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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/_defNewGeneration.cpp.incl"
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27
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28 //
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29 // DefNewGeneration functions.
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30
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31 // Methods of protected closure types.
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32
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33 DefNewGeneration::IsAliveClosure::IsAliveClosure(Generation* g) : _g(g) {
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34 assert(g->level() == 0, "Optimized for youngest gen.");
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35 }
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36 void DefNewGeneration::IsAliveClosure::do_object(oop p) {
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37 assert(false, "Do not call.");
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38 }
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39 bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
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40 return (HeapWord*)p >= _g->reserved().end() || p->is_forwarded();
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41 }
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42
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43 DefNewGeneration::KeepAliveClosure::
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44 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
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45 GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
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46 assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind.");
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47 _rs = (CardTableRS*)rs;
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48 }
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49
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50 void DefNewGeneration::KeepAliveClosure::do_oop(oop* p) {
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51 // We never expect to see a null reference being processed
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52 // as a weak reference.
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53 assert (*p != NULL, "expected non-null ref");
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54 assert ((*p)->is_oop(), "expected an oop while scanning weak refs");
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55
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56 _cl->do_oop_nv(p);
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57
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58 // Card marking is trickier for weak refs.
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59 // This oop is a 'next' field which was filled in while we
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60 // were discovering weak references. While we might not need
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61 // to take a special action to keep this reference alive, we
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62 // will need to dirty a card as the field was modified.
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63 //
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64 // Alternatively, we could create a method which iterates through
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65 // each generation, allowing them in turn to examine the modified
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66 // field.
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67 //
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68 // We could check that p is also in an older generation, but
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69 // dirty cards in the youngest gen are never scanned, so the
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70 // extra check probably isn't worthwhile.
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71 if (Universe::heap()->is_in_reserved(p)) {
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72 _rs->inline_write_ref_field_gc(p, *p);
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73 }
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74 }
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75
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76 DefNewGeneration::FastKeepAliveClosure::
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77 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
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78 DefNewGeneration::KeepAliveClosure(cl) {
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79 _boundary = g->reserved().end();
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80 }
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81
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82 void DefNewGeneration::FastKeepAliveClosure::do_oop(oop* p) {
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83 assert (*p != NULL, "expected non-null ref");
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84 assert ((*p)->is_oop(), "expected an oop while scanning weak refs");
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85
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86 _cl->do_oop_nv(p);
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87
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88 // Optimized for Defnew generation if it's the youngest generation:
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89 // we set a younger_gen card if we have an older->youngest
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90 // generation pointer.
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91 if (((HeapWord*)(*p) < _boundary) && Universe::heap()->is_in_reserved(p)) {
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92 _rs->inline_write_ref_field_gc(p, *p);
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93 }
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94 }
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95
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96 DefNewGeneration::EvacuateFollowersClosure::
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97 EvacuateFollowersClosure(GenCollectedHeap* gch, int level,
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98 ScanClosure* cur, ScanClosure* older) :
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99 _gch(gch), _level(level),
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100 _scan_cur_or_nonheap(cur), _scan_older(older)
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101 {}
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102
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103 void DefNewGeneration::EvacuateFollowersClosure::do_void() {
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104 do {
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105 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
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106 _scan_older);
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107 } while (!_gch->no_allocs_since_save_marks(_level));
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108 }
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109
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110 DefNewGeneration::FastEvacuateFollowersClosure::
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111 FastEvacuateFollowersClosure(GenCollectedHeap* gch, int level,
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112 DefNewGeneration* gen,
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113 FastScanClosure* cur, FastScanClosure* older) :
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114 _gch(gch), _level(level), _gen(gen),
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115 _scan_cur_or_nonheap(cur), _scan_older(older)
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116 {}
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117
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118 void DefNewGeneration::FastEvacuateFollowersClosure::do_void() {
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119 do {
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120 _gch->oop_since_save_marks_iterate(_level, _scan_cur_or_nonheap,
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121 _scan_older);
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122 } while (!_gch->no_allocs_since_save_marks(_level));
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123 guarantee(_gen->promo_failure_scan_stack() == NULL
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124 || _gen->promo_failure_scan_stack()->length() == 0,
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125 "Failed to finish scan");
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126 }
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127
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128 ScanClosure::ScanClosure(DefNewGeneration* g, bool gc_barrier) :
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129 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
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130 {
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131 assert(_g->level() == 0, "Optimized for youngest generation");
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132 _boundary = _g->reserved().end();
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133 }
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134
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135 FastScanClosure::FastScanClosure(DefNewGeneration* g, bool gc_barrier) :
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136 OopsInGenClosure(g), _g(g), _gc_barrier(gc_barrier)
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137 {
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138 assert(_g->level() == 0, "Optimized for youngest generation");
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139 _boundary = _g->reserved().end();
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140 }
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141
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142 ScanWeakRefClosure::ScanWeakRefClosure(DefNewGeneration* g) :
