342
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1 /*
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2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 class G1CollectedHeap;
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26 class CMTask;
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27 typedef GenericTaskQueue<oop> CMTaskQueue;
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28 typedef GenericTaskQueueSet<oop> CMTaskQueueSet;
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29
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30 // A generic CM bit map. This is essentially a wrapper around the BitMap
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31 // class, with one bit per (1<<_shifter) HeapWords.
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32
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33 class CMBitMapRO {
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34 protected:
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35 HeapWord* _bmStartWord; // base address of range covered by map
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36 size_t _bmWordSize; // map size (in #HeapWords covered)
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37 const int _shifter; // map to char or bit
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38 VirtualSpace _virtual_space; // underlying the bit map
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39 BitMap _bm; // the bit map itself
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40
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41 public:
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42 // constructor
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43 CMBitMapRO(ReservedSpace rs, int shifter);
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44
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45 enum { do_yield = true };
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46
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47 // inquiries
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48 HeapWord* startWord() const { return _bmStartWord; }
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49 size_t sizeInWords() const { return _bmWordSize; }
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50 // the following is one past the last word in space
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51 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
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52
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53 // read marks
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54
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55 bool isMarked(HeapWord* addr) const {
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56 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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57 "outside underlying space?");
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58 return _bm.at(heapWordToOffset(addr));
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59 }
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60
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61 // iteration
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62 bool iterate(BitMapClosure* cl) { return _bm.iterate(cl); }
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63 bool iterate(BitMapClosure* cl, MemRegion mr);
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64
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65 // Return the address corresponding to the next marked bit at or after
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66 // "addr", and before "limit", if "limit" is non-NULL. If there is no
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67 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
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68 HeapWord* getNextMarkedWordAddress(HeapWord* addr,
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69 HeapWord* limit = NULL) const;
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70 // Return the address corresponding to the next unmarked bit at or after
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71 // "addr", and before "limit", if "limit" is non-NULL. If there is no
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72 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
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73 HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,
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74 HeapWord* limit = NULL) const;
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75
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76 // conversion utilities
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77 // XXX Fix these so that offsets are size_t's...
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78 HeapWord* offsetToHeapWord(size_t offset) const {
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79 return _bmStartWord + (offset << _shifter);
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80 }
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81 size_t heapWordToOffset(HeapWord* addr) const {
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82 return pointer_delta(addr, _bmStartWord) >> _shifter;
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83 }
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84 int heapWordDiffToOffsetDiff(size_t diff) const;
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85 HeapWord* nextWord(HeapWord* addr) {
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86 return offsetToHeapWord(heapWordToOffset(addr) + 1);
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87 }
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88
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89 void mostly_disjoint_range_union(BitMap* from_bitmap,
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90 size_t from_start_index,
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91 HeapWord* to_start_word,
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92 size_t word_num);
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93
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94 // debugging
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95 NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
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96 };
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97
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98 class CMBitMap : public CMBitMapRO {
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99
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100 public:
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101 // constructor
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102 CMBitMap(ReservedSpace rs, int shifter) :
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103 CMBitMapRO(rs, shifter) {}
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104
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105 // write marks
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106 void mark(HeapWord* addr) {
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107 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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108 "outside underlying space?");
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109 _bm.at_put(heapWordToOffset(addr), true);
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110 }
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111 void clear(HeapWord* addr) {
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112 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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113 "outside underlying space?");
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114 _bm.at_put(heapWordToOffset(addr), false);
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115 }
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116 bool parMark(HeapWord* addr) {
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117 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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118 "outside underlying space?");
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119 return _bm.par_at_put(heapWordToOffset(addr), true);
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120 }
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121 bool parClear(HeapWord* addr) {
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122 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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123 "outside underlying space?");
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124 return _bm.par_at_put(heapWordToOffset(addr), false);
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125 }
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126 void markRange(MemRegion mr);
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127 void clearAll();
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128 void clearRange(MemRegion mr);
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129
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130 // Starting at the bit corresponding to "addr" (inclusive), find the next
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131 // "1" bit, if any. This bit starts some run of consecutive "1"'s; find
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132 // the end of this run (stopping at "end_addr"). Return the MemRegion
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133 // covering from the start of the region corresponding to the first bit
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134 // of the run to the end of the region corresponding to the last bit of
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135 // the run. If there is no "1" bit at or after "addr", return an empty
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136 // MemRegion.
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137 MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
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138 };
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139
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140 // Represents a marking stack used by the CM collector.
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141 // Ideally this should be GrowableArray<> just like MSC's marking stack(s).
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142 class CMMarkStack {
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143 ConcurrentMark* _cm;
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144 oop* _base; // bottom of stack
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145 jint _index; // one more than last occupied index
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146 jint _capacity; // max #elements
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147 jint _oops_do_bound; // Number of elements to include in next iteration.
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148 NOT_PRODUCT(jint _max_depth;) // max depth plumbed during run
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149
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150 bool _overflow;
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151 DEBUG_ONLY(bool _drain_in_progress;)
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152 DEBUG_ONLY(bool _drain_in_progress_yields;)
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153
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154 public:
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155 CMMarkStack(ConcurrentMark* cm);
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156 ~CMMarkStack();
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157
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158 void allocate(size_t size);
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159
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160 oop pop() {
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161 if (!isEmpty()) {
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162 return _base[--_index] ;
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163 }
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164 return NULL;
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165 }
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166
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167 // If overflow happens, don't do the push, and record the overflow.
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168 // *Requires* that "ptr" is already marked.
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169 void push(oop ptr) {
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170 if (isFull()) {
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171 // Record overflow.
