0
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1 /*
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2 * Copyright 2002-2007 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
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26 # include "incls/_precompiled.incl"
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27 # include "incls/_psScavenge.cpp.incl"
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28
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29 HeapWord* PSScavenge::_to_space_top_before_gc = NULL;
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30 int PSScavenge::_consecutive_skipped_scavenges = 0;
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31 ReferenceProcessor* PSScavenge::_ref_processor = NULL;
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32 CardTableExtension* PSScavenge::_card_table = NULL;
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33 bool PSScavenge::_survivor_overflow = false;
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34 int PSScavenge::_tenuring_threshold = 0;
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35 HeapWord* PSScavenge::_young_generation_boundary = NULL;
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36 elapsedTimer PSScavenge::_accumulated_time;
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37 GrowableArray<markOop>* PSScavenge::_preserved_mark_stack = NULL;
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38 GrowableArray<oop>* PSScavenge::_preserved_oop_stack = NULL;
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39 CollectorCounters* PSScavenge::_counters = NULL;
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40
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41 // Define before use
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42 class PSIsAliveClosure: public BoolObjectClosure {
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43 public:
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44 void do_object(oop p) {
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45 assert(false, "Do not call.");
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46 }
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47 bool do_object_b(oop p) {
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48 return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded();
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49 }
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50 };
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51
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52 PSIsAliveClosure PSScavenge::_is_alive_closure;
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53
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54 class PSKeepAliveClosure: public OopClosure {
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55 protected:
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56 MutableSpace* _to_space;
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57 PSPromotionManager* _promotion_manager;
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58
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59 public:
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60 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
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61 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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62 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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63 _to_space = heap->young_gen()->to_space();
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64
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65 assert(_promotion_manager != NULL, "Sanity");
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66 }
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67
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68 void do_oop(oop* p) {
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69 assert (*p != NULL, "expected non-null ref");
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70 assert ((*p)->is_oop(), "expected an oop while scanning weak refs");
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71
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72 oop obj = oop(*p);
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73 // Weak refs may be visited more than once.
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74 if (PSScavenge::should_scavenge(obj, _to_space)) {
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75 PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p);
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76 }
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77 }
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78 };
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79
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80 class PSEvacuateFollowersClosure: public VoidClosure {
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81 private:
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82 PSPromotionManager* _promotion_manager;
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83 public:
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84 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
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85
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86 void do_void() {
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87 assert(_promotion_manager != NULL, "Sanity");
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88 _promotion_manager->drain_stacks(true);
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89 guarantee(_promotion_manager->stacks_empty(),
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90 "stacks should be empty at this point");
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91 }
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92 };
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93
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94 class PSPromotionFailedClosure : public ObjectClosure {
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95 virtual void do_object(oop obj) {
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96 if (obj->is_forwarded()) {
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97 obj->init_mark();
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98 }
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99 }
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100 };
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101
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102 class PSRefProcTaskProxy: public GCTask {
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103 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
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104 ProcessTask & _rp_task;
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105 uint _work_id;
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106 public:
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107 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
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108 : _rp_task(rp_task),
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109 _work_id(work_id)
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110 { }
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111
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112 private:
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113 virtual char* name() { return (char *)"Process referents by policy in parallel"; }
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114 virtual void do_it(GCTaskManager* manager, uint which);
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115 };
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116
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117 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
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118 {
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119 PSPromotionManager* promotion_manager =
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120 PSPromotionManager::gc_thread_promotion_manager(which);
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121 assert(promotion_manager != NULL, "sanity check");
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122 PSKeepAliveClosure keep_alive(promotion_manager);
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123 PSEvacuateFollowersClosure evac_followers(promotion_manager);
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124 PSIsAliveClosure is_alive;
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125 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
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126 }
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127
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128 class PSRefEnqueueTaskProxy: public GCTask {
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129 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
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130 EnqueueTask& _enq_task;
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131 uint _work_id;
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132
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133 public:
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134 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
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135 : _enq_task(enq_task),
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136 _work_id(work_id)
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137 { }
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138
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139 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
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140 virtual void do_it(GCTaskManager* manager, uint which)
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141 {
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142 _enq_task.work(_work_id);
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143 }
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144 };
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145
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146 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
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147 virtual void execute(ProcessTask& task);
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148 virtual void execute(EnqueueTask& task);
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149 };
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150
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151 void PSRefProcTaskExecutor::execute(ProcessTask& task)
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152 {
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153 GCTaskQueue* q = GCTaskQueue::create();
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154 for(uint i=0; i<ParallelGCThreads; i++) {
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155 q->enqueue(new PSRefProcTaskProxy(task, i));
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156 }
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157 ParallelTaskTerminator terminator(
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158 ParallelScavengeHeap::gc_task_manager()->workers(),
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159 UseDepthFirstScavengeOrder ?
