1 /* 2 * Copyright (c) 2003, 2021, 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 "classfile/vmClasses.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "gc/shared/oopStorageSet.hpp" 30 #include "memory/allocation.hpp" 31 #include "memory/heapInspection.hpp" 32 #include "memory/oopFactory.hpp" 33 #include "memory/resourceArea.hpp" 34 #include "memory/universe.hpp" 35 #include "oops/instanceKlass.hpp" 36 #include "oops/klass.inline.hpp" 37 #include "oops/objArrayKlass.hpp" 38 #include "oops/objArrayOop.inline.hpp" 39 #include "oops/oop.inline.hpp" 40 #include "oops/oopHandle.inline.hpp" 41 #include "prims/jvmtiRawMonitor.hpp" 42 #include "runtime/atomic.hpp" 43 #include "runtime/handles.inline.hpp" 44 #include "runtime/init.hpp" 45 #include "runtime/objectMonitor.inline.hpp" 46 #include "runtime/thread.inline.hpp" 47 #include "runtime/threadSMR.inline.hpp" 48 #include "runtime/vframe.hpp" 49 #include "runtime/vmThread.hpp" 50 #include "runtime/vmOperations.hpp" 51 #include "services/threadService.hpp" 52 53 // TODO: we need to define a naming convention for perf counters 54 // to distinguish counters for: 55 // - standard JSR174 use 56 // - Hotspot extension (public and committed) 57 // - Hotspot extension (private/internal and uncommitted) 58 59 // Default is disabled. 60 bool ThreadService::_thread_monitoring_contention_enabled = false; 61 bool ThreadService::_thread_cpu_time_enabled = false; 62 bool ThreadService::_thread_allocated_memory_enabled = false; 63 64 PerfCounter* ThreadService::_total_threads_count = NULL; 65 PerfVariable* ThreadService::_live_threads_count = NULL; 66 PerfVariable* ThreadService::_peak_threads_count = NULL; 67 PerfVariable* ThreadService::_daemon_threads_count = NULL; 68 volatile int ThreadService::_atomic_threads_count = 0; 69 volatile int ThreadService::_atomic_daemon_threads_count = 0; 70 71 volatile jlong ThreadService::_exited_allocated_bytes = 0; 72 73 ThreadDumpResult* ThreadService::_threaddump_list = NULL; 74 75 static const int INITIAL_ARRAY_SIZE = 10; 76 77 // OopStorage for thread stack sampling 78 static OopStorage* _thread_service_storage = NULL; 79 80 void ThreadService::init() { 81 EXCEPTION_MARK; 82 83 // These counters are for java.lang.management API support. 84 // They are created even if -XX:-UsePerfData is set and in 85 // that case, they will be allocated on C heap. 86 87 _total_threads_count = 88 PerfDataManager::create_counter(JAVA_THREADS, "started", 89 PerfData::U_Events, CHECK); 90 91 _live_threads_count = 92 PerfDataManager::create_variable(JAVA_THREADS, "live", 93 PerfData::U_None, CHECK); 94 95 _peak_threads_count = 96 PerfDataManager::create_variable(JAVA_THREADS, "livePeak", 97 PerfData::U_None, CHECK); 98 99 _daemon_threads_count = 100 PerfDataManager::create_variable(JAVA_THREADS, "daemon", 101 PerfData::U_None, CHECK); 102 103 if (os::is_thread_cpu_time_supported()) { 104 _thread_cpu_time_enabled = true; 105 } 106 107 _thread_allocated_memory_enabled = true; // Always on, so enable it 108 109 // Initialize OopStorage for thread stack sampling walking 110 _thread_service_storage = OopStorageSet::create_strong("ThreadService OopStorage", 111 mtServiceability); 112 } 113 114 void ThreadService::reset_peak_thread_count() { 115 // Acquire the lock to update the peak thread count 116 // to synchronize with thread addition and removal. 117 MutexLocker mu(Threads_lock); 118 _peak_threads_count->set_value(get_live_thread_count()); 119 } 120 121 static bool is_hidden_thread(JavaThread *thread) { 122 // hide VM internal or JVMTI agent threads 123 return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread(); 124 } 125 126 void ThreadService::add_thread(JavaThread* thread, bool daemon) { 127 assert(Threads_lock->owned_by_self(), "must have threads lock"); 128 129 // Do not count hidden threads 130 if (is_hidden_thread(thread)) { 131 return; 132 } 133 134 _total_threads_count->inc(); 135 _live_threads_count->inc(); 136 Atomic::inc(&_atomic_threads_count); 137 int count = _atomic_threads_count; 138 139 if (count > _peak_threads_count->get_value()) { 140 _peak_threads_count->set_value(count); 141 } 142 143 if (daemon) { 144 _daemon_threads_count->inc(); 145 Atomic::inc(&_atomic_daemon_threads_count); 146 } 147 } 148 149 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) { 150 Atomic::dec(&_atomic_threads_count); 151 152 if (daemon) { 153 Atomic::dec(&_atomic_daemon_threads_count); 154 } 155 } 156 157 void