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0
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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/_collectorPolicy.cpp.incl"
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27
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28 // CollectorPolicy methods.
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29
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30 void CollectorPolicy::initialize_flags() {
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31 if (PermSize > MaxPermSize) {
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32 MaxPermSize = PermSize;
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33 }
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34 PermSize = align_size_down(PermSize, min_alignment());
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35 MaxPermSize = align_size_up(MaxPermSize, max_alignment());
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36
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37 MinPermHeapExpansion = align_size_down(MinPermHeapExpansion, min_alignment());
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38 MaxPermHeapExpansion = align_size_down(MaxPermHeapExpansion, min_alignment());
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39
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40 MinHeapDeltaBytes = align_size_up(MinHeapDeltaBytes, min_alignment());
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41
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42 SharedReadOnlySize = align_size_up(SharedReadOnlySize, max_alignment());
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43 SharedReadWriteSize = align_size_up(SharedReadWriteSize, max_alignment());
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44 SharedMiscDataSize = align_size_up(SharedMiscDataSize, max_alignment());
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45
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46 assert(PermSize % min_alignment() == 0, "permanent space alignment");
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47 assert(MaxPermSize % max_alignment() == 0, "maximum permanent space alignment");
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48 assert(SharedReadOnlySize % max_alignment() == 0, "read-only space alignment");
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49 assert(SharedReadWriteSize % max_alignment() == 0, "read-write space alignment");
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50 assert(SharedMiscDataSize % max_alignment() == 0, "misc-data space alignment");
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51 if (PermSize < M) {
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52 vm_exit_during_initialization("Too small initial permanent heap");
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53 }
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54 }
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55
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56 void CollectorPolicy::initialize_size_info() {
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57 // User inputs from -mx and ms are aligned
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58 _initial_heap_byte_size = align_size_up(Arguments::initial_heap_size(),
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59 min_alignment());
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60 _min_heap_byte_size = align_size_up(Arguments::min_heap_size(),
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61 min_alignment());
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62 _max_heap_byte_size = align_size_up(MaxHeapSize, max_alignment());
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63
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64 // Check validity of heap parameters from launcher
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65 if (_initial_heap_byte_size == 0) {
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66 _initial_heap_byte_size = NewSize + OldSize;
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67 } else {
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68 Universe::check_alignment(_initial_heap_byte_size, min_alignment(),
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69 "initial heap");
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70 }
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71 if (_min_heap_byte_size == 0) {
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72 _min_heap_byte_size = NewSize + OldSize;
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73 } else {
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74 Universe::check_alignment(_min_heap_byte_size, min_alignment(),
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75 "initial heap");
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76 }
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77
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78 // Check heap parameter properties
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79 if (_initial_heap_byte_size < M) {
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80 vm_exit_during_initialization("Too small initial heap");
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81 }
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82 // Check heap parameter properties
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83 if (_min_heap_byte_size < M) {
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84 vm_exit_during_initialization("Too small minimum heap");
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85 }
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86 if (_initial_heap_byte_size <= NewSize) {
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87 // make sure there is at least some room in old space
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88 vm_exit_during_initialization("Too small initial heap for new size specified");
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89 }
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90 if (_max_heap_byte_size < _min_heap_byte_size) {
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91 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
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92 }
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93 if (_initial_heap_byte_size < _min_heap_byte_size) {
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94 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
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95 }
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96 if (_max_heap_byte_size < _initial_heap_byte_size) {
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97 vm_exit_during_initialization("Incompatible initial and maximum heap sizes specified");
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98 }
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99 }
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100
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101 void CollectorPolicy::initialize_perm_generation(PermGen::Name pgnm) {
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102 _permanent_generation =
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103 new PermanentGenerationSpec(pgnm, PermSize, MaxPermSize,
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104 SharedReadOnlySize,
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105 SharedReadWriteSize,
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106 SharedMiscDataSize,
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107 SharedMiscCodeSize);
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108 if (_permanent_generation == NULL) {
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109 vm_exit_during_initialization("Unable to allocate gen spec");
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110 }
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111 }
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112
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113
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114 GenRemSet* CollectorPolicy::create_rem_set(MemRegion whole_heap,
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115 int max_covered_regions) {
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116 switch (rem_set_name()) {
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117 case GenRemSet::CardTable: {
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118 if (barrier_set_name() != BarrierSet::CardTableModRef)
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119 vm_exit_during_initialization("Mismatch between RS and BS.");
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120 CardTableRS* res = new CardTableRS(whole_heap, max_covered_regions);
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121 return res;
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122 }
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123 default:
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124 guarantee(false, "unrecognized GenRemSet::Name");
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125 return NULL;
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126 }
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127 }
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128
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129 // GenCollectorPolicy methods.
