935 void ThreadSnapshot::oops_do(OopClosure* f) { 936 f->do_oop(&_threadObj); 937 f->do_oop(&_blocker_object); 938 f->do_oop(&_blocker_object_owner); 939 if (_stack_trace != NULL) { 940 _stack_trace->oops_do(f); 941 } 942 if (_concurrent_locks != NULL) { 943 _concurrent_locks->oops_do(f); 944 } 945 } 946 947 void ThreadSnapshot::metadata_do(void f(Metadata*)) { 948 if (_stack_trace != NULL) { 949 _stack_trace->metadata_do(f); 950 } 951 } 952 953 954 DeadlockCycle::DeadlockCycle() { 955 _is_deadlock = false; 956 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true); 957 _next = NULL; 958 } 959 960 DeadlockCycle::~DeadlockCycle() { 961 delete _threads; 962 } 963 964 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const { 965 st->cr(); 966 st->print_cr("Found one Java-level deadlock:"); 967 st->print("============================="); 968 969 JavaThread* currentThread; 970 ObjectMonitor* waitingToLockMonitor; 971 JvmtiRawMonitor* waitingToLockRawMonitor; 972 oop waitingToLockBlocker; 973 int len = _threads->length(); 974 for (int i = 0; i < len; i++) { 975 currentThread = _threads->at(i); 976 waitingToLockMonitor = currentThread->current_pending_monitor(); 977 waitingToLockRawMonitor = currentThread->current_pending_raw_monitor(); 978 waitingToLockBlocker = currentThread->current_park_blocker(); 979 st->cr(); 980 st->print_cr("\"%s\":", currentThread->get_thread_name()); 981 const char* owner_desc = ",\n which is held by"; 982 983 // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor 984 // sets the current pending monitor, it is possible to then see a pending raw monitor as well. 985 if (waitingToLockRawMonitor != NULL) { 986 st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor)); 987 Thread* owner = waitingToLockRawMonitor->owner(); 988 // Could be NULL as the raw monitor could be released at any time if held by non-JavaThread 989 if (owner != NULL) { 990 if (owner->is_Java_thread()) { 991 currentThread = (JavaThread*) owner; 992 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 993 } else { 994 st->print_cr(",\n which has now been released"); 995 } 996 } else { 997 st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner)); 998 } 999 } 1000 1001 if (waitingToLockMonitor != NULL) { 1002 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor)); 1003 oop obj = (oop)waitingToLockMonitor->object(); 1004 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj), 1005 obj->klass()->external_name()); 1006 1007 if (!currentThread->current_pending_monitor_is_from_java()) { 1008 owner_desc = "\n in JNI, which is held by"; 1009 } 1010 currentThread = Threads::owning_thread_from_monitor_owner(t_list, 1011 (address)waitingToLockMonitor->owner()); 1012 if (currentThread == NULL) { 1013 // The deadlock was detected at a safepoint so the JavaThread 1014 // that owns waitingToLockMonitor should be findable, but 1015 // if it is not findable, then the previous currentThread is 1016 // blocked permanently. 1017 st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc, 1018 p2i(waitingToLockMonitor->owner())); 1019 continue; 1020 } 1021 } else { 1022 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)", 1023 p2i(waitingToLockBlocker), 1024 waitingToLockBlocker->klass()->external_name()); 1025 assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()), 1026 "Must be an AbstractOwnableSynchronizer"); 1027 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 1028 currentThread = java_lang_Thread::thread(ownerObj); 1029 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL"); 1030 } 1031 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 1032 } 1033 1034 st->cr(); 1035 1036 // Print stack traces 1037 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace; 1038 JavaMonitorsInStackTrace = true; 1039 st->print_cr("Java stack information for the threads listed above:"); 1040 st->print_cr("==================================================="); 1041 for (int j = 0; j < len; j++) { 1042 currentThread = _threads->at(j); 1043 st->print_cr("\"%s\":", currentThread->get_thread_name()); 1044 currentThread->print_stack_on(st); 1045 } 1046 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace; 1047 } 1048 1049 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread, 1050 bool include_jvmti_agent_threads, 1051 bool include_jni_attaching_threads) { 1052 assert(cur_thread == Thread::current(), "Check current thread"); 1053 1054 int init_size = ThreadService::get_live_thread_count(); 1055 _threads_array = new GrowableArray<instanceHandle>(init_size); 1056 1057 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) { 1058 // skips JavaThreads in the process of exiting 1059 // and also skips VM internal JavaThreads 1060 // Threads in _thread_new or _thread_new_trans state are included. 1061 // i.e. threads have been started but not yet running. 1062 if (jt->threadObj() == NULL || 1063 jt->is_exiting() || 1064 !java_lang_Thread::is_alive(jt->threadObj()) || 1065 jt->is_hidden_from_external_view()) { 1066 continue; 1067 } 1068 1069 // skip agent threads 1070 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) { 1071 continue; 1072 } 1073 1074 // skip jni threads in the process of attaching 1075 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) { 1076 continue; 1077 } 1078 1079 instanceHandle h(cur_thread, (instanceOop) jt->threadObj()); 1080 _threads_array->append(h); 1081 } 1082 }