1 /*
   2  * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/systemDictionary.hpp"
  27 #include "memory/allocation.hpp"
  28 #include "memory/heapInspection.hpp"
  29 #include "memory/oopFactory.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "oops/instanceKlass.hpp"
  32 #include "oops/objArrayKlass.hpp"
  33 #include "oops/objArrayOop.inline.hpp"
  34 #include "oops/oop.inline.hpp"
  35 #include "runtime/atomic.hpp"
  36 #include "runtime/handles.inline.hpp"
  37 #include "runtime/init.hpp"
  38 #include "runtime/objectMonitor.inline.hpp"
  39 #include "runtime/thread.inline.hpp"
  40 #include "runtime/threadSMR.inline.hpp"
  41 #include "runtime/vframe.hpp"
  42 #include "runtime/vmThread.hpp"
  43 #include "runtime/vmOperations.hpp"
  44 #include "services/threadService.hpp"
  45 
  46 // TODO: we need to define a naming convention for perf counters
  47 // to distinguish counters for:
  48 //   - standard JSR174 use
  49 //   - Hotspot extension (public and committed)
  50 //   - Hotspot extension (private/internal and uncommitted)
  51 
  52 // Default is disabled.
  53 bool ThreadService::_thread_monitoring_contention_enabled = false;
  54 bool ThreadService::_thread_cpu_time_enabled = false;
  55 bool ThreadService::_thread_allocated_memory_enabled = false;
  56 
  57 PerfCounter*  ThreadService::_total_threads_count = NULL;
  58 PerfVariable* ThreadService::_live_threads_count = NULL;
  59 PerfVariable* ThreadService::_peak_threads_count = NULL;
  60 PerfVariable* ThreadService::_daemon_threads_count = NULL;
  61 volatile int ThreadService::_atomic_threads_count = 0;
  62 volatile int ThreadService::_atomic_daemon_threads_count = 0;
  63 
  64 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
  65 
  66 static const int INITIAL_ARRAY_SIZE = 10;
  67 
  68 void ThreadService::init() {
  69   EXCEPTION_MARK;
  70 
  71   // These counters are for java.lang.management API support.
  72   // They are created even if -XX:-UsePerfData is set and in
  73   // that case, they will be allocated on C heap.
  74 
  75   _total_threads_count =
  76                 PerfDataManager::create_counter(JAVA_THREADS, "started",
  77                                                 PerfData::U_Events, CHECK);
  78 
  79   _live_threads_count =
  80                 PerfDataManager::create_variable(JAVA_THREADS, "live",
  81                                                  PerfData::U_None, CHECK);
  82 
  83   _peak_threads_count =
  84                 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
  85                                                  PerfData::U_None, CHECK);
  86 
  87   _daemon_threads_count =
  88                 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
  89                                                  PerfData::U_None, CHECK);
  90 
  91   if (os::is_thread_cpu_time_supported()) {
  92     _thread_cpu_time_enabled = true;
  93   }
  94 
  95   _thread_allocated_memory_enabled = true; // Always on, so enable it
  96 }
  97 
  98 void ThreadService::reset_peak_thread_count() {
  99   // Acquire the lock to update the peak thread count
 100   // to synchronize with thread addition and removal.
 101   MutexLocker mu(Threads_lock);
 102   _peak_threads_count->set_value(get_live_thread_count());
 103 }
 104 
 105 static bool is_hidden_thread(JavaThread *thread) {
 106   // hide VM internal or JVMTI agent threads
 107   return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
 108 }
 109 
 110 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
 111   assert(Threads_lock->owned_by_self(), "must have threads lock");
 112 
 113   // Do not count hidden threads
 114   if (is_hidden_thread(thread)) {
 115     return;
 116   }
 117 
 118   _total_threads_count->inc();
 119   _live_threads_count->inc();
 120   Atomic::inc(&_atomic_threads_count);
 121   int count = _atomic_threads_count;
 122 
 123   if (count > _peak_threads_count->get_value()) {
 124     _peak_threads_count->set_value(count);
 125   }
 126 
 127   if (daemon) {
 128     _daemon_threads_count->inc();
 129     Atomic::inc(&_atomic_daemon_threads_count);
 130   }
 131 }
 132 
 133 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
 134   Atomic::dec(&_atomic_threads_count);
 135 
 136   if (daemon) {
 137     Atomic::dec(&_atomic_daemon_threads_count);
 138   }
 139 }
 140 
 141 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
 142   assert(Threads_lock->owned_by_self(), "must have threads lock");
 143 
 144   // Do not count hidden threads
 145   if (is_hidden_thread(thread)) {
 146     return;
 147   }
 148 
 149   assert(!thread->is_terminated(), "must not be terminated");
 150   if (!thread->is_exiting()) {
 151     // JavaThread::exit() skipped calling current_thread_exiting()
 152     decrement_thread_counts(thread, daemon);
 153   }
 154 
 155   int daemon_count = _atomic_daemon_threads_count;
 156   int count = _atomic_threads_count;
 157 
 158   // Counts are incremented at the same time, but atomic counts are
 159   // decremented earlier than perf counts.
