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 "memory/resourceArea.hpp" 31 #include "runtime/handles.inline.hpp" 32 #include "runtime/mutexLocker.hpp" 33 34 ConcurrentG1RefineThread:: 35 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread *next, 36 CardTableEntryClosure* refine_closure, 37 uint worker_id_offset, uint worker_id) : 38 ConcurrentGCThread(), 39 _refine_closure(refine_closure), 40 _worker_id_offset(worker_id_offset), 41 _worker_id(worker_id), 42 _active(false), 43 _next(next), 44 _monitor(NULL), 45 _cg1r(cg1r), 46 _vtime_accum(0.0) 47 { 48 49 // Each thread has its own monitor. The i-th thread is responsible for signaling 50 // to thread i+1 if the number of buffers in the queue exceeds a threshold for this 51 // thread. Monitors are also used to wake up the threads during termination. 52 // The 0th worker in notified by mutator threads and has a special monitor. 53 // The last worker is used for young gen rset size sampling. 54 if (worker_id > 0) { 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 if (_worker_id < cg1r()->worker_thread_num()) { 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 } else { 75 set_active(true); 76 } 77 } 78 79 void ConcurrentG1RefineThread::sample_young_list_rs_lengths() { 80 SuspendibleThreadSetJoiner sts_join; 81 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 82 G1CollectorPolicy* g1p = g1h->g1_policy(); 83 if (g1p->adaptive_young_list_length()) { 84 int regions_visited = 0; 85 g1h->young_list()->rs_length_sampling_init(); 86 while (g1h->young_list()->rs_length_sampling_more()) { 87 g1h->young_list()->rs_length_sampling_next(); 88 ++regions_visited; 89 90 // we try to yield every time we visit 10 regions 91 if (regions_visited == 10) { 92 if (sts_join.should_yield()) { 93 sts_join.yield(); 94 // we just abandon the iteration 95 break; 96 } 97 regions_visited = 0; 98 } 99 } 100 101 g1p->revise_young_list_target_length_if_necessary(); 102 } 103 } 104 105 void ConcurrentG1RefineThread::run_young_rs_sampling() { 106 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 107 _vtime_start = os::elapsedVTime(); 108 while(!_should_terminate) { 109 sample_young_list_rs_lengths(); 110 111 if (os::supports_vtime()) { 112 _vtime_accum = (os::elapsedVTime() - _vtime_start); 113 } else { 114 _vtime_accum = 0.0; 115 } 116 117 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 118 if (_should_terminate) { 119 break; 120 } 121 _monitor->wait(Mutex::_no_safepoint_check_flag, G1ConcRefinementServiceIntervalMillis); 122 } 123 } 124 125 void ConcurrentG1RefineThread::wait_for_completed_buffers() { 126 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 127 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 128 while (!_should_terminate && !is_active()) { 129 _monitor->wait(Mutex::_no_safepoint_check_flag); 130 } 131 } 132 133 bool ConcurrentG1RefineThread::is_active() { 134 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 135 return _worker_id > 0 ? _active : dcqs.process_completed_buffers(); 136 } 137 138 void ConcurrentG1RefineThread::activate() { 139 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 140 if (_worker_id > 0) { 141 if (G1TraceConcRefinement) { 142 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 143 gclog_or_tty->print_cr("G1-Refine-activated worker %d, on threshold %d, current %d", 144 _worker_id, _threshold, (int)dcqs.completed_buffers_num()); 145 } 146 set_active(true); 147 } else { 148 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 149 dcqs.set_process_completed(true); 150 } 151 _monitor->notify(); 152 } 153 154 void ConcurrentG1RefineThread::deactivate() { 155 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 156 if (_worker_id > 0) { 157 if (G1TraceConcRefinement) { 158 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 159 gclog_or_tty->print_cr("G1-Refine-deactivated worker %d, off threshold %d, current %d", 160 _worker_id, _deactivation_threshold, (int)dcqs.completed_buffers_num()); 161 } 162 set_active(false); 163 } else { 164 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 165 dcqs.set_process_completed(false); 166 } 167 } 168 169 void ConcurrentG1RefineThread::run() { 170 initialize_in_thread(); 171 wait_for_universe_init(); 172 173 if (_worker_id >= cg1r()->worker_thread_num()) { 174 run_young_rs_sampling(); 175 terminate(); 176 return; 177 } 178 179 _vtime_start = os::elapsedVTime(); 180 while (!_should_terminate) { 181 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 182 183 // Wait for work 184 wait_for_completed_buffers(); 185 186 if (_should_terminate) { 187 break; 188 } 189 190 { 191 SuspendibleThreadSetJoiner sts_join; 192 193 do { 194 int curr_buffer_num = (int)dcqs.completed_buffers_num(); 195 // If the number of the buffers falls down into the yellow zone, 196 // that means that the transition period after the evacuation pause has ended. 197 if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) { 198 dcqs.set_completed_queue_padding(0); 199 } 200 201 if (_worker_id > 0 && curr_buffer_num <= _deactivation_threshold) { 202 // If the number of the buffer has fallen below our threshold 203 // we should deactivate. The predecessor will reactivate this 204 // thread should the number of the buffers cross the threshold again. 205 deactivate(); 206 break; 207 } 208 209 // Check if we need to activate the next thread. 210 if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) { 211 _next->activate(); 212 } 213 } while (dcqs.apply_closure_to_completed_buffer(_refine_closure, _worker_id + _worker_id_offset, cg1r()->green_zone())); 214 215 // We can exit the loop above while being active if there was a yield request. 216 if (is_active()) { 217 deactivate(); 218 } 219 } 220 221 if (os::supports_vtime()) { 222 _vtime_accum = (os::elapsedVTime() - _vtime_start); 223 } else { 224 _vtime_accum = 0.0; 225 } 226 } 227 assert(_should_terminate, "just checking"); 228 terminate(); 229 } 230 231 void ConcurrentG1RefineThread::stop() { 232 // it is ok to take late safepoints here, if needed 233 { 234 MutexLockerEx mu(Terminator_lock); 235 _should_terminate = true; 236 } 237 238 { 239 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 240 _monitor->notify(); 241 } 242 243 { 244 MutexLockerEx mu(Terminator_lock); 245 while (!_has_terminated) { 246 Terminator_lock->wait(); 247 } 248 } 249 if (G1TraceConcRefinement) { 250 gclog_or_tty->print_cr("G1-Refine-stop"); 251 } 252 } 253