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172 _overflow = true;
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173 return;
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174 } else {
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175 _base[_index++] = ptr;
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176 NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
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177 }
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178 }
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179 // Non-block impl. Note: concurrency is allowed only with other
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180 // "par_push" operations, not with "pop" or "drain". We would need
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181 // parallel versions of them if such concurrency was desired.
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182 void par_push(oop ptr);
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183
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184 // Pushes the first "n" elements of "ptr_arr" on the stack.
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185 // Non-block impl. Note: concurrency is allowed only with other
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186 // "par_adjoin_arr" or "push" operations, not with "pop" or "drain".
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187 void par_adjoin_arr(oop* ptr_arr, int n);
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188
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189 // Pushes the first "n" elements of "ptr_arr" on the stack.
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190 // Locking impl: concurrency is allowed only with
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191 // "par_push_arr" and/or "par_pop_arr" operations, which use the same
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192 // locking strategy.
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193 void par_push_arr(oop* ptr_arr, int n);
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194
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195 // If returns false, the array was empty. Otherwise, removes up to "max"
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196 // elements from the stack, and transfers them to "ptr_arr" in an
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197 // unspecified order. The actual number transferred is given in "n" ("n
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198 // == 0" is deliberately redundant with the return value.) Locking impl:
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199 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
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200 // operations, which use the same locking strategy.
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201 bool par_pop_arr(oop* ptr_arr, int max, int* n);
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202
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203 // Drain the mark stack, applying the given closure to all fields of
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204 // objects on the stack. (That is, continue until the stack is empty,
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205 // even if closure applications add entries to the stack.) The "bm"
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206 // argument, if non-null, may be used to verify that only marked objects
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207 // are on the mark stack. If "yield_after" is "true", then the
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208 // concurrent marker performing the drain offers to yield after
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209 // processing each object. If a yield occurs, stops the drain operation
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210 // and returns false. Otherwise, returns true.
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211 template<class OopClosureClass>
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212 bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
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213
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214 bool isEmpty() { return _index == 0; }
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215 bool isFull() { return _index == _capacity; }
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216 int maxElems() { return _capacity; }
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217
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218 bool overflow() { return _overflow; }
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219 void clear_overflow() { _overflow = false; }
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220
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221 int size() { return _index; }
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222
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223 void setEmpty() { _index = 0; clear_overflow(); }
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224
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225 // Record the current size; a subsequent "oops_do" will iterate only over
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226 // indices valid at the time of this call.
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227 void set_oops_do_bound(jint bound = -1) {
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228 if (bound == -1) {
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229 _oops_do_bound = _index;
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230 } else {
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231 _oops_do_bound = bound;
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232 }
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233 }
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234 jint oops_do_bound() { return _oops_do_bound; }
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235 // iterate over the oops in the mark stack, up to the bound recorded via
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236 // the call above.
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237 void oops_do(OopClosure* f);
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238 };
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239
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240 class CMRegionStack {
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241 MemRegion* _base;
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242 jint _capacity;
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243 jint _index;
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244 jint _oops_do_bound;
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245 bool _overflow;
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246 public:
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247 CMRegionStack();
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248 ~CMRegionStack();
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249 void allocate(size_t size);
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250
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251 // This is lock-free; assumes that it will only be called in parallel
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252 // with other "push" operations (no pops).
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253 void push(MemRegion mr);
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254
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255 // Lock-free; assumes that it will only be called in parallel
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256 // with other "pop" operations (no pushes).
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257 MemRegion pop();
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258
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259 bool isEmpty() { return _index == 0; }
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260 bool isFull() { return _index == _capacity; }
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261
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262 bool overflow() { return _overflow; }
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263 void clear_overflow() { _overflow = false; }
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264
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265 int size() { return _index; }
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266
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267 // It iterates over the entries in the region stack and it
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268 // invalidates (i.e. assigns MemRegion()) the ones that point to
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269 // regions in the collection set.
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270 bool invalidate_entries_into_cset();
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271
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272 // This gives an upper bound up to which the iteration in
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273 // invalidate_entries_into_cset() will reach. This prevents
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274 // newly-added entries to be unnecessarily scanned.
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275 void set_oops_do_bound() {
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276 _oops_do_bound = _index;
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277 }
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278
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279 void setEmpty() { _index = 0; clear_overflow(); }
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280 };
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281
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282 // this will enable a variety of different statistics per GC task
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283 #define _MARKING_STATS_ 0
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284 // this will enable the higher verbose levels
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285 #define _MARKING_VERBOSE_ 0
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286
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287 #if _MARKING_STATS_
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288 #define statsOnly(statement) \
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289 do { \
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290 statement ; \
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291 } while (0)
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292 #else // _MARKING_STATS_
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293 #define statsOnly(statement) \
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294 do { \
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295 } while (0)
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296 #endif // _MARKING_STATS_
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297
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298 // Some extra guarantees that I like to also enable in optimised mode
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299 // when debugging. If you want to enable them, comment out the assert
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300 // macro and uncomment out the guaratee macro
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301 // #define tmp_guarantee_CM(expr, str) guarantee(expr, str)
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302 #define tmp_guarantee_CM(expr, str) assert(expr, str)
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303
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304 typedef enum {
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305 no_verbose = 0, // verbose turned off
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306 stats_verbose, // only prints stats at the end of marking
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307 low_verbose, // low verbose, mostly per region and per major event
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308 medium_verbose, // a bit more detailed than low
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309 high_verbose // per object verbose
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310 } CMVerboseLevel;
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311
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312
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313 class ConcurrentMarkThread;
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314
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315 class ConcurrentMark {
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316 friend class ConcurrentMarkThread;
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317 friend class CMTask;
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318 friend class CMBitMapClosure;
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319 friend class CSMarkOopClosure;
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320 friend class CMGlobalObjectClosure;
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321 friend class CMRemarkTask;
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322 friend class CMConcurrentMarkingTask;
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323 friend class G1ParNoteEndTask;
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324 friend class CalcLiveObjectsClosure;
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325
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326 protected:
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327 ConcurrentMarkThread* _cmThread; // the thread doing the work
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328 G1CollectedHeap* _g1h; // the heap.
