342
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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 #include "incls/_precompiled.incl"
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26 #include "incls/_concurrentG1RefineThread.cpp.incl"
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27
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28 // ======= Concurrent Mark Thread ========
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29
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30 // The CM thread is created when the G1 garbage collector is used
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31
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32 ConcurrentG1RefineThread::
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33 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r) :
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34 ConcurrentGCThread(),
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35 _cg1r(cg1r),
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36 _started(false),
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37 _in_progress(false),
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38 _do_traversal(false),
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39 _vtime_accum(0.0),
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40 _co_tracker(G1CRGroup),
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41 _interval_ms(5.0)
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42 {
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43 create_and_start();
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44 }
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45
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46 const long timeout = 200; // ms.
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47
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48 void ConcurrentG1RefineThread::traversalBasedRefinement() {
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49 _cg1r->wait_for_ConcurrentG1Refine_enabled();
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50 MutexLocker x(G1ConcRefine_mon);
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51 while (_cg1r->enabled()) {
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52 MutexUnlocker ux(G1ConcRefine_mon);
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53 ResourceMark rm;
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54 HandleMark hm;
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55
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56 if (TraceG1Refine) gclog_or_tty->print_cr("G1-Refine starting pass");
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57 _sts.join();
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58 bool no_sleep = _cg1r->refine();
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59 _sts.leave();
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60 if (!no_sleep) {
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61 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
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62 // We do this only for the timeout; we don't expect this to be signalled.
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63 CGC_lock->wait(Mutex::_no_safepoint_check_flag, timeout);
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64 }
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65 }
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66 }
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67
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68 void ConcurrentG1RefineThread::queueBasedRefinement() {
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69 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
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70 // Wait for completed log buffers to exist.
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71 {
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72 MutexLockerEx x(DirtyCardQ_CBL_mon, Mutex::_no_safepoint_check_flag);
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73 while (!_do_traversal && !dcqs.process_completed_buffers() &&
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74 !_should_terminate) {
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75 DirtyCardQ_CBL_mon->wait(Mutex::_no_safepoint_check_flag);
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76 }
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77 }
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78
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79 if (_should_terminate) {
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80 return;
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81 }
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82
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83 // Now we take them off (this doesn't hold locks while it applies
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84 // closures.) (If we did a full collection, then we'll do a full
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85 // traversal.
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86 _sts.join();
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87 if (_do_traversal) {
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88 (void)_cg1r->refine();
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89 switch (_cg1r->get_last_pya()) {
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90 case PYA_cancel: case PYA_continue:
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91 // Continue was caught and handled inside "refine". If it's still
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92 // "continue" when we get here, we're done.
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93 _do_traversal = false;
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94 break;
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95 case PYA_restart:
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96 assert(_do_traversal, "Because of Full GC.");
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97 break;
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98 }
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99 } else {
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100 int n_logs = 0;
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101 int lower_limit = 0;
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102 double start_vtime_sec; // only used when G1SmoothConcRefine is on
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103 int prev_buffer_num; // only used when G1SmoothConcRefine is on
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104
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105 if (G1SmoothConcRefine) {
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106 lower_limit = 0;
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107 start_vtime_sec = os::elapsedVTime();
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108 prev_buffer_num = (int) dcqs.completed_buffers_num();
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109 } else {
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110 lower_limit = DCQBarrierProcessCompletedThreshold / 4; // For now.
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111 }
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112 while (dcqs.apply_closure_to_completed_buffer(0, lower_limit)) {
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113 double end_vtime_sec;
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114 double elapsed_vtime_sec;
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115 int elapsed_vtime_ms;
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116 int curr_buffer_num;
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117
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118 if (G1SmoothConcRefine) {
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119 end_vtime_sec = os::elapsedVTime();
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120 elapsed_vtime_sec = end_vtime_sec - start_vtime_sec;
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121 elapsed_vtime_ms = (int) (elapsed_vtime_sec * 1000.0);
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122 curr_buffer_num = (int) dcqs.completed_buffers_num();
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123
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124 if (curr_buffer_num > prev_buffer_num ||
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125 curr_buffer_num > DCQBarrierProcessCompletedThreshold) {
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126 decreaseInterval(elapsed_vtime_ms);
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127 } else if (curr_buffer_num < prev_buffer_num) {
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128 increaseInterval(elapsed_vtime_ms);
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129 }
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130 }
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131
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132 sample_young_list_rs_lengths();
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133 _co_tracker.update(false);
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134
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135 if (G1SmoothConcRefine) {
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136 start_vtime_sec = os::elapsedVTime();
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137 prev_buffer_num = curr_buffer_num;
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138
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139 _sts.leave();
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140 os::sleep(Thread::current(), (jlong) _interval_ms, false);
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141 _sts.join();
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142 }
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143
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144 n_logs++;
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145 }
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146 // Make sure we harvest the PYA, if any.