 160   assert(_live_threads_count->get_value() > count,
 161     "thread count mismatch %d : %d",
 162     (int)_live_threads_count->get_value(), count);
 163 
 164   _live_threads_count->dec(1);
 165   if (daemon) {
 166     assert(_daemon_threads_count->get_value() > daemon_count,
 167       "thread count mismatch %d : %d",
 168       (int)_daemon_threads_count->get_value(), daemon_count);
 169 
 170     _daemon_threads_count->dec(1);
 171   }
 172 
 173   // Counts are incremented at the same time, but atomic counts are
 174   // decremented earlier than perf counts.
 175   assert(_daemon_threads_count->get_value() >= daemon_count,
 176     "thread count mismatch %d : %d",
 177     (int)_daemon_threads_count->get_value(), daemon_count);
 178   assert(_live_threads_count->get_value() >= count,
 179     "thread count mismatch %d : %d",
 180     (int)_live_threads_count->get_value(), count);
 181   assert(_live_threads_count->get_value() > 0 ||
 182     (_live_threads_count->get_value() == 0 && count == 0 &&
 183     _daemon_threads_count->get_value() == 0 && daemon_count == 0),
 184     "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
 185     (int)_live_threads_count->get_value(), count,
 186     (int)_daemon_threads_count->get_value(), daemon_count);
 187   assert(_daemon_threads_count->get_value() > 0 ||
 188     (_daemon_threads_count->get_value() == 0 && daemon_count == 0),
 189     "thread counts should reach 0 at the same time, daemon %d,%d",
 190     (int)_daemon_threads_count->get_value(), daemon_count);
 191 }
 192 
 193 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
 194   // Do not count hidden threads
 195   if (is_hidden_thread(jt)) {
 196     return;
 197   }
 198 
 199   assert(jt == JavaThread::current(), "Called by current thread");
 200   assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
 201 
 202   decrement_thread_counts(jt, daemon);
 203 }
 204 
 205 // FIXME: JVMTI should call this function
 206 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
 207   assert(thread != NULL, "should be non-NULL");
 208   debug_only(Thread::check_for_dangling_thread_pointer(thread);)
 209 
 210   ObjectMonitor *wait_obj = thread->current_waiting_monitor();
 211 
 212   oop obj = NULL;
 213   if (wait_obj != NULL) {
 214     // thread is doing an Object.wait() call
 215     obj = (oop) wait_obj->object();
 216     assert(obj != NULL, "Object.wait() should have an object");
 217   } else {
 218     ObjectMonitor *enter_obj = thread->current_pending_monitor();
 219     if (enter_obj != NULL) {
 220       // thread is trying to enter() or raw_enter() an ObjectMonitor.
 221       obj = (oop) enter_obj->object();
 222     }
 223     // If obj == NULL, then ObjectMonitor is raw which doesn't count.
