rev 4818 : 8016304: ThreadMXBean.getDeadlockedThreads reports bogus deadlocks on JDK 8
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   1 /*
   2  * Copyright (c) 2003, 2013, 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 "oops/instanceKlass.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/handles.inline.hpp"
  33 #include "runtime/init.hpp"
  34 #include "runtime/thread.hpp"
  35 #include "runtime/vframe.hpp"
  36 #include "runtime/vmThread.hpp"
  37 #include "runtime/vm_operations.hpp"
  38 #include "services/threadService.hpp"
  39 
  40 // TODO: we need to define a naming convention for perf counters
  41 // to distinguish counters for:
  42 //   - standard JSR174 use
  43 //   - Hotspot extension (public and committed)
  44 //   - Hotspot extension (private/internal and uncommitted)
  45 
  46 // Default is disabled.
  47 bool ThreadService::_thread_monitoring_contention_enabled = false;
  48 bool ThreadService::_thread_cpu_time_enabled = false;
  49 bool ThreadService::_thread_allocated_memory_enabled = false;
  50 
  51 PerfCounter*  ThreadService::_total_threads_count = NULL;
  52 PerfVariable* ThreadService::_live_threads_count = NULL;
  53 PerfVariable* ThreadService::_peak_threads_count = NULL;
  54 PerfVariable* ThreadService::_daemon_threads_count = NULL;
  55 volatile int ThreadService::_exiting_threads_count = 0;
  56 volatile int ThreadService::_exiting_daemon_threads_count = 0;
  57 
  58 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
  59 
  60 static const int INITIAL_ARRAY_SIZE = 10;
  61 
  62 void ThreadService::init() {
  63   EXCEPTION_MARK;
  64 
  65   // These counters are for java.lang.management API support.
  66   // They are created even if -XX:-UsePerfData is set and in
  67   // that case, they will be allocated on C heap.
  68 
  69   _total_threads_count =
  70                 PerfDataManager::create_counter(JAVA_THREADS, "started",
  71                                                 PerfData::U_Events, CHECK);
  72 
  73   _live_threads_count =
  74                 PerfDataManager::create_variable(JAVA_THREADS, "live",
  75                                                  PerfData::U_None, CHECK);
  76 
  77   _peak_threads_count =
  78                 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
  79                                                  PerfData::U_None, CHECK);
  80 
  81   _daemon_threads_count =
  82                 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
  83                                                  PerfData::U_None, CHECK);
  84 
  85   if (os::is_thread_cpu_time_supported()) {
  86     _thread_cpu_time_enabled = true;
  87   }
  88 
  89   _thread_allocated_memory_enabled = true; // Always on, so enable it
  90 }
  91 
  92 void ThreadService::reset_peak_thread_count() {
  93   // Acquire the lock to update the peak thread count
  94   // to synchronize with thread addition and removal.
