src/share/vm/runtime/task.cpp

*** 1,7 ****
  /*
!  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 45,54 ****
--- 45,56 ----
    }
  }
  #endif
  
  void PeriodicTask::real_time_tick(int delay_time) {
+   assert(Thread::current()->is_Watcher_thread(), "must be WatcherThread");
+ 
  #ifndef PRODUCT
    if (ProfilerCheckIntervals) {
      _ticks++;
      _timer.stop();
      int ms = (int)(_timer.seconds() * 1000.0);
*** 58,67 ****
--- 60,71 ----
      _intervalHistogram[ms]++;
    }
  #endif
  
    {
+     // The WatcherThread is not a JavaThread so we do not honor the
+     // safepoint protocol for the PeriodicTask_lock.
      MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
      int orig_num_tasks = _num_tasks;
  
      for(int index = 0; index < _num_tasks; index++) {
        _tasks[index]->execute_if_pending(delay_time);
*** 72,83 ****
      }
    }
  }
  
  int PeriodicTask::time_to_wait() {
!   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ?
!                      NULL : PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
  
    if (_num_tasks == 0) {
      return 0; // sleep until shutdown or a task is enrolled
    }
  
--- 76,86 ----
      }
    }
  }
  
  int PeriodicTask::time_to_wait() {
!   assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
  
    if (_num_tasks == 0) {
      return 0; // sleep until shutdown or a task is enrolled
    }
  
*** 96,132 ****
           _interval %  PeriodicTask::interval_gran == 0,
                "improper PeriodicTask interval time");
  }
  
  PeriodicTask::~PeriodicTask() {
    disenroll();
  }
  
! /* enroll could be called from a JavaThread, so we have to check for
!  * safepoint when taking the lock to avoid deadlocking */
  void PeriodicTask::enroll() {
!   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ?
!                      NULL : PeriodicTask_lock);
  
    if (_num_tasks == PeriodicTask::max_tasks) {
      fatal("Overflow in PeriodicTask table");
    }
    _tasks[_num_tasks++] = this;
  
    WatcherThread* thread = WatcherThread::watcher_thread();
!   if (thread) {
      thread->unpark();
    } else {
      WatcherThread::start();
    }
  }
  
! /* disenroll could be called from a JavaThread, so we have to check for
!  * safepoint when taking the lock to avoid deadlocking */
  void PeriodicTask::disenroll() {
!   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ?
!                      NULL : PeriodicTask_lock);
  
    int index;
    for(index = 0; index < _num_tasks && _tasks[index] != this; index++)
      ;
  
--- 99,143 ----
           _interval %  PeriodicTask::interval_gran == 0,
                "improper PeriodicTask interval time");
  }
  
  PeriodicTask::~PeriodicTask() {
+   // This PeriodicTask may have already been disenrolled by a call
+   // to disenroll() before the PeriodicTask was deleted.
    disenroll();
  }
  
! // enroll the current PeriodicTask
  void PeriodicTask::enroll() {
!   // Follow normal safepoint aware lock enter protocol if the caller does
!   // not already own the PeriodicTask_lock. Otherwise, we don't try to
!   // enter it again because VM internal Mutexes do not support recursion.
!   //
!   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL
!                                                       : PeriodicTask_lock);
  
    if (_num_tasks == PeriodicTask::max_tasks) {
      fatal("Overflow in PeriodicTask table");
    }
    _tasks[_num_tasks++] = this;
  
    WatcherThread* thread = WatcherThread::watcher_thread();
!   if (thread != NULL) {
      thread->unpark();
    } else {
      WatcherThread::start();
    }
  }
  
! // disenroll the current PeriodicTask
  void PeriodicTask::disenroll() {
!   // Follow normal safepoint aware lock enter protocol if the caller does
!   // not already own the PeriodicTask_lock. Otherwise, we don't try to
!   // enter it again because VM internal Mutexes do not support recursion.
!   //
!   MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL
!                                                       : PeriodicTask_lock);
  
    int index;
    for(index = 0; index < _num_tasks && _tasks[index] != this; index++)
      ;