Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/parNew/parNewGeneration.cpp @ 1665:a93a9eda13f7
6962947: shared TaskQueue statistics
Reviewed-by: tonyp, ysr
| author | jcoomes |
|---|---|
| date | Fri, 16 Jul 2010 21:33:21 -0700 |
| parents | c18cbe5936b8 |
| children | 94251661de76 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 25 # include "incls/_precompiled.incl" | |
| 26 # include "incls/_parNewGeneration.cpp.incl" | |
| 27 | |
| 28 #ifdef _MSC_VER | |
| 29 #pragma warning( push ) | |
| 30 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
| 31 #endif | |
| 32 ParScanThreadState::ParScanThreadState(Space* to_space_, | |
| 33 ParNewGeneration* gen_, | |
| 34 Generation* old_gen_, | |
| 35 int thread_num_, | |
| 36 ObjToScanQueueSet* work_queue_set_, | |
| 695 | 37 GrowableArray<oop>** overflow_stack_set_, |
| 0 | 38 size_t desired_plab_sz_, |
| 39 ParallelTaskTerminator& term_) : | |
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40 _to_space(to_space_), _old_gen(old_gen_), _young_gen(gen_), _thread_num(thread_num_), |
| 0 | 41 _work_queue(work_queue_set_->queue(thread_num_)), _to_space_full(false), |
| 695 | 42 _overflow_stack(overflow_stack_set_[thread_num_]), |
| 0 | 43 _ageTable(false), // false ==> not the global age table, no perf data. |
| 44 _to_space_alloc_buffer(desired_plab_sz_), | |
| 45 _to_space_closure(gen_, this), _old_gen_closure(gen_, this), | |
| 46 _to_space_root_closure(gen_, this), _old_gen_root_closure(gen_, this), | |
| 47 _older_gen_closure(gen_, this), | |
| 48 _evacuate_followers(this, &_to_space_closure, &_old_gen_closure, | |
| 49 &_to_space_root_closure, gen_, &_old_gen_root_closure, | |
| 50 work_queue_set_, &term_), | |
| 51 _is_alive_closure(gen_), _scan_weak_ref_closure(gen_, this), | |
| 52 _keep_alive_closure(&_scan_weak_ref_closure), | |
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53 _promotion_failure_size(0), |
| 0 | 54 _pushes(0), _pops(0), _steals(0), _steal_attempts(0), _term_attempts(0), |
| 55 _strong_roots_time(0.0), _term_time(0.0) | |
| 56 { | |
| 57 _survivor_chunk_array = | |
| 58 (ChunkArray*) old_gen()->get_data_recorder(thread_num()); | |
| 59 _hash_seed = 17; // Might want to take time-based random value. | |
| 60 _start = os::elapsedTime(); | |
| 61 _old_gen_closure.set_generation(old_gen_); | |
| 62 _old_gen_root_closure.set_generation(old_gen_); | |
| 63 } | |
| 64 #ifdef _MSC_VER | |
| 65 #pragma warning( pop ) | |
| 66 #endif | |
| 67 | |
| 68 void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, | |
| 69 size_t plab_word_size) { | |
| 70 ChunkArray* sca = survivor_chunk_array(); | |
| 71 if (sca != NULL) { | |
| 72 // A non-null SCA implies that we want the PLAB data recorded. | |
| 73 sca->record_sample(plab_start, plab_word_size); | |
| 74 } | |
| 75 } | |
| 76 | |
| 77 bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { | |
| 78 return new_obj->is_objArray() && | |
| 79 arrayOop(new_obj)->length() > ParGCArrayScanChunk && | |
| 80 new_obj != old_obj; | |
| 81 } | |
| 82 | |
| 83 void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { | |
| 84 assert(old->is_objArray(), "must be obj array"); | |
| 85 assert(old->is_forwarded(), "must be forwarded"); | |
| 86 assert(Universe::heap()->is_in_reserved(old), "must be in heap."); | |
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87 assert(!old_gen()->is_in(old), "must be in young generation."); |
| 0 | 88 |
| 89 objArrayOop obj = objArrayOop(old->forwardee()); | |
| 90 // Process ParGCArrayScanChunk elements now | |
| 91 // and push the remainder back onto queue | |
| 92 int start = arrayOop(old)->length(); | |
| 93 int end = obj->length(); | |
| 94 int remainder = end - start; | |
| 95 assert(start <= end, "just checking"); | |
| 96 if (remainder > 2 * ParGCArrayScanChunk) { | |
| 97 // Test above combines last partial chunk with a full chunk | |
| 98 end = start + ParGCArrayScanChunk; | |
| 99 arrayOop(old)->set_length(end); | |
| 100 // Push remainder. | |
| 101 bool ok = work_queue()->push(old); | |
| 102 assert(ok, "just popped, push must be okay"); | |
| 103 note_push(); | |
| 104 } else { | |
| 105 // Restore length so that it can be used if there | |
| 106 // is a promotion failure and forwarding pointers | |
| 107 // must be removed. | |
| 108 arrayOop(old)->set_length(end); | |
| 109 } | |
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110 |
| 0 | 111 // process our set of indices (include header in first chunk) |
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112 // should make sure end is even (aligned to HeapWord in case of compressed oops) |
| 0 | 113 if ((HeapWord *)obj < young_old_boundary()) { |
| 114 // object is in to_space | |
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115 obj->oop_iterate_range(&_to_space_closure, start, end); |
| 0 | 116 } else { |
| 117 // object is in old generation | |
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118 obj->oop_iterate_range(&_old_gen_closure, start, end); |
| 0 | 119 } |
| 120 } | |
| 121 | |