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143 OopClosure(g->ref_processor()), _g(g)
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144 {
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145 assert(_g->level() == 0, "Optimized for youngest generation");
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146 _boundary = _g->reserved().end();
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147 }
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148
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149
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150 DefNewGeneration::DefNewGeneration(ReservedSpace rs,
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151 size_t initial_size,
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152 int level,
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153 const char* policy)
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154 : Generation(rs, initial_size, level),
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155 _objs_with_preserved_marks(NULL),
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156 _preserved_marks_of_objs(NULL),
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157 _promo_failure_scan_stack(NULL),
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158 _promo_failure_drain_in_progress(false),
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159 _should_allocate_from_space(false)
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160 {
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161 MemRegion cmr((HeapWord*)_virtual_space.low(),
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162 (HeapWord*)_virtual_space.high());
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163 Universe::heap()->barrier_set()->resize_covered_region(cmr);
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164
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165 if (GenCollectedHeap::heap()->collector_policy()->has_soft_ended_eden()) {
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166 _eden_space = new ConcEdenSpace(this);
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167 } else {
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168 _eden_space = new EdenSpace(this);
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169 }
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170 _from_space = new ContiguousSpace();
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171 _to_space = new ContiguousSpace();
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172
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173 if (_eden_space == NULL || _from_space == NULL || _to_space == NULL)
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174 vm_exit_during_initialization("Could not allocate a new gen space");
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175
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176 // Compute the maximum eden and survivor space sizes. These sizes
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177 // are computed assuming the entire reserved space is committed.
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178 // These values are exported as performance counters.
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179 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
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180 uintx size = _virtual_space.reserved_size();
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181 _max_survivor_size = compute_survivor_size(size, alignment);
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182 _max_eden_size = size - (2*_max_survivor_size);
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183
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184 // allocate the performance counters
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185
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186 // Generation counters -- generation 0, 3 subspaces
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187 _gen_counters = new GenerationCounters("new", 0, 3, &_virtual_space);
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188 _gc_counters = new CollectorCounters(policy, 0);
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189
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190 _eden_counters = new CSpaceCounters("eden", 0, _max_eden_size, _eden_space,
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191 _gen_counters);
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192 _from_counters = new CSpaceCounters("s0", 1, _max_survivor_size, _from_space,
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193 _gen_counters);
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194 _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space,
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195 _gen_counters);
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196
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197 compute_space_boundaries(0);
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198 update_counters();
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199 _next_gen = NULL;
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200 _tenuring_threshold = MaxTenuringThreshold;
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201 _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize;
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202 }
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203
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204 void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size) {
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205 uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
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206
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207 // Compute sizes
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208 uintx size = _virtual_space.committed_size();
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209 uintx survivor_size = compute_survivor_size(size, alignment);
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210 uintx eden_size = size - (2*survivor_size);
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211 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
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212
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213 if (eden_size < minimum_eden_size) {
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214 // May happen due to 64Kb rounding, if so adjust eden size back up
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215 minimum_eden_size = align_size_up(minimum_eden_size, alignment);
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216 uintx maximum_survivor_size = (size - minimum_eden_size) / 2;
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217 uintx unaligned_survivor_size =
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218 align_size_down(maximum_survivor_size, alignment);
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219 survivor_size = MAX2(unaligned_survivor_size, alignment);
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220 eden_size = size - (2*survivor_size);
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221 assert(eden_size > 0 && survivor_size <= eden_size, "just checking");
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222 assert(eden_size >= minimum_eden_size, "just checking");
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223 }
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224
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225 char *eden_start = _virtual_space.low();
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226 char *from_start = eden_start + eden_size;
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227 char *to_start = from_start + survivor_size;
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228 char *to_end = to_start + survivor_size;
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229
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230 assert(to_end == _virtual_space.high(), "just checking");
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231 assert(Space::is_aligned((HeapWord*)eden_start), "checking alignment");
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232 assert(Space::is_aligned((HeapWord*)from_start), "checking alignment");
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233 assert(Space::is_aligned((HeapWord*)to_start), "checking alignment");
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234
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235 MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)from_start);
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236 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start);
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237 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
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238
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239 eden()->initialize(edenMR, (minimum_eden_size == 0));
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240 // If minumum_eden_size != 0, we will not have cleared any
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241 // portion of eden above its top. This can cause newly
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242 // expanded space not to be mangled if using ZapUnusedHeapArea.
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243 // We explicitly do such mangling here.
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244 if (ZapUnusedHeapArea && (minimum_eden_size != 0)) {
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245 eden()->mangle_unused_area();
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246 }
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247 from()->initialize(fromMR, true);
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248 to()->initialize(toMR , true);
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249 eden()->set_next_compaction_space(from());
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250 // The to-space is normally empty before a compaction so need
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251 // not be considered. The exception is during promotion
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252 // failure handling when to-space can contain live objects.