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160 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()
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161 : (TaskQueueSetSuper*) PSPromotionManager::stack_array_breadth());
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162 if (task.marks_oops_alive() && ParallelGCThreads > 1) {
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163 for (uint j=0; j<ParallelGCThreads; j++) {
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164 q->enqueue(new StealTask(&terminator));
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165 }
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166 }
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167 ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q);
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168 }
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169
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170
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171 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
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172 {
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173 GCTaskQueue* q = GCTaskQueue::create();
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174 for(uint i=0; i<ParallelGCThreads; i++) {
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175 q->enqueue(new PSRefEnqueueTaskProxy(task, i));
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176 }
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177 ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q);
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178 }
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179
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180 // This method contains all heap specific policy for invoking scavenge.
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181 // PSScavenge::invoke_no_policy() will do nothing but attempt to
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182 // scavenge. It will not clean up after failed promotions, bail out if
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183 // we've exceeded policy time limits, or any other special behavior.
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184 // All such policy should be placed here.
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185 //
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186 // Note that this method should only be called from the vm_thread while
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187 // at a safepoint!
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188 void PSScavenge::invoke()
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189 {
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190 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
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191 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
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192 assert(!Universe::heap()->is_gc_active(), "not reentrant");
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193
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194 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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195 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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196
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197 PSAdaptiveSizePolicy* policy = heap->size_policy();
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198
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199 // Before each allocation/collection attempt, find out from the
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200 // policy object if GCs are, on the whole, taking too long. If so,
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201 // bail out without attempting a collection.
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202 if (!policy->gc_time_limit_exceeded()) {
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203 IsGCActiveMark mark;
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204
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205 bool scavenge_was_done = PSScavenge::invoke_no_policy();
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206
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207 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
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208 if (UsePerfData)
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209 counters->update_full_follows_scavenge(0);
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210 if (!scavenge_was_done ||
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211 policy->should_full_GC(heap->old_gen()->free_in_bytes())) {
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212 if (UsePerfData)
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213 counters->update_full_follows_scavenge(full_follows_scavenge);
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214
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215 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
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216 if (UseParallelOldGC) {
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217 PSParallelCompact::invoke_no_policy(false);
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218 } else {
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219 PSMarkSweep::invoke_no_policy(false);
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220 }
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221 }
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222 }
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223 }
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224
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225 // This method contains no policy. You should probably
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226 // be calling invoke() instead.
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227 bool PSScavenge::invoke_no_policy() {
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228 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
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229 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
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230
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231 TimeStamp scavenge_entry;
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232 TimeStamp scavenge_midpoint;
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233 TimeStamp scavenge_exit;
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234
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235 scavenge_entry.update();
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236
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237 if (GC_locker::check_active_before_gc()) {
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238 return false;
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239 }
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240
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241 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
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242 GCCause::Cause gc_cause = heap->gc_cause();
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243 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
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244
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245 // Check for potential problems.
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246 if (!should_attempt_scavenge()) {
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247 return false;
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248 }
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249
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250 bool promotion_failure_occurred = false;
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251
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252 PSYoungGen* young_gen = heap->young_gen();
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253 PSOldGen* old_gen = heap->old_gen();
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254 PSPermGen* perm_gen = heap->perm_gen();
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255 PSAdaptiveSizePolicy* size_policy = heap->size_policy();
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256 heap->increment_total_collections();
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257
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258 AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
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259
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260 if ((gc_cause != GCCause::_java_lang_system_gc) ||
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261 UseAdaptiveSizePolicyWithSystemGC) {
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262 // Gather the feedback data for eden occupancy.