ThreadService::remove_thread(JavaThread* thread, bool daemon) { 158 assert(Threads_lock->owned_by_self(), "must have threads lock"); 159 160 // Include hidden thread allcations in exited_allocated_bytes 161 ThreadService::incr_exited_allocated_bytes(thread->cooked_allocated_bytes()); 162 163 // Do not count hidden threads 164 if (is_hidden_thread(thread)) { 165 return; 166 } 167 168 assert(!thread->is_terminated(), "must not be terminated"); 169 if (!thread->is_exiting()) { 170 // JavaThread::exit() skipped calling current_thread_exiting() 171 decrement_thread_counts(thread, daemon); 172 } 173 174 int daemon_count = _atomic_daemon_threads_count; 175 int count = _atomic_threads_count; 176 177 // Counts are incremented at the same time, but atomic counts are 178 // decremented earlier than perf counts. 179 assert(_live_threads_count->get_value() > count, 180 "thread count mismatch %d : %d", 181 (int)_live_threads_count->get_value(), count); 182 183 _live_threads_count->dec(1); 184 if (daemon) { 185 assert(_daemon_threads_count->get_value() > daemon_count, 186 "thread count mismatch %d : %d", 187 (int)_daemon_threads_count->get_value(), daemon_count); 188 189 _daemon_threads_count->dec(1); 190 } 191 192 // Counts are incremented at the same time, but atomic counts are 193 // decremented earlier than perf counts. 194 assert(_daemon_threads_count->get_value() >= daemon_count, 195 "thread count mismatch %d : %d", 196 (int)_daemon_threads_count->get_value(), daemon_count); 197 assert(_live_threads_count->get_value() >= count, 198 "thread count mismatch %d : %d", 199 (int)_live_threads_count->get_value(), count); 200 assert(_live_threads_count->get_value() > 0 || 201 (_live_threads_count->get_value() == 0 && count == 0 && 202 _daemon_threads_count->get_value() == 0 && daemon_count == 0), 203 "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d", 204 (int)_live_threads_count->get_value(), count, 205 (int)_daemon_threads_count->get_value(), daemon_count); 206 assert(_daemon_threads_count->get_value() > 0 || 207 (_daemon_threads_count->get_value() == 0 && daemon_count == 0), 208 "thread counts should reach 0 at the same time, daemon %d,%d", 209 (int)_daemon_threads_count->get_value(), daemon_count); 210 } 211 212 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) { 213 // Do not count hidden threads 214 if (is_hidden_thread(jt)) { 215 return; 216 } 217 218 assert(jt == JavaThread::current(), "Called by current thread"); 219 assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting"); 220 221 decrement_thread_counts(jt, daemon); 222 } 223 224 // FIXME: JVMTI should call this function 225 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) { 226 assert(thread != NULL, "should be non-NULL"); 227 debug_only(Thread::check_for_dangling_thread_pointer(thread);) 228 229 // This function can be called on a target JavaThread that is not 230 // the caller and we are not at a safepoint. So it is possible for 231 // the waiting or pending condition to be over/stale and for the 232 // first stage of async deflation to clear the object field in 233 // the ObjectMonitor. It is also possible for the object to be 234 // inflated again and to be associated with a completely different 235 // ObjectMonitor by the time this object reference is processed 236 // by the caller. 237 ObjectMonitor *wait_obj = thread->current_waiting_monitor(); 238 239 oop obj = NULL; 240 if (wait_obj != NULL) { 241 // thread is doing an Object.wait() call 242 obj = wait_obj->object(); 243 } else { 244 ObjectMonitor *enter_obj = thread->current_pending_monitor(); 245 if (enter_obj != NULL) { 246 // thread is trying to enter() an ObjectMonitor. 247 obj = enter_obj->object(); 248 } 249 } 250 251 Handle h(Thread::current(), obj); 252 return h; 253 } 254 255 bool ThreadService::set_thread_monitoring_contention(bool flag) { 256 MutexLocker m(Management_lock); 257 258 bool prev = _thread_monitoring_contention_enabled; 259 _thread_monitoring_contention_enabled = flag; 260 261 return prev; 262 } 263 264 bool ThreadService::set_thread_cpu_time_enabled(bool flag) { 265 MutexLocker m(Management_lock); 266 267 bool prev = _thread_cpu_time_enabled; 268 _thread_cpu_time_enabled = flag; 269 270 return prev; 271 } 272 273 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) { 274 MutexLocker m(Management_lock); 275 276 bool prev = _thread_allocated_memory_enabled; 277 _thread_allocated_memory_enabled = flag; 278 279 return prev; 280 } 281 282 void ThreadService::metadata_do(void