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329 size_t _parallel_marking_threads; // the number of marking
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330 // threads we'll use
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331 double _sleep_factor; // how much we have to sleep, with
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332 // respect to the work we just did, to
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333 // meet the marking overhead goal
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334 double _marking_task_overhead; // marking target overhead for
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335 // a single task
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336
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337 // same as the two above, but for the cleanup task
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338 double _cleanup_sleep_factor;
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339 double _cleanup_task_overhead;
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340
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341 // Stuff related to age cohort processing.
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342 struct ParCleanupThreadState {
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343 char _pre[64];
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344 UncleanRegionList list;
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345 char _post[64];
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346 };
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347 ParCleanupThreadState** _par_cleanup_thread_state;
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348
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349 // CMS marking support structures
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350 CMBitMap _markBitMap1;
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351 CMBitMap _markBitMap2;
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352 CMBitMapRO* _prevMarkBitMap; // completed mark bitmap
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353 CMBitMap* _nextMarkBitMap; // under-construction mark bitmap
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354 bool _at_least_one_mark_complete;
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355
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356 BitMap _region_bm;
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357 BitMap _card_bm;
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358
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359 // Heap bounds
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360 HeapWord* _heap_start;
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361 HeapWord* _heap_end;
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362
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363 // For gray objects
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364 CMMarkStack _markStack; // Grey objects behind global finger.
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365 CMRegionStack _regionStack; // Grey regions behind global finger.
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366 HeapWord* volatile _finger; // the global finger, region aligned,
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367 // always points to the end of the
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368 // last claimed region
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369
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370 // marking tasks
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371 size_t _max_task_num; // maximum task number
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372 size_t _active_tasks; // task num currently active
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373 CMTask** _tasks; // task queue array (max_task_num len)
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374 CMTaskQueueSet* _task_queues; // task queue set
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375 ParallelTaskTerminator _terminator; // for termination
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376
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377 // Two sync barriers that are used to synchronise tasks when an
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378 // overflow occurs. The algorithm is the following. All tasks enter
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379 // the first one to ensure that they have all stopped manipulating
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380 // the global data structures. After they exit it, they re-initialise
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381 // their data structures and task 0 re-initialises the global data
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382 // structures. Then, they enter the second sync barrier. This
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383 // ensure, that no task starts doing work before all data
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384 // structures (local and global) have been re-initialised. When they
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385 // exit it, they are free to start working again.
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386 WorkGangBarrierSync _first_overflow_barrier_sync;
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387 WorkGangBarrierSync _second_overflow_barrier_sync;
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388
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389
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390 // this is set by any task, when an overflow on the global data
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391 // structures is detected.
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392 volatile bool _has_overflown;
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393 // true: marking is concurrent, false: we're in remark
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394 volatile bool _concurrent;
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395 // set at the end of a Full GC so that marking aborts
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396 volatile bool _has_aborted;
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397 // used when remark aborts due to an overflow to indicate that
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398 // another concurrent marking phase should start
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399 volatile bool _restart_for_overflow;
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400
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401 // This is true from the very start of concurrent marking until the
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402 // point when all the tasks complete their work. It is really used
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403 // to determine the points between the end of concurrent marking and
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404 // time of remark.
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405 volatile bool _concurrent_marking_in_progress;
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406
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407 // verbose level
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408 CMVerboseLevel _verbose_level;
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409
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410 COTracker _cleanup_co_tracker;
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411
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412 // These two fields are used to implement the optimisation that
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413 // avoids pushing objects on the global/region stack if there are
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414 // no collection set regions above the lowest finger.
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415
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416 // This is the lowest finger (among the global and local fingers),
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417 // which is calculated before a new collection set is chosen.
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418 HeapWord* _min_finger;
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419 // If this flag is true, objects/regions that are marked below the
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420 // finger should be pushed on the stack(s). If this is flag is
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421 // false, it is safe not to push them on the stack(s).
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422 bool _should_gray_objects;
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423
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424 // All of these times are in ms.
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425 NumberSeq _init_times;
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426 NumberSeq _remark_times;
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427 NumberSeq _remark_mark_times;
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428 NumberSeq _remark_weak_ref_times;
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429 NumberSeq _cleanup_times;
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430 double _total_counting_time;
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431 double _total_rs_scrub_time;
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432
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433 double* _accum_task_vtime; // accumulated task vtime
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434
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435 WorkGang* _parallel_workers;
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436
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437 void weakRefsWork(bool clear_all_soft_refs);
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438
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439 void swapMarkBitMaps();
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440
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441 // It resets the global marking data structures, as well as the
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442 // task local ones; should be called during initial mark.
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443 void reset();
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444 // It resets all the marking data structures.
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445 void clear_marking_state();
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446
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447 // It should be called to indicate which phase we're in (concurrent
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448 // mark or remark) and how many threads are currently active.
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449 void set_phase(size_t active_tasks, bool concurrent);
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450 // We do this after we're done with marking so that the marking data
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451 // structures are initialised to a sensible and predictable state.
