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 ObjectMonitorHandle omh; 212 ObjectMonitor *wait_obj = thread->current_waiting_monitor(&omh); 213 214 oop obj = NULL; 215 if (wait_obj != NULL) { 216 // thread is doing an Object.wait() call 217 obj = (oop) wait_obj->object(); 218 assert(obj != NULL, "Object.wait() should have an object"); 219 } else { 220 ObjectMonitorHandle omh; 221 ObjectMonitor *enter_obj = thread->current_pending_monitor(&omh); 222 if (enter_obj != NULL) { 223 // thread is trying to enter() an ObjectMonitor. 224 obj = (oop) enter_obj->object(); 225 assert(obj != NULL, "ObjectMonitor should have an associated object!"); 226 } 227 } 228 229 Handle h(Thread::current(), obj); 230 return h; 231 } 232 233 bool ThreadService::set_thread_monitoring_contention(bool flag) { 234 MutexLocker m(Management_lock); 235 236 bool prev = _thread_monitoring_contention_enabled; 237 _thread_monitoring_contention_enabled = flag; 238 239 return prev; 240 } 241 242 bool ThreadService::set_thread_cpu_time_enabled(bool flag) { 243 MutexLocker m(Management_lock); 244 245 bool prev = _thread_cpu_time_enabled; 246 _thread_cpu_time_enabled = flag; 247 248 return prev; 249 } 250 251 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) { 252 MutexLocker m(Management_lock); 253 254 bool prev = _thread_allocated_memory_enabled; 255 _thread_allocated_memory_enabled = flag; 256 257 return prev; 258 } 259 260 // GC support 261 void ThreadService::oops_do(OopClosure* f) { 262 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 263 dump->oops_do(f); 264 } 265 } 266 267 void ThreadService::metadata_do(void f(Metadata*)) { 268 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 269 dump->metadata_do(f); 270 } 271 } 272 273 void ThreadService::add_thread_dump(ThreadDumpResult* dump) { 274 MutexLocker ml(Management_lock); 275 if (_threaddump_list == NULL) { 276 _threaddump_list = dump; 277 } else { 278 dump->set_next(_threaddump_list); 279 _threaddump_list = dump; 280 } 281 } 282 283 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) { 284 MutexLocker ml(Management_lock); 285 286 ThreadDumpResult* prev = NULL; 287 bool found = false; 288 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) { 289 if (d == dump) { 290 if (prev == NULL) { 291 _threaddump_list = dump->next(); 292 } else { 293 prev->set_next(dump->next()); 294 } 295 found = true; 296 break; 297 } 298 } 299 assert(found, "The threaddump result to be removed must exist."); 300 } 301 302 // Dump stack trace of threads specified in the given threads array. 303 // Returns StackTraceElement[][] each element is the stack trace of a thread in 304 // the corresponding entry in the given threads array 305 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads, 306 int num_threads, 307 TRAPS) { 308 assert(num_threads > 0, "just checking"); 309 310 ThreadDumpResult dump_result; 311 VM_ThreadDump op(&dump_result, 312 threads, 313 num_threads, 314 -1, /* entire stack */ 315 false, /* with locked monitors */ 316 false /* with locked synchronizers */); 317 VMThread::execute(&op); 318 319 // Allocate the resulting StackTraceElement[][] object 320 321 ResourceMark rm(THREAD); 322 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH); 323 ObjArrayKlass* ik = ObjArrayKlass::cast(k); 324 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH); 325 objArrayHandle result_obj(THREAD, r); 326 327 int num_snapshots = dump_result.num_snapshots(); 328 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots"); 329 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot"); 330 int i = 0; 331 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) { 332 ThreadStackTrace* stacktrace = ts->get_stack_trace(); 333 if (stacktrace == NULL) { 334 // No stack trace 335 result_obj->obj_at_put(i, NULL); 336 } else { 337 // Construct an array of java/lang/StackTraceElement object 338 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH); 339 result_obj->obj_at_put(i, backtrace_h()); 340 } 341 } 342 343 return result_obj; 344 } 345 346 void