1 /* 2 * Copyright (c) 2003, 2018, 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/objArrayOop.inline.hpp" 33 #include "oops/oop.inline.hpp" 34 #include "runtime/atomic.hpp" 35 #include "runtime/handles.inline.hpp" 36 #include "runtime/init.hpp" 37 #include "runtime/thread.inline.hpp" 38 #include "runtime/threadSMR.inline.hpp" 39 #include "runtime/vframe.hpp" 40 #include "runtime/vmThread.hpp" 41 #include "runtime/vm_operations.hpp" 42 #include "services/threadService.hpp" 43 44 // TODO: we need to define a naming convention for perf counters 45 // to distinguish counters for: 46 // - standard JSR174 use 47 // - Hotspot extension (public and committed) 48 // - Hotspot extension (private/internal and uncommitted) 49 50 // Default is disabled. 51 bool ThreadService::_thread_monitoring_contention_enabled = false; 52 bool ThreadService::_thread_cpu_time_enabled = false; 53 bool ThreadService::_thread_allocated_memory_enabled = false; 54 55 PerfCounter* ThreadService::_total_threads_count = NULL; 56 PerfVariable* ThreadService::_live_threads_count = NULL; 57 PerfVariable* ThreadService::_peak_threads_count = NULL; 58 PerfVariable* ThreadService::_daemon_threads_count = NULL; 59 volatile int ThreadService::_exiting_threads_count = 0; 60 volatile int ThreadService::_exiting_daemon_threads_count = 0; 61 62 ThreadDumpResult* ThreadService::_threaddump_list = NULL; 63 64 static const int INITIAL_ARRAY_SIZE = 10; 65 66 void ThreadService::init() { 67 EXCEPTION_MARK; 68 69 // These counters are for java.lang.management API support. 70 // They are created even if -XX:-UsePerfData is set and in 71 // that case, they will be allocated on C heap. 72 73 _total_threads_count = 74 PerfDataManager::create_counter(JAVA_THREADS, "started", 75 PerfData::U_Events, CHECK); 76 77 _live_threads_count = 78 PerfDataManager::create_variable(JAVA_THREADS, "live", 79 PerfData::U_None, CHECK); 80 81 _peak_threads_count = 82 PerfDataManager::create_variable(JAVA_THREADS, "livePeak", 83 PerfData::U_None, CHECK); 84 85 _daemon_threads_count = 86 PerfDataManager::create_variable(JAVA_THREADS, "daemon", 87 PerfData::U_None, CHECK); 88 89 if (os::is_thread_cpu_time_supported()) { 90 _thread_cpu_time_enabled = true; 91 } 92 93 _thread_allocated_memory_enabled = true; // Always on, so enable it 94 } 95 96 void ThreadService::reset_peak_thread_count() { 97 // Acquire the lock to update the peak thread count 98 // to synchronize with thread addition and removal. 99 MutexLockerEx mu(Threads_lock); 100 _peak_threads_count->set_value(get_live_thread_count()); 101 } 102 103 void ThreadService::add_thread(JavaThread* thread, bool daemon) { 104 // Do not count VM internal or JVMTI agent threads 105 if (thread->is_hidden_from_external_view() || 106 thread->is_jvmti_agent_thread()) { 107 return; 108 } 109 110 _total_threads_count->inc(); 111 _live_threads_count->inc(); 112 113 if (_live_threads_count->get_value() > _peak_threads_count->get_value()) { 114 _peak_threads_count->set_value(_live_threads_count->get_value()); 115 } 116 117 if (daemon) { 118 _daemon_threads_count->inc(); 119 } 120 } 121 122 void ThreadService::remove_thread(JavaThread* thread, bool daemon) { 123 Atomic::dec(&_exiting_threads_count); 124 125 if (thread->is_hidden_from_external_view() || 126 thread->is_jvmti_agent_thread()) { 127 return; 128 } 129 130 _live_threads_count->set_value(_live_threads_count->get_value() - 1); 131 132 if (daemon) { 133 _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1); 134 Atomic::dec(&_exiting_daemon_threads_count); 135 } 136 } 137 138 void ThreadService::current_thread_exiting(JavaThread* jt) { 139 assert(jt == JavaThread::current(), "Called by current thread"); 140 Atomic::inc(&_exiting_threads_count); 141 142 oop threadObj = jt->threadObj(); 143 if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) { 144 Atomic::inc(&_exiting_daemon_threads_count); 145 } 146 } 147 148 // FIXME: JVMTI should call this function 149 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) { 150 assert(thread != NULL, "should be non-NULL"); 151 debug_only(Thread::check_for_dangling_thread_pointer(thread);) 152 153 ObjectMonitor *wait_obj = thread->current_waiting_monitor(); 154 155 oop obj = NULL; 156 if (wait_obj != NULL) { 157 // thread is doing an Object.wait() call 158 obj = (oop) wait_obj->object(); 159 assert(obj != NULL, "Object.wait() should have an object"); 160 } else { 161 ObjectMonitor *enter_obj = thread->current_pending_monitor(); 162 if (enter_obj != NULL) { 163 // thread is trying to enter() or raw_enter() an ObjectMonitor. 