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130
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131 void GenCollectorPolicy::initialize_size_policy(size_t init_eden_size,
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132 size_t init_promo_size,
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133 size_t init_survivor_size) {
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134 double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;
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135 _size_policy = new AdaptiveSizePolicy(init_eden_size,
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136 init_promo_size,
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137 init_survivor_size,
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138 max_gc_minor_pause_sec,
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139 GCTimeRatio);
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140 }
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141
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142 size_t GenCollectorPolicy::compute_max_alignment() {
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143 // The card marking array and the offset arrays for old generations are
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144 // committed in os pages as well. Make sure they are entirely full (to
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145 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
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146 // byte entry and the os page size is 4096, the maximum heap size should
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147 // be 512*4096 = 2MB aligned.
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148 size_t alignment = GenRemSet::max_alignment_constraint(rem_set_name());
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149
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150 // Parallel GC does its own alignment of the generations to avoid requiring a
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151 // large page (256M on some platforms) for the permanent generation. The
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152 // other collectors should also be updated to do their own alignment and then
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153 // this use of lcm() should be removed.
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154 if (UseLargePages && !UseParallelGC) {
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155 // in presence of large pages we have to make sure that our
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156 // alignment is large page aware
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157 alignment = lcm(os::large_page_size(), alignment);
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158 }
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159
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160 return alignment;
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161 }
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162
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163 void GenCollectorPolicy::initialize_flags() {
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164 // All sizes must be multiples of the generation granularity.
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165 set_min_alignment((uintx) Generation::GenGrain);
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166 set_max_alignment(compute_max_alignment());
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167 assert(max_alignment() >= min_alignment() &&
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168 max_alignment() % min_alignment() == 0,
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169 "invalid alignment constraints");
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170
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171 CollectorPolicy::initialize_flags();
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172
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173 // All generational heaps have a youngest gen; handle those flags here.
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174
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175 // Adjust max size parameters
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176 if (NewSize > MaxNewSize) {
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177 MaxNewSize = NewSize;
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178 }
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179 NewSize = align_size_down(NewSize, min_alignment());
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180 MaxNewSize = align_size_down(MaxNewSize, min_alignment());
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181
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182 // Check validity of heap flags
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183 assert(NewSize % min_alignment() == 0, "eden space alignment");
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184 assert(MaxNewSize % min_alignment() == 0, "survivor space alignment");
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185
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186 if (NewSize < 3*min_alignment()) {
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187 // make sure there room for eden and two survivor spaces
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188 vm_exit_during_initialization("Too small new size specified");
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189 }
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190 if (SurvivorRatio < 1 || NewRatio < 1) {
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191 vm_exit_during_initialization("Invalid heap ratio specified");
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192 }
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193 }
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194
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195 void TwoGenerationCollectorPolicy::initialize_flags() {
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196 GenCollectorPolicy::initialize_flags();
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197
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198 OldSize = align_size_down(OldSize, min_alignment());
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199 if (NewSize + OldSize > MaxHeapSize) {
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200 MaxHeapSize = NewSize + OldSize;
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201 }
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202 MaxHeapSize = align_size_up(MaxHeapSize, max_alignment());
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203
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204 always_do_update_barrier = UseConcMarkSweepGC;
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205 BlockOffsetArrayUseUnallocatedBlock =
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206 BlockOffsetArrayUseUnallocatedBlock || ParallelGCThreads > 0;
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207
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208 // Check validity of heap flags
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209 assert(OldSize % min_alignment() == 0, "old space alignment");
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210 assert(MaxHeapSize % max_alignment() == 0, "maximum heap alignment");
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211 }
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212
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213 void GenCollectorPolicy::initialize_size_info() {
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214 CollectorPolicy::initialize_size_info();
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215
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216 // Minimum sizes of the generations may be different than
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217 // the initial sizes.