| 122 | |
| 123 void ParScanThreadState::trim_queues(int max_size) { | |
| 124 ObjToScanQueue* queue = work_queue(); | |
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125 do { |
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126 while (queue->size() > (juint)max_size) { |
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127 oop obj_to_scan; |
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128 if (queue->pop_local(obj_to_scan)) { |
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129 note_pop(); |
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130 if ((HeapWord *)obj_to_scan < young_old_boundary()) { |
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131 if (obj_to_scan->is_objArray() && |
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132 obj_to_scan->is_forwarded() && |
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133 obj_to_scan->forwardee() != obj_to_scan) { |
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134 scan_partial_array_and_push_remainder(obj_to_scan); |
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135 } else { |
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136 // object is in to_space |
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137 obj_to_scan->oop_iterate(&_to_space_closure); |
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138 } |
| 0 | 139 } else { |
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140 // object is in old generation |
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141 obj_to_scan->oop_iterate(&_old_gen_closure); |
| 0 | 142 } |
| 143 } | |
| 144 } | |
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145 // For the case of compressed oops, we have a private, non-shared |
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146 // overflow stack, so we eagerly drain it so as to more evenly |
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147 // distribute load early. Note: this may be good to do in |
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148 // general rather than delay for the final stealing phase. |
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149 // If applicable, we'll transfer a set of objects over to our |
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150 // work queue, allowing them to be stolen and draining our |
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151 // private overflow stack. |
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152 } while (ParGCTrimOverflow && young_gen()->take_from_overflow_list(this)); |
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153 } |
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154 |
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155 bool ParScanThreadState::take_from_overflow_stack() { |
| 695 | 156 assert(ParGCUseLocalOverflow, "Else should not call"); |
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157 assert(young_gen()->overflow_list() == NULL, "Error"); |
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158 ObjToScanQueue* queue = work_queue(); |
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159 GrowableArray<oop>* of_stack = overflow_stack(); |
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160 uint num_overflow_elems = of_stack->length(); |
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161 uint num_take_elems = MIN2(MIN2((queue->max_elems() - queue->size())/4, |
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162 (juint)ParGCDesiredObjsFromOverflowList), |
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163 num_overflow_elems); |
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164 // Transfer the most recent num_take_elems from the overflow |
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165 // stack to our work queue. |
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166 for (size_t i = 0; i != num_take_elems; i++) { |
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167 oop cur = of_stack->pop(); |
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168 oop obj_to_push = cur->forwardee(); |
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169 assert(Universe::heap()->is_in_reserved(cur), "Should be in heap"); |
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170 assert(!old_gen()->is_in_reserved(cur), "Should be in young gen"); |
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171 assert(Universe::heap()->is_in_reserved(obj_to_push), "Should be in heap"); |
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172 if (should_be_partially_scanned(obj_to_push, cur)) { |
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173 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
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174 obj_to_push = cur; |
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175 } |
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176 bool ok = queue->push(obj_to_push); |
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177 assert(ok, "Should have succeeded"); |
| 0 | 178 } |