164 obj = (oop) enter_obj->object(); 165 } 166 // If obj == NULL, then ObjectMonitor is raw which doesn't count. 167 } 168 169 Handle h(Thread::current(), obj); 170 return h; 171 } 172 173 bool ThreadService::set_thread_monitoring_contention(bool flag) { 174 MutexLocker m(Management_lock); 175 176 bool prev = _thread_monitoring_contention_enabled; 177 _thread_monitoring_contention_enabled = flag; 178 179 return prev; 180 } 181 182 bool ThreadService::set_thread_cpu_time_enabled(bool flag) { 183 MutexLocker m(Management_lock); 184 185 bool prev = _thread_cpu_time_enabled; 186 _thread_cpu_time_enabled = flag; 187 188 return prev; 189 } 190 191 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) { 192 MutexLocker m(Management_lock); 193 194 bool prev = _thread_allocated_memory_enabled; 195 _thread_allocated_memory_enabled = flag; 196 197 return prev; 198 } 199 200 // GC support 201 void ThreadService::oops_do(OopClosure* f) { 202 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 203 dump->oops_do(f); 204 } 205 } 206 207 void ThreadService::metadata_do(void f(Metadata*)) { 208 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) { 209 dump->metadata_do(f); 210 } 211 } 212 213 void ThreadService::add_thread_dump(ThreadDumpResult* dump) { 214 MutexLocker ml(Management_lock); 215 if (_threaddump_list == NULL) { 216 _threaddump_list = dump; 217 } else { 218 dump->set_next(_threaddump_list); 219 _threaddump_list = dump; 220 } 221 } 222 223 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) { 224 MutexLocker ml(Management_lock); 225 226 ThreadDumpResult* prev = NULL; 227 bool found = false; 228 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) { 229 if (d == dump) { 230 if (prev == NULL) { 231 _threaddump_list = dump->next(); 232 } else { 233 prev->set_next(dump->next()); 234 } 235 found = true; 236 break; 237 } 238 } 239 assert(found, "The threaddump result to be removed must exist."); 240 } 241 242 // Dump stack trace of threads specified in the given threads array. 243 // Returns StackTraceElement[][] each element is the stack trace of a thread in 244 // the corresponding entry in the given threads array 245 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads, 246 int num_threads, 247 TRAPS) { 248 assert(num_threads > 0, "just checking"); 249 250 ThreadDumpResult dump_result; 251 VM_ThreadDump op(&dump_result, 252 threads, 253 num_threads, 254 -1, /* entire stack */ 255 false, /* with locked monitors */ 256 false /* with locked synchronizers */); 257 VMThread::execute(&op); 258 259 // Allocate the resulting StackTraceElement[][] object 260 261 ResourceMark rm(THREAD); 262 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH); 263 ObjArrayKlass* ik = ObjArrayKlass::cast(k); 264 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH); 265 objArrayHandle result_obj(THREAD, r); 266 267 int num_snapshots = dump_result.num_snapshots(); 268 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots"); 269 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot"); 270 int i = 0; 271 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) { 272 ThreadStackTrace* stacktrace = ts->get_stack_trace(); 273 if (stacktrace == NULL) { 274 // No stack trace 275 result_obj->obj_at_put(i, NULL); 276 } else { 277 // Construct an array of java/lang/StackTraceElement object 278 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH); 279 result_obj->obj_at_put(i, backtrace_h()); 280 } 281 } 282 283 return result_obj; 284 } 285 286 void ThreadService::reset_contention_count_stat(JavaThread* thread) { 287 ThreadStatistics* stat = thread->get_thread_stat(); 288 if (stat != NULL) { 289 stat->reset_count_stat(); 290 } 291 } 292 293 void ThreadService::reset_contention_time_stat(JavaThread* thread) { 294 ThreadStatistics* stat = thread->get_thread_stat(); 295 if (stat != NULL) { 296 stat->reset_time_stat(); 297 } 298 } 299 300 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true 301 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) { 302 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 303 304 // This code was modified from the original Threads::find_deadlocks code. 305 int globalDfn = 0, thisDfn; 306 ObjectMonitor* waitingToLockMonitor = NULL; 307 oop waitingToLockBlocker = NULL; 308 bool blocked_on_monitor = false; 309 JavaThread *currentThread, *previousThread; 310 int num_deadlocks = 0; 311 312 // Initialize the depth-first-number for each JavaThread. 