ThreadService::reset_contention_count_stat(JavaThread* thread) { 347 ThreadStatistics* stat = thread->get_thread_stat(); 348 if (stat != NULL) { 349 stat->reset_count_stat(); 350 } 351 } 352 353 void ThreadService::reset_contention_time_stat(JavaThread* thread) { 354 ThreadStatistics* stat = thread->get_thread_stat(); 355 if (stat != NULL) { 356 stat->reset_time_stat(); 357 } 358 } 359 360 // Find deadlocks involving raw monitors, object monitors and concurrent locks 361 // if concurrent_locks is true. 362 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) { 363 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 364 365 // This code was modified from the original Threads::find_deadlocks code. 366 int globalDfn = 0, thisDfn; 367 ObjectMonitorHandle omh; 368 ObjectMonitor* waitingToLockMonitor = NULL; 369 JvmtiRawMonitor* waitingToLockRawMonitor = NULL; 370 oop waitingToLockBlocker = NULL; 371 bool blocked_on_monitor = false; 372 JavaThread *currentThread, *previousThread; 373 int num_deadlocks = 0; 374 375 // Initialize the depth-first-number for each JavaThread. 376 JavaThreadIterator jti(t_list); 377 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 378 jt->set_depth_first_number(-1); 379 } 380 381 DeadlockCycle* deadlocks = NULL; 382 DeadlockCycle* last = NULL; 383 DeadlockCycle* cycle = new DeadlockCycle(); 384 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 385 if (jt->depth_first_number() >= 0) { 386 // this thread was already visited 387 continue; 388 } 389 390 thisDfn = globalDfn; 391 jt->set_depth_first_number(globalDfn++); 392 previousThread = jt; 393 currentThread = jt; 394 395 cycle->reset(); 396 397 if (waitingToLockMonitor != NULL) { 398 // Done with the current waitingToLockMonitor value so release 399 // the ObjectMonitorHandle manually before we use it again: 400 omh.unset_om_ptr(); 401 } 402 // When there is a deadlock, all the monitors involved in the dependency 403 // cycle must be contended and heavyweight. So we only care about the 404 // heavyweight monitor a thread is waiting to lock. 405 waitingToLockMonitor = jt->current_pending_monitor(&omh); 406 // JVM TI raw monitors can also be involved in deadlocks, and we can be 407 // waiting to lock both a raw monitor and ObjectMonitor at the same time. 408 // It isn't clear how to make deadlock detection work correctly if that 409 // happens. 410 waitingToLockRawMonitor = jt->current_pending_raw_monitor(); 411 412 if (concurrent_locks) { 413 waitingToLockBlocker = jt->current_park_blocker(); 414 } 415 416 while (waitingToLockMonitor != NULL || 417 waitingToLockRawMonitor != NULL || 418 waitingToLockBlocker != NULL) { 419 cycle->add_thread(currentThread); 420 // Give preference to the raw monitor 421 if (waitingToLockRawMonitor != NULL) { 422 Thread* owner = waitingToLockRawMonitor->owner(); 423 if (owner != NULL && // the raw monitor could be released at any time 424 owner->is_Java_thread()) { 425 // only JavaThreads can be reported here 426 currentThread = (JavaThread*) owner; 427 } 428 } else if (waitingToLockMonitor != NULL) { 429 address currentOwner = (address)waitingToLockMonitor->owner(); 430 if (currentOwner != NULL) { 431 currentThread = Threads::owning_thread_from_monitor_owner(t_list, 432 currentOwner); 433 if (currentThread == NULL) { 434 // This function is called at a safepoint so the JavaThread 435 // that owns waitingToLockMonitor should be findable, but 436 // if it is not findable, then the previous currentThread is 437 // blocked permanently. We record this as a deadlock. 438 num_deadlocks++; 439 440 cycle->set_deadlock(true); 441 442 // add this cycle to the deadlocks list 443 if (deadlocks == NULL) { 444 deadlocks = cycle; 445 } else { 446 last->set_next(cycle); 447 } 448 last = cycle; 449 cycle = new DeadlockCycle(); 450 break; 451 } 452 } 453 } else { 454 if (concurrent_locks) { 455 if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { 456 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 457 // This JavaThread (if there is one) is protected by the 458 // ThreadsListSetter in VM_FindDeadlocks::doit(). 