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218 if (!FLAG_IS_DEFAULT(NewSize)) {
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219 _min_gen0_size = NewSize;
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220 } else {
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221 _min_gen0_size = align_size_down(_min_heap_byte_size / (NewRatio+1),
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222 min_alignment());
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223 // We bound the minimum size by NewSize below (since it historically
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224 // would have been NewSize and because the NewRatio calculation could
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225 // yield a size that is too small) and bound it by MaxNewSize above.
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226 // This is not always best. The NewSize calculated by CMS (which has
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227 // a fixed minimum of 16m) can sometimes be "too" large. Consider
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228 // the case where -Xmx32m. The CMS calculated NewSize would be about
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229 // half the entire heap which seems too large. But the counter
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230 // example is seen when the client defaults for NewRatio are used.
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231 // An initial young generation size of 640k was observed
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232 // with -Xmx128m -XX:MaxNewSize=32m when NewSize was not used
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233 // as a lower bound as with
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234 // _min_gen0_size = MIN2(_min_gen0_size, MaxNewSize);
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235 // and 640k seemed too small a young generation.
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236 _min_gen0_size = MIN2(MAX2(_min_gen0_size, NewSize), MaxNewSize);
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237 }
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238
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239 // Parameters are valid, compute area sizes.
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240 size_t max_new_size = align_size_down(_max_heap_byte_size / (NewRatio+1),
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241 min_alignment());
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242 max_new_size = MIN2(MAX2(max_new_size, _min_gen0_size), MaxNewSize);
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243
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244 // desired_new_size is used to set the initial size. The
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245 // initial size must be greater than the minimum size.
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246 size_t desired_new_size =
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247 align_size_down(_initial_heap_byte_size / (NewRatio+1),
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248 min_alignment());
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249
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250 size_t new_size = MIN2(MAX2(desired_new_size, _min_gen0_size), max_new_size);
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251
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252 _initial_gen0_size = new_size;
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253 _max_gen0_size = max_new_size;
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254 }
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255
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256 void TwoGenerationCollectorPolicy::initialize_size_info() {
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257 GenCollectorPolicy::initialize_size_info();
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258
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259 // Minimum sizes of the generations may be different than
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260 // the initial sizes. An inconsistently is permitted here
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261 // in the total size that can be specified explicitly by
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262 // command line specification of OldSize and NewSize and
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263 // also a command line specification of -Xms. Issue a warning
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264 // but allow the values to pass.
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265 if (!FLAG_IS_DEFAULT(OldSize)) {
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266 _min_gen1_size = OldSize;
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267 // The generation minimums and the overall heap mimimum should
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268 // be within one heap alignment.
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269 if ((_min_gen1_size + _min_gen0_size + max_alignment()) <
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270 _min_heap_byte_size) {
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271 warning("Inconsistency between minimum heap size and minimum "
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272 "generation sizes: using min heap = " SIZE_FORMAT,
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273 _min_heap_byte_size);
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274 }
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275 } else {
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276 _min_gen1_size = _min_heap_byte_size - _min_gen0_size;
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277 }
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278
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279 _initial_gen1_size = _initial_heap_byte_size - _initial_gen0_size;
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280 _max_gen1_size = _max_heap_byte_size - _max_gen0_size;
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281 }
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282
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283 HeapWord* GenCollectorPolicy::mem_allocate_work(size_t size,
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284 bool is_tlab,
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285 bool* gc_overhead_limit_was_exceeded) {
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286 GenCollectedHeap *gch = GenCollectedHeap::heap();
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287
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288 debug_only(gch->check_for_valid_allocation_state());
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289 assert(gch->no_gc_in_progress(), "Allocation during gc not allowed");
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290 HeapWord* result = NULL;
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291
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292 // Loop until the allocation is satisified,
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293 // or unsatisfied after GC.