 224   }
 225 
 226   Handle h(Thread::current(), obj);
 227   return h;
 228 }
 229 
 230 bool ThreadService::set_thread_monitoring_contention(bool flag) {
 231   MutexLocker m(Management_lock);
 232 
 233   bool prev = _thread_monitoring_contention_enabled;
 234   _thread_monitoring_contention_enabled = flag;
 235 
 236   return prev;
 237 }
 238 
 239 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
 240   MutexLocker m(Management_lock);
 241 
 242   bool prev = _thread_cpu_time_enabled;
 243   _thread_cpu_time_enabled = flag;
 244 
 245   return prev;
 246 }
 247 
 248 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
 249   MutexLocker m(Management_lock);
 250 
 251   bool prev = _thread_allocated_memory_enabled;
 252   _thread_allocated_memory_enabled = flag;
 253 
 254   return prev;
 255 }
 256 
 257 // GC support
 258 void ThreadService::oops_do(OopClosure* f) {
 259   for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
 260     dump->oops_do(f);
 261   }
 262 }
 263 
 264 void ThreadService::metadata_do(void f(Metadata*)) {
 265   for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
 266     dump->metadata_do(f);
 267   }
 268 }
 269 
 270 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
 271   MutexLocker ml(Management_lock);
 272   if (_threaddump_list == NULL) {
 273     _threaddump_list = dump;
 274   } else {
 275     dump->set_next(_threaddump_list);
 276     _threaddump_list = dump;
 277   }
 278 }
 279 
 280 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
 281   MutexLocker ml(Management_lock);
 282 
 283   ThreadDumpResult* prev = NULL;
 284   bool found = false;
 285   for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
 286     if (d == dump) {
 287       if (prev == NULL) {
 288         _threaddump_list = dump->next();
 289       } else {
 290         prev->set_next(dump->next());
 291       }
 292       found = true;
 293       break;
 294     }
 295   }
 296   assert(found, "The threaddump result to be removed must exist.");
 297 }
 298 
 299 // Dump stack trace of threads specified in the given threads array.
 300 // Returns StackTraceElement[][] each element is the stack trace of a thread in
 301 // the corresponding entry in the given threads array
 302 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
 303                                         int num_threads,
 304                                         TRAPS) {
 305   assert(num_threads > 0, "just checking");
 306 
 307   ThreadDumpResult dump_result;
 308   VM_ThreadDump op(&dump_result,
 309                    threads,
 310                    num_threads,
 311                    -1,    /* entire stack */
 312                    false, /* with locked monitors */
 313                    false  /* with locked synchronizers */);
 314   VMThread::execute(&op);
 315 
 316   // Allocate the resulting StackTraceElement[][] object
 317 
 318   ResourceMark rm(THREAD);
 319   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
 320   ObjArrayKlass* ik = ObjArrayKlass::cast(k);
 321   objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
 322   objArrayHandle result_obj(THREAD, r);
 323 
 324   int num_snapshots = dump_result.num_snapshots();
 325   assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
 326   assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
 327   int i = 0;
 328   for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
 329     ThreadStackTrace* stacktrace = ts->get_stack_trace();
 330     if (stacktrace == NULL) {
 331       // No stack trace
 332       result_obj->obj_at_put(i, NULL);
 333     } else {
 334       // Construct an array of java/lang/StackTraceElement object
 335       Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
 336       result_obj->obj_at_put(i, backtrace_h());
 337     }
 338   }
 339 
 340   return result_obj;
 341 }
 342 
 343 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
 344   ThreadStatistics* stat = thread->get_thread_stat();
 345   if (stat != NULL) {
 346     stat->reset_count_stat();
 347   }
 348 }
 349 
 350 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
 351   ThreadStatistics* stat = thread->get_thread_stat();
 352   if (stat != NULL) {
 353     stat->reset_time_stat();
 354   }
 355 }
 356 
 357 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
 358 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
 359   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 360 
 361   // This code was modified from the original Threads::find_deadlocks code.
 362   int globalDfn = 0, thisDfn;
 363   ObjectMonitor* waitingToLockMonitor = NULL;
 364   oop waitingToLockBlocker = NULL;
 365   bool blocked_on_monitor = false;
 366   JavaThread *currentThread, *previousThread;
 367   int num_deadlocks = 0;
 368 
 369   // Initialize the depth-first-number for each JavaThread.
 370   JavaThreadIterator jti(t_list);
 371   for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
 372     jt->set_depth_first_number(-1);
 373   }
 374 
 375   DeadlockCycle* deadlocks = NULL;
 376   DeadlockCycle* last = NULL;
 377   DeadlockCycle* cycle = new DeadlockCycle();
 378   for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
 379     if (jt->depth_first_number() >= 0) {
 380       // this thread was already visited
 381       continue;
 382     }
 383 
 384     thisDfn = globalDfn;
 385     jt->set_depth_first_number(globalDfn++);
 386     previousThread = jt;
 387     currentThread = jt;
 388 
 389     cycle->reset();
 390 
 391     // When there is a deadlock, all the monitors involved in the dependency
 392     // cycle must be contended and heavyweight. So we only care about the
 393     // heavyweight monitor a thread is waiting to lock.
