1 /* |
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2 * Copyright (c) 2005, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #include "precompiled.hpp" |
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26 #include "gc/cms/cmsHeap.hpp" |
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27 #include "gc/cms/cmsVMOperations.hpp" |
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28 #include "gc/cms/concurrentMarkSweepGeneration.inline.hpp" |
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29 #include "gc/cms/concurrentMarkSweepThread.hpp" |
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30 #include "gc/shared/gcLocker.hpp" |
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31 #include "gc/shared/gcTimer.hpp" |
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32 #include "gc/shared/gcTraceTime.inline.hpp" |
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33 #include "gc/shared/isGCActiveMark.hpp" |
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34 #include "memory/universe.hpp" |
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35 #include "runtime/handles.inline.hpp" |
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36 #include "runtime/interfaceSupport.inline.hpp" |
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37 #include "runtime/os.hpp" |
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38 #include "utilities/dtrace.hpp" |
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39 |
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40 ////////////////////////////////////////////////////////// |
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41 // Methods in abstract class VM_CMS_Operation |
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42 ////////////////////////////////////////////////////////// |
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43 void VM_CMS_Operation::verify_before_gc() { |
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44 if (VerifyBeforeGC && |
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45 CMSHeap::heap()->total_collections() >= VerifyGCStartAt) { |
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46 GCTraceTime(Info, gc, phases, verify) tm("Verify Before", _collector->_gc_timer_cm); |
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47 HandleMark hm; |
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48 FreelistLocker x(_collector); |
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49 MutexLocker y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); |
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50 CMSHeap::heap()->prepare_for_verify(); |
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51 Universe::verify(); |
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52 } |
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53 } |
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54 |
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55 void VM_CMS_Operation::verify_after_gc() { |
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56 if (VerifyAfterGC && |
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57 CMSHeap::heap()->total_collections() >= VerifyGCStartAt) { |
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58 GCTraceTime(Info, gc, phases, verify) tm("Verify After", _collector->_gc_timer_cm); |
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59 HandleMark hm; |
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60 FreelistLocker x(_collector); |
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61 MutexLocker y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); |
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62 Universe::verify(); |
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63 } |
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64 } |
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65 |
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66 bool VM_CMS_Operation::lost_race() const { |
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67 if (CMSCollector::abstract_state() == CMSCollector::Idling) { |
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68 // We lost a race to a foreground collection |
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69 // -- there's nothing to do |
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70 return true; |
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71 } |
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72 assert(CMSCollector::abstract_state() == legal_state(), |
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73 "Inconsistent collector state?"); |
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74 return false; |
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75 } |
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76 |
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77 bool VM_CMS_Operation::doit_prologue() { |
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78 assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); |
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79 assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); |
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80 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), |
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81 "Possible deadlock"); |
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82 |
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83 Heap_lock->lock(); |
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84 if (lost_race()) { |
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85 assert(_prologue_succeeded == false, "Initialized in c'tor"); |
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86 Heap_lock->unlock(); |
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87 } else { |
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88 _prologue_succeeded = true; |
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89 } |
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90 return _prologue_succeeded; |
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91 } |
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92 |
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93 void VM_CMS_Operation::doit_epilogue() { |
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94 assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); |
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95 assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); |
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96 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), |
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97 "Possible deadlock"); |
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98 |
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99 if (Universe::has_reference_pending_list()) { |
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100 Heap_lock->notify_all(); |
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101 } |
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102 Heap_lock->unlock(); |
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103 } |
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104 |
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105 ////////////////////////////////////////////////////////// |
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106 // Methods in class VM_CMS_Initial_Mark |
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107 ////////////////////////////////////////////////////////// |
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108 void VM_CMS_Initial_Mark::doit() { |
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109 if (lost_race()) { |
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110 // Nothing to do. |
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111 return; |
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112 } |
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113 HS_PRIVATE_CMS_INITMARK_BEGIN(); |
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114 GCIdMark gc_id_mark(_gc_id); |
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115 |
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116 _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark"); |
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117 |
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118 CMSHeap* heap = CMSHeap::heap(); |
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119 GCCauseSetter gccs(heap, GCCause::_cms_initial_mark); |
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120 |
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121 VM_CMS_Operation::verify_before_gc(); |
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122 |
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123 IsGCActiveMark x; // stop-world GC active |
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124 _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, heap->gc_cause()); |
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125 |
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126 VM_CMS_Operation::verify_after_gc(); |
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127 |
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128 _collector->_gc_timer_cm->register_gc_pause_end(); |
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129 |
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130 HS_PRIVATE_CMS_INITMARK_END(); |
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131 } |
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132 |
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133 ////////////////////////////////////////////////////////// |
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134 // Methods in class VM_CMS_Final_Remark_Operation |
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135 ////////////////////////////////////////////////////////// |
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136 void VM_CMS_Final_Remark::doit() { |
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137 if (lost_race()) { |
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138 // Nothing to do. |
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139 return; |
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140 } |
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141 HS_PRIVATE_CMS_REMARK_BEGIN(); |
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142 GCIdMark gc_id_mark(_gc_id); |
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143 |
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144 _collector->_gc_timer_cm->register_gc_pause_start("Final Mark"); |
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145 |
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146 CMSHeap* heap = CMSHeap::heap(); |