  95   MutexLockerEx mu(Threads_lock);
  96   _peak_threads_count->set_value(get_live_thread_count());
  97 }
  98 
  99 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
 100   // Do not count VM internal or JVMTI agent threads
 101   if (thread->is_hidden_from_external_view() ||
 102       thread->is_jvmti_agent_thread()) {
 103     return;
 104   }
 105 
 106   _total_threads_count->inc();
 107   _live_threads_count->inc();
 108 
 109   if (_live_threads_count->get_value() > _peak_threads_count->get_value()) {
 110     _peak_threads_count->set_value(_live_threads_count->get_value());
 111   }
 112 
 113   if (daemon) {
 114     _daemon_threads_count->inc();
 115   }
 116 }
 117 
 118 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
 119   Atomic::dec((jint*) &_exiting_threads_count);
 120 
 121   if (thread->is_hidden_from_external_view() ||
 122       thread->is_jvmti_agent_thread()) {
 123     return;
 124   }
 125 
 126   _live_threads_count->set_value(_live_threads_count->get_value() - 1);
 127 
 128   if (daemon) {
 129     _daemon_threads_count->set_value(_daemon_threads_count->get_value() - 1);
 130     Atomic::dec((jint*) &_exiting_daemon_threads_count);
 131   }
 132 }
 133 
 134 void ThreadService::current_thread_exiting(JavaThread* jt) {
 135   assert(jt == JavaThread::current(), "Called by current thread");
 136   Atomic::inc((jint*) &_exiting_threads_count);
 137 
 138   oop threadObj = jt->threadObj();
 139   if (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)) {
 140     Atomic::inc((jint*) &_exiting_daemon_threads_count);
 141   }
 142 }
 143 
 144 // FIXME: JVMTI should call this function
 145 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
 146   assert(thread != NULL, "should be non-NULL");
 147   assert(Threads_lock->owned_by_self(), "must grab Threads_lock or be at safepoint");
 148 
 149   ObjectMonitor *wait_obj = thread->current_waiting_monitor();
 150 
 151   oop obj = NULL;
 152   if (wait_obj != NULL) {
 153     // thread is doing an Object.wait() call
 154     obj = (oop) wait_obj->object();
 155     assert(obj != NULL, "Object.wait() should have an object");
 156   } else {
 157     ObjectMonitor *enter_obj = thread->current_pending_monitor();
 158     if (enter_obj != NULL) {
 159       // thread is trying to enter() or raw_enter() an ObjectMonitor.
 160       obj = (oop) enter_obj->object();
 161     }
 162     // If obj == NULL, then ObjectMonitor is raw which doesn't count.
 163   }
 164 
 165   Handle h(obj);
 166   return h;
 167 }
 168 
 169 bool ThreadService::set_thread_monitoring_contention(bool flag) {
 170   MutexLocker m(Management_lock);
 171 
 172   bool prev = _thread_monitoring_contention_enabled;
 173   _thread_monitoring_contention_enabled = flag;
 174 
 175   return prev;
 176 }
 177 
 178 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
 179   MutexLocker m(Management_lock);
 180 
 181   bool prev = _thread_cpu_time_enabled;
 182   _thread_cpu_time_enabled = flag;
 183 
 184   return prev;
 185 }
 186 
 187 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
 188   MutexLocker m(Management_lock);
 189 
 190   bool prev = _thread_allocated_memory_enabled;
 191   _thread_allocated_memory_enabled = flag;
 192 
 193   return prev;
 194 }
 195 
 196 // GC support
 197 void ThreadService::oops_do(OopClosure* f) {
 198   for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
 199     dump->oops_do(f);
 200   }
 201 }
 202 
 203 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
 204   MutexLocker ml(Management_lock);
 205   if (_threaddump_list == NULL) {
 206     _threaddump_list = dump;
 207   } else {
 208     dump->set_next(_threaddump_list);
 209     _threaddump_list = dump;
 210   }
 211 }
 212 
 213 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
 214   MutexLocker ml(Management_lock);
 215 
 216   ThreadDumpResult* prev = NULL;
 217   bool found = false;
 218   for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
 219     if (d == dump) {
 220       if (prev == NULL) {
 221         _threaddump_list = dump->next();
 222       } else {
 223         prev->set_next(dump->next());
 224       }
 225       found = true;
 226       break;
 227     }
 228   }
 229   assert(found, "The threaddump result to be removed must exist.");
 230 }
 231 
 232 // Dump stack trace of threads specified in the given threads array.