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253 from()->set_next_compaction_space(NULL);
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254 }
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255
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256 void DefNewGeneration::swap_spaces() {
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257 ContiguousSpace* s = from();
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258 _from_space = to();
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259 _to_space = s;
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260 eden()->set_next_compaction_space(from());
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261 // The to-space is normally empty before a compaction so need
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262 // not be considered. The exception is during promotion
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263 // failure handling when to-space can contain live objects.
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264 from()->set_next_compaction_space(NULL);
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265
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266 if (UsePerfData) {
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267 CSpaceCounters* c = _from_counters;
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268 _from_counters = _to_counters;
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269 _to_counters = c;
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270 }
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271 }
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272
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273 bool DefNewGeneration::expand(size_t bytes) {
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274 MutexLocker x(ExpandHeap_lock);
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275 bool success = _virtual_space.expand_by(bytes);
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276
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277 // Do not attempt an expand-to-the reserve size. The
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278 // request should properly observe the maximum size of
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279 // the generation so an expand-to-reserve should be
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280 // unnecessary. Also a second call to expand-to-reserve
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281 // value potentially can cause an undue expansion.
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282 // For example if the first expand fail for unknown reasons,
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283 // but the second succeeds and expands the heap to its maximum
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284 // value.
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285 if (GC_locker::is_active()) {
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286 if (PrintGC && Verbose) {
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287 gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
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288 }
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289 }
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290
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291 return success;
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292 }
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293
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294
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295 void DefNewGeneration::compute_new_size() {
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296 // This is called after a gc that includes the following generation
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297 // (which is required to exist.) So from-space will normally be empty.
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298 // Note that we check both spaces, since if scavenge failed they revert roles.
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299 // If not we bail out (otherwise we would have to relocate the objects)
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300 if (!from()->is_empty() || !to()->is_empty()) {
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301 return;
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302 }
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303
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304 int next_level = level() + 1;
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305 GenCollectedHeap* gch = GenCollectedHeap::heap();
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306 assert(next_level < gch->_n_gens,
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307 "DefNewGeneration cannot be an oldest gen");
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308
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309 Generation* next_gen = gch->_gens[next_level];
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310 size_t old_size = next_gen->capacity();
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311 size_t new_size_before = _virtual_space.committed_size();
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312 size_t min_new_size = spec()->init_size();
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313 size_t max_new_size = reserved().byte_size();
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314 assert(min_new_size <= new_size_before &&
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315 new_size_before <= max_new_size,
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316 "just checking");
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317 // All space sizes must be multiples of Generation::GenGrain.
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318 size_t alignment = Generation::GenGrain;
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319
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320 // Compute desired new generation size based on NewRatio and
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321 // NewSizeThreadIncrease
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322 size_t desired_new_size = old_size/NewRatio;
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323 int threads_count = Threads::number_of_non_daemon_threads();
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324 size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
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325 desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
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326
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327 // Adjust new generation size
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328 desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);
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329 assert(desired_new_size <= max_new_size, "just checking");
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330
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331 bool changed = false;
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332 if (desired_new_size > new_size_before) {
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333 size_t change = desired_new_size - new_size_before;
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334 assert(change % alignment == 0, "just checking");
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335 if (expand(change)) {
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336 changed = true;
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337 }
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338 // If the heap failed to expand to the desired size,
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339 // "changed" will be false. If the expansion failed
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340 // (and at this point it was expected to succeed),
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341 // ignore the failure (leaving "changed" as false).
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342 }
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343 if (desired_new_size < new_size_before && eden()->is_empty()) {
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344 // bail out of shrinking if objects in eden
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345 size_t change = new_size_before - desired_new_size;
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346 assert(change % alignment == 0, "just checking");
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347 _virtual_space.shrink_by(change);
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348 changed = true;
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349 }
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350 if (changed) {
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351 compute_space_boundaries(eden()->used());
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352 MemRegion cmr((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
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353 Universe::heap()->barrier_set()->resize_covered_region(cmr);
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354 if (Verbose && PrintGC) {
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355 size_t new_size_after = _virtual_space.committed_size();
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356 size_t eden_size_after = eden()->capacity();
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357 size_t survivor_size_after = from()->capacity();
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358 gclog_or_tty->print("New generation size " SIZE_FORMAT "K->" SIZE_FORMAT "K [eden="
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359 SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]",
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360 new_size_before/K, new_size_after/K, eden_size_after/K, survivor_size_after/K);
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|
|
361 if (WizardMode) {
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|
362 gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]",
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|
363 thread_increase_size/K, threads_count);
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|
364 }
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|
365 gclog_or_tty->cr();
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366 }
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|
|
367 }
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|
|
368 }
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369
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370 void DefNewGeneration::object_iterate_since_last_GC(ObjectClosure* cl) {
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|
371 // $$$ This may be wrong in case of "scavenge failure"?