 394     waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
 395     if (concurrent_locks) {
 396       waitingToLockBlocker = jt->current_park_blocker();
 397     }
 398     while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
 399       cycle->add_thread(currentThread);
 400       if (waitingToLockMonitor != NULL) {
 401         address currentOwner = (address)waitingToLockMonitor->owner();
 402         if (currentOwner != NULL) {
 403           currentThread = Threads::owning_thread_from_monitor_owner(t_list,
 404                                                                     currentOwner);
 405           if (currentThread == NULL) {
 406             // This function is called at a safepoint so the JavaThread
 407             // that owns waitingToLockMonitor should be findable, but
 408             // if it is not findable, then the previous currentThread is
 409             // blocked permanently. We record this as a deadlock.
 410             num_deadlocks++;
 411 
 412             cycle->set_deadlock(true);
 413 
 414             // add this cycle to the deadlocks list
 415             if (deadlocks == NULL) {
 416               deadlocks = cycle;
 417             } else {
 418               last->set_next(cycle);
 419             }
 420             last = cycle;
 421             cycle = new DeadlockCycle();
 422             break;
 423           }
 424         }
 425       } else {
 426         if (concurrent_locks) {
 427           if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
 428             oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
 429             // This JavaThread (if there is one) is protected by the
 430             // ThreadsListSetter in VM_FindDeadlocks::doit().
 431             currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
 432           } else {
 433             currentThread = NULL;
 434           }
 435         }
 436       }
 437 
 438       if (currentThread == NULL) {
 439         // No dependency on another thread
 440         break;
 441       }
 442       if (currentThread->depth_first_number() < 0) {
 443         // First visit to this thread
 444         currentThread->set_depth_first_number(globalDfn++);
 445       } else if (currentThread->depth_first_number() < thisDfn) {
 446         // Thread already visited, and not on a (new) cycle
 447         break;
 448       } else if (currentThread == previousThread) {
 449         // Self-loop, ignore
 450         break;
 451       } else {
 452         // We have a (new) cycle
 453         num_deadlocks++;
 454 
 455         cycle->set_deadlock(true);
 456 
 457         // add this cycle to the deadlocks list
 458         if (deadlocks == NULL) {
 459           deadlocks = cycle;
 460         } else {
 461           last->set_next(cycle);
 462         }
 463         last = cycle;
 464         cycle = new DeadlockCycle();
 465         break;
 466       }
 467       previousThread = currentThread;
 468       waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
 469       if (concurrent_locks) {
 470         waitingToLockBlocker = currentThread->current_park_blocker();
 471       }
 472     }
 473 
 474   }
 475   delete cycle;
 476   return deadlocks;
 477 }
 478 
 479 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
 480 
 481   // Create a new ThreadDumpResult object and append to the list.
 482   // If GC happens before this function returns, Method*
 483   // in the stack trace will be visited.
 484   ThreadService::add_thread_dump(this);
 485 }
 486 
 487 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
 488   // Create a new ThreadDumpResult object and append to the list.
 489   // If GC happens before this function returns, oops
 490   // will be visited.
 491   ThreadService::add_thread_dump(this);
 492 }
 493 
 494 ThreadDumpResult::~ThreadDumpResult() {
 495   ThreadService::remove_thread_dump(this);
 496 
 497   // free all the ThreadSnapshot objects created during
 498   // the VM_ThreadDump operation
 499   ThreadSnapshot* ts = _snapshots;
 500   while (ts != NULL) {
 501     ThreadSnapshot* p = ts;
 502     ts = ts->next();
 503     delete p;
 504   }
 505 }
 506 
 507 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
 508   ThreadSnapshot* ts = new ThreadSnapshot();
 509   link_thread_snapshot(ts);
 510   return ts;
 511 }
 512 
 513 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
 514   // Note: it is very important that the ThreadSnapshot* gets linked before
 515   // ThreadSnapshot::initialize gets called. This is to ensure that
 516   // ThreadSnapshot::oops_do can get called prior to the field
 517   // ThreadSnapshot::_threadObj being assigned a value (to prevent a dangling
 518   // oop).