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263 young_gen->eden_space()->accumulate_statistics();
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264 }
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265
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266 if (PrintHeapAtGC) {
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267 Universe::print_heap_before_gc();
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268 }
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269
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270 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
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271 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
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272
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273 size_t prev_used = heap->used();
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274 assert(promotion_failed() == false, "Sanity");
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275
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276 // Fill in TLABs
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277 heap->accumulate_statistics_all_tlabs();
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278 heap->ensure_parsability(true); // retire TLABs
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279
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280 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
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281 HandleMark hm; // Discard invalid handles created during verification
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282 gclog_or_tty->print(" VerifyBeforeGC:");
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283 Universe::verify(true);
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284 }
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285
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286 {
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287 ResourceMark rm;
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288 HandleMark hm;
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289
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290 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
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291 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
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292 TraceTime t1("GC", PrintGC, !PrintGCDetails, gclog_or_tty);
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293 TraceCollectorStats tcs(counters());
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294 TraceMemoryManagerStats tms(false /* not full GC */);
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295
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296 if (TraceGen0Time) accumulated_time()->start();
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297
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298 // Let the size policy know we're starting
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299 size_policy->minor_collection_begin();
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300
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301 // Verify the object start arrays.
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302 if (VerifyObjectStartArray &&
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303 VerifyBeforeGC) {
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304 old_gen->verify_object_start_array();
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305 perm_gen->verify_object_start_array();
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306 }
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307
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308 // Verify no unmarked old->young roots
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309 if (VerifyRememberedSets) {
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310 CardTableExtension::verify_all_young_refs_imprecise();
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311 }
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312
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313 if (!ScavengeWithObjectsInToSpace) {
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314 assert(young_gen->to_space()->is_empty(),
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315 "Attempt to scavenge with live objects in to_space");
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316 young_gen->to_space()->clear();
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317 } else if (ZapUnusedHeapArea) {
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318 young_gen->to_space()->mangle_unused_area();
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319 }
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320 save_to_space_top_before_gc();
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321
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322 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
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323 COMPILER2_PRESENT(DerivedPointerTable::clear());
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324
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325 reference_processor()->enable_discovery();
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326
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327 // We track how much was promoted to the next generation for
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328 // the AdaptiveSizePolicy.
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329 size_t old_gen_used_before = old_gen->used_in_bytes();
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330
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331 // For PrintGCDetails
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332 size_t young_gen_used_before = young_gen->used_in_bytes();
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333
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334 // Reset our survivor overflow.
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335 set_survivor_overflow(false);
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336
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337 // We need to save the old/perm top values before
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338 // creating the promotion_manager. We pass the top
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339 // values to the card_table, to prevent it from
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340 // straying into the promotion labs.
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341 HeapWord* old_top = old_gen->object_space()->top();
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342 HeapWord* perm_top = perm_gen->object_space()->top();
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343
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344 // Release all previously held resources
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345 gc_task_manager()->release_all_resources();
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346
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347 PSPromotionManager::pre_scavenge();
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348
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349 // We'll use the promotion manager again later.
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350 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
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351 {
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352 // TraceTime("Roots");
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353
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354 GCTaskQueue* q = GCTaskQueue::create();
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355
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356 for(uint i=0; i<ParallelGCThreads; i++) {
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357 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i));
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358 }
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359
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360 q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top));
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361
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362 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
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363 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
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364 // We scan the thread roots in parallel
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365 Threads::create_thread_roots_tasks(q);
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366 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
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367 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
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368 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
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369 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
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370 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
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371
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372 ParallelTaskTerminator terminator(
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373 gc_task_manager()->workers(),
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374 promotion_manager->depth_first() ?
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375 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()
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376 : (TaskQueueSetSuper*) promotion_manager->stack_array_breadth());
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377 if (ParallelGCThreads>1) {
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378 for (uint j=0; j<ParallelGCThreads; j++) {
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379 q->enqueue(new StealTask(&terminator));
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380 }
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381 }
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382
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383 gc_task_manager()->execute_and_wait(q);
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384 }
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385
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386 scavenge_midpoint.update();
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387
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388 // Process reference objects discovered during scavenge
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389 {
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390 #ifdef COMPILER2
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391 ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy();
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392 #else
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393 ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy();
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394 #endif // COMPILER2
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395
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396 PSKeepAliveClosure keep_alive(promotion_manager);
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397 PSEvacuateFollowersClosure evac_followers(promotion_manager);
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398 assert(soft_ref_policy != NULL,"No soft reference policy");
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399 if (reference_processor()->processing_is_mt()) {
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400 PSRefProcTaskExecutor task_executor;
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401 reference_processor()->process_discovered_references(
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402 soft_ref_policy, &_is_alive_closure, &keep_alive, &evac_followers,
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403 &task_executor);
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404 } else {
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405 reference_processor()->process_discovered_references(
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406 soft_ref_policy, &_is_alive_closure, &keep_alive, &evac_followers,
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407 NULL);
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408 }
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409 }
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410
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411 // Enqueue reference objects discovered during scavenge.