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|
372 eden()->object_iterate(cl);
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|
373 }
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374
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375 void DefNewGeneration::younger_refs_iterate(OopsInGenClosure* cl) {
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376 assert(false, "NYI -- are you sure you want to call this?");
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|
377 }
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|
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378
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|
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379
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|
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380 size_t DefNewGeneration::capacity() const {
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|
381 return eden()->capacity()
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|
382 + from()->capacity(); // to() is only used during scavenge
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383 }
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|
|
384
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385
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386 size_t DefNewGeneration::used() const {
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387 return eden()->used()
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388 + from()->used(); // to() is only used during scavenge
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|
|
389 }
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|
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390
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|
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391
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|
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392 size_t DefNewGeneration::free() const {
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393 return eden()->free()
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394 + from()->free(); // to() is only used during scavenge
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|
395 }
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|
|
396
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|
|
397 size_t DefNewGeneration::max_capacity() const {
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|
398 const size_t alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
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|
|
399 const size_t reserved_bytes = reserved().byte_size();
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|
400 return reserved_bytes - compute_survivor_size(reserved_bytes, alignment);
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401 }
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402
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|
|
403 size_t DefNewGeneration::unsafe_max_alloc_nogc() const {
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|
404 return eden()->free();
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|
|
405 }
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406
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|
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407 size_t DefNewGeneration::capacity_before_gc() const {
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|
408 return eden()->capacity();
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|
|
409 }
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|
410
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|
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411 size_t DefNewGeneration::contiguous_available() const {
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|
412 return eden()->free();
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413 }
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|
414
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415
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416 HeapWord** DefNewGeneration::top_addr() const { return eden()->top_addr(); }
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417 HeapWord** DefNewGeneration::end_addr() const { return eden()->end_addr(); }
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418
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|
|
419 void DefNewGeneration::object_iterate(ObjectClosure* blk) {
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420 eden()->object_iterate(blk);
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|
|
421 from()->object_iterate(blk);
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|
|
422 }
|
|
|
423
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|
424
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|
|
425 void DefNewGeneration::space_iterate(SpaceClosure* blk,
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|
426 bool usedOnly) {
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|
|
427 blk->do_space(eden());
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|
428 blk->do_space(from());
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|
|
429 blk->do_space(to());
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|
|
430 }
|
|
|
431
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|
|
432 // The last collection bailed out, we are running out of heap space,
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|
433 // so we try to allocate the from-space, too.
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|
|
434 HeapWord* DefNewGeneration::allocate_from_space(size_t size) {
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|
|
435 HeapWord* result = NULL;
|
|
|
436 if (PrintGC && Verbose) {
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|
|
437 gclog_or_tty->print("DefNewGeneration::allocate_from_space(%u):"
|
|
|
438 " will_fail: %s"
|
|
|
439 " heap_lock: %s"
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|
|
440 " free: " SIZE_FORMAT,
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|
|
441 size,
|
|
|
442 GenCollectedHeap::heap()->incremental_collection_will_fail() ? "true" : "false",
|
|
|
443 Heap_lock->is_locked() ? "locked" : "unlocked",
|
|
|
444 from()->free());
|
|
|
445 }
|
|
|
446 if (should_allocate_from_space() || GC_locker::is_active_and_needs_gc()) {
|
|
|
447 if (Heap_lock->owned_by_self() ||
|
|
|
448 (SafepointSynchronize::is_at_safepoint() &&
|
|
|
449 Thread::current()->is_VM_thread())) {
|
|
|
450 // If the Heap_lock is not locked by this thread, this will be called
|
|
|
451 // again later with the Heap_lock held.
|
|
|
452 result = from()->allocate(size);
|
|
|
453 } else if (PrintGC && Verbose) {
|
|
|
454 gclog_or_tty->print_cr(" Heap_lock is not owned by self");
|
|
|
455 }
|
|
|
456 } else if (PrintGC && Verbose) {
|
|
|
457 gclog_or_tty->print_cr(" should_allocate_from_space: NOT");
|
|
|
458 }
|
|
|
459 if (PrintGC && Verbose) {
|
|
|
460 gclog_or_tty->print_cr(" returns %s", result == NULL ? "NULL" : "object");
|
|
|
461 }
|
|
|
462 return result;
|
|
|
463 }
|
|
|
464
|
|
|
465 HeapWord* DefNewGeneration::expand_and_allocate(size_t size,
|
|
|
466 bool is_tlab,
|
|
|
467 bool parallel) {
|
|
|
468 // We don't attempt to expand the young generation (but perhaps we should.)