 519   ThreadSnapshot* ts = new ThreadSnapshot();
 520   link_thread_snapshot(ts);
 521   ts->initialize(t_list(), thread);
 522   return ts;
 523 }
 524 
 525 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
 526   assert(_num_threads == 0 || _num_snapshots < _num_threads,
 527          "_num_snapshots must be less than _num_threads");
 528   _num_snapshots++;
 529   if (_snapshots == NULL) {
 530     _snapshots = ts;
 531   } else {
 532     _last->set_next(ts);
 533   }
 534   _last = ts;
 535 }
 536 
 537 void ThreadDumpResult::oops_do(OopClosure* f) {
 538   for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
 539     ts->oops_do(f);
 540   }
 541 }
 542 
 543 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
 544   for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
 545     ts->metadata_do(f);
 546   }
 547 }
 548 
 549 ThreadsList* ThreadDumpResult::t_list() {
 550   return _setter.list();
 551 }
 552 
 553 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
 554   _method = jvf->method();
 555   _bci = jvf->bci();
 556   _class_holder = _method->method_holder()->klass_holder();
 557   _locked_monitors = NULL;
 558   if (with_lock_info) {
 559     ResourceMark rm;
 560     GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
 561     int length = list->length();
 562     if (length > 0) {
 563       _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
 564       for (int i = 0; i < length; i++) {
 565         MonitorInfo* monitor = list->at(i);
 566         assert(monitor->owner() != NULL, "This monitor must have an owning object");
 567         _locked_monitors->append(monitor->owner());
 568       }
 569     }
 570   }
 571 }
 572 
 573 void StackFrameInfo::oops_do(OopClosure* f) {
 574   if (_locked_monitors != NULL) {
 575     int length = _locked_monitors->length();
 576     for (int i = 0; i < length; i++) {
 577       f->do_oop((oop*) _locked_monitors->adr_at(i));
 578     }
 579   }
 580   f->do_oop(&_class_holder);
 581 }
 582 
 583 void StackFrameInfo::metadata_do(void f(Metadata*)) {
 584   f(_method);
 585 }
 586 
 587 void StackFrameInfo::print_on(outputStream* st) const {
 588   ResourceMark rm;
 589   java_lang_Throwable::print_stack_element(st, method(), bci());
 590   int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
 591   for (int i = 0; i < len; i++) {
 592     oop o = _locked_monitors->at(i);
 593     st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
 594   }
 595 
 596 }
 597 
 598 // Iterate through monitor cache to find JNI locked monitors
 599 class InflatedMonitorsClosure: public MonitorClosure {
 600 private:
 601   ThreadStackTrace* _stack_trace;
 602   Thread* _thread;
 603 public:
 604   InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
 605     _thread = t;
 606     _stack_trace = st;
 607   }
 608   void do_monitor(ObjectMonitor* mid) {
 609     if (mid->owner() == _thread) {
 610       oop object = (oop) mid->object();
 611       if (!_stack_trace->is_owned_monitor_on_stack(object)) {
 612         _stack_trace->add_jni_locked_monitor(object);
 613       }
 614     }
 615   }
 616 };
 617 
 618 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
 619   _thread = t;
 620   _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
 621   _depth = 0;
 622   _with_locked_monitors = with_locked_monitors;
 623   if (_with_locked_monitors) {
 624     _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
 625   } else {
 626     _jni_locked_monitors = NULL;
 627   }
 628 }
 629 
 630 ThreadStackTrace::~ThreadStackTrace() {
 631   for (int i = 0; i < _frames->length(); i++) {
 632     delete _frames->at(i);
 633   }
 634   delete _frames;
 635   if (_jni_locked_monitors != NULL) {
 636     delete _jni_locked_monitors;
 637   }
 638 }
 639 
 640 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
 641   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
 642 
 643   if (_thread->has_last_Java_frame()) {
 644     RegisterMap reg_map(_thread);
 645     vframe* start_vf = _thread->last_java_vframe(&reg_map);
 646     int count = 0;
 647     for (vframe* f = start_vf; f; f = f->sender() ) {