459 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL; 460 } else { 461 currentThread = NULL; 462 } 463 } 464 } 465 466 if (currentThread == NULL) { 467 // No dependency on another thread 468 break; 469 } 470 if (currentThread->depth_first_number() < 0) { 471 // First visit to this thread 472 currentThread->set_depth_first_number(globalDfn++); 473 } else if (currentThread->depth_first_number() < thisDfn) { 474 // Thread already visited, and not on a (new) cycle 475 break; 476 } else if (currentThread == previousThread) { 477 // Self-loop, ignore 478 break; 479 } else { 480 // We have a (new) cycle 481 num_deadlocks++; 482 483 cycle->set_deadlock(true); 484 485 // add this cycle to the deadlocks list 486 if (deadlocks == NULL) { 487 deadlocks = cycle; 488 } else { 489 last->set_next(cycle); 490 } 491 last = cycle; 492 cycle = new DeadlockCycle(); 493 break; 494 } 495 previousThread = currentThread; 496 if (waitingToLockMonitor != NULL) { 497 // Done with the current waitingToLockMonitor value so release 498 // the ObjectMonitorHandle manually before we use it again: 499 omh.unset_om_ptr(); 500 } 501 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(&omh); 502 if (concurrent_locks) { 503 waitingToLockBlocker = currentThread->current_park_blocker(); 504 } 505 } 506 507 } 508 delete cycle; 509 return deadlocks; 510 } 511 512 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() { 513 514 // Create a new ThreadDumpResult object and append to the list. 515 // If GC happens before this function returns, Method* 516 // in the stack trace will be visited. 517 ThreadService::add_thread_dump(this); 518 } 519 520 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() { 521 // Create a new ThreadDumpResult object and append to the list. 522 // If GC happens before this function returns, oops 523 // will be visited. 524 ThreadService::add_thread_dump(this); 525 } 526 527 ThreadDumpResult::~ThreadDumpResult() { 528 ThreadService::remove_thread_dump(this); 529 530 // free all the ThreadSnapshot objects created during 531 // the VM_ThreadDump operation 532 ThreadSnapshot* ts = _snapshots; 533 while (ts != NULL) { 534 ThreadSnapshot* p = ts; 535 ts = ts->next(); 536 delete p; 537 } 538 } 539 540 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() { 541 ThreadSnapshot* ts = new ThreadSnapshot(); 542 link_thread_snapshot(ts); 543 return ts; 544 } 545 546 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) { 547 // Note: it is very important that the ThreadSnapshot* gets linked before 548 // ThreadSnapshot::initialize gets called. This is to ensure that 549 // ThreadSnapshot::oops_do can get called prior to the field 550 // ThreadSnapshot::_threadObj being assigned a value (to prevent a dangling 551 // oop). 552 ThreadSnapshot* ts = new ThreadSnapshot(); 553 link_thread_snapshot(ts); 554 ts->initialize(t_list(), thread); 555 return ts; 556 } 557 558 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) { 559 assert(_num_threads == 0 || _num_snapshots < _num_threads, 560 "_num_snapshots must be less than _num_threads"); 561 _num_snapshots++; 562 if (_snapshots == NULL) { 563 _snapshots = ts; 564 } else { 565 _last->set_next(ts); 566 } 567 _last = ts; 568 } 569 570 void ThreadDumpResult::oops_do(OopClosure* f) { 571 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 572 ts->oops_do(f); 573 } 574 } 575 576 void ThreadDumpResult::metadata_do(void f(Metadata*)) { 577 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 578 ts->metadata_do(f); 579 } 580 } 581 582 ThreadsList* ThreadDumpResult::t_list() { 583 return _setter.list(); 584 } 585 586 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) { 587 _method = jvf->method(); 588 _bci = jvf->bci(); 589 _class_holder = _method->method_holder()->klass_holder(); 590 _locked_monitors = NULL; 591 if (with_lock_info) { 592 ResourceMark rm; 593 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors(); 594 int length = list->length(); 595 if (length > 0) { 596 