 233 // Returns StackTraceElement[][] each element is the stack trace of a thread in
 234 // the corresponding entry in the given threads array
 235 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
 236                                         int num_threads,
 237                                         TRAPS) {
 238   assert(num_threads > 0, "just checking");
 239 
 240   ThreadDumpResult dump_result;
 241   VM_ThreadDump op(&dump_result,
 242                    threads,
 243                    num_threads,
 244                    -1,    /* entire stack */
 245                    false, /* with locked monitors */
 246                    false  /* with locked synchronizers */);
 247   VMThread::execute(&op);
 248 
 249   // Allocate the resulting StackTraceElement[][] object
 250 
 251   ResourceMark rm(THREAD);
 252   Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
 253   ObjArrayKlass* ik = ObjArrayKlass::cast(k);
 254   objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
 255   objArrayHandle result_obj(THREAD, r);
 256 
 257   int num_snapshots = dump_result.num_snapshots();
 258   assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
 259   int i = 0;
 260   for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
 261     ThreadStackTrace* stacktrace = ts->get_stack_trace();
 262     if (stacktrace == NULL) {
 263       // No stack trace
 264       result_obj->obj_at_put(i, NULL);
 265     } else {
 266       // Construct an array of java/lang/StackTraceElement object
 267       Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
 268       result_obj->obj_at_put(i, backtrace_h());
 269     }
 270   }
 271 
 272   return result_obj;
 273 }
 274 
 275 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
 276   ThreadStatistics* stat = thread->get_thread_stat();
 277   if (stat != NULL) {
 278     stat->reset_count_stat();
 279   }
 280 }
 281 
 282 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
 283   ThreadStatistics* stat = thread->get_thread_stat();
 284   if (stat != NULL) {
 285     stat->reset_time_stat();
 286   }
 287 }
 288 
 289 // Find deadlocks involving object monitors and concurrent locks if concurrent_locks is true
 290 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(bool concurrent_locks) {
 291   // This code was modified from the original Threads::find_deadlocks code.
 292   int globalDfn = 0, thisDfn;
 293   ObjectMonitor* waitingToLockMonitor = NULL;
 294   oop waitingToLockBlocker = NULL;
 295   bool blocked_on_monitor = false;
 296   JavaThread *currentThread, *previousThread;
 297   int num_deadlocks = 0;
 298 
 299   for (JavaThread* p = Threads::first(); p != NULL; p = p->next()) {
 300     // Initialize the depth-first-number
 301     p->set_depth_first_number(-1);
 302   }
 303 
 304   DeadlockCycle* deadlocks = NULL;
 305   DeadlockCycle* last = NULL;
 306   DeadlockCycle* cycle = new DeadlockCycle();
 307   for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
 308     if (jt->depth_first_number() >= 0) {
 309       // this thread was already visited
 310       continue;
 311     }
 312 
 313     thisDfn = globalDfn;
 314     jt->set_depth_first_number(globalDfn++);
 315     previousThread = jt;
 316     currentThread = jt;
 317 
 318     cycle->reset();
 319 
 320     // When there is a deadlock, all the monitors involved in the dependency
 321     // cycle must be contended and heavyweight. So we only care about the
 322     // heavyweight monitor a thread is waiting to lock.
 323     waitingToLockMonitor = (ObjectMonitor*)jt->current_pending_monitor();
 324     if (concurrent_locks) {
 325       waitingToLockBlocker = jt->current_park_blocker();
 326     }
 327     while (waitingToLockMonitor != NULL || waitingToLockBlocker != NULL) {
 328       cycle->add_thread(currentThread);
 329       if (waitingToLockMonitor != NULL) {
 330         address currentOwner = (address)waitingToLockMonitor->owner();
 331         if (currentOwner != NULL) {
 332           currentThread = Threads::owning_thread_from_monitor_owner(
 333                             currentOwner,
 334                             false /* no locking needed */);
 335           if (currentThread == NULL) {
 336             // This function is called at a safepoint so the JavaThread
 337             // that owns waitingToLockMonitor should be findable, but
 338             // if it is not findable, then the previous currentThread is
 339             // blocked permanently. We record this as a deadlock.