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412 if (reference_processor()->processing_is_mt()) {
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413 PSRefProcTaskExecutor task_executor;
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414 reference_processor()->enqueue_discovered_references(&task_executor);
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415 } else {
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416 reference_processor()->enqueue_discovered_references(NULL);
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417 }
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418
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419 // Finally, flush the promotion_manager's labs, and deallocate its stacks.
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420 assert(promotion_manager->claimed_stack_empty(), "Sanity");
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421 PSPromotionManager::post_scavenge();
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422
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423 promotion_failure_occurred = promotion_failed();
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424 if (promotion_failure_occurred) {
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425 clean_up_failed_promotion();
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426 if (PrintGC) {
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427 gclog_or_tty->print("--");
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428 }
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429 }
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430
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431 // Let the size policy know we're done. Note that we count promotion
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432 // failure cleanup time as part of the collection (otherwise, we're
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433 // implicitly saying it's mutator time).
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434 size_policy->minor_collection_end(gc_cause);
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435
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436 if (!promotion_failure_occurred) {
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437 // Swap the survivor spaces.
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438 young_gen->eden_space()->clear();
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439 young_gen->from_space()->clear();
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440 young_gen->swap_spaces();
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441
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442 size_t survived = young_gen->from_space()->used_in_bytes();
|
|
443 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
|
|
444 size_policy->update_averages(_survivor_overflow, survived, promoted);
|
|
445
|
|
446 if (UseAdaptiveSizePolicy) {
|
|
447 // Calculate the new survivor size and tenuring threshold
|
|
448
|
|
449 if (PrintAdaptiveSizePolicy) {
|
|
450 gclog_or_tty->print("AdaptiveSizeStart: ");
|
|
451 gclog_or_tty->stamp();
|
|
452 gclog_or_tty->print_cr(" collection: %d ",
|
|
453 heap->total_collections());
|
|
454
|
|
455 if (Verbose) {
|
|
456 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
|
|
457 " perm_gen_capacity: %d ",
|
|
458 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
|
|
459 perm_gen->capacity_in_bytes());
|
|
460 }
|
|
461 }
|
|
462
|
|
463
|
|
464 if (UsePerfData) {
|
|
465 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
|
|
466 counters->update_old_eden_size(
|
|
467 size_policy->calculated_eden_size_in_bytes());
|
|
468 counters->update_old_promo_size(
|
|
469 size_policy->calculated_promo_size_in_bytes());
|
|
470 counters->update_old_capacity(old_gen->capacity_in_bytes());
|
|
471 counters->update_young_capacity(young_gen->capacity_in_bytes());
|
|
472 counters->update_survived(survived);
|
|
473 counters->update_promoted(promoted);
|
|
474 counters->update_survivor_overflowed(_survivor_overflow);
|
|
475 }
|
|
476
|
|
477 size_t survivor_limit =
|
|
478 size_policy->max_survivor_size(young_gen->max_size());
|
|
479 _tenuring_threshold =
|
|
480 size_policy->compute_survivor_space_size_and_threshold(
|
|
481 _survivor_overflow,
|
|
482 _tenuring_threshold,
|
|
483 survivor_limit);
|
|
484
|
|
485 if (PrintTenuringDistribution) {
|
|
486 gclog_or_tty->cr();
|
|
487 gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)",
|
|
488 size_policy->calculated_survivor_size_in_bytes(),
|
|
489 _tenuring_threshold, MaxTenuringThreshold);
|
|
490 }
|
|
491
|
|
492 if (UsePerfData) {
|
|
493 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
|
|
494 counters->update_tenuring_threshold(_tenuring_threshold);
|
|
495 counters->update_survivor_size_counters();
|
|
496 }
|
|
497
|
|
498 // Do call at minor collections?