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true); 597 for (int i = 0; i < length; i++) { 598 MonitorInfo* monitor = list->at(i); 599 assert(monitor->owner() != NULL, "This monitor must have an owning object"); 600 _locked_monitors->append(monitor->owner()); 601 } 602 } 603 } 604 } 605 606 void StackFrameInfo::oops_do(OopClosure* f) { 607 if (_locked_monitors != NULL) { 608 int length = _locked_monitors->length(); 609 for (int i = 0; i < length; i++) { 610 f->do_oop((oop*) _locked_monitors->adr_at(i)); 611 } 612 } 613 f->do_oop(&_class_holder); 614 } 615 616 void StackFrameInfo::metadata_do(void f(Metadata*)) { 617 f(_method); 618 } 619 620 void StackFrameInfo::print_on(outputStream* st) const { 621 ResourceMark rm; 622 java_lang_Throwable::print_stack_element(st, method(), bci()); 623 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0); 624 for (int i = 0; i < len; i++) { 625 oop o = _locked_monitors->at(i); 626 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name()); 627 } 628 629 } 630 631 // Iterate through monitor cache to find JNI locked monitors 632 class InflatedMonitorsClosure: public MonitorClosure { 633 private: 634 ThreadStackTrace* _stack_trace; 635 Thread* _thread; 636 public: 637 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) { 638 _thread = t; 639 _stack_trace = st; 640 } 641 void do_monitor(ObjectMonitor* mid) { 642 if (mid->owner() == _thread) { 643 oop object = (oop) mid->object(); 644 if (!_stack_trace->is_owned_monitor_on_stack(object)) { 645 _stack_trace->add_jni_locked_monitor(object); 646 } 647 } 648 } 649 }; 650 651 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) { 652 _thread = t; 653 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true); 654 _depth = 0; 655 _with_locked_monitors = with_locked_monitors; 656 if (_with_locked_monitors) { 657 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true); 658 } else { 659 _jni_locked_monitors = NULL; 660 } 661 } 662 663 ThreadStackTrace::~ThreadStackTrace() { 664 for (int i = 0; i < _frames->length(); i++) { 665 delete _frames->at(i); 666 } 667 delete _frames; 668 if (_jni_locked_monitors != NULL) { 669 delete _jni_locked_monitors; 670 } 671 } 672 673 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) { 674 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 675 676 if (_thread->has_last_Java_frame()) { 677 RegisterMap reg_map(_thread); 678 vframe* start_vf = _thread->last_java_vframe(®_map); 679 int count = 0; 680 for (vframe* f = start_vf; f; f = f->sender() ) { 681 if (maxDepth >= 0 && count == maxDepth) { 682 // Skip frames if more than maxDepth 683 break; 684 } 685 if (f->is_java_frame()) { 686 javaVFrame* jvf = javaVFrame::cast(f); 687 add_stack_frame(jvf); 688 count++; 689 } else { 690 // Ignore non-Java frames 691 } 692 } 693 } 694 695 if (_with_locked_monitors) { 696 // Iterate inflated monitors and find monitors locked by this thread 697 // not found in the stack 698 InflatedMonitorsClosure imc(_thread, this); 699 ObjectSynchronizer::monitors_iterate(&imc); 700 } 701 } 702 703 704 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) { 705 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 706 707 bool found = false; 708 int num_frames = get_stack_depth(); 709 for (int depth = 0; depth < num_frames; depth++) { 710 StackFrameInfo* frame = stack_frame_at(depth); 711 int len = frame->num_locked_monitors(); 712 GrowableArray<oop>* locked_monitors = frame->locked_monitors(); 713 for (int j = 0; j < len; j++) { 714 oop monitor = locked_monitors->at(j); 715 assert(monitor != NULL, "must be a Java object"); 716 if (monitor == object) { 717 found = true; 718 break; 719 } 720 } 721 } 722 return found; 723 } 724 725 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) { 726 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass(); 727 assert(ik != NULL, "must be loaded in 1.4+"); 728 729 // Allocate an array of java/lang/StackTraceElement object 730 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH); 731 objArrayHandle backtrace(THREAD, ste); 732 for (int j = 0; j < _depth; j++) { 733 StackFrameInfo* frame = _frames->at(j); 734 methodHandle mh(THREAD, frame->method()); 735 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH); 736 backtrace->obj_at_put(j, element); 737 } 738 return backtrace; 739 } 740 741 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) { 742 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors); 743 _frames->append(frame); 744 _depth++; 745 } 746 747 void ThreadStackTrace::oops_do(OopClosure* f) { 748 int length = _frames->length(); 749 for (int i = 0; i < length; i++) { 750 _frames->at(i)->oops_do(f); 751 } 752 753 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); 754 for (int j = 0; j < length; j++) { 755 f->do_oop((oop*) _jni_locked_monitors->adr_at(j)); 756 } 757 } 758 759 void ThreadStackTrace::metadata_do(void f(Metadata*)) { 760 int length = _frames->length(); 761 for (int i = 0; i < length; i++) { 762 _frames->at(i)->metadata_do(f); 763 } 764 } 765 766 767 ConcurrentLocksDump::~ConcurrentLocksDump() { 768 if (_retain_map_on_free) { 769 return; 770 } 771 772 for (ThreadConcurrentLocks* t = _map; t != NULL;) { 773 ThreadConcurrentLocks* tcl = t; 774 t = t->next(); 775 delete tcl; 776 } 777 } 778 779 void ConcurrentLocksDump::dump_at_safepoint() { 780 // dump all locked concurrent locks 781 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 782 783 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */); 784 785 // Find all instances of AbstractOwnableSynchronizer 786 HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(), 787 aos_objects); 788 // Build a map of thread to its owned AQS locks 789 build_map(aos_objects); 790 791 delete aos_objects; 792 } 793 794 795 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer 796 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) { 797 int length = aos_objects->length(); 798 for (int i = 0; i < length; i++) { 799 oop o = aos_objects->at(i); 800 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o); 801 if (owner_thread_obj != NULL) { 802 // See comments in ThreadConcurrentLocks to see how this 803 // JavaThread* is protected. 804 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj); 805 assert(o->is_instance(), "Must be an instanceOop"); 806 add_lock(thread, (instanceOop) o); 807 } 808 } 809 } 810 811 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) { 812 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread); 813 if (tcl != NULL) { 814 tcl->add_lock(o); 815 return; 816 } 817 818 // First owned lock found for this thread 819 tcl = new ThreadConcurrentLocks(thread); 820 tcl->add_lock(o); 821 if (_map == NULL) { 822 _map = tcl; 823 } else { 824 _last->set_next(tcl); 825 } 826 _last = tcl; 827 } 828 829 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) { 830 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) { 831 if (tcl->java_thread() == thread) { 832 return tcl; 833 } 834 } 835 return NULL; 836 } 837 838 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) { 839 st->print_cr(" Locked ownable synchronizers:"); 840 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t); 841 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL); 842 if (locks == NULL || locks->is_empty()) { 843 st->print_cr("\t- None"); 844 st->cr(); 845 return; 846 } 847 848 for (int i = 0; i < locks->length(); i++) { 849 instanceOop obj = locks->at(i); 850 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name()); 851 } 852 st->cr(); 853 } 854 855 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) { 856 _thread = thread; 857 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true); 858 _next = NULL; 859 } 860 861 ThreadConcurrentLocks::~ThreadConcurrentLocks() { 862 delete _owned_locks; 863 } 864 865 void ThreadConcurrentLocks::add_lock(instanceOop o) { 866 _owned_locks->append(o); 867 } 868 869 void ThreadConcurrentLocks::oops_do(OopClosure* f) { 870 int length = _owned_locks->length(); 871 for (int i = 0; i < length; i++) { 872 f->do_oop((oop*) _owned_locks->adr_at(i)); 873 } 874 } 875 876 ThreadStatistics::ThreadStatistics() { 877 _contended_enter_count = 0; 878 _monitor_wait_count = 0; 879 _sleep_count = 0; 880 _count_pending_reset = false; 881 _timer_pending_reset = false; 882 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts)); 883 } 884 885 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) { 886 _thread = thread; 887 _threadObj = thread->threadObj(); 888 889 ThreadStatistics* stat = thread->get_thread_stat(); 890 _contended_enter_ticks = stat->contended_enter_ticks(); 891 _contended_enter_count = stat->contended_enter_count(); 892 _monitor_wait_ticks = stat->monitor_wait_ticks(); 893 _monitor_wait_count = stat->monitor_wait_count(); 894 _sleep_ticks = stat->sleep_ticks(); 895 _sleep_count = stat->sleep_count(); 896 897 _thread_status = java_lang_Thread::get_thread_status(_threadObj); 898 _is_ext_suspended = thread->is_being_ext_suspended(); 899 _is_in_native = (thread->thread_state() == _thread_in_native); 900 901 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER || 902 _thread_status == java_lang_Thread::IN_OBJECT_WAIT || 903 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) { 904 905 Handle obj = ThreadService::get_current_contended_monitor(thread); 906 if (obj() == NULL) { 907 // monitor no longer exists; thread is not blocked 908 _thread_status = java_lang_Thread::RUNNABLE; 909 } else { 910 _blocker_object = obj(); 911 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj); 912 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER) 913 || (owner != NULL && owner->is_attaching_via_jni())) { 914 // ownership information of the monitor is not available 915 // (may no longer be owned or releasing to some other thread) 916 // make this thread in RUNNABLE state. 917 // And when the owner thread is in attaching state, the java thread 918 // is not completely initialized. For example thread name and id 919 // and may not be set, so hide the attaching thread. 920 _thread_status = java_lang_Thread::RUNNABLE; 921 _blocker_object = NULL; 922 } else if (owner != NULL) { 923 _blocker_object_owner = owner->threadObj(); 924 } 925 } 926 } 927 928 // Support for JSR-166 locks 929 if (_thread_status == java_lang_Thread::PARKED || _thread_status == java_lang_Thread::PARKED_TIMED) { 930 _blocker_object = thread->current_park_blocker(); 931 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { 932 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object); 933 } 934 } 935 } 936 937 ThreadSnapshot::~ThreadSnapshot() { 938 delete _stack_trace; 939 delete _concurrent_locks; 940 } 941 942 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) { 943 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors); 944 _stack_trace->dump_stack_at_safepoint(max_depth); 945 } 946 947 948 void ThreadSnapshot::oops_do(OopClosure* f) { 949 f->do_oop(&_threadObj); 950 f->do_oop(&_blocker_object); 951 f->do_oop(&_blocker_object_owner); 952 if (_stack_trace != NULL) { 953 _stack_trace->oops_do(f); 954 } 955 if (_concurrent_locks != NULL) { 956 _concurrent_locks->oops_do(f); 957 } 958 } 959 960 void ThreadSnapshot::metadata_do(void f(Metadata*)) { 961 if (_stack_trace != NULL) { 962 _stack_trace->metadata_do(f); 963 } 964 } 965 966 967 DeadlockCycle::DeadlockCycle() { 968 _is_deadlock = false; 969 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true); 970 _next = NULL; 971 } 972 973 DeadlockCycle::~DeadlockCycle() { 974 delete _threads; 975 } 976 977 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const { 978 st->cr(); 979 st->print_cr("Found one Java-level deadlock:"); 980 st->print("============================="); 981 982 JavaThread* currentThread; 983 JvmtiRawMonitor* waitingToLockRawMonitor; 984 oop waitingToLockBlocker; 985 int len = _threads->length(); 986 for (int i = 0; i < len; i++) { 987 currentThread = _threads->at(i); 988 ObjectMonitorHandle omh; 989 ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor(&omh); 990 waitingToLockRawMonitor = currentThread->current_pending_raw_monitor(); 991 waitingToLockBlocker = currentThread->current_park_blocker(); 992 st->cr(); 993 