f(Metadata*)) { 283 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 284 dump->metadata_do(f); 285 } 286 } 287 288 void ThreadService::add_thread_dump(ThreadDumpResult* dump) { 289 MutexLocker ml(Management_lock); 290 if (_threaddump_list == NULL) { 291 _threaddump_list = dump; 292 } else { 293 dump->set_next(_threaddump_list); 294 _threaddump_list = dump; 295 } 296 } 297 298 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) { 299 MutexLocker ml(Management_lock); 300 301 ThreadDumpResult* prev = NULL; 302 bool found = false; 303 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) { 304 if (d == dump) { 305 if (prev == NULL) { 306 _threaddump_list = dump->next(); 307 } else { 308 prev->set_next(dump->next()); 309 } 310 found = true; 311 break; 312 } 313 } 314 assert(found, "The threaddump result to be removed must exist."); 315 } 316 317 // Dump stack trace of threads specified in the given threads array. 318 // Returns StackTraceElement[][] each element is the stack trace of a thread in 319 // the corresponding entry in the given threads array 320 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads, 321 int num_threads, 322 TRAPS) { 323 assert(num_threads > 0, "just checking"); 324 325 ThreadDumpResult dump_result; 326 VM_ThreadDump op(&dump_result, 327 threads, 328 num_threads, 329 -1, /* entire stack */ 330 false, /* with locked monitors */ 331 false /* with locked synchronizers */); 332 VMThread::execute(&op); 333 334 // Allocate the resulting StackTraceElement[][] object 335 336 ResourceMark rm(THREAD); 337 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH); 338 ObjArrayKlass* ik = ObjArrayKlass::cast(k); 339 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH); 340 objArrayHandle result_obj(THREAD, r); 341 342 int num_snapshots = dump_result.num_snapshots(); 343 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots"); 344 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot"); 345 int i = 0; 346 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) { 347 ThreadStackTrace* stacktrace = ts->get_stack_trace(); 348 if (stacktrace == NULL) { 349 // No stack trace 350 result_obj->obj_at_put(i, NULL); 351 } else { 352 // Construct an array of java/lang/StackTraceElement object 353 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH); 354 result_obj->obj_at_put(i, backtrace_h()); 355 } 356 } 357 358 return result_obj; 359 } 360 361 void ThreadService::reset_contention_count_stat(JavaThread* thread) { 362 ThreadStatistics* stat = thread->get_thread_stat(); 363 if (stat != NULL) { 364 stat->reset_count_stat(); 365 } 366 } 367 368 void ThreadService::reset_contention_time_stat(JavaThread* thread) { 369 ThreadStatistics* stat = thread->get_thread_stat(); 370 if (stat != NULL) { 371 stat->reset_time_stat(); 372 } 373 } 374 375 // Find deadlocks involving raw monitors, object monitors and concurrent locks 376 // if concurrent_locks is true. 377 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) { 378 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 379 380 // This code was modified from the original Threads::find_deadlocks code. 381 int globalDfn = 0, thisDfn; 382 ObjectMonitor* waitingToLockMonitor = NULL; 383 JvmtiRawMonitor* waitingToLockRawMonitor = NULL; 384 oop waitingToLockBlocker = NULL; 385 bool blocked_on_monitor = false; 386 JavaThread *currentThread, *previousThread; 387 int num_deadlocks = 0; 388 389 // Initialize the depth-first-number for each JavaThread. 390 JavaThreadIterator jti(t_list); 391 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 392 jt->set_depth_first_number(-1); 393 } 394 395 DeadlockCycle* deadlocks = NULL; 396 DeadlockCycle* last = NULL; 397 DeadlockCycle* cycle = new DeadlockCycle(); 398 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 399 if (jt->depth_first_number() >= 0) { 400 // this thread was already visited 401 continue; 402 } 403 404 thisDfn = globalDfn; 405 jt->set_depth_first_number(globalDfn++); 406 previousThread = jt; 407 currentThread = jt; 408 409 cycle->reset(); 410 411 // The ObjectMonitor* can't be async deflated since we are at a safepoint. 412 // When there is a deadlock, all the monitors involved in the dependency 413 // cycle must be contended and heavyweight. So we only care about the 414 // heavyweight monitor a thread is waiting to lock. 415 waitingToLockMonitor = jt->current_pending_monitor(); 416 // JVM TI raw monitors can also be involved in deadlocks, and we can be 417 // waiting to lock both a raw monitor and ObjectMonitor at the same time. 418 // It isn't clear how to make deadlock detection work correctly if that 419 // happens. 