1 /* 2 * Copyright (c) 2001, 2010, 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_implementation/g1/concurrentG1Refine.hpp" 27 #include "gc_implementation/g1/concurrentG1RefineThread.hpp" 28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 29 #include "gc_implementation/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 uint worker_id_offset, uint worker_id) : 37 ConcurrentGCThread(), 38 _worker_id_offset(worker_id_offset), 39 _worker_id(worker_id), 40 _active(false), 41 _next(next), 42 _monitor(NULL), 43 _cg1r(cg1r), 44 _vtime_accum(0.0) 45 { 46 47 // Each thread has its own monitor. The i-th thread is responsible for signalling 48 // to thread i+1 if the number of buffers in the queue exceeds a threashold for this 49 // thread. Monitors are also used to wake up the threads during termination. 50 // The 0th worker in notified by mutator threads and has a special monitor. 51 // The last worker is used for young gen rset size sampling. 52 if (worker_id > 0) { 53 _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true); 54 } else { 55 _monitor = DirtyCardQ_CBL_mon; 56 } 57 initialize(); 58 create_and_start(); 59 } 60 61 void ConcurrentG1RefineThread::initialize() { 62 if (_worker_id < cg1r()->worker_thread_num()) { 63 // Current thread activation threshold 64 _threshold = MIN2<int>(cg1r()->thread_threshold_step() * (_worker_id + 1) + cg1r()->green_zone(), 65 cg1r()->yellow_zone()); 66 // A thread deactivates once the number of buffer reached a deactivation threshold 67 _deactivation_threshold = MAX2<int>(_threshold - cg1r()->thread_threshold_step(), cg1r()->green_zone()); 68 } else { 69 set_active(true); 70 } 71 } 72 73 void ConcurrentG1RefineThread::sample_young_list_rs_lengths() { 74 SuspendibleThreadSetJoiner sts; 75 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 76 G1CollectorPolicy* g1p = g1h->g1_policy(); 77 if (g1p->adaptive_young_list_length()) { 78 int regions_visited = 0; 79 g1h->young_list()->rs_length_sampling_init(); 80 while (g1h->young_list()->rs_length_sampling_more()) { 81 g1h->young_list()->rs_length_sampling_next(); 82 ++regions_visited; 83 84 // we try to yield every time we visit 10 regions 85 if (regions_visited == 10) { 86 if (sts.should_yield()) { 87 sts.yield(); 88 // we just abandon the iteration 89 break; 90 } 91 regions_visited = 0; 92 } 93 } 94 95 g1p->revise_young_list_target_length_if_necessary(); 96 } 97 } 98 99 void ConcurrentG1RefineThread::run_young_rs_sampling() { 100 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 101 _vtime_start = os::elapsedVTime(); 102 while(!_should_terminate) { 103 sample_young_list_rs_lengths(); 104 105 if (os::supports_vtime()) { 106 _vtime_accum = (os::elapsedVTime() - _vtime_start); 107 } else { 108 _vtime_accum = 0.0; 109 } 110 111 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 112 if (_should_terminate) { 113 break; 114 } 115 _monitor->wait(Mutex::_no_safepoint_check_flag, G1ConcRefinementServiceIntervalMillis); 116 } 117 } 118 119 void ConcurrentG1RefineThread::wait_for_completed_buffers() { 120 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 121 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 122 while (!_should_terminate && !is_active()) { 123 _monitor->wait(Mutex::_no_safepoint_check_flag); 124 } 125 } 126 127 bool ConcurrentG1RefineThread::is_active() { 128 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 129 return _worker_id > 0 ? _active : dcqs.process_completed_buffers(); 130 } 131 132 void ConcurrentG1RefineThread::activate() { 133 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 134 if (_worker_id > 0) { 135 if (G1TraceConcRefinement) { 136 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 137 gclog_or_tty->print_cr("G1-Refine-activated worker %d, on threshold %d, current %d", 138 _worker_id, _threshold, (int)dcqs.completed_buffers_num()); 139 } 140 set_active(true); 141 } else { 142 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 143 dcqs.set_process_completed(true); 144 } 145 _monitor->notify(); 146 } 147 148 void ConcurrentG1RefineThread::deactivate() { 149 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 150 if (_worker_id > 0) { 151 if (G1TraceConcRefinement) { 152 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 153 gclog_or_tty->print_cr("G1-Refine-deactivated worker %d, off threshold %d, current %d", 154 _worker_id, _deactivation_threshold, (int)dcqs.completed_buffers_num()); 155 } 156 set_active(false); 157 } else { 158 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 159 dcqs.set_process_completed(false); 160 } 161 } 162 163 void ConcurrentG1RefineThread::run() { 164 initialize_in_thread(); 165 wait_for_universe_init(); 166 167 if (_worker_id >= cg1r()->worker_thread_num()) { 168 run_young_rs_sampling(); 169 terminate(); 170 return; 171 } 172 173 _vtime_start = os::elapsedVTime(); 174 while (!_should_terminate) { 175 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set(); 176 177 // Wait for work 178 wait_for_completed_buffers(); 179 180 if (_should_terminate) { 181 break; 182 } 183 184 { 185 SuspendibleThreadSetJoiner sts; 186 187 do { 188 int curr_buffer_num = (int)dcqs.completed_buffers_num(); 189 // If the number of the buffers falls down into the yellow zone, 190 // that means that the transition period after the evacuation pause has ended. 191 if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) { 192 dcqs.set_completed_queue_padding(0); 193 } 194 195 if (_worker_id > 0 && curr_buffer_num <= _deactivation_threshold) { 196 // If the number of the buffer has fallen below our threshold 197 // we should deactivate. The predecessor will reactivate this 198 // thread should the number of the buffers cross the threshold again. 199 deactivate(); 200 break; 201 } 202 203 // Check if we need to activate the next thread. 204 if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) { 205 _next->activate(); 206 } 207 } while (dcqs.apply_closure_to_completed_buffer(_worker_id + _worker_id_offset, cg1r()->green_zone())); 208 209 // We can exit the loop above while being active if there was a yield request. 210 if (is_active()) { 211 deactivate(); 212 } 213 } 214 215 if (os::supports_vtime()) { 216 _vtime_accum = (os::elapsedVTime() - _vtime_start); 217 } else { 218 _vtime_accum = 0.0; 219 } 220 } 221 assert(_should_terminate, "just checking"); 222 terminate(); 223 } 224 225 void ConcurrentG1RefineThread::stop() { 226 // it is ok to take late safepoints here, if needed 227 { 228 MutexLockerEx mu(Terminator_lock); 229 _should_terminate = true; 230 } 231 232 { 233 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 234 _monitor->notify(); 235 } 236 237 { 238 MutexLockerEx mu(Terminator_lock); 239 while (!_has_terminated) { 240 Terminator_lock->wait(); 241 } 242 } 243 if (G1TraceConcRefinement) { 244 gclog_or_tty->print_cr("G1-Refine-stop"); 245 } 246 } 247 248 void ConcurrentG1RefineThread::print() const { 249 print_on(tty); 250 } 251 252 void ConcurrentG1RefineThread::print_on(outputStream* st) const { 253 st->print("\"G1 Concurrent Refinement Thread#%d\" ", _worker_id); 254 Thread::print_on(st); 255 st->cr(); 256 }