313 JavaThreadIterator jti(t_list); 314 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 315 jt->set_depth_first_number(-1); 316 } 317 318 DeadlockCycle* deadlocks = NULL; 319 DeadlockCycle* last = NULL; 320 DeadlockCycle* cycle = new DeadlockCycle(); 321 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) { 322 if (jt->depth_first_number() >= 0) { 323 // this thread was already visited 324 continue; 325 } 326 327 thisDfn = globalDfn; 328 jt->set_depth_first_number(globalDfn++); 329 previousThread = jt; 330 currentThread = jt; 331 332 cycle->reset(); 333 334 // When there is a deadlock, all the monitors involved in the dependency 335 // cycle must be contended and heavyweight. So we only care about the 336 // heavyweight monitor a thread is waiting to lock. 337 waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor(); 338 if (concurrent_locks) { 339 waitingToLockBlocker = jt->current_park_blocker(); 340 } 341 while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) { 342 cycle->add_thread(currentThread); 343 if (waitingToLockMonitor != NULL) { 344 address currentOwner = (address)waitingToLockMonitor->owner(); 345 if (currentOwner != NULL) { 346 currentThread = Threads::owning_thread_from_monitor_owner(t_list, 347 currentOwner); 348 if (currentThread == NULL) { 349 // This function is called at a safepoint so the JavaThread 350 // that owns waitingToLockMonitor should be findable, but 351 // if it is not findable, then the previous currentThread is 352 // blocked permanently. We record this as a deadlock. 353 num_deadlocks++; 354 355 cycle->set_deadlock(true); 356 357 // add this cycle to the deadlocks list 358 if (deadlocks == NULL) { 359 deadlocks = cycle; 360 } else { 361 last->set_next(cycle); 362 } 363 last = cycle; 364 cycle = new DeadlockCycle(); 365 break; 366 } 367 } 368 } else { 369 if (concurrent_locks) { 370 if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) { 371 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 372 // This JavaThread (if there is one) is protected by the 373 // ThreadsListSetter in VM_FindDeadlocks::doit(). 374 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL; 375 } else { 376 currentThread = NULL; 377 } 378 } 379 } 380 381 if (currentThread == NULL) { 382 // No dependency on another thread 383 break; 384 } 385 if (currentThread->depth_first_number() < 0) { 386 // First visit to this thread 387 currentThread->set_depth_first_number(globalDfn++); 388 } else if (currentThread->depth_first_number() < thisDfn) { 389 // Thread already visited, and not on a (new) cycle 390 break; 391 } else if (currentThread == previousThread) { 392 // Self-loop, ignore 393 break; 394 } else { 395 // We have a (new) cycle 396 num_deadlocks++; 397 398 cycle->set_deadlock(true); 399 400 // add this cycle to the deadlocks list 401 if (deadlocks == NULL) { 402 deadlocks = cycle; 403 } else { 404 last->set_next(cycle); 405 } 406 last = cycle; 407 cycle = new DeadlockCycle(); 408 break; 409 } 410 previousThread = currentThread; 411 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); 412 if (concurrent_locks) { 413 waitingToLockBlocker = currentThread->current_park_blocker(); 414 } 415 } 416 417 } 418 delete cycle; 419 return deadlocks; 420 } 421 422 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL), _setter() { 423 424 // Create a new ThreadDumpResult object and append to the list. 425 // If GC happens before this function returns, Method* 426 // in the stack trace will be visited. 427 ThreadService::add_thread_dump(this); 428 } 429 430 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL), _setter() { 431 // Create a new ThreadDumpResult object and append to the list. 432 // If GC happens before this function returns, oops 433 // will be visited. 