420 waitingToLockRawMonitor = jt->current_pending_raw_monitor(); 421 422 if (concurrent_locks) { 423 waitingToLockBlocker = jt->current_park_blocker(); 424 } 425 426 while (waitingToLockMonitor != NULL || 427 waitingToLockRawMonitor != NULL || 428 waitingToLockBlocker != NULL) { 429 cycle->add_thread(currentThread); 430 // Give preference to the raw monitor 431 if (waitingToLockRawMonitor != NULL) { 432 Thread* owner = waitingToLockRawMonitor->owner(); 433 if (owner != NULL && // the raw monitor could be released at any time 434 owner->is_Java_thread()) { 435 currentThread = owner->as_Java_thread(); 436 } 437 } else if (waitingToLockMonitor != NULL) { 438 if (waitingToLockMonitor->has_owner()) { 439 currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor); 440 if (currentThread == NULL) { 441 // This function is called at a safepoint so the JavaThread 442 // that owns waitingToLockMonitor should be findable, but 443 // if it is not findable, then the previous currentThread is 444 // blocked permanently. We record this as a deadlock. 445 num_deadlocks++; 446 447 cycle->set_deadlock(true); 448 449 // add this cycle to the deadlocks list 450 if (deadlocks == NULL) { 451 deadlocks = cycle; 452 } else { 453 last->set_next(cycle); 454 } 455 last = cycle; 456 cycle = new DeadlockCycle(); 457 break; 458 } 459 } 460 } else { 461 if (concurrent_locks) { 462 if (waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { 463 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 464 // This JavaThread (if there is one) is protected by the 465 // ThreadsListSetter in VM_FindDeadlocks::doit(). 466 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL; 467 } else { 468 currentThread = NULL; 469 } 470 } 471 } 472 473 if (currentThread == NULL) { 474 // No dependency on another thread 475 break; 476 } 477 if (currentThread->depth_first_number() < 0) { 478 // First visit to this thread 479 currentThread->set_depth_first_number(globalDfn++); 480 } else if (currentThread->depth_first_number() < thisDfn) { 481 // Thread already visited, and not on a (new) cycle 482 break; 483 } else if (currentThread == previousThread) { 484 // Self-loop, ignore 485 break; 486 } else { 487 // We have a (new) cycle 488 num_deadlocks++; 489 490 cycle->set_deadlock(true); 491 492 // add this cycle to the deadlocks list 493 if (deadlocks == NULL) { 494 deadlocks = cycle; 495 } else { 496 last->set_next(cycle); 497 } 498 last = cycle; 499 cycle = new DeadlockCycle(); 500 break; 501 } 502 previousThread = currentThread; 503 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); 504 if (concurrent_locks) { 505 waitingToLockBlocker = currentThread->current_park_blocker(); 506 } 507 } 508 509 } 510 delete cycle; 511 return deadlocks; 512 } 513 514 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() { 515 516 // Create a new ThreadDumpResult object and append to the list. 517 // If GC happens before this function returns, Method* 518 // in the stack trace will be visited. 519 ThreadService::add_thread_dump(this); 520 } 521 522 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() { 523 // Create a new ThreadDumpResult object and append to the list. 524 // If GC happens before this function returns, oops 525 // will be visited. 526 ThreadService::add_thread_dump(this); 527 } 528 529 ThreadDumpResult::~ThreadDumpResult() { 530 ThreadService::remove_thread_dump(this); 531 532 // free all the ThreadSnapshot objects created during 533 // the VM_ThreadDump operation 534 ThreadSnapshot* ts = _snapshots; 535 while (ts != NULL) { 536 ThreadSnapshot* p = ts; 537 ts = ts->next(); 538 delete p; 539 } 540 } 541 542 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() { 543 ThreadSnapshot* ts = new ThreadSnapshot(); 544 link_thread_snapshot(ts); 545 return ts; 546 } 547 548 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) { 549 ThreadSnapshot* ts = new ThreadSnapshot(); 550 link_thread_snapshot(ts); 551 ts->initialize(t_list(), thread); 552 return ts; 553 } 554 555 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) { 556 assert(_num_threads == 0 || _num_snapshots < _num_threads, 557 "_num_snapshots must be less than _num_threads"); 558 _num_snapshots++; 559 if (_snapshots == NULL) { 560 _snapshots = ts; 561 } else { 562 _last->set_next(ts); 563 } 564 _last = ts; 565 } 566 