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