 648       if (maxDepth >= 0 && count == maxDepth) {
 649         // Skip frames if more than maxDepth
 650         break;
 651       }
 652       if (f->is_java_frame()) {
 653         javaVFrame* jvf = javaVFrame::cast(f);
 654         add_stack_frame(jvf);
 655         count++;
 656       } else {
 657         // Ignore non-Java frames
 658       }
 659     }
 660   }
 661 
 662   if (_with_locked_monitors) {
 663     // Iterate inflated monitors and find monitors locked by this thread
 664     // not found in the stack
 665     InflatedMonitorsClosure imc(_thread, this);
 666     ObjectSynchronizer::monitors_iterate(&imc);
 667   }
 668 }
 669 
 670 
 671 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
 672   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
 673 
 674   bool found = false;
 675   int num_frames = get_stack_depth();
 676   for (int depth = 0; depth < num_frames; depth++) {
 677     StackFrameInfo* frame = stack_frame_at(depth);
 678     int len = frame->num_locked_monitors();
 679     GrowableArray<oop>* locked_monitors = frame->locked_monitors();
 680     for (int j = 0; j < len; j++) {
 681       oop monitor = locked_monitors->at(j);
 682       assert(monitor != NULL, "must be a Java object");
 683       if (oopDesc::equals(monitor, object)) {
 684         found = true;
 685         break;
 686       }
 687     }
 688   }
 689   return found;
 690 }
 691 
 692 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
 693   InstanceKlass* ik = SystemDictionary::StackTraceElement_klass();
 694   assert(ik != NULL, "must be loaded in 1.4+");
 695 
 696   // Allocate an array of java/lang/StackTraceElement object
 697   objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
 698   objArrayHandle backtrace(THREAD, ste);
 699   for (int j = 0; j < _depth; j++) {
 700     StackFrameInfo* frame = _frames->at(j);
 701     methodHandle mh(THREAD, frame->method());
 702     oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
 703     backtrace->obj_at_put(j, element);
 704   }
 705   return backtrace;
 706 }
 707 
 708 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
 709   StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
 710   _frames->append(frame);
 711   _depth++;
 712 }
 713 
 714 void ThreadStackTrace::oops_do(OopClosure* f) {
 715   int length = _frames->length();
 716   for (int i = 0; i < length; i++) {
 717     _frames->at(i)->oops_do(f);
 718   }
 719 
 720   length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
 721   for (int j = 0; j < length; j++) {
 722     f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
 723   }
 724 }
 725 
 726 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
 727   int length = _frames->length();
 728   for (int i = 0; i < length; i++) {
 729     _frames->at(i)->metadata_do(f);
 730   }
 731 }
 732 
 733 
 734 ConcurrentLocksDump::~ConcurrentLocksDump() {
 735   if (_retain_map_on_free) {
 736     return;
 737   }
 738 
 739   for (ThreadConcurrentLocks* t = _map; t != NULL;)  {
 740     ThreadConcurrentLocks* tcl = t;
 741     t = t->next();
 742     delete tcl;
 743   }
 744 }
 745 
 746 void ConcurrentLocksDump::dump_at_safepoint() {
 747   // dump all locked concurrent locks
 748   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
 749 
 750   GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */);
 751 
 752   // Find all instances of AbstractOwnableSynchronizer
 753   HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
 754                                               aos_objects);
 755   // Build a map of thread to its owned AQS locks
 756   build_map(aos_objects);
 757 
 758   delete aos_objects;
 759 }
 760 
 761 
 762 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
 763 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
 764   int length = aos_objects->length();
 765   for (int i = 0; i < length; i++) {
 766     oop o = aos_objects->at(i);
 767     oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
 768     if (owner_thread_obj != NULL) {
 769       // See comments in ThreadConcurrentLocks to see how this
 770       // JavaThread* is protected.