434 ThreadService::add_thread_dump(this); 435 } 436 437 ThreadDumpResult::~ThreadDumpResult() { 438 ThreadService::remove_thread_dump(this); 439 440 // free all the ThreadSnapshot objects created during 441 // the VM_ThreadDump operation 442 ThreadSnapshot* ts = _snapshots; 443 while (ts != NULL) { 444 ThreadSnapshot* p = ts; 445 ts = ts->next(); 446 delete p; 447 } 448 } 449 450 451 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) { 452 assert(_num_threads == 0 || _num_snapshots < _num_threads, 453 "_num_snapshots must be less than _num_threads"); 454 _num_snapshots++; 455 if (_snapshots == NULL) { 456 _snapshots = ts; 457 } else { 458 _last->set_next(ts); 459 } 460 _last = ts; 461 } 462 463 void ThreadDumpResult::oops_do(OopClosure* f) { 464 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 465 ts->oops_do(f); 466 } 467 } 468 469 void ThreadDumpResult::metadata_do(void f(Metadata*)) { 470 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) { 471 ts->metadata_do(f); 472 } 473 } 474 475 ThreadsList* ThreadDumpResult::t_list() { 476 return _setter.list(); 477 } 478 479 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) { 480 _method = jvf->method(); 481 _bci = jvf->bci(); 482 _class_holder = _method->method_holder()->klass_holder(); 483 _locked_monitors = NULL; 484 if (with_lock_info) { 485 ResourceMark rm; 486 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors(); 487 int length = list->length(); 488 if (length > 0) { 489 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true); 490 for (int i = 0; i < length; i++) { 491 MonitorInfo* monitor = list->at(i); 492 assert(monitor->owner() != NULL, "This monitor must have an owning object"); 493 _locked_monitors->append(monitor->owner()); 494 } 495 } 496 } 497 } 498 499 void StackFrameInfo::oops_do(OopClosure* f) { 500 if (_locked_monitors != NULL) { 501 int length = _locked_monitors->length(); 502 for (int i = 0; i < length; i++) { 503 f->do_oop((oop*) _locked_monitors->adr_at(i)); 504 } 505 } 506 f->do_oop(&_class_holder); 507 } 508 509 void StackFrameInfo::metadata_do(void f(Metadata*)) { 510 f(_method); 511 } 512 513 void StackFrameInfo::print_on(outputStream* st) const { 514 ResourceMark rm; 515 java_lang_Throwable::print_stack_element(st, method(), bci()); 516 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0); 517 for (int i = 0; i < len; i++) { 518 oop o = _locked_monitors->at(i); 519 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name()); 520 } 521 522 } 523 524 // Iterate through monitor cache to find JNI locked monitors 525 class InflatedMonitorsClosure: public MonitorClosure { 526 private: 527 ThreadStackTrace* _stack_trace; 528 Thread* _thread; 529 public: 530 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) { 531 _thread = t; 532 _stack_trace = st; 533 } 534 void do_monitor(ObjectMonitor* mid) { 535 if (mid->owner() == _thread) { 536 oop object = (oop) mid->object(); 537 if (!_stack_trace->is_owned_monitor_on_stack(object)) { 538 _stack_trace->add_jni_locked_monitor(object); 539 } 540 } 541 } 542 }; 543 544 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) { 545 _thread = t; 546 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true); 547 _depth = 0; 548 _with_locked_monitors = with_locked_monitors; 549 if (_with_locked_monitors) { 550 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true); 551 } else { 552 _jni_locked_monitors = NULL; 553 } 554 } 555 556 ThreadStackTrace::~ThreadStackTrace() { 557 for (int i = 0; i < _frames->length(); i++) { 558 delete _frames->at(i); 559 } 560 delete _frames; 561 if (_jni_locked_monitors != NULL) { 562 delete _jni_locked_monitors; 563 } 564 } 565 566 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) { 567 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 568 569 if (_thread->has_last_Java_frame()) { 570 RegisterMap reg_map(_thread); 571 vframe* start_vf = _thread->last_java_vframe(®_map); 572 int count = 0; 573 for (vframe* f = start_vf; f; f = f->sender() ) { 574 if (maxDepth >= 0 && count == maxDepth) { 575 // Skip frames if more than maxDepth 576 break; 577 } 578 if (f->is_java_frame()) { 579 javaVFrame* jvf = javaVFrame::cast(f); 580 add_stack_frame(jvf); 581 count++; 582 } else { 583 // Ignore non-Java frames 584 } 585 } 586 } 587 588 if (_with_locked_monitors) { 589 // Iterate