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452 void set_non_marking_state();
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453
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454 // prints all gathered CM-related statistics
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455 void print_stats();
|
|
456
|
|
457 // accessor methods
|
|
458 size_t parallel_marking_threads() { return _parallel_marking_threads; }
|
|
459 double sleep_factor() { return _sleep_factor; }
|
|
460 double marking_task_overhead() { return _marking_task_overhead;}
|
|
461 double cleanup_sleep_factor() { return _cleanup_sleep_factor; }
|
|
462 double cleanup_task_overhead() { return _cleanup_task_overhead;}
|
|
463
|
|
464 HeapWord* finger() { return _finger; }
|
|
465 bool concurrent() { return _concurrent; }
|
|
466 size_t active_tasks() { return _active_tasks; }
|
|
467 ParallelTaskTerminator* terminator() { return &_terminator; }
|
|
468
|
|
469 // It claims the next available region to be scanned by a marking
|
|
470 // task. It might return NULL if the next region is empty or we have
|
|
471 // run out of regions. In the latter case, out_of_regions()
|
|
472 // determines whether we've really run out of regions or the task
|
|
473 // should call claim_region() again. This might seem a bit
|
|
474 // awkward. Originally, the code was written so that claim_region()
|
|
475 // either successfully returned with a non-empty region or there
|
|
476 // were no more regions to be claimed. The problem with this was
|
|
477 // that, in certain circumstances, it iterated over large chunks of
|
|
478 // the heap finding only empty regions and, while it was working, it
|
|
479 // was preventing the calling task to call its regular clock
|
|
480 // method. So, this way, each task will spend very little time in
|
|
481 // claim_region() and is allowed to call the regular clock method
|
|
482 // frequently.
|
|
483 HeapRegion* claim_region(int task);
|
|
484
|
|
485 // It determines whether we've run out of regions to scan.
|
|
486 bool out_of_regions() { return _finger == _heap_end; }
|
|
487
|
|
488 // Returns the task with the given id
|
|
489 CMTask* task(int id) {
|
|
490 guarantee( 0 <= id && id < (int) _active_tasks, "task id not within "
|
|
491 "active bounds" );
|
|
492 return _tasks[id];
|
|
493 }
|
|
494
|
|
495 // Returns the task queue with the given id
|
|
496 CMTaskQueue* task_queue(int id) {
|
|
497 guarantee( 0 <= id && id < (int) _active_tasks, "task queue id not within "
|
|
498 "active bounds" );
|
|
499 return (CMTaskQueue*) _task_queues->queue(id);
|
|
500 }
|
|
501
|
|
502 // Returns the task queue set
|
|
503 CMTaskQueueSet* task_queues() { return _task_queues; }
|
|
504
|
|
505 // Access / manipulation of the overflow flag which is set to
|
|
506 // indicate that the global stack or region stack has overflown
|
|
507 bool has_overflown() { return _has_overflown; }
|
|
508 void set_has_overflown() { _has_overflown = true; }
|
|
509 void clear_has_overflown() { _has_overflown = false; }
|
|
510
|
|
511 bool has_aborted() { return _has_aborted; }
|
|
512 bool restart_for_overflow() { return _restart_for_overflow; }
|
|
513
|
|
514 // Methods to enter the two overflow sync barriers
|
|
515 void enter_first_sync_barrier(int task_num);
|
|
516 void enter_second_sync_barrier(int task_num);
|
|
517
|
|
518 public:
|
|
519 // Manipulation of the global mark stack.
|
|
520 // Notice that the first mark_stack_push is CAS-based, whereas the
|
|
521 // two below are Mutex-based. This is OK since the first one is only
|
|
522 // called during evacuation pauses and doesn't compete with the
|
|
523 // other two (which are called by the marking tasks during
|
|
524 // concurrent marking or remark).
|
|
525 bool mark_stack_push(oop p) {
|
|
526 _markStack.par_push(p);
|
|
527 if (_markStack.overflow()) {
|
|
528 set_has_overflown();
|
|
529 return false;
|
|
530 }
|
|
531 return true;
|
|
532 }
|
|
533 bool mark_stack_push(oop* arr, int n) {
|
|
534 _markStack.par_push_arr(arr, n);
|
|
535 if (_markStack.overflow()) {
|
|
536 set_has_overflown();
|
|
537 return false;
|
|
538 }
|
|
539 return true;
|
|
540 }
|
|
541 void mark_stack_pop(oop* arr, int max, int* n) {
|
|
542 _markStack.par_pop_arr(arr, max, n);
|
|
543 }
|
|
544 size_t mark_stack_size() { return _markStack.size(); }
|
|
545 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
|
|
546 bool mark_stack_overflow() { return _markStack.overflow(); }
|
|
547 bool mark_stack_empty() { return _markStack.isEmpty(); }
|
|
548
|
|
549 // Manipulation of the region stack
|
|
550 bool region_stack_push(MemRegion mr) {
|
|
551 _regionStack.push(mr);
|
|
552 if (_regionStack.overflow()) {
|
|
553 set_has_overflown();
|
|
554 return false;
|
|
555 }
|
|
556 return true;
|
|
557 }
|
|
558 MemRegion region_stack_pop() { return _regionStack.pop(); }
|
|
559 int region_stack_size() { return _regionStack.size(); }
|
|
560 bool region_stack_overflow() { return _regionStack.overflow(); }
|
|
561 bool region_stack_empty() { return _regionStack.isEmpty(); }
|
|
562
|
|
563 bool concurrent_marking_in_progress() {
|
|
564 return _concurrent_marking_in_progress;
|
|
565 }
|
|
566 void set_concurrent_marking_in_progress() {
|
|
567 _concurrent_marking_in_progress = true;
|
|
568 }
|
|
569 void clear_concurrent_marking_in_progress() {
|
|
570 _concurrent_marking_in_progress = false;
|
|
571 }
|
|
572
|
|
573 void update_accum_task_vtime(int i, double vtime) {
|
|
574 _accum_task_vtime[i] += vtime;
|
|
575 }
|
|
576
|
|
577 double all_task_accum_vtime() {
|
|
578 double ret = 0.0;
|
|
579 for (int i = 0; i < (int)_max_task_num; ++i)
|
|
580 ret += _accum_task_vtime[i];
|
|
581 return ret;
|
|
582 }
|
|
583
|
|
584 // Attempts to steal an object from the task queues of other tasks
|
|
585 bool try_stealing(int task_num, int* hash_seed, oop& obj) {
|
|
586 return _task_queues->steal(task_num, hash_seed, obj);
|
|
587 }
|
|
588
|
|
589 // It grays an object by first marking it. Then, if it's behind the
|
|
590 // global finger, it also pushes it on the global stack.
