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