1 /*
   2  * Copyright (c) 2001, 2015, 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 "gc/g1/concurrentG1Refine.hpp"
  27 #include "gc/g1/concurrentG1RefineThread.hpp"
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1CollectorPolicy.hpp"
  30 #include "gc/g1/suspendibleThreadSet.hpp"
  31 #include "logging/log.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "runtime/handles.inline.hpp"
  34 #include "runtime/mutexLocker.hpp"
  35 
  36 ConcurrentG1RefineThread::
  37 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread *next,
  38                          CardTableEntryClosure* refine_closure,
  39                          uint worker_id_offset, uint worker_id) :
  40   ConcurrentGCThread(),
  41   _refine_closure(refine_closure),
  42   _worker_id_offset(worker_id_offset),
  43   _worker_id(worker_id),
  44   _active(false),
  45   _next(next),
  46   _monitor(NULL),
  47   _cg1r(cg1r),
  48   _vtime_accum(0.0)
  49 {
  50 
  51   // Each thread has its own monitor. The i-th thread is responsible for signaling
  52   // to thread i+1 if the number of buffers in the queue exceeds a threshold for this
  53   // thread. Monitors are also used to wake up the threads during termination.
  54   // The 0th (primary) worker is notified by mutator threads and has a special monitor.
  55   if (!is_primary()) {
  56     _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true,
  57                            Monitor::_safepoint_check_never);
  58   } else {
  59     _monitor = DirtyCardQ_CBL_mon;
  60   }
  61   initialize();
  62   create_and_start();
  63 
  64   // set name
  65   set_name("G1 Refine#%d", worker_id);
  66 }
  67 
  68 void ConcurrentG1RefineThread::initialize() {
  69   // Current thread activation threshold
  70   _threshold = MIN2<int>(cg1r()->thread_threshold_step() * (_worker_id + 1) + cg1r()->green_zone(),
  71                          cg1r()->yellow_zone());
  72   // A thread deactivates once the number of buffer reached a deactivation threshold
  73   _deactivation_threshold = MAX2<int>(_threshold - cg1r()->thread_threshold_step(), cg1r()->green_zone());
  74 }
  75 
  76 void ConcurrentG1RefineThread::wait_for_completed_buffers() {
  77   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  78   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
  79   while (!_should_terminate && !is_active()) {
  80     _monitor->wait(Mutex::_no_safepoint_check_flag);
  81   }
  82 }
  83 
  84 bool ConcurrentG1RefineThread::is_active() {
  85   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  86   return is_primary() ? dcqs.process_completed_buffers() : _active;
  87 }
  88 
  89 void ConcurrentG1RefineThread::activate() {
  90   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
  91   if (!is_primary()) {
  92     log_debug(gc, refine)("G1-Refine-activated worker %d, on threshold %d, current %d",
  93                           _worker_id, _threshold, JavaThread::dirty_card_queue_set().completed_buffers_num());



  94     set_active(true);
  95   } else {
  96     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  97     dcqs.set_process_completed(true);
  98   }
  99   _monitor->notify();
 100 }
 101 
 102 void ConcurrentG1RefineThread::deactivate() {
 103   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
 104   if (!is_primary()) {
 105     log_debug(gc, refine)("G1-Refine-deactivated worker %d, off threshold %d, current %d",
 106                           _worker_id, _deactivation_threshold, JavaThread::dirty_card_queue_set().completed_buffers_num());



 107     set_active(false);
 108   } else {
 109     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 110     dcqs.set_process_completed(false);
 111   }
 112 }
 113 
 114 void ConcurrentG1RefineThread::run() {
 115   initialize_in_thread();
 116   wait_for_universe_init();
 117 
 118   run_service();
 119 
 120   terminate();
 121 }
 122 
 123 void ConcurrentG1RefineThread::run_service() {
 124   _vtime_start = os::elapsedVTime();
 125 
 126   while (!_should_terminate) {
 127     // Wait for work
 128     wait_for_completed_buffers();
 129     if (_should_terminate) {
 130       break;
 131     }
 132 
 133     {
 134       SuspendibleThreadSetJoiner sts_join;
 135       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 136 
 137       do {
 138         int curr_buffer_num = (int)dcqs.completed_buffers_num();
 139         // If the number of the buffers falls down into the yellow zone,
 140         // that means that the transition period after the evacuation pause has ended.
 141         if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {
 142           dcqs.set_completed_queue_padding(0);
 143         }
 144 
 145         if (!is_primary() && curr_buffer_num <= _deactivation_threshold) {
 146           // If the number of the buffer has fallen below our threshold
 147           // we should deactivate. The predecessor will reactivate this
 148           // thread should the number of the buffers cross the threshold again.
 149           deactivate();
 150           break;
 151         }
 152 
 153         // Check if we need to activate the next thread.
 154         if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) {
 155           _next->activate();
 156         }
 157       } while (dcqs.apply_closure_to_completed_buffer(_refine_closure, _worker_id + _worker_id_offset, cg1r()->green_zone()));
 158 
 159       // We can exit the loop above while being active if there was a yield request.
 160       if (is_active()) {
 161         deactivate();
 162       }
 163     }
 164 
 165     if (os::supports_vtime()) {
 166       _vtime_accum = (os::elapsedVTime() - _vtime_start);
 167     } else {
 168       _vtime_accum = 0.0;
 169     }
 170   }
 171 
 172   log_debug(gc, refine)("G1-Refine-stop");


 173 }
 174 
 175 void ConcurrentG1RefineThread::stop() {
 176   // it is ok to take late safepoints here, if needed
 177   {
 178     MutexLockerEx mu(Terminator_lock);
 179     _should_terminate = true;
 180   }
 181 
 182   stop_service();
 183 
 184   {
 185     MutexLockerEx mu(Terminator_lock);
 186     while (!_has_terminated) {
 187       Terminator_lock->wait();
 188     }
 189   }
 190 }
 191 
 192 void ConcurrentG1RefineThread::stop_service() {
 193   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
 194   _monitor->notify();
 195 }
--- EOF ---