|
|
591 void deal_with_reference(oop obj);
|
|
592
|
|
593 ConcurrentMark(ReservedSpace rs, int max_regions);
|
|
594 ~ConcurrentMark();
|
|
595 ConcurrentMarkThread* cmThread() { return _cmThread; }
|
|
596
|
|
597 CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
|
|
598 CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
|
|
599
|
|
600 // The following three are interaction between CM and
|
|
601 // G1CollectedHeap
|
|
602
|
|
603 // This notifies CM that a root during initial-mark needs to be
|
|
604 // grayed and it's MT-safe. Currently, we just mark it. But, in the
|
|
605 // future, we can experiment with pushing it on the stack and we can
|
|
606 // do this without changing G1CollectedHeap.
|
|
607 void grayRoot(oop p);
|
|
608 // It's used during evacuation pauses to gray a region, if
|
|
609 // necessary, and it's MT-safe. It assumes that the caller has
|
|
610 // marked any objects on that region. If _should_gray_objects is
|
|
611 // true and we're still doing concurrent marking, the region is
|
|
612 // pushed on the region stack, if it is located below the global
|
|
613 // finger, otherwise we do nothing.
|
|
614 void grayRegionIfNecessary(MemRegion mr);
|
|
615 // It's used during evacuation pauses to mark and, if necessary,
|
|
616 // gray a single object and it's MT-safe. It assumes the caller did
|
|
617 // not mark the object. If _should_gray_objects is true and we're
|
|
618 // still doing concurrent marking, the objects is pushed on the
|
|
619 // global stack, if it is located below the global finger, otherwise
|
|
620 // we do nothing.
|
|
621 void markAndGrayObjectIfNecessary(oop p);
|
|
622
|
|
623 // This iterates over the bitmap of the previous marking and prints
|
|
624 // out all objects that are marked on the bitmap and indicates
|
|
625 // whether what they point to is also marked or not.
|
|
626 void print_prev_bitmap_reachable();
|
|
627
|
|
628 // Clear the next marking bitmap (will be called concurrently).
|
|
629 void clearNextBitmap();
|
|
630
|
|
631 // main CMS steps and related support
|
|
632 void checkpointRootsInitial();
|
|
633
|
|
634 // These two do the work that needs to be done before and after the
|
|
635 // initial root checkpoint. Since this checkpoint can be done at two
|
|
636 // different points (i.e. an explicit pause or piggy-backed on a
|
|
637 // young collection), then it's nice to be able to easily share the
|
|
638 // pre/post code. It might be the case that we can put everything in
|
|
639 // the post method. TP
|
|
640 void checkpointRootsInitialPre();
|
|
641 void checkpointRootsInitialPost();
|
|
642
|
|
643 // Do concurrent phase of marking, to a tentative transitive closure.
|
|
644 void markFromRoots();
|
|
645
|
|
646 // Process all unprocessed SATB buffers. It is called at the
|
|
647 // beginning of an evacuation pause.
|
|
648 void drainAllSATBBuffers();
|
|
649
|
|
650 void checkpointRootsFinal(bool clear_all_soft_refs);
|
|
651 void checkpointRootsFinalWork();
|
|
652 void calcDesiredRegions();
|
|
653 void cleanup();
|
|
654 void completeCleanup();
|
|
655
|
|
656 // Mark in the previous bitmap. NB: this is usually read-only, so use
|
|
657 // this carefully!
|
|
658 void markPrev(oop p);
|
|
659 void clear(oop p);
|
|
660 // Clears marks for all objects in the given range, for both prev and
|
|
661 // next bitmaps. NB: the previous bitmap is usually read-only, so use
|
|
662 // this carefully!
|
|
663 void clearRangeBothMaps(MemRegion mr);
|
|
664
|
|
665 // Record the current top of the mark and region stacks; a
|
|
666 // subsequent oops_do() on the mark stack and
|
|
667 // invalidate_entries_into_cset() on the region stack will iterate
|
|
668 // only over indices valid at the time of this call.
|
|
669 void set_oops_do_bound() {
|
|
670 _markStack.set_oops_do_bound();
|
|
671 _regionStack.set_oops_do_bound();
|
|
672 }
|
|
673 // Iterate over the oops in the mark stack and all local queues. It
|
|
674 // also calls invalidate_entries_into_cset() on the region stack.