 340             num_deadlocks++;
 341 
 342             cycle->set_deadlock(true);
 343 
 344             // add this cycle to the deadlocks list
 345             if (deadlocks == NULL) {
 346               deadlocks = cycle;
 347             } else {
 348               last->set_next(cycle);
 349             }
 350             last = cycle;
 351             cycle = new DeadlockCycle();
 352             break;
 353           }
 354         }
 355       } else {
 356         if (concurrent_locks) {
 357           if (waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
 358             oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
 359             currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
 360           } else {
 361             currentThread = NULL;
 362           }
 363         }
 364       }
 365 
 366       if (currentThread == NULL) {
 367         // No dependency on another thread
 368         break;
 369       }
 370       if (currentThread->depth_first_number() < 0) {
 371         // First visit to this thread
 372         currentThread->set_depth_first_number(globalDfn++);
 373       } else if (currentThread->depth_first_number() < thisDfn) {
 374         // Thread already visited, and not on a (new) cycle
 375         break;
 376       } else if (currentThread == previousThread) {
 377         // Self-loop, ignore
 378         break;
 379       } else {
 380         // We have a (new) cycle
 381         num_deadlocks++;
 382 
 383         cycle->set_deadlock(true);
 384 
 385         // add this cycle to the deadlocks list
 386         if (deadlocks == NULL) {
 387           deadlocks = cycle;
 388         } else {
 389           last->set_next(cycle);
 390         }
 391         last = cycle;
 392         cycle = new DeadlockCycle();
 393         break;
 394       }
 395       previousThread = currentThread;
 396       waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
 397       if (concurrent_locks) {
 398         waitingToLockBlocker = currentThread->current_park_blocker();
 399       }
 400     }
 401 
 402   }
 403   delete cycle;
 404   return deadlocks;
 405 }
 406 
 407 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
 408 
 409   // Create a new ThreadDumpResult object and append to the list.
 410   // If GC happens before this function returns, Method*
 411   // in the stack trace will be visited.
 412   ThreadService::add_thread_dump(this);
 413 }
 414 
 415 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _next(NULL), _last(NULL) {
 416   // Create a new ThreadDumpResult object and append to the list.
 417   // If GC happens before this function returns, oops
 418   // will be visited.
 419   ThreadService::add_thread_dump(this);
 420 }
 421 
 422 ThreadDumpResult::~ThreadDumpResult() {
 423   ThreadService::remove_thread_dump(this);
 424 
 425   // free all the ThreadSnapshot objects created during
 426   // the VM_ThreadDump operation
 427   ThreadSnapshot* ts = _snapshots;
 428   while (ts != NULL) {
 429     ThreadSnapshot* p = ts;
 430     ts = ts->next();
 431     delete p;
 432   }
 433 }
 434 
 435 
 436 void ThreadDumpResult::add_thread_snapshot(ThreadSnapshot* ts) {
 437   assert(_num_threads == 0 || _num_snapshots < _num_threads,
 438          "_num_snapshots must be less than _num_threads");
 439   _num_snapshots++;
 440   if (_snapshots == NULL) {
 441     _snapshots = ts;
 442   } else {
 443     _last->set_next(ts);
 444   }
 445   _last = ts;
 446 }
 447 
 448 void ThreadDumpResult::oops_do(OopClosure* f) {
 449   for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
 450     ts->oops_do(f);
 451   }
 452 }
 453 
 454 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
 455   _method = jvf->method();
 456   _bci = jvf->bci();
 457   _locked_monitors = NULL;
 458   if (with_lock_info) {
 459     ResourceMark rm;
 460     GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
 461     int length = list->length();
 462     if (length > 0) {
 463       _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
 464       for (int i = 0; i < length; i++) {
 465         MonitorInfo* monitor = list->at(i);
 466         assert(monitor->owner(), "This monitor must have an owning object");
 467         _locked_monitors->append(monitor->owner());
 468       }
 469     }
 470   }
 471 }