567 void ThreadDumpResult::metadata_do(void f(Metadata*)) { 568 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 569 ts->metadata_do(f); 570 } 571 } 572 573 ThreadsList* ThreadDumpResult::t_list() { 574 return _setter.list(); 575 } 576 577 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) { 578 _method = jvf->method(); 579 _bci = jvf->bci(); 580 _class_holder = OopHandle(_thread_service_storage, _method->method_holder()->klass_holder()); 581 _locked_monitors = NULL; 582 if (with_lock_info) { 583 Thread* current_thread = Thread::current(); 584 ResourceMark rm(current_thread); 585 HandleMark hm(current_thread); 586 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors(); 587 int length = list->length(); 588 if (length > 0) { 589 _locked_monitors = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(length, mtServiceability); 590 for (int i = 0; i < length; i++) { 591 MonitorInfo* monitor = list->at(i); 592 assert(monitor->owner() != NULL, "This monitor must have an owning object"); 593 _locked_monitors->append(OopHandle(_thread_service_storage, monitor->owner())); 594 } 595 } 596 } 597 } 598 599 StackFrameInfo::~StackFrameInfo() { 600 if (_locked_monitors != NULL) { 601 for (int i = 0; i < _locked_monitors->length(); i++) { 602 _locked_monitors->at(i).release(_thread_service_storage); 603 } 604 delete _locked_monitors; 605 } 606 _class_holder.release(_thread_service_storage); 607 } 608 609 void StackFrameInfo::metadata_do(void f(Metadata*)) { 610 f(_method); 611 } 612 613 void StackFrameInfo::print_on(outputStream* st) const { 614 ResourceMark rm; 615 java_lang_Throwable::print_stack_element(st, method(), bci()); 616 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0); 617 for (int i = 0; i < len; i++) { 618 oop o = _locked_monitors->at(i).resolve(); 619 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name()); 620 } 621 622 } 623 624 // Iterate through monitor cache to find JNI locked monitors 625 class InflatedMonitorsClosure: public MonitorClosure { 626 private: 627 ThreadStackTrace* _stack_trace; 628 public: 629 InflatedMonitorsClosure(ThreadStackTrace* st) { 630 _stack_trace = st; 631 } 632 void do_monitor(ObjectMonitor* mid) { 633 oop object = mid->object(); 634 if (!_stack_trace->is_owned_monitor_on_stack(object)) { 635 _stack_trace->add_jni_locked_monitor(object); 636 } 637 } 638 }; 639 640 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) { 641 _thread = t; 642 _frames = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, mtServiceability); 643 _depth = 0; 644 _with_locked_monitors = with_locked_monitors; 645 if (_with_locked_monitors) { 646 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability); 647 } else { 648 _jni_locked_monitors = NULL; 649 } 650 } 651 652 void ThreadStackTrace::add_jni_locked_monitor(oop object) { 653 _jni_locked_monitors->append(OopHandle(_thread_service_storage, object)); 654 } 655 656 ThreadStackTrace::~ThreadStackTrace() { 657 for (int i = 0; i < _frames->length(); i++) { 658 delete _frames->at(i); 659 } 660 delete _frames; 661 if (_jni_locked_monitors != NULL) { 662 for (int i = 0; i < _jni_locked_monitors->length(); i++) { 663 _jni_locked_monitors->at(i).release(_thread_service_storage); 664 } 665 delete _jni_locked_monitors; 666 } 667 } 668 669 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) { 670 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 671 672 if (_thread->has_last_Java_frame()) { 673 RegisterMap reg_map(_thread); 674 vframe* start_vf = _thread->last_java_vframe(®_map); 675 int count = 0; 676 for (vframe* f = start_vf; f; f = f->sender() ) { 677 if (maxDepth >= 0 && count == maxDepth) { 678 // Skip frames if more than maxDepth 679 break; 680 } 681 if (f->is_java_frame()) { 682 javaVFrame* jvf = javaVFrame::cast(f); 683 add_stack_frame(jvf); 684 count++; 685 } else { 686 // Ignore non-Java frames 687 } 688 } 689 } 690 691 if (_with_locked_monitors) { 692 // Iterate inflated monitors and find monitors locked by this thread 693 // not found in the stack 694 InflatedMonitorsClosure imc(this); 695 ObjectSynchronizer::monitors_iterate(&imc, _thread); 696 } 697 } 698 699 700 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) { 701 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 702 703 bool found = false; 704 int num_frames = get_stack_depth(); 705 for (int depth = 0; depth < num_frames; depth++) { 706 StackFrameInfo* frame = stack_frame_at(depth); 707 int len = frame->num_locked_monitors(); 708 