|
|
675 void oops_do(OopClosure* f);
|
|
676 // It is called at the end of an evacuation pause during marking so
|
|
677 // that CM is notified of where the new end of the heap is. It
|
|
678 // doesn't do anything if concurrent_marking_in_progress() is false,
|
|
679 // unless the force parameter is true.
|
|
680 void update_g1_committed(bool force = false);
|
|
681
|
|
682 void complete_marking_in_collection_set();
|
|
683
|
|
684 // It indicates that a new collection set is being chosen.
|
|
685 void newCSet();
|
|
686 // It registers a collection set heap region with CM. This is used
|
|
687 // to determine whether any heap regions are located above the finger.
|
|
688 void registerCSetRegion(HeapRegion* hr);
|
|
689
|
|
690 // Returns "true" if at least one mark has been completed.
|
|
691 bool at_least_one_mark_complete() { return _at_least_one_mark_complete; }
|
|
692
|
|
693 bool isMarked(oop p) const {
|
|
694 assert(p != NULL && p->is_oop(), "expected an oop");
|
|
695 HeapWord* addr = (HeapWord*)p;
|
|
696 assert(addr >= _nextMarkBitMap->startWord() ||
|
|
697 addr < _nextMarkBitMap->endWord(), "in a region");
|
|
698
|
|
699 return _nextMarkBitMap->isMarked(addr);
|
|
700 }
|
|
701
|
|
702 inline bool not_yet_marked(oop p) const;
|
|
703
|
|
704 // XXX Debug code
|
|
705 bool containing_card_is_marked(void* p);
|
|
706 bool containing_cards_are_marked(void* start, void* last);
|
|
707
|
|
708 bool isPrevMarked(oop p) const {
|
|
709 assert(p != NULL && p->is_oop(), "expected an oop");
|
|
710 HeapWord* addr = (HeapWord*)p;
|
|
711 assert(addr >= _prevMarkBitMap->startWord() ||
|
|
712 addr < _prevMarkBitMap->endWord(), "in a region");
|
|
713
|
|
714 return _prevMarkBitMap->isMarked(addr);
|
|
715 }
|
|
716
|
|
717 inline bool do_yield_check(int worker_i = 0);
|
|
718 inline bool should_yield();
|
|
719
|
|
720 // Called to abort the marking cycle after a Full GC takes palce.
|
|
721 void abort();
|
|
722
|
|
723 void disable_co_trackers();
|
|
724
|
|
725 // This prints the global/local fingers. It is used for debugging.
|
|
726 NOT_PRODUCT(void print_finger();)
|
|
727
|
|
728 void print_summary_info();
|
|
729
|
|
730 // The following indicate whether a given verbose level has been
|
|
731 // set. Notice that anything above stats is conditional to
|
|
732 // _MARKING_VERBOSE_ having been set to 1
|
|
733 bool verbose_stats()
|
|
734 { return _verbose_level >= stats_verbose; }
|
|
735 bool verbose_low()
|
|
736 { return _MARKING_VERBOSE_ && _verbose_level >= low_verbose; }
|
|
737 bool verbose_medium()
|
|
738 { return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose; }
|
|
739 bool verbose_high()
|
|
740 { return _MARKING_VERBOSE_ && _verbose_level >= high_verbose; }
|
|
741 };
|
|
742
|
|
743 // A class representing a marking task.
|
|
744 class CMTask : public TerminatorTerminator {
|
|
745 private:
|
|
746 enum PrivateConstants {
|
|
747 // the regular clock call is called once the scanned words reaches
|
|
748 // this limit
|
|
749 words_scanned_period = 12*1024,
|
|
750 // the regular clock call is called once the number of visited
|
|
751 // references reaches this limit
|
|
752 refs_reached_period = 384,
|
|
753 // initial value for the hash seed, used in the work stealing code
|
|
754 init_hash_seed = 17,
|
|
755 // how many entries will be transferred between global stack and
|
|
756 // local queues
|
|
757 global_stack_transfer_size = 16
|
|
758 };
|
|
759
|
|
760 int _task_id;
|
|
761 G1CollectedHeap* _g1h;
|
|
762 ConcurrentMark* _cm;
|
|
763 CMBitMap* _nextMarkBitMap;
|
|
764 // the task queue of this task
|
|
765 CMTaskQueue* _task_queue;
|
|
766 // the task queue set---needed for stealing
|
|
767 CMTaskQueueSet* _task_queues;
|
|
768 // indicates whether the task has been claimed---this is only for
|
|
769 // debugging purposes
|
|
770 bool _claimed;
|
|
771
|
|
772 // number of calls to this task
|
|
773 int _calls;
|
|
774
|
|
775 // concurrent overhead over a single CPU for this task
|
|
776 COTracker _co_tracker;
|
|
777
|
|
778 // when the virtual timer reaches this time, the marking step should
|
|
779 // exit
|
|
780 double _time_target_ms;
|
|
781 // the start time of the current marking step
|
|
782 double _start_time_ms;
|
|
783
|
|
784 // the oop closure used for iterations over oops
|
|
785 OopClosure* _oop_closure;
|
|
786
|
|
787 // the region this task is scanning, NULL if we're not scanning any
|
|
788 HeapRegion* _curr_region;
|
|
789 // the local finger of this task, NULL if we're not scanning a region
|
|
790 HeapWord* _finger;
|
|
791 // limit of the region this task is scanning, NULL if we're not scanning one
|
|
792 HeapWord* _region_limit;
|
|
793
|
|
794 // This is used only when we scan regions popped from the region
|
|
795 // stack. It records what the last object on such a region we
|
|
796 // scanned was. It is used to ensure that, if we abort region
|
|
797 // iteration, we do not rescan the first part of the region. This
|
|
798 // should be NULL when we're not scanning a region from the region
|
|
799 // stack.