inflated monitors and find monitors locked by this thread 590 // not found in the stack 591 InflatedMonitorsClosure imc(_thread, this); 592 ObjectSynchronizer::monitors_iterate(&imc); 593 } 594 } 595 596 597 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) { 598 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 599 600 bool found = false; 601 int num_frames = get_stack_depth(); 602 for (int depth = 0; depth < num_frames; depth++) { 603 StackFrameInfo* frame = stack_frame_at(depth); 604 int len = frame->num_locked_monitors(); 605 GrowableArray<oop>* locked_monitors = frame->locked_monitors(); 606 for (int j = 0; j < len; j++) { 607 oop monitor = locked_monitors->at(j); 608 assert(monitor != NULL, "must be a Java object"); 609 if (oopDesc::equals(monitor, object)) { 610 found = true; 611 break; 612 } 613 } 614 } 615 return found; 616 } 617 618 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) { 619 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass(); 620 assert(ik != NULL, "must be loaded in 1.4+"); 621 622 // Allocate an array of java/lang/StackTraceElement object 623 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH); 624 objArrayHandle backtrace(THREAD, ste); 625 for (int j = 0; j < _depth; j++) { 626 StackFrameInfo* frame = _frames->at(j); 627 methodHandle mh(THREAD, frame->method()); 628 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH); 629 backtrace->obj_at_put(j, element); 630 } 631 return backtrace; 632 } 633 634 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) { 635 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors); 636 _frames->append(frame); 637 _depth++; 638 } 639 640 void ThreadStackTrace::oops_do(OopClosure* f) { 641 int length = _frames->length(); 642 for (int i = 0; i < length; i++) { 643 _frames->at(i)->oops_do(f); 644 } 645 646 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0); 647 for (int j = 0; j < length; j++) { 648 f->do_oop((oop*) _jni_locked_monitors->adr_at(j)); 649 } 650 } 651 652 void ThreadStackTrace::metadata_do(void f(Metadata*)) { 653 int length = _frames->length(); 654 for (int i = 0; i < length; i++) { 655 _frames->at(i)->metadata_do(f); 656 } 657 } 658 659 660 ConcurrentLocksDump::~ConcurrentLocksDump() { 661 if (_retain_map_on_free) { 662 return; 663 } 664 665 for (ThreadConcurrentLocks* t = _map; t != NULL;) { 666 ThreadConcurrentLocks* tcl = t; 667 t = t->next(); 668 delete tcl; 669 } 670 } 671 672 void ConcurrentLocksDump::dump_at_safepoint() { 673 // dump all locked concurrent locks 674 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 675 676 ResourceMark rm; 677 678 GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE); 679 680 // Find all instances of AbstractOwnableSynchronizer 681 HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(), 682 aos_objects); 683 // Build a map of thread to its owned AQS locks 684 build_map(aos_objects); 685 } 686 687 688 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer 689 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) { 690 int length = aos_objects->length(); 691 for (int i = 0; i < length; i++) { 692 oop o = aos_objects->at(i); 693 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o); 694 if (owner_thread_obj != NULL) { 695 // See comments in ThreadConcurrentLocks to see how this 696 // JavaThread* is protected. 697 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj); 698 assert(o->is_instance(), "Must be an instanceOop"); 699 add_lock(thread, (instanceOop) o); 700 } 701 } 702 } 703 704 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) { 705 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread); 706 if (tcl != NULL) { 707 tcl->add_lock(o); 708 return; 709 } 710 711 // First owned lock found for this thread 712 tcl = new ThreadConcurrentLocks(thread); 713 tcl->add_lock(o); 714 if (_map == NULL) { 715 _map = tcl; 716 } else { 717 _last->set_next(tcl); 718 } 719 _last = tcl; 720 } 721 722 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) { 723 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) { 724 if (tcl->java_thread() == thread) { 725 return tcl; 726 } 727 } 728 return NULL; 729 } 730 731 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) { 732 st->print_cr(" Locked ownable synchronizers:"); 733 