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1 /* |
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2 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved. |
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3 * |
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4 * This code is free software; you can redistribute it and/or modify it |
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5 * under the terms of the GNU General Public License version 2 only, as |
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6 * published by the Free Software Foundation. |
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7 * |
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8 * This code is distributed in the hope that it will be useful, but WITHOUT |
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9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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11 * version 2 for more details (a copy is included in the LICENSE file that |
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12 * accompanied this code). |
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13 * |
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14 * You should have received a copy of the GNU General Public License version |
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15 * 2 along with this work; if not, write to the Free Software Foundation, |
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16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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17 * |
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18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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19 * or visit www.oracle.com if you need additional information or have any |
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20 * questions. |
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21 * |
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22 */ |
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23 |
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24 #include "precompiled.hpp" |
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25 |
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26 #include "gc/shared/stringdedup/stringDedup.hpp" |
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27 #include "gc/shared/stringdedup/stringDedup.inline.hpp" |
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28 #include "gc/shared/workgroup.hpp" |
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29 #include "gc/shenandoah/shenandoahCollectionSet.hpp" |
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30 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp" |
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31 #include "gc/shenandoah/shenandoahHeap.hpp" |
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32 #include "gc/shenandoah/shenandoahHeap.inline.hpp" |
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33 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" |
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34 #include "gc/shenandoah/shenandoahStringDedup.hpp" |
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35 #include "gc/shenandoah/shenandoahStrDedupQueue.hpp" |
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36 #include "gc/shenandoah/shenandoahTimingTracker.hpp" |
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37 #include "gc/shenandoah/shenandoahUtils.hpp" |
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38 #include "runtime/thread.hpp" |
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39 |
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40 void ShenandoahStringDedup::initialize() { |
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41 assert(UseShenandoahGC, "String deduplication available with Shenandoah GC"); |
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42 StringDedup::initialize_impl<ShenandoahStrDedupQueue, StringDedupStat>(); |
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43 } |
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44 |
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45 /* Enqueue candidates for deduplication. |
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46 * The method should only be called by GC worker threads during marking phases. |
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47 */ |
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48 void ShenandoahStringDedup::enqueue_candidate(oop java_string) { |
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49 assert(Thread::current()->is_Worker_thread(), |
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50 "Only from a GC worker thread"); |
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51 |
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52 if (java_string->age() <= StringDeduplicationAgeThreshold) { |
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53 const markOop mark = java_string->mark(); |
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54 |
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55 // Having/had displaced header, too risk to deal with them, skip |
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56 if (mark == markOopDesc::INFLATING() || mark->has_displaced_mark_helper()) { |
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57 return; |
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58 } |
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59 |
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60 // Increase string age and enqueue it when it rearches age threshold |
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61 markOop new_mark = mark->incr_age(); |
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62 if (mark == java_string->cas_set_mark(new_mark, mark)) { |
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63 if (mark->age() == StringDeduplicationAgeThreshold) { |
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64 StringDedupQueue::push(ShenandoahWorkerSession::worker_id(), java_string); |
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65 } |
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66 } |
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67 } |
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68 } |
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69 |
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70 // Deduplicate a string, return true if it is deduplicated. |
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71 void ShenandoahStringDedup::deduplicate(oop java_string) { |
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72 assert(is_enabled(), "String deduplication not enabled"); |
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73 StringDedupStat dummy; // Statistics from this path is never used |
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74 StringDedupTable::deduplicate(java_string, &dummy); |
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75 } |
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76 |
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77 void ShenandoahStringDedup::parallel_oops_do(OopClosure* cl, uint worker_id) { |
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78 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); |
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79 assert(is_enabled(), "String deduplication not enabled"); |
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80 |
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81 ShenandoahWorkerTimings* worker_times = ShenandoahHeap::heap()->phase_timings()->worker_times(); |
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82 |
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83 StringDedupUnlinkOrOopsDoClosure sd_cl(NULL, cl); |
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84 |
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85 { |
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86 ShenandoahWorkerTimingsTracker x(worker_times, ShenandoahPhaseTimings::StringDedupQueueRoots, worker_id); |
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87 StringDedupQueue::unlink_or_oops_do(&sd_cl); |
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88 } |
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89 { |
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90 ShenandoahWorkerTimingsTracker x(worker_times, ShenandoahPhaseTimings::StringDedupTableRoots, worker_id); |
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91 StringDedupTable::unlink_or_oops_do(&sd_cl, worker_id); |
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92 } |
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93 } |
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94 |
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95 void ShenandoahStringDedup::oops_do_slow(OopClosure* cl) { |
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96 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); |
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97 assert(is_enabled(), "String deduplication not enabled"); |
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98 ShenandoahAlwaysTrueClosure always_true; |
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99 StringDedupUnlinkOrOopsDoClosure sd_cl(&always_true, cl); |
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100 StringDedupQueue::unlink_or_oops_do(&sd_cl); |
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101 StringDedupTable::unlink_or_oops_do(&sd_cl, 0); |
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102 } |
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103 |
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104 class ShenandoahIsMarkedNextClosure : public BoolObjectClosure { |
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105 private: |
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106 ShenandoahMarkingContext* const _mark_context; |
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107 |
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108 public: |
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109 ShenandoahIsMarkedNextClosure() : _mark_context(ShenandoahHeap::heap()->marking_context()) { } |
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110 |
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111 bool do_object_b(oop obj) { |
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112 return _mark_context->is_marked(obj); |
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113 } |
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114 }; |
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115 |
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116 void ShenandoahStringDedup::parallel_cleanup() { |
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117 assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint"); |
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118 log_debug(gc, stringdedup)("String dedup cleanup"); |
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119 ShenandoahIsMarkedNextClosure cl; |
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120 |
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121 unlink_or_oops_do(&cl, NULL, true); |
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122 } |
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123 |
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124 // |
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125 // Task for parallel unlink_or_oops_do() operation on the deduplication queue |
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126 // and table. |
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127 // |
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128 class ShenandoahStringDedupUnlinkOrOopsDoTask : public AbstractGangTask { |
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129 private: |
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130 StringDedupUnlinkOrOopsDoClosure _cl; |
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131 |
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132 public: |
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133 ShenandoahStringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive, |
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134 OopClosure* keep_alive, |
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135 bool allow_resize_and_rehash) : |
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136 AbstractGangTask("StringDedupUnlinkOrOopsDoTask"), |
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137 _cl(is_alive, keep_alive) { |
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138 StringDedup::gc_prologue(allow_resize_and_rehash); |
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139 } |
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140 |
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141 ~ShenandoahStringDedupUnlinkOrOopsDoTask() { |
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142 StringDedup::gc_epilogue(); |
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143 } |
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144 |
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145 virtual void work(uint worker_id) { |
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146 StringDedupQueue::unlink_or_oops_do(&_cl); |
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147 StringDedupTable::unlink_or_oops_do(&_cl, worker_id); |
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148 } |
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149 }; |
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150 |
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151 void ShenandoahStringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, |
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152 OopClosure* keep_alive, |
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153 bool allow_resize_and_rehash) { |
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154 assert(is_enabled(), "String deduplication not enabled"); |
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155 |
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156 ShenandoahStringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash); |
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157 ShenandoahHeap* heap = ShenandoahHeap::heap(); |
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158 heap->workers()->run_task(&task); |
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159 } |