|
|
|
469 return allocate(size, is_tlab);
|
|
|
470 }
|
|
|
471
|
|
|
472
|
|
|
473 void DefNewGeneration::collect(bool full,
|
|
|
474 bool clear_all_soft_refs,
|
|
|
475 size_t size,
|
|
|
476 bool is_tlab) {
|
|
|
477 assert(full || size > 0, "otherwise we don't want to collect");
|
|
|
478 GenCollectedHeap* gch = GenCollectedHeap::heap();
|
|
|
479 _next_gen = gch->next_gen(this);
|
|
|
480 assert(_next_gen != NULL,
|
|
|
481 "This must be the youngest gen, and not the only gen");
|
|
|
482
|
|
|
483 // If the next generation is too full to accomodate promotion
|
|
|
484 // from this generation, pass on collection; let the next generation
|
|
|
485 // do it.
|
|
|
486 if (!collection_attempt_is_safe()) {
|
|
|
487 gch->set_incremental_collection_will_fail();
|
|
|
488 return;
|
|
|
489 }
|
|
|
490 assert(to()->is_empty(), "Else not collection_attempt_is_safe");
|
|
|
491
|
|
|
492 init_assuming_no_promotion_failure();
|
|
|
493
|
|
|
494 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty);
|
|
|
495 // Capture heap used before collection (for printing).
|
|
|
496 size_t gch_prev_used = gch->used();
|
|
|
497
|
|
|
498 SpecializationStats::clear();
|
|
|
499
|
|
|
500 // These can be shared for all code paths
|
|
|
501 IsAliveClosure is_alive(this);
|
|
|
502 ScanWeakRefClosure scan_weak_ref(this);
|
|
|
503
|
|
|
504 age_table()->clear();
|
|
|
505 to()->clear();
|
|
|
506
|
|
|
507 gch->rem_set()->prepare_for_younger_refs_iterate(false);
|
|
|
508
|
|
|
509 assert(gch->no_allocs_since_save_marks(0),
|
|
|
510 "save marks have not been newly set.");
|
|
|
511
|
|
|
512 // Weak refs.
|
|
|
513 // FIXME: Are these storage leaks, or are they resource objects?
|
|
|
514 #ifdef COMPILER2
|
|
|
515 ReferencePolicy *soft_ref_policy = new LRUMaxHeapPolicy();
|
|
|
516 #else
|
|
|
517 ReferencePolicy *soft_ref_policy = new LRUCurrentHeapPolicy();
|
|
|
518 #endif // COMPILER2
|
|
|
519
|
|
|
520 // Not very pretty.
|
|
|
521 CollectorPolicy* cp = gch->collector_policy();
|
|
|
522
|
|
|
523 FastScanClosure fsc_with_no_gc_barrier(this, false);
|
|
|
524 FastScanClosure fsc_with_gc_barrier(this, true);
|
|
|
525
|
|
|
526 set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
|
|
|
527 FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
|
|
|
528 &fsc_with_no_gc_barrier,
|
|
|
529 &fsc_with_gc_barrier);
|
|
|
530
|
|
|
531 assert(gch->no_allocs_since_save_marks(0),
|
|
|
532 "save marks have not been newly set.");
|
|
|
533
|
|
|
534 gch->gen_process_strong_roots(_level,
|
|
|
535 true, // Process younger gens, if any, as
|
|
|
536 // strong roots.
|
|
|
537 false,// not collecting permanent generation.
|
|
|
538 SharedHeap::SO_AllClasses,
|
|
|
539 &fsc_with_gc_barrier,
|
|
|
540 &fsc_with_no_gc_barrier);
|
|
|
541
|
|
|
542 // "evacuate followers".
|
|
|
543 evacuate_followers.do_void();
|
|
|
544
|
|
|
545 FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
|
|
|
546 ref_processor()->process_discovered_references(
|
|
|
547 soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, NULL);
|
|
|
548 if (!promotion_failed()) {
|
|
|
549 // Swap the survivor spaces.
|
|
|
550 eden()->clear();
|
|
|
551 from()->clear();
|
|
|
552 swap_spaces();
|
|
|
553
|
|
|
554 assert(to()->is_empty(), "to space should be empty now");
|
|
|
555
|
|
|
556 // Set the desired survivor size to half the real survivor space
|
|
|
557 _tenuring_threshold =
|
|
|
558 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize);
|
|
|
559
|
|
|
560 if (PrintGC && !PrintGCDetails) {
|
|
|
561 gch->print_heap_change(gch_prev_used);
|
|
|
562 }
|
|
|
563 } else {
|
|
|
564 assert(HandlePromotionFailure,
|
|
|
565 "Should not be here unless promotion failure handling is on");
|
|
|
566 assert(_promo_failure_scan_stack != NULL &&
|
|
|
567 _promo_failure_scan_stack->length() == 0, "post condition");
|
|
|
568
|
|
|
569 // deallocate stack and it's elements
|
|
|
570 delete _promo_failure_scan_stack;
|
|
|
571 _promo_failure_scan_stack = NULL;
|
|
|
572
|
|
|
573 remove_forwarding_pointers();
|
|
|
574 if (PrintGCDetails) {
|
|
|
575 gclog_or_tty->print(" (promotion failed)");
|
|
|
576 }
|
|
|
577 // Add to-space to the list of space to compact
|
|
|
578 // when a promotion failure has occurred. In that
|
|
|
579 // case there can be live objects in to-space
|
|
|
580 // as a result of a partial evacuation of eden
|
|
|
581 // and from-space.
