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 "memory/resourceArea.hpp"
  32 #include "runtime/handles.inline.hpp"
  33 #include "runtime/mutexLocker.hpp"
  34 
  35 ConcurrentG1RefineThread::
  36 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread *next,
  37                          CardTableEntryClosure* refine_closure,
  38                          uint worker_id_offset, uint worker_id) :
  39   ConcurrentGCThread(),
  40   _refine_closure(refine_closure),
  41   _worker_id_offset(worker_id_offset),
  42   _worker_id(worker_id),
  43   _active(false),
  44   _next(next),
  45   _monitor(NULL),
  46   _cg1r(cg1r),
  47   _vtime_accum(0.0)
  48 {
  49 
  50   // Each thread has its own monitor. The i-th thread is responsible for signaling
  51   // to thread i+1 if the number of buffers in the queue exceeds a threshold for this
  52   // thread. Monitors are also used to wake up the threads during termination.
  53   // The 0th (primary) worker is notified by mutator threads and has a special monitor.
  54   if (!is_primary()) {
  55     _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true,
  56                            Monitor::_safepoint_check_never);
  57   } else {
  58     _monitor = DirtyCardQ_CBL_mon;
  59   }
  60   initialize();
  61   create_and_start();
  62 
  63   // set name
  64   set_name("G1 Refine#%d", worker_id);
  65 }
  66 
  67 void ConcurrentG1RefineThread::initialize() {
  68   // Current thread activation threshold
  69   _threshold = MIN2<int>(cg1r()->thread_threshold_step() * (_worker_id + 1) + cg1r()->green_zone(),
  70                          cg1r()->yellow_zone());
  71   // A thread deactivates once the number of buffer reached a deactivation threshold
  72   _deactivation_threshold = MAX2<int>(_threshold - cg1r()->thread_threshold_step(), cg1r()->green_zone());
  73 }
  74 
  75 void ConcurrentG1RefineThread::wait_for_completed_buffers() {
  76   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  77   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
  78   while (!_should_terminate && !is_active()) {
  79     _monitor->wait(Mutex::_no_safepoint_check_flag);
  80   }
  81 }
  82 
  83 bool ConcurrentG1RefineThread::is_active() {
  84   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  85   return is_primary() ? dcqs.process_completed_buffers() : _active;
  86 }
  87 
  88 void ConcurrentG1RefineThread::activate() {
  89   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
  90   if (!is_primary()) {
  91     if (G1TraceConcRefinement) {
  92       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  93       gclog_or_tty->print_cr("G1-Refine-activated worker %d, on threshold %d, current %d",
  94                              _worker_id, _threshold, (int)dcqs.completed_buffers_num());
  95     }
  96     set_active(true);
  97   } else {
  98     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  99     dcqs.set_process_completed(true);
 100   }
 101   _monitor->notify();
 102 }
 103 
 104 void ConcurrentG1RefineThread::deactivate() {
 105   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
 106   if (!is_primary()) {
 107     if (G1TraceConcRefinement) {
 108       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 109       gclog_or_tty->print_cr("G1-Refine-deactivated worker %d, off threshold %d, current %d",
 110                              _worker_id, _deactivation_threshold, (int)dcqs.completed_buffers_num());
 111     }
 112     set_active(false);
 113   } else {
 114     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 115     dcqs.set_process_completed(false);
 116   }
 117 }
 118 
 119 void ConcurrentG1RefineThread::run() {
 120   initialize_in_thread();
 121   wait_for_universe_init();
 122 
 123   run_service();
 124 
 125   terminate();
 126 }
 127 
 128 void ConcurrentG1RefineThread::run_service() {
 129   _vtime_start = os::elapsedVTime();
 130 
 131   while (!_should_terminate) {
 132     // Wait for work
 133     wait_for_completed_buffers();
 134     if (_should_terminate) {
 135       break;
 136     }
 137 
 138     {
 139       SuspendibleThreadSetJoiner sts_join;
 140       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 141 
 142       do {
 143         int curr_buffer_num = (int)dcqs.completed_buffers_num();
 144         // If the number of the buffers falls down into the yellow zone,
 145         // that means that the transition period after the evacuation pause has ended.
 146         if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {
 147           dcqs.set_completed_queue_padding(0);
 148         }
 149 
 150         if (!is_primary() && curr_buffer_num <= _deactivation_threshold) {
 151           // If the number of the buffer has fallen below our threshold
 152           // we should deactivate. The predecessor will reactivate this
 153           // thread should the number of the buffers cross the threshold again.
 154           deactivate();
 155           break;
 156         }
 157 
 158         // Check if we need to activate the next thread.
 159         if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) {
 160           _next->activate();
 161         }
 162       } while (dcqs.apply_closure_to_completed_buffer(_refine_closure, _worker_id + _worker_id_offset, cg1r()->green_zone()));
 163 
 164       // We can exit the loop above while being active if there was a yield request.
 165       if (is_active()) {
 166         deactivate();
 167       }
 168     }
 169 
 170     if (os::supports_vtime()) {
 171       _vtime_accum = (os::elapsedVTime() - _vtime_start);
 172     } else {
 173       _vtime_accum = 0.0;
 174     }
 175   }
 176 
 177   if (G1TraceConcRefinement) {
 178     gclog_or_tty->print_cr("G1-Refine-stop");
 179   }
 180 }
 181 
 182 void ConcurrentG1RefineThread::stop() {
 183   // it is ok to take late safepoints here, if needed
 184   {
 185     MutexLockerEx mu(Terminator_lock);
 186     _should_terminate = true;
 187   }
 188 
 189   stop_service();
 190 
 191   {
 192     MutexLockerEx mu(Terminator_lock);
 193     while (!_has_terminated) {
 194       Terminator_lock->wait();
 195     }
 196   }
 197 }
 198 
 199 void ConcurrentG1RefineThread::stop_service() {
 200   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
 201   _monitor->notify();
 202 }
--- EOF ---