 472 
 473 void StackFrameInfo::oops_do(OopClosure* f) {
 474   if (_locked_monitors != NULL) {
 475     int length = _locked_monitors->length();
 476     for (int i = 0; i < length; i++) {
 477       f->do_oop((oop*) _locked_monitors->adr_at(i));
 478     }
 479   }
 480 }
 481 
 482 void StackFrameInfo::print_on(outputStream* st) const {
 483   ResourceMark rm;
 484   java_lang_Throwable::print_stack_element(st, method(), bci());
 485   int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
 486   for (int i = 0; i < len; i++) {
 487     oop o = _locked_monitors->at(i);
 488     InstanceKlass* ik = InstanceKlass::cast(o->klass());
 489     st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", (address)o, ik->external_name());
 490   }
 491 
 492 }
 493 
 494 // Iterate through monitor cache to find JNI locked monitors
 495 class InflatedMonitorsClosure: public MonitorClosure {
 496 private:
 497   ThreadStackTrace* _stack_trace;
 498   Thread* _thread;
 499 public:
 500   InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
 501     _thread = t;
 502     _stack_trace = st;
 503   }
 504   void do_monitor(ObjectMonitor* mid) {
 505     if (mid->owner() == _thread) {
 506       oop object = (oop) mid->object();
 507       if (!_stack_trace->is_owned_monitor_on_stack(object)) {
 508         _stack_trace->add_jni_locked_monitor(object);
 509       }
 510     }
 511   }
 512 };
 513 
 514 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
 515   _thread = t;
 516   _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
 517   _depth = 0;
 518   _with_locked_monitors = with_locked_monitors;
 519   if (_with_locked_monitors) {
 520     _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
 521   } else {
 522     _jni_locked_monitors = NULL;
 523   }
 524 }
 525 
 526 ThreadStackTrace::~ThreadStackTrace() {
 527   for (int i = 0; i < _frames->length(); i++) {
 528     delete _frames->at(i);
 529   }
 530   delete _frames;
 531   if (_jni_locked_monitors != NULL) {
 532     delete _jni_locked_monitors;
 533   }
 534 }
 535 
 536 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
 537   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
 538 
 539   if (_thread->has_last_Java_frame()) {
 540     RegisterMap reg_map(_thread);
 541     vframe* start_vf = _thread->last_java_vframe(&reg_map);
 542     int count = 0;
 543     for (vframe* f = start_vf; f; f = f->sender() ) {
 544       if (f->is_java_frame()) {
 545         javaVFrame* jvf = javaVFrame::cast(f);
 546         add_stack_frame(jvf);
 547         count++;
 548       } else {
 549         // Ignore non-Java frames
 550       }
 551       if (maxDepth > 0 && count == maxDepth) {
 552         // Skip frames if more than maxDepth
 553         break;
 554       }
 555     }
 556   }
 557 
 558   if (_with_locked_monitors) {
 559     // Iterate inflated monitors and find monitors locked by this thread
 560     // not found in the stack
 561     InflatedMonitorsClosure imc(_thread, this);
 562     ObjectSynchronizer::monitors_iterate(&imc);
 563   }
 564 }
 565 
 566 
 567 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
 568   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
 569 
 570   bool found = false;
 571   int num_frames = get_stack_depth();
 572   for (int depth = 0; depth < num_frames; depth++) {
 573     StackFrameInfo* frame = stack_frame_at(depth);
 574     int len = frame->num_locked_monitors();
 575     GrowableArray<oop>* locked_monitors = frame->locked_monitors();
 576     for (int j = 0; j < len; j++) {
 577       oop monitor = locked_monitors->at(j);
 578       assert(monitor != NULL && monitor->is_instance(), "must be a Java object");
 579       if (monitor == object) {
 580         found = true;
 581         break;
 582       }
 583     }
 584   }
 585   return found;
 586 }
 587 
 588 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
 589   Klass* k = SystemDictionary::StackTraceElement_klass();
 590   assert(k != NULL, "must be loaded in 1.4+");
 591   instanceKlassHandle ik(THREAD, k);
 592 
 593   // Allocate an array of java/lang/StackTraceElement object
 594   objArrayOop ste = oopFactory::new_objArray(ik(), _depth, CHECK_NH);
 595   objArrayHandle backtrace(THREAD, ste);
 596   for (int j = 0; j < _depth; j++) {
 597     StackFrameInfo* frame = _frames->at(j);