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t); 734 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL); 735 if (locks == NULL || locks->is_empty()) { 736 st->print_cr("\t- None"); 737 st->cr(); 738 return; 739 } 740 741 for (int i = 0; i < locks->length(); i++) { 742 instanceOop obj = locks->at(i); 743 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name()); 744 } 745 st->cr(); 746 } 747 748 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) { 749 _thread = thread; 750 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true); 751 _next = NULL; 752 } 753 754 ThreadConcurrentLocks::~ThreadConcurrentLocks() { 755 delete _owned_locks; 756 } 757 758 void ThreadConcurrentLocks::add_lock(instanceOop o) { 759 _owned_locks->append(o); 760 } 761 762 void ThreadConcurrentLocks::oops_do(OopClosure* f) { 763 int length = _owned_locks->length(); 764 for (int i = 0; i < length; i++) { 765 f->do_oop((oop*) _owned_locks->adr_at(i)); 766 } 767 } 768 769 ThreadStatistics::ThreadStatistics() { 770 _contended_enter_count = 0; 771 _monitor_wait_count = 0; 772 _sleep_count = 0; 773 _count_pending_reset = false; 774 _timer_pending_reset = false; 775 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts)); 776 } 777 778 ThreadSnapshot::ThreadSnapshot(ThreadsList * t_list, JavaThread* thread) { 779 _thread = thread; 780 _threadObj = thread->threadObj(); 781 _stack_trace = NULL; 782 _concurrent_locks = NULL; 783 _next = NULL; 784 785 ThreadStatistics* stat = thread->get_thread_stat(); 786 _contended_enter_ticks = stat->contended_enter_ticks(); 787 _contended_enter_count = stat->contended_enter_count(); 788 _monitor_wait_ticks = stat->monitor_wait_ticks(); 789 _monitor_wait_count = stat->monitor_wait_count(); 790 _sleep_ticks = stat->sleep_ticks(); 791 _sleep_count = stat->sleep_count(); 792 793 _blocker_object = NULL; 794 _blocker_object_owner = NULL; 795 796 _thread_status = java_lang_Thread::get_thread_status(_threadObj); 797 _is_ext_suspended = thread->is_being_ext_suspended(); 798 _is_in_native = (thread->thread_state() == _thread_in_native); 799 800 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER || 801 _thread_status == java_lang_Thread::IN_OBJECT_WAIT || 802 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) { 803 804 Handle obj = ThreadService::get_current_contended_monitor(thread); 805 if (obj() == NULL) { 806 // monitor no longer exists; thread is not blocked 807 _thread_status = java_lang_Thread::RUNNABLE; 808 } else { 809 _blocker_object = obj(); 810 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj); 811 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER) 812 || (owner != NULL && owner->is_attaching_via_jni())) { 813 // ownership information of the monitor is not available 814 // (may no longer be owned or releasing to some other thread) 815 // make this thread in RUNNABLE state. 816 // And when the owner thread is in attaching state, the java thread 817 // is not completely initialized. For example thread name and id 818 // and may not be set, so hide the attaching thread. 819 _thread_status = java_lang_Thread::RUNNABLE; 820 _blocker_object = NULL; 821 } else if (owner != NULL) { 822 _blocker_object_owner = owner->threadObj(); 823 } 824 } 825 } 826 827 // Support for JSR-166 locks 828 if (JDK_Version::current().supports_thread_park_blocker() && 829 (_thread_status == java_lang_Thread::PARKED || 830 _thread_status == java_lang_Thread::PARKED_TIMED)) { 831 832 _blocker_object = thread->current_park_blocker(); 833 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) { 834 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object); 835 } 836 } 837 } 838 839 ThreadSnapshot::~ThreadSnapshot() { 840 delete _stack_trace; 841 delete _concurrent_locks; 842 } 843 844 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) { 845 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors); 846 _stack_trace->dump_stack_at_safepoint(max_depth); 847 } 848 849 850 void ThreadSnapshot::oops_do(OopClosure* f) { 851 f->do_oop(&_threadObj); 852 f->do_oop(&_blocker_object); 853 f->do_oop(&_blocker_object_owner); 854 if (_stack_trace != NULL) { 855 _stack_trace->oops_do(f); 856 } 857 if (_concurrent_locks != NULL) { 858 _concurrent_locks->oops_do(f); 859 } 860 } 861 862 void ThreadSnapshot::metadata_do(void