|
|
|
582 swap_spaces(); // For the sake of uniformity wrt ParNewGeneration::collect().
|
|
|
583 from()->set_next_compaction_space(to());
|
|
|
584 gch->set_incremental_collection_will_fail();
|
|
|
585
|
|
|
586 // Reset the PromotionFailureALot counters.
|
|
|
587 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
|
|
|
588 }
|
|
|
589 // set new iteration safe limit for the survivor spaces
|
|
|
590 from()->set_concurrent_iteration_safe_limit(from()->top());
|
|
|
591 to()->set_concurrent_iteration_safe_limit(to()->top());
|
|
|
592 SpecializationStats::print();
|
|
|
593 update_time_of_last_gc(os::javaTimeMillis());
|
|
|
594 }
|
|
|
595
|
|
|
596 class RemoveForwardPointerClosure: public ObjectClosure {
|
|
|
597 public:
|
|
|
598 void do_object(oop obj) {
|
|
|
599 obj->init_mark();
|
|
|
600 }
|
|
|
601 };
|
|
|
602
|
|
|
603 void DefNewGeneration::init_assuming_no_promotion_failure() {
|
|
|
604 _promotion_failed = false;
|
|
|
605 from()->set_next_compaction_space(NULL);
|
|
|
606 }
|
|
|
607
|
|
|
608 void DefNewGeneration::remove_forwarding_pointers() {
|
|
|
609 RemoveForwardPointerClosure rspc;
|
|
|
610 eden()->object_iterate(&rspc);
|
|
|
611 from()->object_iterate(&rspc);
|
|
|
612 // Now restore saved marks, if any.
|
|
|
613 if (_objs_with_preserved_marks != NULL) {
|
|
|
614 assert(_preserved_marks_of_objs != NULL, "Both or none.");
|
|
|
615 assert(_objs_with_preserved_marks->length() ==
|
|
|
616 _preserved_marks_of_objs->length(), "Both or none.");
|
|
|
617 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
|
|
|
618 oop obj = _objs_with_preserved_marks->at(i);
|
|
|
619 markOop m = _preserved_marks_of_objs->at(i);
|
|
|
620 obj->set_mark(m);
|
|
|
621 }
|
|
|
622 delete _objs_with_preserved_marks;
|
|
|
623 delete _preserved_marks_of_objs;
|
|
|
624 _objs_with_preserved_marks = NULL;
|
|
|
625 _preserved_marks_of_objs = NULL;
|
|
|
626 }
|
|
|
627 }
|
|
|
628
|
|
|
629 void DefNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) {
|
|
|
630 if (m->must_be_preserved_for_promotion_failure(obj)) {
|
|
|
631 if (_objs_with_preserved_marks == NULL) {
|
|
|
632 assert(_preserved_marks_of_objs == NULL, "Both or none.");
|
|
|
633 _objs_with_preserved_marks = new (ResourceObj::C_HEAP)
|
|
|
634 GrowableArray<oop>(PreserveMarkStackSize, true);
|
|
|
635 _preserved_marks_of_objs = new (ResourceObj::C_HEAP)
|
|
|
636 GrowableArray<markOop>(PreserveMarkStackSize, true);
|
|
|
637 }
|
|
|
638 _objs_with_preserved_marks->push(obj);
|
|
|
639 _preserved_marks_of_objs->push(m);
|
|
|
640 }
|
|
|
641 }
|
|
|
642
|
|
|
643 void DefNewGeneration::handle_promotion_failure(oop old) {
|
|
|
644 preserve_mark_if_necessary(old, old->mark());
|
|
|
645 // forward to self
|
|
|
646 old->forward_to(old);
|
|
|
647 _promotion_failed = true;
|
|
|
648
|
|
|
649 push_on_promo_failure_scan_stack(old);
|
|
|
650
|
|
|
651 if (!_promo_failure_drain_in_progress) {
|
|
|
652 // prevent recursion in copy_to_survivor_space()
|
|
|
653 _promo_failure_drain_in_progress = true;
|
|
|
654 drain_promo_failure_scan_stack();
|
|
|
655 _promo_failure_drain_in_progress = false;
|
|
|
656 }
|
|
|
657 }
|
|
|
658
|
|
|
659 oop DefNewGeneration::copy_to_survivor_space(oop old, oop* from) {
|
|
|
660 assert(is_in_reserved(old) && !old->is_forwarded(),
|
|
|
661 "shouldn't be scavenging this oop");
|
|
|
662 size_t s = old->size();
|
|
|
663 oop obj = NULL;
|
|
|
664
|
|
|
665 // Try allocating obj in to-space (unless too old)
|
|
|
666 if (old->age() < tenuring_threshold()) {
|
|
|
667 obj = (oop) to()->allocate(s);
|
|
|
668 }
|
|
|
669
|
|
|
670 // Otherwise try allocating obj tenured
|
|
|
671 if (obj == NULL) {
|
|
|
672 obj = _next_gen->promote(old, s, from);
|
|
|
673 if (obj == NULL) {
|
|
|
674 if (!HandlePromotionFailure) {
|
|
|
675 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag
|
|
|
676 // is incorrectly set. In any case, its seriously wrong to be here!