GrowableArray<OopHandle>* locked_monitors = frame->locked_monitors(); 709 for (int j = 0; j < len; j++) { 710 oop monitor = locked_monitors->at(j).resolve(); 711 assert(monitor != NULL, "must be a Java object"); 712 if (monitor == object) { 713 found = true; 714 break; 715 } 716 } 717 } 718 return found; 719 } 720 721 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) { 722 InstanceKlass* ik = vmClasses::StackTraceElement_klass(); 723 assert(ik != NULL, "must be loaded in 1.4+"); 724 725 // Allocate an array of java/lang/StackTraceElement object 726 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH); 727 objArrayHandle backtrace(THREAD, ste); 728 for (int j = 0; j < _depth; j++) { 729 StackFrameInfo* frame = _frames->at(j); 730 methodHandle mh(THREAD, frame->method()); 731 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH); 732 backtrace->obj_at_put(j, element); 733 } 734 return backtrace; 735 } 736 737 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) { 738 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors); 739 _frames->append(frame); 740 _depth++; 741 } 742 743 void ThreadStackTrace::metadata_do(void f(Metadata*)) { 744 int length = _frames->length(); 745 for (int i = 0; i < length; i++) { 746 _frames->at(i)->metadata_do(f); 747 } 748 } 749 750 751 ConcurrentLocksDump::~ConcurrentLocksDump() { 752 if (_retain_map_on_free) { 753 return; 754 } 755 756 for (ThreadConcurrentLocks* t = _map; t != NULL;) { 757 ThreadConcurrentLocks* tcl = t; 758 t = t->next(); 759 delete tcl; 760 } 761 } 762 763 void ConcurrentLocksDump::dump_at_safepoint() { 764 // dump all locked concurrent locks 765 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 766 767 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<oop>(INITIAL_ARRAY_SIZE, mtServiceability); 768 769 // Find all instances of AbstractOwnableSynchronizer 770 HeapInspection::find_instances_at_safepoint(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(), 771 aos_objects); 772 // Build a map of thread to its owned AQS locks 773 build_map(aos_objects); 774 775 delete aos_objects; 776 } 777 778 779 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer 780 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) { 781 int length = aos_objects->length(); 782 for (int i = 0; i < length; i++) { 783 oop o = aos_objects->at(i); 784 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o); 785 if (owner_thread_obj != NULL) { 786 // See comments in ThreadConcurrentLocks to see how this 787 // JavaThread* is protected. 788 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj); 789 assert(o->is_instance(), "Must be an instanceOop"); 790 add_lock(thread, (instanceOop) o); 791 } 792 } 793 } 794 795 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) { 796 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread); 797 if (tcl != NULL) { 798 tcl->add_lock(o); 799 return; 800 } 801 802 // First owned lock found for this thread 803 tcl = new ThreadConcurrentLocks(thread); 804 tcl->add_lock(o); 805 if (_map == NULL) { 806 _map = tcl; 807 } else { 808 _last->set_next(tcl); 809 } 810 _last = tcl; 811 } 812 813 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) { 814 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) { 815 if (tcl->java_thread() == thread) { 816 return tcl; 817 } 818 } 819 return NULL; 820 } 821 822 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) { 823 st->print_cr(" Locked ownable synchronizers:"); 824 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t); 825 GrowableArray<OopHandle>* locks = (tcl != NULL ? tcl->owned_locks() : NULL); 826 if (locks == NULL || locks->is_empty()) { 827 st->print_cr("\t- None"); 828 st->cr(); 829 return; 830 } 831 832 for (int i = 0; i < locks->length(); i++) { 833 oop obj = locks->at(i).resolve(); 834 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name()); 835 } 836 st->cr(); 837 } 838 839 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) { 840 _thread = thread; 841 _owned_locks = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<OopHandle>(INITIAL_ARRAY_SIZE, mtServiceability); 842 _next = NULL; 843 } 844 845 ThreadConcurrentLocks::~ThreadConcurrentLocks() { 846 for (int i = 0; i < _owned_locks->length(); i++) { 847 _owned_locks->at(i).release(_thread_service_storage); 848 } 849 delete _owned_locks; 850 } 851 852 void ThreadConcurrentLocks::add_lock(instanceOop o) { 853 _owned_locks->append(OopHandle(_thread_service_storage, o)); 854 } 855 856 