|
|
800 HeapWord* _region_finger;
|
|
801
|
|
802 // the number of words this task has scanned
|
|
803 size_t _words_scanned;
|
|
804 // When _words_scanned reaches this limit, the regular clock is
|
|
805 // called. Notice that this might be decreased under certain
|
|
806 // circumstances (i.e. when we believe that we did an expensive
|
|
807 // operation).
|
|
808 size_t _words_scanned_limit;
|
|
809 // the initial value of _words_scanned_limit (i.e. what it was
|
|
810 // before it was decreased).
|
|
811 size_t _real_words_scanned_limit;
|
|
812
|
|
813 // the number of references this task has visited
|
|
814 size_t _refs_reached;
|
|
815 // When _refs_reached reaches this limit, the regular clock is
|
|
816 // called. Notice this this might be decreased under certain
|
|
817 // circumstances (i.e. when we believe that we did an expensive
|
|
818 // operation).
|
|
819 size_t _refs_reached_limit;
|
|
820 // the initial value of _refs_reached_limit (i.e. what it was before
|
|
821 // it was decreased).
|
|
822 size_t _real_refs_reached_limit;
|
|
823
|
|
824 // used by the work stealing stuff
|
|
825 int _hash_seed;
|
|
826 // if this is true, then the task has aborted for some reason
|
|
827 bool _has_aborted;
|
|
828 // set when the task aborts because it has met its time quota
|
|
829 bool _has_aborted_timed_out;
|
|
830 // true when we're draining SATB buffers; this avoids the task
|
|
831 // aborting due to SATB buffers being available (as we're already
|
|
832 // dealing with them)
|
|
833 bool _draining_satb_buffers;
|
|
834
|
|
835 // number sequence of past step times
|
|
836 NumberSeq _step_times_ms;
|
|
837 // elapsed time of this task
|
|
838 double _elapsed_time_ms;
|
|
839 // termination time of this task
|
|
840 double _termination_time_ms;
|
|
841 // when this task got into the termination protocol
|
|
842 double _termination_start_time_ms;
|
|
843
|
|
844 // true when the task is during a concurrent phase, false when it is
|
|
845 // in the remark phase (so, in the latter case, we do not have to
|
|
846 // check all the things that we have to check during the concurrent
|
|
847 // phase, i.e. SATB buffer availability...)
|
|
848 bool _concurrent;
|
|
849
|
|
850 TruncatedSeq _marking_step_diffs_ms;
|
|
851
|
|
852 // LOTS of statistics related with this task
|
|
853 #if _MARKING_STATS_
|
|
854 NumberSeq _all_clock_intervals_ms;
|
|
855 double _interval_start_time_ms;
|
|
856
|
|
857 int _aborted;
|
|
858 int _aborted_overflow;
|
|
859 int _aborted_cm_aborted;
|
|
860 int _aborted_yield;
|
|
861 int _aborted_timed_out;
|
|
862 int _aborted_satb;
|
|
863 int _aborted_termination;
|
|
864
|
|
865 int _steal_attempts;
|
|
866 int _steals;
|
|
867
|
|
868 int _clock_due_to_marking;
|
|
869 int _clock_due_to_scanning;
|
|
870
|
|
871 int _local_pushes;
|
|
872 int _local_pops;
|
|
873 int _local_max_size;
|
|
874 int _objs_scanned;
|
|
875
|
|
876 int _global_pushes;
|
|
877 int _global_pops;
|
|
878 int _global_max_size;
|
|
879
|
|
880 int _global_transfers_to;
|
|
881 int _global_transfers_from;
|
|
882
|
|
883 int _region_stack_pops;
|
|
884
|
|
885 int _regions_claimed;
|
|
886 int _objs_found_on_bitmap;
|
|
887
|
|
888 int _satb_buffers_processed;
|
|
889 #endif // _MARKING_STATS_
|
|
890
|
|
891 // it updates the local fields after this task has claimed
|
|
892 // a new region to scan
|
|
893 void setup_for_region(HeapRegion* hr);
|
|
894 // it brings up-to-date the limit of the region
|
|
895 void update_region_limit();
|
|
896 // it resets the local fields after a task has finished scanning a
|
|
897 // region
|
|
898 void giveup_current_region();
|
|
899
|
|
900 // called when either the words scanned or the refs visited limit
|
|
901 // has been reached
|
|
902 void reached_limit();
|
|
903 // recalculates the words scanned and refs visited limits
|
|
904 void recalculate_limits();
|
|
905 // decreases the words scanned and refs visited limits when we reach
|
|
906 // an expensive operation
|
|
907 void decrease_limits();
|
|
908 // it checks whether the words scanned or refs visited reached their
|
|
909 // respective limit and calls reached_limit() if they have
|
|
910 void check_limits() {
|
|
911 if (_words_scanned >= _words_scanned_limit ||
|
|
912 _refs_reached >= _refs_reached_limit)
|
|
913 reached_limit();
|
|
914 }
|
|
915 // this is supposed to be called regularly during a marking step as
|
|
916 // it checks a bunch of conditions that might cause the marking step
|
|
917 // to abort
|
|
918 void regular_clock_call();
|
|
919 bool concurrent() { return _concurrent; }
|
|
920
|
|
921 public:
|
|
922 // It resets the task; it should be called right at the beginning of
|
|
923 // a marking phase.
|
|
924 void reset(CMBitMap* _nextMarkBitMap);
|
|
925 // it clears all the fields that correspond to a claimed region.