 598     methodHandle mh(THREAD, frame->method());
 599     oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
 600     backtrace->obj_at_put(j, element);
 601   }
 602   return backtrace;
 603 }
 604 
 605 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
 606   StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
 607   _frames->append(frame);
 608   _depth++;
 609 }
 610 
 611 void ThreadStackTrace::oops_do(OopClosure* f) {
 612   int length = _frames->length();
 613   for (int i = 0; i < length; i++) {
 614     _frames->at(i)->oops_do(f);
 615   }
 616 
 617   length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
 618   for (int j = 0; j < length; j++) {
 619     f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
 620   }
 621 }
 622 
 623 ConcurrentLocksDump::~ConcurrentLocksDump() {
 624   if (_retain_map_on_free) {
 625     return;
 626   }
 627 
 628   for (ThreadConcurrentLocks* t = _map; t != NULL;)  {
 629     ThreadConcurrentLocks* tcl = t;
 630     t = t->next();
 631     delete tcl;
 632   }
 633 }
 634 
 635 void ConcurrentLocksDump::dump_at_safepoint() {
 636   // dump all locked concurrent locks
 637   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
 638 
 639   if (JDK_Version::is_gte_jdk16x_version()) {
 640     ResourceMark rm;
 641 
 642     GrowableArray<oop>* aos_objects = new GrowableArray<oop>(INITIAL_ARRAY_SIZE);
 643 
 644     // Find all instances of AbstractOwnableSynchronizer
 645     HeapInspection::find_instances_at_safepoint(SystemDictionary::abstract_ownable_synchronizer_klass(),
 646                                                 aos_objects);
 647     // Build a map of thread to its owned AQS locks
 648     build_map(aos_objects);
 649   }
 650 }
 651 
 652 
 653 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
 654 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
 655   int length = aos_objects->length();
 656   for (int i = 0; i < length; i++) {
 657     oop o = aos_objects->at(i);
 658     oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
 659     if (owner_thread_obj != NULL) {
 660       JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
 661       assert(o->is_instance(), "Must be an instanceOop");
 662       add_lock(thread, (instanceOop) o);
 663     }
 664   }
 665 }
 666 
 667 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
 668   ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
 669   if (tcl != NULL) {
 670     tcl->add_lock(o);
 671     return;
 672   }
 673 
 674   // First owned lock found for this thread
 675   tcl = new ThreadConcurrentLocks(thread);
 676   tcl->add_lock(o);
 677   if (_map == NULL) {
 678     _map = tcl;
 679   } else {
 680     _last->set_next(tcl);
 681   }
 682   _last = tcl;
 683 }
 684 
 685 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
 686   for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
 687     if (tcl->java_thread() == thread) {
 688       return tcl;
 689     }
 690   }
 691   return NULL;
 692 }
 693 
 694 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
 695   st->print_cr("   Locked ownable synchronizers:");
 696   ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
 697   GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
 698   if (locks == NULL || locks->is_empty()) {
 699     st->print_cr("\t- None");
 700     st->cr();
 701     return;
 702   }
 703 
 704   for (int i = 0; i < locks->length(); i++) {
 705     instanceOop obj = locks->at(i);
 706     InstanceKlass* ik = InstanceKlass::cast(obj->klass());
 707     st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", (address)obj, ik->external_name());
 708   }
 709   st->cr();
 710 }
 711 
 712 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
 713   _thread = thread;
 714   _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
 715   _next = NULL;
 716 }
 717 
 718 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
 719   delete _owned_locks;
 720 }
 721 
 722 void ThreadConcurrentLocks::add_lock(instanceOop o) {
 723   _owned_locks->append(o);
 724 }
 725 
 726 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
 727   int length = _owned_locks->length();
 728   for (int i = 0; i < length; i++) {
 729     f->do_oop((oop*) _owned_locks->adr_at(i));
 730   }
 731 }
 732 
 733 ThreadStatistics::ThreadStatistics() {