ThreadStatistics::ThreadStatistics() { 857 _contended_enter_count = 0; 858 _monitor_wait_count = 0; 859 _sleep_count = 0; 860 _count_pending_reset = false; 861 _timer_pending_reset = false; 862 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts)); 863 } 864 865 oop ThreadSnapshot::threadObj() const { return _threadObj.resolve(); } 866 867 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) { 868 _thread = thread; 869 oop threadObj = thread->threadObj(); 870 _threadObj = OopHandle(_thread_service_storage, threadObj); 871 872 ThreadStatistics* stat = thread->get_thread_stat(); 873 _contended_enter_ticks = stat->contended_enter_ticks(); 874 _contended_enter_count = stat->contended_enter_count(); 875 _monitor_wait_ticks = stat->monitor_wait_ticks(); 876 _monitor_wait_count = stat->monitor_wait_count(); 877 _sleep_ticks = stat->sleep_ticks(); 878 _sleep_count = stat->sleep_count(); 879 880 // If thread is still attaching then threadObj will be NULL. 881 _thread_status = threadObj == NULL ? JavaThreadStatus::NEW 882 : java_lang_Thread::get_thread_status(threadObj); 883 884 _is_suspended = thread->is_suspended(); 885 _is_in_native = (thread->thread_state() == _thread_in_native); 886 887 Handle obj = ThreadService::get_current_contended_monitor(thread); 888 889 oop blocker_object = NULL; 890 oop blocker_object_owner = NULL; 891 892 if (_thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER || 893 _thread_status == JavaThreadStatus::IN_OBJECT_WAIT || 894 _thread_status == JavaThreadStatus::IN_OBJECT_WAIT_TIMED) { 895 896 if (obj() == NULL) { 897 // monitor no longer exists; thread is not blocked 898 _thread_status = JavaThreadStatus::RUNNABLE; 899 } else { 900 blocker_object = obj(); 901 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj); 902 if ((owner == NULL && _thread_status == JavaThreadStatus::BLOCKED_ON_MONITOR_ENTER) 903 || (owner != NULL && owner->is_attaching_via_jni())) { 904 // ownership information of the monitor is not available 905 // (may no longer be owned or releasing to some other thread) 906 // make this thread in RUNNABLE state. 907 // And when the owner thread is in attaching state, the java thread 908 // is not completely initialized. For example thread name and id 909 // and may not be set, so hide the attaching thread. 910 _thread_status = JavaThreadStatus::RUNNABLE; 911 blocker_object = NULL; 912 } else if (owner != NULL) { 913 blocker_object_owner = owner->threadObj(); 914 } 915 } 916 } 917 918 // Support for JSR-166 locks 919 if (_thread_status == JavaThreadStatus::PARKED || _thread_status == JavaThreadStatus::PARKED_TIMED) { 920 blocker_object = thread->current_park_blocker(); 921 if (blocker_object != NULL && blocker_object->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) { 922 blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(blocker_object); 923 } 924 } 925 926 if (blocker_object != NULL) { 927 _blocker_object = OopHandle(_thread_service_storage, blocker_object); 928 } 929 if (blocker_object_owner != NULL) { 930 _blocker_object_owner = OopHandle(_thread_service_storage, blocker_object_owner); 931 } 932 } 933 934 oop ThreadSnapshot::blocker_object() const { return _blocker_object.resolve(); } 935 oop ThreadSnapshot::blocker_object_owner() const { return _blocker_object_owner.resolve(); } 936 937 ThreadSnapshot::~ThreadSnapshot() { 938 _blocker_object.release(_thread_service_storage); 939 _blocker_object_owner.release(_thread_service_storage); 940 _threadObj.release(_thread_service_storage); 941 942 delete _stack_trace; 943 delete _concurrent_locks; 944 } 945 946 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) { 947 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors); 948 _stack_trace->dump_stack_at_safepoint(max_depth); 949 } 950 951 952 void ThreadSnapshot::metadata_do(void f(Metadata*)) { 953 if (_stack_trace != NULL) { 954 _stack_trace->metadata_do(f); 955 } 956 } 957 958 959 DeadlockCycle::DeadlockCycle() { 960 _is_deadlock = false; 961 _threads = new (ResourceObj::C_HEAP, mtServiceability) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, mtServiceability); 962 _next = NULL; 963 } 964 965 DeadlockCycle::~DeadlockCycle() { 966 delete _threads; 967 } 968 969 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const { 970 st->cr(); 971 st->print_cr("Found one Java-level deadlock:"); 972 st->print("============================="); 973 974 JavaThread* currentThread; 975 JvmtiRawMonitor* waitingToLockRawMonitor; 976 oop waitingToLockBlocker; 977 int len = _threads->length(); 978 for (int i = 0; i < len; i++) { 979 currentThread = _threads->at(i); 980 // The ObjectMonitor* can't be async deflated since we are at a safepoint. 