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294 for (int try_count = 1; /* return or throw */; try_count += 1) {
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295 HandleMark hm; // discard any handles allocated in each iteration
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296
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297 // First allocation attempt is lock-free.
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298 Generation *gen0 = gch->get_gen(0);
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299 assert(gen0->supports_inline_contig_alloc(),
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300 "Otherwise, must do alloc within heap lock");
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301 if (gen0->should_allocate(size, is_tlab)) {
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302 result = gen0->par_allocate(size, is_tlab);
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303 if (result != NULL) {
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304 assert(gch->is_in_reserved(result), "result not in heap");
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305 return result;
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306 }
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307 }
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308 unsigned int gc_count_before; // read inside the Heap_lock locked region
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309 {
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310 MutexLocker ml(Heap_lock);
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311 if (PrintGC && Verbose) {
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312 gclog_or_tty->print_cr("TwoGenerationCollectorPolicy::mem_allocate_work:"
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313 " attempting locked slow path allocation");
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314 }
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315 // Note that only large objects get a shot at being
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316 // allocated in later generations.
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317 bool first_only = ! should_try_older_generation_allocation(size);
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318
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319 result = gch->attempt_allocation(size, is_tlab, first_only);
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320 if (result != NULL) {
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321 assert(gch->is_in_reserved(result), "result not in heap");
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322 return result;
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323 }
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324
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325 // There are NULL's returned for different circumstances below.
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326 // In general gc_overhead_limit_was_exceeded should be false so
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327 // set it so here and reset it to true only if the gc time
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328 // limit is being exceeded as checked below.
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329 *gc_overhead_limit_was_exceeded = false;
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330
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331 if (GC_locker::is_active_and_needs_gc()) {
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332 if (is_tlab) {
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333 return NULL; // Caller will retry allocating individual object
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334 }
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335 if (!gch->is_maximal_no_gc()) {
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336 // Try and expand heap to satisfy request
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337 result = expand_heap_and_allocate(size, is_tlab);
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338 // result could be null if we are out of space
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339 if (result != NULL) {
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340 return result;
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341 }
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342 }
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343
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344 // If this thread is not in a jni critical section, we stall
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345 // the requestor until the critical section has cleared and
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346 // GC allowed. When the critical section clears, a GC is
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347 // initiated by the last thread exiting the critical section; so
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348 // we retry the allocation sequence from the beginning of the loop,
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349 // rather than causing more, now probably unnecessary, GC attempts.
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350 JavaThread* jthr = JavaThread::current();
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351 if (!jthr->in_critical()) {
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352 MutexUnlocker mul(Heap_lock);
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353 // Wait for JNI critical section to be exited
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354 GC_locker::stall_until_clear();
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355 continue;
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356 } else {
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357 if (CheckJNICalls) {
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358 fatal("Possible deadlock due to allocating while"
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359 " in jni critical section");
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360 }
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361 return NULL;
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362 }
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363 }
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364
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365 // Read the gc count while the heap lock is held.
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366 gc_count_before = Universe::heap()->total_collections();
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367 }
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368
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369 // Allocation has failed and a collection is about
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370 // to be done. If the gc time limit was exceeded the
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371 // last time a collection was done, return NULL so
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372 // that an out-of-memory will be thrown. Clear
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373 // gc_time_limit_exceeded so that subsequent attempts
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374 // at a collection will be made.
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375 if (size_policy()->gc_time_limit_exceeded()) {
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376 *gc_overhead_limit_was_exceeded = true;
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377 size_policy()->set_gc_time_limit_exceeded(false);
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378 return NULL;
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379 }
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380
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381 VM_GenCollectForAllocation op(size,
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382 is_tlab,
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383 gc_count_before);
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384 VMThread::execute(&op);
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385 if (op.prologue_succeeded()) {
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386 result = op.result();
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387 if (op.gc_locked()) {
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388 assert(result == NULL, "must be NULL if gc_locked() is true");
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389 continue; // retry and/or stall as necessary
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390 }
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391 assert(result == NULL || gch->is_in_reserved(result),
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392 "result not in heap");
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393 return result;
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394 }
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395
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396 // Give a warning if we seem to be looping forever.