|
|
499 // Don't check if the size_policy is ready at this
|
|
500 // level. Let the size_policy check that internally.
|
|
501 if (UseAdaptiveSizePolicy &&
|
|
502 UseAdaptiveGenerationSizePolicyAtMinorCollection &&
|
|
503 ((gc_cause != GCCause::_java_lang_system_gc) ||
|
|
504 UseAdaptiveSizePolicyWithSystemGC)) {
|
|
505
|
|
506 // Calculate optimial free space amounts
|
|
507 assert(young_gen->max_size() >
|
|
508 young_gen->from_space()->capacity_in_bytes() +
|
|
509 young_gen->to_space()->capacity_in_bytes(),
|
|
510 "Sizes of space in young gen are out-of-bounds");
|
|
511 size_t max_eden_size = young_gen->max_size() -
|
|
512 young_gen->from_space()->capacity_in_bytes() -
|
|
513 young_gen->to_space()->capacity_in_bytes();
|
|
514 size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
|
|
515 young_gen->eden_space()->used_in_bytes(),
|
|
516 old_gen->used_in_bytes(),
|
|
517 perm_gen->used_in_bytes(),
|
|
518 young_gen->eden_space()->capacity_in_bytes(),
|
|
519 old_gen->max_gen_size(),
|
|
520 max_eden_size,
|
|
521 false /* full gc*/,
|
|
522 gc_cause);
|
|
523
|
|
524 }
|
|
525 // Resize the young generation at every collection
|
|
526 // even if new sizes have not been calculated. This is
|
|
527 // to allow resizes that may have been inhibited by the
|
|
528 // relative location of the "to" and "from" spaces.
|
|
529
|
|
530 // Resizing the old gen at minor collects can cause increases
|
|
531 // that don't feed back to the generation sizing policy until
|
|
532 // a major collection. Don't resize the old gen here.
|
|
533
|
|
534 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
|
|
535 size_policy->calculated_survivor_size_in_bytes());
|
|
536
|
|
537 if (PrintAdaptiveSizePolicy) {
|
|
538 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
|
|
539 heap->total_collections());
|
|
540 }
|
|
541 }
|
|
542
|
|
543 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
|
|
544 // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
|
|
545 // Also update() will case adaptive NUMA chunk resizing.
|
|
546 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
|
|
547 young_gen->eden_space()->update();
|
|
548
|
|
549 heap->gc_policy_counters()->update_counters();
|
|
550
|
|
551 heap->resize_all_tlabs();
|
|
552
|
|
553 assert(young_gen->to_space()->is_empty(), "to space should be empty now");
|
|
554 }
|
|
555
|
|
556 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
|
|
557
|
|
558 NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
|
|
559
|
|
560 // Re-verify object start arrays
|
|
561 if (VerifyObjectStartArray &&
|
|
562 VerifyAfterGC) {
|
|
563 old_gen->verify_object_start_array();
|
|
564 perm_gen->verify_object_start_array();
|
|
565 }
|
|
566
|
|
567 // Verify all old -> young cards are now precise
|
|
568 if (VerifyRememberedSets) {
|
|
569 // Precise verification will give false positives. Until this is fixed,
|
|
570 // use imprecise verification.
|
|
571 // CardTableExtension::verify_all_young_refs_precise();
|
|
572 CardTableExtension::verify_all_young_refs_imprecise();
|
|
573 }
|
|
574
|
|
575 if (TraceGen0Time) accumulated_time()->stop();
|
|
576
|
|
577 if (PrintGC) {
|
|
578 if (PrintGCDetails) {
|
|
579 // Don't print a GC timestamp here. This is after the GC so
|
|
580 // would be confusing.