 734   _contended_enter_count = 0;
 735   _monitor_wait_count = 0;
 736   _sleep_count = 0;
 737   _count_pending_reset = false;
 738   _timer_pending_reset = false;
 739   memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
 740 }
 741 
 742 ThreadSnapshot::ThreadSnapshot(JavaThread* thread) {
 743   _thread = thread;
 744   _threadObj = thread->threadObj();
 745   _stack_trace = NULL;
 746   _concurrent_locks = NULL;
 747   _next = NULL;
 748 
 749   ThreadStatistics* stat = thread->get_thread_stat();
 750   _contended_enter_ticks = stat->contended_enter_ticks();
 751   _contended_enter_count = stat->contended_enter_count();
 752   _monitor_wait_ticks = stat->monitor_wait_ticks();
 753   _monitor_wait_count = stat->monitor_wait_count();
 754   _sleep_ticks = stat->sleep_ticks();
 755   _sleep_count = stat->sleep_count();
 756 
 757   _blocker_object = NULL;
 758   _blocker_object_owner = NULL;
 759 
 760   _thread_status = java_lang_Thread::get_thread_status(_threadObj);
 761   _is_ext_suspended = thread->is_being_ext_suspended();
 762   _is_in_native = (thread->thread_state() == _thread_in_native);
 763 
 764   if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
 765       _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
 766       _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
 767 
 768     Handle obj = ThreadService::get_current_contended_monitor(thread);
 769     if (obj() == NULL) {
 770       // monitor no longer exists; thread is not blocked
 771       _thread_status = java_lang_Thread::RUNNABLE;
 772     } else {
 773       _blocker_object = obj();
 774       JavaThread* owner = ObjectSynchronizer::get_lock_owner(obj, false);
 775       if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
 776           || (owner != NULL && owner->is_attaching_via_jni())) {
 777         // ownership information of the monitor is not available
 778         // (may no longer be owned or releasing to some other thread)
 779         // make this thread in RUNNABLE state.
 780         // And when the owner thread is in attaching state, the java thread
 781         // is not completely initialized. For example thread name and id
 782         // and may not be set, so hide the attaching thread.
 783         _thread_status = java_lang_Thread::RUNNABLE;
 784         _blocker_object = NULL;
 785       } else if (owner != NULL) {
 786         _blocker_object_owner = owner->threadObj();
 787       }
 788     }
 789   }
 790 
 791   // Support for JSR-166 locks
 792   if (JDK_Version::current().supports_thread_park_blocker() &&
 793         (_thread_status == java_lang_Thread::PARKED ||
 794          _thread_status == java_lang_Thread::PARKED_TIMED)) {
 795 
 796     _blocker_object = thread->current_park_blocker();
 797     if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::abstract_ownable_synchronizer_klass())) {
 798       _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
 799     }
 800   }
 801 }
 802 
 803 ThreadSnapshot::~ThreadSnapshot() {
 804   delete _stack_trace;
 805   delete _concurrent_locks;
 806 }
 807 
 808 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
 809   _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
 810   _stack_trace->dump_stack_at_safepoint(max_depth);
 811 }
 812 
 813 
 814 void ThreadSnapshot::oops_do(OopClosure* f) {
 815   f->do_oop(&_threadObj);
 816   f->do_oop(&_blocker_object);
 817   f->do_oop(&_blocker_object_owner);
 818   if (_stack_trace != NULL) {
 819     _stack_trace->oops_do(f);
 820   }
 821   if (_concurrent_locks != NULL) {
 822     _concurrent_locks->oops_do(f);
 823   }
 824 }
 825 
 826 DeadlockCycle::DeadlockCycle() {
 827   _is_deadlock = false;
 828   _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
 829   _next = NULL;
 830 }
 831 
 832 DeadlockCycle::~DeadlockCycle() {
 833   delete _threads;
 834 }
 835 
 836 void DeadlockCycle::print_on(outputStream* st) const {
 837   st->cr();
 838   st->print_cr("Found one Java-level deadlock:");
 839   st->print("=============================");
 840 
 841   JavaThread* currentThread;
 842   ObjectMonitor* waitingToLockMonitor;
 843   oop waitingToLockBlocker;
 844   int len = _threads->length();
 845   for (int i = 0; i < len; i++) {
 846     currentThread = _threads->at(i);
 847     waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor();