 771       JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
 772       assert(o->is_instance(), "Must be an instanceOop");
 773       add_lock(thread, (instanceOop) o);
 774     }
 775   }
 776 }
 777 
 778 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
 779   ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
 780   if (tcl != NULL) {
 781     tcl->add_lock(o);
 782     return;
 783   }
 784 
 785   // First owned lock found for this thread
 786   tcl = new ThreadConcurrentLocks(thread);
 787   tcl->add_lock(o);
 788   if (_map == NULL) {
 789     _map = tcl;
 790   } else {
 791     _last->set_next(tcl);
 792   }
 793   _last = tcl;
 794 }
 795 
 796 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
 797   for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
 798     if (tcl->java_thread() == thread) {
 799       return tcl;
 800     }
 801   }
 802   return NULL;
 803 }
 804 
 805 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
 806   st->print_cr("   Locked ownable synchronizers:");
 807   ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
 808   GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
 809   if (locks == NULL || locks->is_empty()) {
 810     st->print_cr("\t- None");
 811     st->cr();
 812     return;
 813   }
 814 
 815   for (int i = 0; i < locks->length(); i++) {
 816     instanceOop obj = locks->at(i);
 817     st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
 818   }
 819   st->cr();
 820 }
 821 
 822 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
 823   _thread = thread;
 824   _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
 825   _next = NULL;
 826 }
 827 
 828 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
 829   delete _owned_locks;
 830 }
 831 
 832 void ThreadConcurrentLocks::add_lock(instanceOop o) {
 833   _owned_locks->append(o);
 834 }
 835 
 836 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
 837   int length = _owned_locks->length();
 838   for (int i = 0; i < length; i++) {
 839     f->do_oop((oop*) _owned_locks->adr_at(i));
 840   }
 841 }
 842 
 843 ThreadStatistics::ThreadStatistics() {
 844   _contended_enter_count = 0;
 845   _monitor_wait_count = 0;
 846   _sleep_count = 0;
 847   _count_pending_reset = false;
 848   _timer_pending_reset = false;
 849   memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
 850 }
 851 
 852 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
 853   _thread = thread;
 854   _threadObj = thread->threadObj();
 855 
 856   ThreadStatistics* stat = thread->get_thread_stat();
 857   _contended_enter_ticks = stat->contended_enter_ticks();
 858   _contended_enter_count = stat->contended_enter_count();
 859   _monitor_wait_ticks = stat->monitor_wait_ticks();
 860   _monitor_wait_count = stat->monitor_wait_count();
 861   _sleep_ticks = stat->sleep_ticks();
 862   _sleep_count = stat->sleep_count();
 863 
 864   _thread_status = java_lang_Thread::get_thread_status(_threadObj);
 865   _is_ext_suspended = thread->is_being_ext_suspended();
 866   _is_in_native = (thread->thread_state() == _thread_in_native);
 867 
 868   if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
 869       _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
 870       _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
 871 
 872     Handle obj = ThreadService::get_current_contended_monitor(thread);
 873     if (obj() == NULL) {
 874       // monitor no longer exists; thread is not blocked
 875       _thread_status = java_lang_Thread::RUNNABLE;
 876     } else {
 877       _blocker_object = obj();
 878       JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
 879       if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
 880           || (owner != NULL && owner->is_attaching_via_jni())) {
 881         // ownership information of the monitor is not available
 882         // (may no longer be owned or releasing to some other thread)
 883         // make this thread in RUNNABLE state.
 884         // And when the owner thread is in attaching state, the java thread
 885         // is not completely initialized. For example thread name and id
 886         // and may not be set, so hide the attaching thread.