|
|
|
677 vm_exit_out_of_memory(s*wordSize, "promotion");
|
|
|
678 }
|
|
|
679
|
|
|
680 handle_promotion_failure(old);
|
|
|
681 return old;
|
|
|
682 }
|
|
|
683 } else {
|
|
|
684 // Prefetch beyond obj
|
|
|
685 const intx interval = PrefetchCopyIntervalInBytes;
|
|
|
686 Prefetch::write(obj, interval);
|
|
|
687
|
|
|
688 // Copy obj
|
|
|
689 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)obj, s);
|
|
|
690
|
|
|
691 // Increment age if obj still in new generation
|
|
|
692 obj->incr_age();
|
|
|
693 age_table()->add(obj, s);
|
|
|
694 }
|
|
|
695
|
|
|
696 // Done, insert forward pointer to obj in this header
|
|
|
697 old->forward_to(obj);
|
|
|
698
|
|
|
699 return obj;
|
|
|
700 }
|
|
|
701
|
|
|
702 void DefNewGeneration::push_on_promo_failure_scan_stack(oop obj) {
|
|
|
703 if (_promo_failure_scan_stack == NULL) {
|
|
|
704 _promo_failure_scan_stack = new (ResourceObj::C_HEAP)
|
|
|
705 GrowableArray<oop>(40, true);
|
|
|
706 }
|
|
|
707
|
|
|
708 _promo_failure_scan_stack->push(obj);
|
|
|
709 }
|
|
|
710
|
|
|
711 void DefNewGeneration::drain_promo_failure_scan_stack() {
|
|
|
712 assert(_promo_failure_scan_stack != NULL, "precondition");
|
|
|
713
|
|
|
714 while (_promo_failure_scan_stack->length() > 0) {
|
|
|
715 oop obj = _promo_failure_scan_stack->pop();
|
|
|
716 obj->oop_iterate(_promo_failure_scan_stack_closure);
|
|
|
717 }
|
|
|
718 }
|
|
|
719
|
|
|
720 void DefNewGeneration::save_marks() {
|
|
|
721 eden()->set_saved_mark();
|
|
|
722 to()->set_saved_mark();
|
|
|
723 from()->set_saved_mark();
|
|
|
724 }
|
|
|
725
|
|
|
726
|
|
|
727 void DefNewGeneration::reset_saved_marks() {
|
|
|
728 eden()->reset_saved_mark();
|
|
|
729 to()->reset_saved_mark();
|
|
|
730 from()->reset_saved_mark();
|
|
|
731 }
|
|
|
732
|
|
|
733
|
|
|
734 bool DefNewGeneration::no_allocs_since_save_marks() {
|
|
|
735 assert(eden()->saved_mark_at_top(), "Violated spec - alloc in eden");
|
|
|
736 assert(from()->saved_mark_at_top(), "Violated spec - alloc in from");
|
|
|
737 return to()->saved_mark_at_top();
|
|
|
738 }
|
|
|
739
|
|
|
740 #define DefNew_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
|
|
|
741 \
|
|
|
742 void DefNewGeneration:: \
|
|
|
743 oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl) { \
|
|
|
744 cl->set_generation(this); \
|
|
|
745 eden()->oop_since_save_marks_iterate##nv_suffix(cl); \
|
|
|
746 to()->oop_since_save_marks_iterate##nv_suffix(cl); \
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747 from()->oop_since_save_marks_iterate##nv_suffix(cl); \
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748 cl->reset_generation(); \
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749 save_marks(); \
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750 }
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751
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752 ALL_SINCE_SAVE_MARKS_CLOSURES(DefNew_SINCE_SAVE_MARKS_DEFN)
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753
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754 #undef DefNew_SINCE_SAVE_MARKS_DEFN
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755
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756 void DefNewGeneration::contribute_scratch(ScratchBlock*& list, Generation* requestor,
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757 size_t max_alloc_words) {
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758 if (requestor == this || _promotion_failed) return;
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759 assert(requestor->level() > level(), "DefNewGeneration must be youngest");
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760
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761 /* $$$ Assert this? "trace" is a "MarkSweep" function so that's not appropriate.