st->print_cr("\"%s\":", currentThread->get_thread_name()); 994 const char* owner_desc = ",\n which is held by"; 995 996 // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor 997 // sets the current pending monitor, it is possible to then see a pending raw monitor as well. 998 if (waitingToLockRawMonitor != NULL) { 999 st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor)); 1000 Thread* owner = waitingToLockRawMonitor->owner(); 1001 // Could be NULL as the raw monitor could be released at any time if held by non-JavaThread 1002 if (owner != NULL) { 1003 if (owner->is_Java_thread()) { 1004 currentThread = (JavaThread*) owner; 1005 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 1006 } else { 1007 st->print_cr(",\n which has now been released"); 1008 } 1009 } else { 1010 st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner)); 1011 } 1012 } 1013 1014 if (waitingToLockMonitor != NULL) { 1015 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor)); 1016 oop obj = (oop)waitingToLockMonitor->object(); 1017 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj), 1018 obj->klass()->external_name()); 1019 1020 if (!currentThread->current_pending_monitor_is_from_java()) { 1021 owner_desc = "\n in JNI, which is held by"; 1022 } 1023 currentThread = Threads::owning_thread_from_monitor_owner(t_list, 1024 (address)waitingToLockMonitor->owner()); 1025 if (currentThread == NULL) { 1026 // The deadlock was detected at a safepoint so the JavaThread 1027 // that owns waitingToLockMonitor should be findable, but 1028 // if it is not findable, then the previous currentThread is 1029 // blocked permanently. 1030 st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc, 1031 p2i(waitingToLockMonitor->owner())); 1032 continue; 1033 } 1034 } else { 1035 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)", 1036 p2i(waitingToLockBlocker), 1037 waitingToLockBlocker->klass()->external_name()); 1038 assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()), 1039 "Must be an AbstractOwnableSynchronizer"); 1040 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 1041 currentThread = java_lang_Thread::thread(ownerObj); 1042 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL"); 1043 } 1044 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 1045 } 1046 1047 st->cr(); 1048 1049 // Print stack traces 1050 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace; 1051 JavaMonitorsInStackTrace = true; 1052 st->print_cr("Java stack information for the threads listed above:"); 1053 st->print_cr("==================================================="); 1054 for (int j = 0; j < len; j++) { 1055 currentThread = _threads->at(j); 1056 st->print_cr("\"%s\":", currentThread->get_thread_name()); 1057 currentThread->print_stack_on(st); 1058 } 1059 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace; 1060 } 1061 1062 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread, 1063 bool include_jvmti_agent_threads, 1064 bool include_jni_attaching_threads) { 1065 assert(cur_thread == Thread::current(), "Check current thread"); 1066 1067 int init_size = ThreadService::get_live_thread_count(); 1068 _threads_array = new GrowableArray<instanceHandle>(init_size); 1069 1070 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) { 1071 // skips JavaThreads in the process of exiting 1072 // and also skips VM internal JavaThreads 1073 // Threads in _thread_new or _thread_new_trans state are included. 1074 // i.e. threads have been started but not yet running. 1075 if (jt->threadObj() == NULL || 1076 jt->is_exiting() || 1077 !java_lang_Thread::is_alive(jt->threadObj()) || 1078 jt->is_hidden_from_external_view()) { 1079 continue; 1080 } 1081 1082 // skip agent threads 1083 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) { 1084 continue; 1085 } 1086 1087 // skip jni threads in the process of attaching 1088 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) { 1089 continue; 1090 } 1091 1092 instanceHandle h(cur_thread, (instanceOop) jt->threadObj()); 1093 _threads_array->append(h); 1094 } 1095 }