981 ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor(); 982 waitingToLockRawMonitor = currentThread->current_pending_raw_monitor(); 983 waitingToLockBlocker = currentThread->current_park_blocker(); 984 st->cr(); 985 st->print_cr("\"%s\":", currentThread->get_thread_name()); 986 const char* owner_desc = ",\n which is held by"; 987 988 // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor 989 // sets the current pending monitor, it is possible to then see a pending raw monitor as well. 990 if (waitingToLockRawMonitor != NULL) { 991 st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor)); 992 Thread* owner = waitingToLockRawMonitor->owner(); 993 // Could be NULL as the raw monitor could be released at any time if held by non-JavaThread 994 if (owner != NULL) { 995 if (owner->is_Java_thread()) { 996 currentThread = owner->as_Java_thread(); 997 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 998 } else { 999 st->print_cr(",\n which has now been released"); 1000 } 1001 } else { 1002 st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner)); 1003 } 1004 } 1005 1006 if (waitingToLockMonitor != NULL) { 1007 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor)); 1008 oop obj = waitingToLockMonitor->object(); 1009 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj), 1010 obj->klass()->external_name()); 1011 1012 if (!currentThread->current_pending_monitor_is_from_java()) { 1013 owner_desc = "\n in JNI, which is held by"; 1014 } 1015 currentThread = Threads::owning_thread_from_monitor(t_list, waitingToLockMonitor); 1016 if (currentThread == NULL) { 1017 // The deadlock was detected at a safepoint so the JavaThread 1018 // that owns waitingToLockMonitor should be findable, but 1019 // if it is not findable, then the previous currentThread is 1020 // blocked permanently. 1021 st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc, 1022 p2i(waitingToLockMonitor->owner())); 1023 continue; 1024 } 1025 } else { 1026 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)", 1027 p2i(waitingToLockBlocker), 1028 waitingToLockBlocker->klass()->external_name()); 1029 assert(waitingToLockBlocker->is_a(vmClasses::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()), 1030 "Must be an AbstractOwnableSynchronizer"); 1031 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 1032 currentThread = java_lang_Thread::thread(ownerObj); 1033 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL"); 1034 } 1035 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 1036 } 1037 1038 st->cr(); 1039 1040 // Print stack traces 1041 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace; 1042 JavaMonitorsInStackTrace = true; 1043 st->print_cr("Java stack information for the threads listed above:"); 1044 st->print_cr("==================================================="); 1045 for (int j = 0; j < len; j++) { 1046 currentThread = _threads->at(j); 1047 st->print_cr("\"%s\":", currentThread->get_thread_name()); 1048 currentThread->print_stack_on(st); 1049 } 1050 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace; 1051 } 1052 1053 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread, 1054 bool include_jvmti_agent_threads, 1055 bool include_jni_attaching_threads) { 1056 assert(cur_thread == Thread::current(), "Check current thread"); 1057 1058 int init_size = ThreadService::get_live_thread_count(); 1059 _threads_array = new GrowableArray<instanceHandle>(init_size); 1060 1061 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) { 1062 // skips JavaThreads in the process of exiting 1063 // and also skips VM internal JavaThreads 1064 // Threads in _thread_new or _thread_new_trans state are included. 1065 // i.e. threads have been started but not yet running. 1066 if (jt->threadObj() == NULL || 1067 jt->is_exiting() || 1068 !java_lang_Thread::is_alive(jt->threadObj()) || 1069 jt->is_hidden_from_external_view()) { 1070 continue; 1071 } 1072 1073 // skip agent threads 1074 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) { 1075 continue; 1076 } 1077 1078 // skip jni threads in the process of attaching 1079 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) { 1080 continue; 1081 } 1082 1083 instanceHandle h(cur_thread, (instanceOop) jt->threadObj()); 1084 _threads_array->append(h); 1085 } 1086 }