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397 if ((QueuedAllocationWarningCount > 0) &&
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398 (try_count % QueuedAllocationWarningCount == 0)) {
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399 warning("TwoGenerationCollectorPolicy::mem_allocate_work retries %d times \n\t"
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400 " size=%d %s", try_count, size, is_tlab ? "(TLAB)" : "");
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401 }
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402 }
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403 }
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404
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405 HeapWord* GenCollectorPolicy::expand_heap_and_allocate(size_t size,
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406 bool is_tlab) {
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407 GenCollectedHeap *gch = GenCollectedHeap::heap();
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408 HeapWord* result = NULL;
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409 for (int i = number_of_generations() - 1; i >= 0 && result == NULL; i--) {
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410 Generation *gen = gch->get_gen(i);
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411 if (gen->should_allocate(size, is_tlab)) {
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412 result = gen->expand_and_allocate(size, is_tlab);
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413 }
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414 }
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415 assert(result == NULL || gch->is_in_reserved(result), "result not in heap");
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416 return result;
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417 }
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418
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419 HeapWord* GenCollectorPolicy::satisfy_failed_allocation(size_t size,
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420 bool is_tlab) {
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421 GenCollectedHeap *gch = GenCollectedHeap::heap();
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422 GCCauseSetter x(gch, GCCause::_allocation_failure);
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423 HeapWord* result = NULL;
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424
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425 assert(size != 0, "Precondition violated");
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426 if (GC_locker::is_active_and_needs_gc()) {
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427 // GC locker is active; instead of a collection we will attempt
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428 // to expand the heap, if there's room for expansion.
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429 if (!gch->is_maximal_no_gc()) {
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430 result = expand_heap_and_allocate(size, is_tlab);
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431 }
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432 return result; // could be null if we are out of space
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433 } else if (!gch->incremental_collection_will_fail()) {
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434 // The gc_prologues have not executed yet. The value
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|
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435 // for incremental_collection_will_fail() is the remanent
|
|
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436 // of the last collection.
|
|
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437 // Do an incremental collection.
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|
|
438 gch->do_collection(false /* full */,
|
|
|
439 false /* clear_all_soft_refs */,
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|
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440 size /* size */,
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|
|
441 is_tlab /* is_tlab */,
|
|
|
442 number_of_generations() - 1 /* max_level */);
|
|
|
443 } else {
|
|
|
444 // Try a full collection; see delta for bug id 6266275
|
|
|
445 // for the original code and why this has been simplified
|
|
|
446 // with from-space allocation criteria modified and
|
|
|
447 // such allocation moved out of the safepoint path.
|
|
|
448 gch->do_collection(true /* full */,
|
|
|
449 false /* clear_all_soft_refs */,
|
|
|
450 size /* size */,
|
|
|
451 is_tlab /* is_tlab */,
|
|
|
452 number_of_generations() - 1 /* max_level */);
|
|
|
453 }
|
|
|
454
|
|
|
455 result = gch->attempt_allocation(size, is_tlab, false /*first_only*/);
|
|
|
456
|
|
|
457 if (result != NULL) {
|
|
|
458 assert(gch->is_in_reserved(result), "result not in heap");
|
|
|
459 return result;
|
|
|
460 }
|
|
|
461
|
|
|
462 // OK, collection failed, try expansion.
|
|
|
463 result = expand_heap_and_allocate(size, is_tlab);
|
|
|
464 if (result != NULL) {
|
|
|
465 return result;
|
|
|
466 }
|
|
|
467
|
|
|
468 // If we reach this point, we're really out of memory. Try every trick
|
|
|
469 // we can to reclaim memory. Force collection of soft references. Force
|
|
|
470 // a complete compaction of the heap. Any additional methods for finding
|
|
|
471 // free memory should be here, especially if they are expensive. If this
|
|
|
472 // attempt fails, an OOM exception will be thrown.