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762 if (to_space->top() > to_space->bottom()) {
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763 trace("to_space not empty when contribute_scratch called");
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764 }
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765 */
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766
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767 ContiguousSpace* to_space = to();
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768 assert(to_space->end() >= to_space->top(), "pointers out of order");
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769 size_t free_words = pointer_delta(to_space->end(), to_space->top());
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770 if (free_words >= MinFreeScratchWords) {
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771 ScratchBlock* sb = (ScratchBlock*)to_space->top();
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772 sb->num_words = free_words;
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773 sb->next = list;
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774 list = sb;
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775 }
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776 }
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777
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778 bool DefNewGeneration::collection_attempt_is_safe() {
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779 if (!to()->is_empty()) {
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780 return false;
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781 }
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782 if (_next_gen == NULL) {
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783 GenCollectedHeap* gch = GenCollectedHeap::heap();
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784 _next_gen = gch->next_gen(this);
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785 assert(_next_gen != NULL,
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786 "This must be the youngest gen, and not the only gen");
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787 }
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788
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789 // Decide if there's enough room for a full promotion
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790 // When using extremely large edens, we effectively lose a
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791 // large amount of old space. Use the "MaxLiveObjectEvacuationRatio"
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|
792 // flag to reduce the minimum evacuation space requirements. If
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|
793 // there is not enough space to evacuate eden during a scavenge,
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|
|
794 // the VM will immediately exit with an out of memory error.
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|
795 // This flag has not been tested
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|
796 // with collectors other than simple mark & sweep.
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|
|
797 //
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|
798 // Note that with the addition of promotion failure handling, the
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|
|
799 // VM will not immediately exit but will undo the young generation
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|
|
800 // collection. The parameter is left here for compatibility.
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|
801 const double evacuation_ratio = MaxLiveObjectEvacuationRatio / 100.0;
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|
|
802
|
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|
803 // worst_case_evacuation is based on "used()". For the case where this
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|
804 // method is called after a collection, this is still appropriate because
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|
|
805 // the case that needs to be detected is one in which a full collection
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|
|
806 // has been done and has overflowed into the young generation. In that
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|
|
807 // case a minor collection will fail (the overflow of the full collection
|
|
|
808 // means there is no space in the old generation for any promotion).
|
|
|
809 size_t worst_case_evacuation = (size_t)(used() * evacuation_ratio);
|
|
|
810
|
|
|
811 return _next_gen->promotion_attempt_is_safe(worst_case_evacuation,
|
|
|
812 HandlePromotionFailure);
|
|
|
813 }
|
|
|
814
|
|
|
815 void DefNewGeneration::gc_epilogue(bool full) {
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|
|
816 // Check if the heap is approaching full after a collection has
|
|
|
817 // been done. Generally the young generation is empty at
|
|
|
818 // a minimum at the end of a collection. If it is not, then
|
|
|
819 // the heap is approaching full.
|
|
|
820 GenCollectedHeap* gch = GenCollectedHeap::heap();
|
|
|
821 clear_should_allocate_from_space();
|
|
|
822 if (collection_attempt_is_safe()) {
|
|
|
823 gch->clear_incremental_collection_will_fail();
|
|
|
824 } else {
|
|
|
825 gch->set_incremental_collection_will_fail();
|
|
|
826 if (full) { // we seem to be running out of space
|
|
|
827 set_should_allocate_from_space();
|
|
|
828 }
|
|
|
829 }
|
|
|
830
|
|
|
831 // update the generation and space performance counters
|
|
|
832 update_counters();
|
|
|
833 gch->collector_policy()->counters()->update_counters();
|
|
|
834 }
|
|
|
835
|
|
|
836 void DefNewGeneration::update_counters() {
|
|
|
837 if (UsePerfData) {
|
|
|
838 _eden_counters->update_all();
|
|
|
839 _from_counters->update_all();
|
|
|
840 _to_counters->update_all();
|
|
|
841 _gen_counters->update_all();
|
|
|
842 }
|
|
|
843 }
|
|
|
844
|
|
|
845 void DefNewGeneration::verify(bool allow_dirty) {
|
|
|
846 eden()->verify(allow_dirty);
|
|
|
847 from()->verify(allow_dirty);
|
|
|
848 to()->verify(allow_dirty);
|
|
|
849 }
|
|
|
850
|
|
|
851 void DefNewGeneration::print_on(outputStream* st) const {
|
|
|
852 Generation::print_on(st);
|
|
|
853 st->print(" eden");
|
|
|
854 eden()->print_on(st);
|
|
|
855 st->print(" from");
|
|
|
856 from()->print_on(st);
|
|
|
857 st->print(" to ");
|
|
|
858 to()->print_on(st);
|
|
|
859 }
|
|
|
860
|
|
|
861
|
|
|
862 const char* DefNewGeneration::name() const {
|
|
|
863 return "def new generation";
|
|
|
864 }
|