|
|
581 young_gen->print_used_change(young_gen_used_before);
|
|
582 }
|
|
583 heap->print_heap_change(prev_used);
|
|
584 }
|
|
585
|
|
586 // Track memory usage and detect low memory
|
|
587 MemoryService::track_memory_usage();
|
|
588 heap->update_counters();
|
|
589 }
|
|
590
|
|
591 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
|
|
592 HandleMark hm; // Discard invalid handles created during verification
|
|
593 gclog_or_tty->print(" VerifyAfterGC:");
|
|
594 Universe::verify(false);
|
|
595 }
|
|
596
|
|
597 if (PrintHeapAtGC) {
|
|
598 Universe::print_heap_after_gc();
|
|
599 }
|
|
600
|
|
601 scavenge_exit.update();
|
|
602
|
|
603 if (PrintGCTaskTimeStamps) {
|
|
604 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
|
|
605 scavenge_entry.ticks(), scavenge_midpoint.ticks(),
|
|
606 scavenge_exit.ticks());
|
|
607 gc_task_manager()->print_task_time_stamps();
|
|
608 }
|
|
609
|
|
610 return !promotion_failure_occurred;
|
|
611 }
|
|
612
|
|
613 // This method iterates over all objects in the young generation,
|
|
614 // unforwarding markOops. It then restores any preserved mark oops,
|
|
615 // and clears the _preserved_mark_stack.
|
|
616 void PSScavenge::clean_up_failed_promotion() {
|
|
617 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
|
|
618 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
|
|
619 assert(promotion_failed(), "Sanity");
|
|
620
|
|
621 PSYoungGen* young_gen = heap->young_gen();
|
|
622
|
|
623 {
|
|
624 ResourceMark rm;
|
|
625
|
|
626 // Unforward all pointers in the young gen.
|
|
627 PSPromotionFailedClosure unforward_closure;
|
|
628 young_gen->object_iterate(&unforward_closure);
|
|
629
|
|
630 if (PrintGC && Verbose) {
|
|
631 gclog_or_tty->print_cr("Restoring %d marks",
|
|
632 _preserved_oop_stack->length());
|
|
633 }
|
|
634
|
|
635 // Restore any saved marks.
|
|
636 for (int i=0; i < _preserved_oop_stack->length(); i++) {
|
|
637 oop obj = _preserved_oop_stack->at(i);
|
|
638 markOop mark = _preserved_mark_stack->at(i);
|
|
639 obj->set_mark(mark);
|
|
640 }
|
|
641
|
|
642 // Deallocate the preserved mark and oop stacks.
|
|
643 // The stacks were allocated as CHeap objects, so
|
|
644 // we must call delete to prevent mem leaks.
|
|
645 delete _preserved_mark_stack;
|
|
646 _preserved_mark_stack = NULL;
|
|
647 delete _preserved_oop_stack;
|
|
648 _preserved_oop_stack = NULL;
|
|
649 }
|
|
650
|
|
651 // Reset the PromotionFailureALot counters.
|
|
652 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
|
|
653 }
|
|
654
|
|
655 // This method is called whenever an attempt to promote an object
|
|
656 // fails. Some markOops will need preserving, some will not. Note
|
|
657 // that the entire eden is traversed after a failed promotion, with
|
|
658 // all forwarded headers replaced by the default markOop. This means
|
|
659 // it is not neccessary to preserve most markOops.
|
|
660 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
|
|
661 if (_preserved_mark_stack == NULL) {
|
|
662 ThreadCritical tc; // Lock and retest
|
|
663 if (_preserved_mark_stack == NULL) {
|
|
664 assert(_preserved_oop_stack == NULL, "Sanity");
|
|
665 _preserved_mark_stack = new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
|
|
666 _preserved_oop_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
|
|
667 }
|
|
668 }
|
|
669
|
|
670 // Because we must hold the ThreadCritical lock before using
|
|
671 // the stacks, we should be safe from observing partial allocations,
|
|
672 // which are also guarded by the ThreadCritical lock.
|
|
673 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
|
|
674 ThreadCritical tc;
|
|
675 _preserved_oop_stack->push(obj);
|
|
676 _preserved_mark_stack->push(obj_mark);
|
|
677 }
|
|
678 }
|
|
679
|
|
680 bool PSScavenge::should_attempt_scavenge() {
|
|
681 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
|
|
682 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
|
|
683 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
|
|
684
|
|
685 if (UsePerfData) {
|
|
686 counters->update_scavenge_skipped(not_skipped);
|
|
687 }
|
|
688
|
|
689 PSYoungGen* young_gen = heap->young_gen();
|
|
690 PSOldGen* old_gen = heap->old_gen();
|
|
691
|
|
692 if (!ScavengeWithObjectsInToSpace) {
|
|
693 // Do not attempt to promote unless to_space is empty
|
|
694 if (!young_gen->to_space()->is_empty()) {
|
|
695 _consecutive_skipped_scavenges++;
|
|
696 if (UsePerfData) {
|
|
697 counters->update_scavenge_skipped(to_space_not_empty);
|
|
698 }
|
|
699 return false;
|
|
700 }
|
|
701 }
|
|
702
|
|
703 // Test to see if the scavenge will likely fail.