 848     waitingToLockBlocker = currentThread->current_park_blocker();
 849     st->cr();
 850     st->print_cr("\"%s\":", currentThread->get_thread_name());
 851     const char* owner_desc = ",\n  which is held by";
 852     if (waitingToLockMonitor != NULL) {
 853       st->print("  waiting to lock monitor " INTPTR_FORMAT, waitingToLockMonitor);
 854       oop obj = (oop)waitingToLockMonitor->object();
 855       if (obj != NULL) {
 856         st->print(" (object "INTPTR_FORMAT ", a %s)", (address)obj,
 857                    (InstanceKlass::cast(obj->klass()))->external_name());
 858 
 859         if (!currentThread->current_pending_monitor_is_from_java()) {
 860           owner_desc = "\n  in JNI, which is held by";
 861         }
 862       } else {
 863         // No Java object associated - a JVMTI raw monitor
 864         owner_desc = " (JVMTI raw monitor),\n  which is held by";
 865       }
 866       currentThread = Threads::owning_thread_from_monitor_owner(
 867                         (address)waitingToLockMonitor->owner(),
 868                         false /* no locking needed */);
 869       if (currentThread == NULL) {
 870         // The deadlock was detected at a safepoint so the JavaThread
 871         // that owns waitingToLockMonitor should be findable, but
 872         // if it is not findable, then the previous currentThread is
 873         // blocked permanently.
 874         st->print("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
 875                   (address)waitingToLockMonitor->owner());
 876         continue;
 877       }
 878     } else {
 879       st->print("  waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
 880                 (address)waitingToLockBlocker,
 881                 (InstanceKlass::cast(waitingToLockBlocker->klass()))->external_name());
 882       assert(waitingToLockBlocker->is_a(SystemDictionary::abstract_ownable_synchronizer_klass()),
 883              "Must be an AbstractOwnableSynchronizer");
 884       oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
 885       currentThread = java_lang_Thread::thread(ownerObj);
 886     }
 887     st->print("%s \"%s\"", owner_desc, currentThread->get_thread_name());
 888   }
 889 
 890   st->cr();
 891   st->cr();
 892 
 893   // Print stack traces
 894   bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
 895   JavaMonitorsInStackTrace = true;
 896   st->print_cr("Java stack information for the threads listed above:");
 897   st->print_cr("===================================================");
 898   for (int j = 0; j < len; j++) {
 899     currentThread = _threads->at(j);
 900     st->print_cr("\"%s\":", currentThread->get_thread_name());
 901     currentThread->print_stack_on(st);
 902   }
 903   JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
 904 }
 905 
 906 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
 907                                              bool include_jvmti_agent_threads,
 908                                              bool include_jni_attaching_threads) {
 909   assert(cur_thread == Thread::current(), "Check current thread");
 910 
 911   int init_size = ThreadService::get_live_thread_count();
 912   _threads_array = new GrowableArray<instanceHandle>(init_size);
 913 
 914   MutexLockerEx ml(Threads_lock);
 915 
 916   for (JavaThread* jt = Threads::first(); jt != NULL; jt = jt->next()) {
 917     // skips JavaThreads in the process of exiting
 918     // and also skips VM internal JavaThreads
 919     // Threads in _thread_new or _thread_new_trans state are included.
 920     // i.e. threads have been started but not yet running.
 921     if (jt->threadObj() == NULL   ||
 922         jt->is_exiting() ||
 923         !java_lang_Thread::is_alive(jt->threadObj())   ||
 924         jt->is_hidden_from_external_view()) {
 925       continue;
 926     }
 927 
 928     // skip agent threads
 929     if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
 930       continue;
 931     }
 932 
 933     // skip jni threads in the process of attaching
 934     if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
 935       continue;
 936     }
 937 
 938     instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
 939     _threads_array->append(h);
 940   }
 941 }
--- EOF ---