f(Metadata*)) { 863 if (_stack_trace != NULL) { 864 _stack_trace->metadata_do(f); 865 } 866 } 867 868 869 DeadlockCycle::DeadlockCycle() { 870 _is_deadlock = false; 871 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true); 872 _next = NULL; 873 } 874 875 DeadlockCycle::~DeadlockCycle() { 876 delete _threads; 877 } 878 879 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const { 880 st->cr(); 881 st->print_cr("Found one Java-level deadlock:"); 882 st->print("============================="); 883 884 JavaThread* currentThread; 885 ObjectMonitor* waitingToLockMonitor; 886 oop waitingToLockBlocker; 887 int len = _threads->length(); 888 for (int i = 0; i < len; i++) { 889 currentThread = _threads->at(i); 890 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(); 891 waitingToLockBlocker = currentThread->current_park_blocker(); 892 st->cr(); 893 st->print_cr("\"%s\":", currentThread->get_thread_name()); 894 const char* owner_desc = ",\n which is held by"; 895 if (waitingToLockMonitor != NULL) { 896 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor)); 897 oop obj = (oop)waitingToLockMonitor->object(); 898 if (obj != NULL) { 899 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj), 900 obj->klass()->external_name()); 901 902 if (!currentThread->current_pending_monitor_is_from_java()) { 903 owner_desc = "\n in JNI, which is held by"; 904 } 905 } else { 906 // No Java object associated - a JVMTI raw monitor 907 owner_desc = " (JVMTI raw monitor),\n which is held by"; 908 } 909 currentThread = Threads::owning_thread_from_monitor_owner(t_list, 910 (address)waitingToLockMonitor->owner()); 911 if (currentThread == NULL) { 912 // The deadlock was detected at a safepoint so the JavaThread 913 // that owns waitingToLockMonitor should be findable, but 914 // if it is not findable, then the previous currentThread is 915 // blocked permanently. 916 st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc, 917 p2i(waitingToLockMonitor->owner())); 918 continue; 919 } 920 } else { 921 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)", 922 p2i(waitingToLockBlocker), 923 waitingToLockBlocker->klass()->external_name()); 924 assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()), 925 "Must be an AbstractOwnableSynchronizer"); 926 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker); 927 currentThread = java_lang_Thread::thread(ownerObj); 928 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL"); 929 } 930 st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name()); 931 } 932 933 st->cr(); 934 st->cr(); 935 936 // Print stack traces 937 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace; 938 JavaMonitorsInStackTrace = true; 939 st->print_cr("Java stack information for the threads listed above:"); 940 st->print_cr("==================================================="); 941 for (int j = 0; j < len; j++) { 942 currentThread = _threads->at(j); 943 st->print_cr("\"%s\":", currentThread->get_thread_name()); 944 currentThread->print_stack_on(st); 945 } 946 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace; 947 } 948 949 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread, 950 bool include_jvmti_agent_threads, 951 bool include_jni_attaching_threads) { 952 assert(cur_thread == Thread::current(), "Check current thread"); 953 954 int init_size = ThreadService::get_live_thread_count(); 955 _threads_array = new GrowableArray<instanceHandle>(init_size); 956 957 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) { 958 // skips JavaThreads in the process of exiting 959 // and also skips VM internal JavaThreads 960 // Threads in _thread_new or _thread_new_trans state are included. 961 // i.e. threads have been started but not yet running. 962 if (jt->threadObj() == NULL || 963 jt->is_exiting() || 964 !java_lang_Thread::is_alive(jt->threadObj()) || 965 jt->is_hidden_from_external_view()) { 966 continue; 967 } 968 969 // skip agent threads 970 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) { 971 continue; 972 } 973 974 // skip jni threads in the process of attaching 975 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) { 976 continue; 977 } 978 979 instanceHandle h(cur_thread, (instanceOop) jt->threadObj()); 980 _threads_array->append(h); 981 } 982 }