|
|
926 void clear_region_fields();
|
|
927
|
|
928 void set_concurrent(bool concurrent) { _concurrent = concurrent; }
|
|
929
|
|
930 void enable_co_tracker() {
|
|
931 guarantee( !_co_tracker.enabled(), "invariant" );
|
|
932 _co_tracker.enable();
|
|
933 }
|
|
934 void disable_co_tracker() {
|
|
935 guarantee( _co_tracker.enabled(), "invariant" );
|
|
936 _co_tracker.disable();
|
|
937 }
|
|
938 bool co_tracker_enabled() {
|
|
939 return _co_tracker.enabled();
|
|
940 }
|
|
941 void reset_co_tracker(double starting_conc_overhead = 0.0) {
|
|
942 _co_tracker.reset(starting_conc_overhead);
|
|
943 }
|
|
944 void start_co_tracker() {
|
|
945 _co_tracker.start();
|
|
946 }
|
|
947 void update_co_tracker(bool force_end = false) {
|
|
948 _co_tracker.update(force_end);
|
|
949 }
|
|
950
|
|
951 // The main method of this class which performs a marking step
|
|
952 // trying not to exceed the given duration. However, it might exit
|
|
953 // prematurely, according to some conditions (i.e. SATB buffers are
|
|
954 // available for processing).
|
|
955 void do_marking_step(double target_ms);
|
|
956
|
|
957 // These two calls start and stop the timer
|
|
958 void record_start_time() {
|
|
959 _elapsed_time_ms = os::elapsedTime() * 1000.0;
|
|
960 }
|
|
961 void record_end_time() {
|
|
962 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
|
|
963 }
|
|
964
|
|
965 // returns the task ID
|
|
966 int task_id() { return _task_id; }
|
|
967
|
|
968 // From TerminatorTerminator. It determines whether this task should
|
|
969 // exit the termination protocol after it's entered it.
|
|
970 virtual bool should_exit_termination();
|
|
971
|
|
972 HeapWord* finger() { return _finger; }
|
|
973
|
|
974 bool has_aborted() { return _has_aborted; }
|
|
975 void set_has_aborted() { _has_aborted = true; }
|
|
976 void clear_has_aborted() { _has_aborted = false; }
|
|
977 bool claimed() { return _claimed; }
|
|
978
|
|
979 void set_oop_closure(OopClosure* oop_closure) {
|
|
980 _oop_closure = oop_closure;
|
|
981 }
|
|
982
|
|
983 // It grays the object by marking it and, if necessary, pushing it
|
|
984 // on the local queue
|
|
985 void deal_with_reference(oop obj);
|
|
986
|
|
987 // It scans an object and visits its children.
|
|
988 void scan_object(oop obj) {
|
|
989 tmp_guarantee_CM( _nextMarkBitMap->isMarked((HeapWord*) obj),
|
|
990 "invariant" );
|
|
991
|
|
992 if (_cm->verbose_high())
|
|
993 gclog_or_tty->print_cr("[%d] we're scanning object "PTR_FORMAT,
|
|
994 _task_id, (void*) obj);
|
|
995
|
|
996 size_t obj_size = obj->size();
|
|
997 _words_scanned += obj_size;
|
|
998
|
|
999 obj->oop_iterate(_oop_closure);
|
|
1000 statsOnly( ++_objs_scanned );
|
|
1001 check_limits();
|
|
1002 }
|
|
1003
|
|
1004 // It pushes an object on the local queue.
|
|
1005 void push(oop obj);
|
|
1006
|
|
1007 // These two move entries to/from the global stack.
|
|
1008 void move_entries_to_global_stack();
|
|
1009 void get_entries_from_global_stack();
|
|
1010
|
|
1011 // It pops and scans objects from the local queue. If partially is
|
|
1012 // true, then it stops when the queue size is of a given limit. If
|
|
1013 // partially is false, then it stops when the queue is empty.
|
|
1014 void drain_local_queue(bool partially);
|
|
1015 // It moves entries from the global stack to the local queue and
|
|
1016 // drains the local queue. If partially is true, then it stops when
|
|
1017 // both the global stack and the local queue reach a given size. If
|
|
1018 // partially if false, it tries to empty them totally.
|
|
1019 void drain_global_stack(bool partially);
|
|
1020 // It keeps picking SATB buffers and processing them until no SATB
|
|
1021 // buffers are available.
|
|
1022 void drain_satb_buffers();
|
|
1023 // It keeps popping regions from the region stack and processing
|
|
1024 // them until the region stack is empty.
|
|
1025 void drain_region_stack(BitMapClosure* closure);
|
|
1026
|
|
1027 // moves the local finger to a new location
|
|
1028 inline void move_finger_to(HeapWord* new_finger) {
|
|
1029 tmp_guarantee_CM( new_finger >= _finger && new_finger < _region_limit,
|
|
1030 "invariant" );
|
|
1031 _finger = new_finger;
|
|
1032 }
|
|
1033
|
|
1034 // moves the region finger to a new location
|
|
1035 inline void move_region_finger_to(HeapWord* new_finger) {
|
|
1036 tmp_guarantee_CM( new_finger < _cm->finger(), "invariant" );
|
|
1037 _region_finger = new_finger;
|
|
1038 }
|
|
1039
|
|
1040 CMTask(int task_num, ConcurrentMark *cm,
|
|
1041 CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
|
|
1042
|
|
1043 // it prints statistics associated with this task
|
|
1044 void print_stats();
|
|
1045
|
|
1046 #if _MARKING_STATS_
|
|
1047 void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
|
|
1048 #endif // _MARKING_STATS_
|
|
1049 };
|