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147 GCCauseSetter gccs(heap, GCCause::_cms_final_remark); |
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148 |
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149 VM_CMS_Operation::verify_before_gc(); |
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150 |
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151 IsGCActiveMark x; // stop-world GC active |
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152 _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, heap->gc_cause()); |
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153 |
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154 VM_CMS_Operation::verify_after_gc(); |
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155 |
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156 _collector->save_heap_summary(); |
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157 _collector->_gc_timer_cm->register_gc_pause_end(); |
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158 |
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159 HS_PRIVATE_CMS_REMARK_END(); |
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160 } |
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161 |
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162 // VM operation to invoke a concurrent collection of a |
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163 // GenCollectedHeap heap. |
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164 void VM_GenCollectFullConcurrent::doit() { |
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165 assert(Thread::current()->is_VM_thread(), "Should be VM thread"); |
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166 assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected"); |
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167 |
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168 CMSHeap* heap = CMSHeap::heap(); |
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169 if (_gc_count_before == heap->total_collections()) { |
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170 // The "full" of do_full_collection call below "forces" |
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171 // a collection; the second arg, 0, below ensures that |
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172 // only the young gen is collected. XXX In the future, |
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173 // we'll probably need to have something in this interface |
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174 // to say do this only if we are sure we will not bail |
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175 // out to a full collection in this attempt, but that's |
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176 // for the future. |
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177 assert(SafepointSynchronize::is_at_safepoint(), |
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178 "We can only be executing this arm of if at a safepoint"); |
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179 GCCauseSetter gccs(heap, _gc_cause); |
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180 heap->do_full_collection(heap->must_clear_all_soft_refs(), GenCollectedHeap::YoungGen); |
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181 } // Else no need for a foreground young gc |
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182 assert((_gc_count_before < heap->total_collections()) || |
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183 (GCLocker::is_active() /* gc may have been skipped */ |
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184 && (_gc_count_before == heap->total_collections())), |
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185 "total_collections() should be monotonically increasing"); |
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186 |
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187 MutexLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); |
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188 assert(_full_gc_count_before <= heap->total_full_collections(), "Error"); |
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189 if (heap->total_full_collections() == _full_gc_count_before) { |
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190 // Nudge the CMS thread to start a concurrent collection. |
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191 CMSCollector::request_full_gc(_full_gc_count_before, _gc_cause); |
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192 } else { |
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193 assert(_full_gc_count_before < heap->total_full_collections(), "Error"); |
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194 FullGCCount_lock->notify_all(); // Inform the Java thread its work is done |
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195 } |
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196 } |
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197 |
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198 bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const { |
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199 Thread* thr = Thread::current(); |
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200 assert(thr != NULL, "Unexpected tid"); |
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201 if (!thr->is_Java_thread()) { |
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202 assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread"); |
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203 CMSHeap* heap = CMSHeap::heap(); |
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204 if (_gc_count_before != heap->total_collections()) { |
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205 // No need to do a young gc, we'll just nudge the CMS thread |
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206 // in the doit() method above, to be executed soon. |
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207 assert(_gc_count_before < heap->total_collections(), |
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208 "total_collections() should be monotonically increasing"); |
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209 return false; // no need for foreground young gc |
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210 } |
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211 } |
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212 return true; // may still need foreground young gc |
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213 } |
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214 |
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215 |
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216 void VM_GenCollectFullConcurrent::doit_epilogue() { |
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217 Thread* thr = Thread::current(); |
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218 assert(thr->is_Java_thread(), "just checking"); |
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219 JavaThread* jt = (JavaThread*)thr; |
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220 |
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221 if (Universe::has_reference_pending_list()) { |
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222 Heap_lock->notify_all(); |
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223 } |
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224 Heap_lock->unlock(); |
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225 |
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226 // It is fine to test whether completed collections has |
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227 // exceeded our request count without locking because |
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228 // the completion count is monotonically increasing; |
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229 // this will break for very long-running apps when the |
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230 // count overflows and wraps around. XXX fix me !!! |
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231 // e.g. at the rate of 1 full gc per ms, this could |
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232 // overflow in about 1000 years. |
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233 CMSHeap* heap = CMSHeap::heap(); |
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234 if (_gc_cause != GCCause::_gc_locker && |
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235 heap->total_full_collections_completed() <= _full_gc_count_before) { |
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236 // maybe we should change the condition to test _gc_cause == |
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237 // GCCause::_java_lang_system_gc or GCCause::_dcmd_gc_run, |
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238 // instead of _gc_cause != GCCause::_gc_locker |
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239 assert(GCCause::is_user_requested_gc(_gc_cause), |
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240 "the only way to get here if this was a System.gc()-induced GC"); |
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241 assert(ExplicitGCInvokesConcurrent, "Error"); |
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242 // Now, wait for witnessing concurrent gc cycle to complete, |
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243 // but do so in native mode, because we want to lock the |
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244 // FullGCEvent_lock, which may be needed by the VM thread |
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245 // or by the CMS thread, so we do not want to be suspended |
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246 // while holding that lock. |
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247 ThreadToNativeFromVM native(jt); |
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248 MutexLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); |
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249 // Either a concurrent or a stop-world full gc is sufficient |
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250 // witness to our request. |
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251 while (heap->total_full_collections_completed() <= _full_gc_count_before) { |
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252 FullGCCount_lock->wait_without_safepoint_check(); |
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253 } |
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254 } |
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255 } |
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