|
|
704 PSAdaptiveSizePolicy* policy = heap->size_policy();
|
|
705
|
|
706 // A similar test is done in the policy's should_full_GC(). If this is
|
|
707 // changed, decide if that test should also be changed.
|
|
708 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
|
|
709 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
|
|
710 bool result = promotion_estimate < old_gen->free_in_bytes();
|
|
711
|
|
712 if (PrintGCDetails && Verbose) {
|
|
713 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: ");
|
|
714 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
|
|
715 " padded_average_promoted " SIZE_FORMAT
|
|
716 " free in old gen " SIZE_FORMAT,
|
|
717 (size_t) policy->average_promoted_in_bytes(),
|
|
718 (size_t) policy->padded_average_promoted_in_bytes(),
|
|
719 old_gen->free_in_bytes());
|
|
720 if (young_gen->used_in_bytes() <
|
|
721 (size_t) policy->padded_average_promoted_in_bytes()) {
|
|
722 gclog_or_tty->print_cr(" padded_promoted_average is greater"
|
|
723 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
|
|
724 }
|
|
725 }
|
|
726
|
|
727 if (result) {
|
|
728 _consecutive_skipped_scavenges = 0;
|
|
729 } else {
|
|
730 _consecutive_skipped_scavenges++;
|
|
731 if (UsePerfData) {
|
|
732 counters->update_scavenge_skipped(promoted_too_large);
|
|
733 }
|
|
734 }
|
|
735 return result;
|
|
736 }
|
|
737
|
|
738 // Used to add tasks
|
|
739 GCTaskManager* const PSScavenge::gc_task_manager() {
|
|
740 assert(ParallelScavengeHeap::gc_task_manager() != NULL,
|
|
741 "shouldn't return NULL");
|
|
742 return ParallelScavengeHeap::gc_task_manager();
|
|
743 }
|
|
744
|
|
745 void PSScavenge::initialize() {
|
|
746 // Arguments must have been parsed
|
|
747
|
|
748 if (AlwaysTenure) {
|
|
749 _tenuring_threshold = 0;
|
|
750 } else if (NeverTenure) {
|
|
751 _tenuring_threshold = markOopDesc::max_age + 1;
|
|
752 } else {
|
|
753 // We want to smooth out our startup times for the AdaptiveSizePolicy
|
|
754 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
|
|
755 MaxTenuringThreshold;
|
|
756 }
|
|
757
|
|
758 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
|
|
759 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
|
|
760
|
|
761 PSYoungGen* young_gen = heap->young_gen();
|
|
762 PSOldGen* old_gen = heap->old_gen();
|
|
763 PSPermGen* perm_gen = heap->perm_gen();
|
|
764
|
|
765 // Set boundary between young_gen and old_gen
|
|
766 assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(),
|
|
767 "perm above old");
|
|
768 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
|
|
769 "old above young");
|
|
770 _young_generation_boundary = young_gen->eden_space()->bottom();
|
|
771
|
|
772 // Initialize ref handling object for scavenging.
|
|
773 MemRegion mr = young_gen->reserved();
|
|
774 _ref_processor = ReferenceProcessor::create_ref_processor(
|
|
775 mr, // span
|
|
776 true, // atomic_discovery
|
|
777 true, // mt_discovery
|
|
778 NULL, // is_alive_non_header
|
|
779 ParallelGCThreads,
|
|
780 ParallelRefProcEnabled);
|
|
781
|
|
782 // Cache the cardtable
|
|
783 BarrierSet* bs = Universe::heap()->barrier_set();
|
|
784 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
|
|
785 _card_table = (CardTableExtension*)bs;
|
|
786
|
|
787 _counters = new CollectorCounters("PSScavenge", 0);
|
|
788 }
|