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147 (void)_cg1r->get_pya();
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148 }
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149 _sts.leave();
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150 }
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151
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152 void ConcurrentG1RefineThread::sample_young_list_rs_lengths() {
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153 G1CollectedHeap* g1h = G1CollectedHeap::heap();
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154 G1CollectorPolicy* g1p = g1h->g1_policy();
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155 if (g1p->adaptive_young_list_length()) {
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156 int regions_visited = 0;
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157
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158 g1h->young_list_rs_length_sampling_init();
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159 while (g1h->young_list_rs_length_sampling_more()) {
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160 g1h->young_list_rs_length_sampling_next();
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161 ++regions_visited;
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162
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163 // we try to yield every time we visit 10 regions
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164 if (regions_visited == 10) {
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165 if (_sts.should_yield()) {
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166 _sts.yield("G1 refine");
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167 // we just abandon the iteration
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168 break;
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169 }
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170 regions_visited = 0;
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171 }
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172 }
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173
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174 g1p->check_prediction_validity();
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175 }
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176 }
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177
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178 void ConcurrentG1RefineThread::run() {
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179 initialize_in_thread();
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180 _vtime_start = os::elapsedVTime();
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181 wait_for_universe_init();
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182
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183 _co_tracker.enable();
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184 _co_tracker.start();
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185
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186 while (!_should_terminate) {
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187 // wait until started is set.
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188 if (G1RSBarrierUseQueue) {
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189 queueBasedRefinement();
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190 } else {
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191 traversalBasedRefinement();
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192 }
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193 _sts.join();
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194 _co_tracker.update();
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195 _sts.leave();
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196 if (os::supports_vtime()) {
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197 _vtime_accum = (os::elapsedVTime() - _vtime_start);
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198 } else {
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199 _vtime_accum = 0.0;
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200 }
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201 }
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202 _sts.join();
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203 _co_tracker.update(true);
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204 _sts.leave();
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205 assert(_should_terminate, "just checking");
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206
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207 terminate();
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208 }
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209
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210
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211 void ConcurrentG1RefineThread::yield() {
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212 if (TraceG1Refine) gclog_or_tty->print_cr("G1-Refine-yield");
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213 _sts.yield("G1 refine");
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214 if (TraceG1Refine) gclog_or_tty->print_cr("G1-Refine-yield-end");
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215 }
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216
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217 void ConcurrentG1RefineThread::stop() {
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218 // it is ok to take late safepoints here, if needed
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219 {
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220 MutexLockerEx mu(Terminator_lock);
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221 _should_terminate = true;
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222 }
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223
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224 {
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225 MutexLockerEx x(DirtyCardQ_CBL_mon, Mutex::_no_safepoint_check_flag);
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226 DirtyCardQ_CBL_mon->notify_all();
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227 }
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228
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229 {
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230 MutexLockerEx mu(Terminator_lock);
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231 while (!_has_terminated) {
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232 Terminator_lock->wait();
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233 }
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234 }
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235 if (TraceG1Refine) gclog_or_tty->print_cr("G1-Refine-stop");
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236 }
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237
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238 void ConcurrentG1RefineThread::print() {
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239 gclog_or_tty->print("\"Concurrent G1 Refinement Thread\" ");
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240 Thread::print();
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241 gclog_or_tty->cr();
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242 }
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243
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244 void ConcurrentG1RefineThread::set_do_traversal(bool b) {
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245 _do_traversal = b;
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246 }
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