 887         _thread_status = java_lang_Thread::RUNNABLE;
 888         _blocker_object = NULL;
 889       } else if (owner != NULL) {
 890         _blocker_object_owner = owner->threadObj();
 891       }
 892     }
 893   }
 894 
 895   // Support for JSR-166 locks
 896   if (_thread_status == java_lang_Thread::PARKED || _thread_status == java_lang_Thread::PARKED_TIMED) {
 897     _blocker_object = thread->current_park_blocker();
 898     if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
 899       _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
 900     }
 901   }
 902 }
 903 
 904 ThreadSnapshot::~ThreadSnapshot() {
 905   delete _stack_trace;
 906   delete _concurrent_locks;
 907 }
 908 
 909 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
 910   _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
 911   _stack_trace->dump_stack_at_safepoint(max_depth);
 912 }
 913 
 914 
 915 void ThreadSnapshot::oops_do(OopClosure* f) {
 916   f->do_oop(&_threadObj);
 917   f->do_oop(&_blocker_object);
 918   f->do_oop(&_blocker_object_owner);
 919   if (_stack_trace != NULL) {
 920     _stack_trace->oops_do(f);
 921   }
 922   if (_concurrent_locks != NULL) {
 923     _concurrent_locks->oops_do(f);
 924   }
 925 }
 926 
 927 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
 928   if (_stack_trace != NULL) {
 929     _stack_trace->metadata_do(f);
 930   }
 931 }
 932 
 933 
 934 DeadlockCycle::DeadlockCycle() {
 935   _is_deadlock = false;
 936   _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
 937   _next = NULL;
 938 }
 939 
 940 DeadlockCycle::~DeadlockCycle() {
 941   delete _threads;
 942 }
 943 
 944 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
 945   st->cr();
 946   st->print_cr("Found one Java-level deadlock:");
 947   st->print("=============================");
 948 
 949   JavaThread* currentThread;
 950   ObjectMonitor* waitingToLockMonitor;
 951   oop waitingToLockBlocker;
 952   int len = _threads->length();
 953   for (int i = 0; i < len; i++) {
 954     currentThread = _threads->at(i);
 955     waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
 956     waitingToLockBlocker = currentThread->current_park_blocker();
 957     st->cr();
 958     st->print_cr("\"%s\":", currentThread->get_thread_name());
 959     const char* owner_desc = ",\n  which is held by";
 960     if (waitingToLockMonitor != NULL) {
 961       st->print("  waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
 962       oop obj = (oop)waitingToLockMonitor->object();
 963       if (obj != NULL) {
 964         st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
 965                    obj->klass()->external_name());
 966 
 967         if (!currentThread->current_pending_monitor_is_from_java()) {
 968           owner_desc = "\n  in JNI, which is held by";
 969         }
 970       } else {
 971         // No Java object associated - a JVMTI raw monitor
 972         owner_desc = " (JVMTI raw monitor),\n  which is held by";
 973       }
 974       currentThread = Threads::owning_thread_from_monitor_owner(t_list,
 975                                                                 (address)waitingToLockMonitor->owner());
 976       if (currentThread == NULL) {
 977         // The deadlock was detected at a safepoint so the JavaThread
 978         // that owns waitingToLockMonitor should be findable, but
 979         // if it is not findable, then the previous currentThread is
 980         // blocked permanently.
 981         st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
 982                   p2i(waitingToLockMonitor->owner()));
 983         continue;
 984       }
 985     } else {
 986       st->print("  waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
 987                 p2i(waitingToLockBlocker),
 988                 waitingToLockBlocker->klass()->external_name());
 989       assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
 990              "Must be an AbstractOwnableSynchronizer");
 991       oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
 992       currentThread = java_lang_Thread::thread(ownerObj);
 993       assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
 994     }
 995     st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
 996   }
 997 
 998   st->cr();
 999   st->cr();
1000 
1001   // Print stack traces
1002   bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
1003   JavaMonitorsInStackTrace = true;
1004   st->print_cr("Java stack information for the threads listed above:");
1005   st->print_cr("===================================================");
1006   for (int j = 0; j < len; j++) {
1007     currentThread = _threads->at(j);
1008     st->print_cr("\"%s\":", currentThread->get_thread_name());
1009     currentThread->print_stack_on(st);
1010   }
1011   JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
1012 }
1013 
1014 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
1015                                              bool include_jvmti_agent_threads,
1016                                              bool include_jni_attaching_threads) {
1017   assert(cur_thread == Thread::current(), "Check current thread");
1018 
1019   int init_size = ThreadService::get_live_thread_count();
1020   _threads_array = new GrowableArray<instanceHandle>(init_size);
1021 
1022   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
1023     // skips JavaThreads in the process of exiting
1024     // and also skips VM internal JavaThreads
1025     // Threads in _thread_new or _thread_new_trans state are included.
1026     // i.e. threads have been started but not yet running.
1027     if (jt->threadObj() == NULL   ||
1028         jt->is_exiting() ||
1029         !java_lang_Thread::is_alive(jt->threadObj())   ||
1030         jt->is_hidden_from_external_view()) {
1031       continue;
1032     }
1033 
1034     // skip agent threads
1035     if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
1036       continue;
1037     }
1038 
1039     // skip jni threads in the process of attaching
1040     if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
1041       continue;
1042     }
1043 
1044     instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
1045     _threads_array->append(h);
1046   }
1047 }