|
|
|
473 {
|
|
|
474 IntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
|
|
|
475
|
|
|
476 gch->do_collection(true /* full */,
|
|
|
477 true /* clear_all_soft_refs */,
|
|
|
478 size /* size */,
|
|
|
479 is_tlab /* is_tlab */,
|
|
|
480 number_of_generations() - 1 /* max_level */);
|
|
|
481 }
|
|
|
482
|
|
|
483 result = gch->attempt_allocation(size, is_tlab, false /* first_only */);
|
|
|
484 if (result != NULL) {
|
|
|
485 assert(gch->is_in_reserved(result), "result not in heap");
|
|
|
486 return result;
|
|
|
487 }
|
|
|
488
|
|
|
489 // What else? We might try synchronous finalization later. If the total
|
|
|
490 // space available is large enough for the allocation, then a more
|
|
|
491 // complete compaction phase than we've tried so far might be
|
|
|
492 // appropriate.
|
|
|
493 return NULL;
|
|
|
494 }
|
|
|
495
|
|
|
496 size_t GenCollectorPolicy::large_typearray_limit() {
|
|
|
497 return FastAllocateSizeLimit;
|
|
|
498 }
|
|
|
499
|
|
|
500 // Return true if any of the following is true:
|
|
|
501 // . the allocation won't fit into the current young gen heap
|
|
|
502 // . gc locker is occupied (jni critical section)
|
|
|
503 // . heap memory is tight -- the most recent previous collection
|
|
|
504 // was a full collection because a partial collection (would
|
|
|
505 // have) failed and is likely to fail again
|
|
|
506 bool GenCollectorPolicy::should_try_older_generation_allocation(
|
|
|
507 size_t word_size) const {
|
|
|
508 GenCollectedHeap* gch = GenCollectedHeap::heap();
|
|
|
509 size_t gen0_capacity = gch->get_gen(0)->capacity_before_gc();
|
|
|
510 return (word_size > heap_word_size(gen0_capacity))
|
|
|
511 || (GC_locker::is_active_and_needs_gc())
|
|
|
512 || ( gch->last_incremental_collection_failed()
|
|
|
513 && gch->incremental_collection_will_fail());
|
|
|
514 }
|
|
|
515
|
|
|
516
|
|
|
517 //
|
|
|
518 // MarkSweepPolicy methods
|
|
|
519 //
|
|
|
520
|
|
|
521 MarkSweepPolicy::MarkSweepPolicy() {
|
|
|
522 initialize_all();
|
|
|
523 }
|
|
|
524
|
|
|
525 void MarkSweepPolicy::initialize_generations() {
|
|
|
526 initialize_perm_generation(PermGen::MarkSweepCompact);
|
|
|
527 _generations = new GenerationSpecPtr[number_of_generations()];
|
|
|
528 if (_generations == NULL)
|
|
|
529 vm_exit_during_initialization("Unable to allocate gen spec");
|
|
|
530
|
|
|
531 if (UseParNewGC && ParallelGCThreads > 0) {
|
|
|
532 _generations[0] = new GenerationSpec(Generation::ParNew, _initial_gen0_size, _max_gen0_size);
|
|
|
533 } else {
|
|
|
534 _generations[0] = new GenerationSpec(Generation::DefNew, _initial_gen0_size, _max_gen0_size);
|
|
|
535 }
|
|
|
536 _generations[1] = new GenerationSpec(Generation::MarkSweepCompact, _initial_gen1_size, _max_gen1_size);
|
|
|
537
|
|
|
538 if (_generations[0] == NULL || _generations[1] == NULL)
|
|
|
539 vm_exit_during_initialization("Unable to allocate gen spec");
|
|
|
540 }
|
|
|
541
|
|
|
542 void MarkSweepPolicy::initialize_gc_policy_counters() {
|
|
|
543 // initialize the policy counters - 2 collectors, 3 generations
|
|
|
544 if (UseParNewGC && ParallelGCThreads > 0) {
|
|
|
545 _gc_policy_counters = new GCPolicyCounters("ParNew:MSC", 2, 3);
|
|
|
546 }
|
|
|
547 else {
|
|
|
548 _gc_policy_counters = new GCPolicyCounters("Copy:MSC", 2, 3);
|
|
|
549 }
|
|
|
550 }
|
