1 /*
   2  * Copyright (c) 2001, 2016, 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/g1RemSet.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                          uint worker_id_offset, uint worker_id,
  39                          size_t activate, size_t deactivate) :
  40   ConcurrentGCThread(),
  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   _activation_threshold(activate),
  49   _deactivation_threshold(deactivate)
  50 {
  51 
  52   // Each thread has its own monitor. The i-th thread is responsible for signaling
  53   // to thread i+1 if the number of buffers in the queue exceeds a threshold for this
  54   // thread. Monitors are also used to wake up the threads during termination.
  55   // The 0th (primary) worker is notified by mutator threads and has a special monitor.
  56   if (!is_primary()) {
  57     _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true,
  58                            Monitor::_safepoint_check_never);
  59   } else {
  60     _monitor = DirtyCardQ_CBL_mon;
  61   }
  62 
  63   // set name
  64   set_name("G1 Refine#%d", worker_id);
  65   create_and_start();
  66 }
  67 
  68 void ConcurrentG1RefineThread::update_thresholds(size_t activate,
  69                                                  size_t deactivate) {
  70   assert(deactivate < activate, "precondition");
  71   _activation_threshold = activate;
  72   _deactivation_threshold = deactivate;
  73 }
  74 
  75 void ConcurrentG1RefineThread::wait_for_completed_buffers() {
  76   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
  77   while (!should_terminate() && !is_active()) {
  78     _monitor->wait(Mutex::_no_safepoint_check_flag);
  79   }
  80 }
  81 
  82 bool ConcurrentG1RefineThread::is_active() {
  83   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  84   return is_primary() ? dcqs.process_completed_buffers() : _active;
  85 }
  86 
  87 void ConcurrentG1RefineThread::activate() {
  88   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
  89   if (!is_primary()) {
  90     set_active(true);
  91   } else {
  92     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
  93     dcqs.set_process_completed(true);
  94   }
  95   _monitor->notify();
  96 }
  97 
  98 void ConcurrentG1RefineThread::deactivate() {
  99   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
 100   if (!is_primary()) {
 101     set_active(false);
 102   } else {
 103     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 104     dcqs.set_process_completed(false);
 105   }
 106 }
 107 
 108 void ConcurrentG1RefineThread::run_service() {
 109   _vtime_start = os::elapsedVTime();
 110 
 111   while (!should_terminate()) {
 112     // Wait for work
 113     wait_for_completed_buffers();
 114     if (should_terminate()) {
 115       break;
 116     }
 117 
 118     size_t buffers_processed = 0;
 119     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 120     log_debug(gc, refine)("Activated %d, on threshold: " SIZE_FORMAT ", current: " SIZE_FORMAT,
 121                           _worker_id, _activation_threshold, dcqs.completed_buffers_num());
 122 
 123     {
 124       SuspendibleThreadSetJoiner sts_join;
 125 
 126       while (!should_terminate()) {
 127         if (sts_join.should_yield()) {
 128           sts_join.yield();
 129           continue;             // Re-check for termination after yield delay.
 130         }
 131 
 132         size_t curr_buffer_num = dcqs.completed_buffers_num();
 133         // If the number of the buffers falls down into the yellow zone,
 134         // that means that the transition period after the evacuation pause has ended.
 135         if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {
 136           dcqs.set_completed_queue_padding(0);
 137         }
 138 
 139         // Check if we need to activate the next thread.
 140         if ((_next != NULL) &&
 141             !_next->is_active() &&
 142             (curr_buffer_num > _next->_activation_threshold)) {
 143           _next->activate();
 144         }
 145 
 146         // Process the next buffer, if there are enough left.
 147         if (!dcqs.refine_completed_buffer_concurrently(_worker_id + _worker_id_offset, _deactivation_threshold)) {
 148           break; // Deactivate, number of buffers fell below threshold.
 149         }
 150         ++buffers_processed;
 151       }
 152     }
 153 
 154     deactivate();
 155     log_debug(gc, refine)("Deactivated %d, off threshold: " SIZE_FORMAT
 156                           ", current: " SIZE_FORMAT ", processed: " SIZE_FORMAT,
 157                           _worker_id, _deactivation_threshold,
 158                           dcqs.completed_buffers_num(),
 159                           buffers_processed);
 160 
 161     if (os::supports_vtime()) {
 162       _vtime_accum = (os::elapsedVTime() - _vtime_start);
 163     } else {
 164       _vtime_accum = 0.0;
 165     }
 166   }
 167 
 168   log_debug(gc, refine)("Stopping %d", _worker_id);
 169 }
 170 
 171 void ConcurrentG1RefineThread::stop_service() {
 172   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);
 173   _monitor->notify();
 174 }