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179 assert(young_gen()->overflow_list() == NULL, "Error"); |
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180 return num_take_elems > 0; // was something transferred? |
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181 } |
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182 |
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183 void ParScanThreadState::push_on_overflow_stack(oop p) { |
| 695 | 184 assert(ParGCUseLocalOverflow, "Else should not call"); |
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185 overflow_stack()->push(p); |
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186 assert(young_gen()->overflow_list() == NULL, "Error"); |
| 0 | 187 } |
| 188 | |
| 189 HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { | |
| 190 | |
| 191 // Otherwise, if the object is small enough, try to reallocate the | |
| 192 // buffer. | |
| 193 HeapWord* obj = NULL; | |
| 194 if (!_to_space_full) { | |
| 195 ParGCAllocBuffer* const plab = to_space_alloc_buffer(); | |
| 196 Space* const sp = to_space(); | |
| 197 if (word_sz * 100 < | |
| 198 ParallelGCBufferWastePct * plab->word_sz()) { | |
| 199 // Is small enough; abandon this buffer and start a new one. | |
| 200 plab->retire(false, false); | |
| 201 size_t buf_size = plab->word_sz(); | |
| 202 HeapWord* buf_space = sp->par_allocate(buf_size); | |
| 203 if (buf_space == NULL) { | |
| 204 const size_t min_bytes = | |
| 205 ParGCAllocBuffer::min_size() << LogHeapWordSize; | |
| 206 size_t free_bytes = sp->free(); | |
| 207 while(buf_space == NULL && free_bytes >= min_bytes) { | |
| 208 buf_size = free_bytes >> LogHeapWordSize; | |
| 209 assert(buf_size == (size_t)align_object_size(buf_size), | |
| 210 "Invariant"); | |
| 211 buf_space = sp->par_allocate(buf_size); | |
| 212 free_bytes = sp->free(); | |
| 213 } | |
| 214 } | |
| 215 if (buf_space != NULL) { | |
| 216 plab->set_word_size(buf_size); | |
| 217 plab->set_buf(buf_space); | |
| 218 record_survivor_plab(buf_space, buf_size); | |
| 219 obj = plab->allocate(word_sz); | |
| 220 // Note that we cannot compare buf_size < word_sz below | |
| 221 // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). | |
| 222 assert(obj != NULL || plab->words_remaining() < word_sz, | |
| 223 "Else should have been able to allocate"); | |
| 224 // It's conceivable that we may be able to use the | |
| 225 // buffer we just grabbed for subsequent small requests | |
| 226 // even if not for this one. | |
| 227 } else { | |
| 228 // We're used up. | |
| 229 _to_space_full = true; | |
| 230 } | |
| 231 | |
| 232 } else { | |
| 233 // Too large; allocate the object individually. | |
| 234 obj = sp->par_allocate(word_sz); | |
| 235 } | |
| 236 } | |
| 237 return obj; | |
| 238 } | |
| 239 | |
| 240 | |
| 241 void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, | |
| 242 size_t word_sz) { | |
| 243 // Is the alloc in the current alloc buffer? | |
| 244 if (to_space_alloc_buffer()->contains(obj)) { | |
| 245 assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), | |
| 246 "Should contain whole object."); | |
| 247 to_space_alloc_buffer()->undo_allocation(obj, word_sz); | |
| 248 } else { | |
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249 CollectedHeap::fill_with_object(obj, word_sz); |
| 0 | 250 } |
| 251 } | |
| 252 | |
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253 void ParScanThreadState::print_and_clear_promotion_failure_size() { |
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254 if (_promotion_failure_size != 0) { |
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255 if (PrintPromotionFailure) { |
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256 gclog_or_tty->print(" (%d: promotion failure size = " SIZE_FORMAT ") ", |
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257 _thread_num, _promotion_failure_size); |
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258 } |
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259 _promotion_failure_size = 0; |
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260 } |
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261 } |
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262 |
| 0 | 263 class ParScanThreadStateSet: private ResourceArray { |
| 264 public: | |
| 265 // Initializes states for the specified number of threads; | |
| 266 ParScanThreadStateSet(int num_threads, | |
| 267 Space& to_space, | |
| 268 ParNewGeneration& gen, | |
| 269 Generation& old_gen, | |
| 270 ObjToScanQueueSet& queue_set, | |
| 695 | 271 GrowableArray<oop>** overflow_stacks_, |
| 0 | 272 size_t desired_plab_sz, |
| 273 ParallelTaskTerminator& term); | |
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274 inline ParScanThreadState& thread_state(int i); |
| 0 | 275 int pushes() { return _pushes; } |
| 276 int pops() { return _pops; } | |
| 277 int steals() { return _steals; } | |
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278 void reset(bool promotion_failed); |
| 0 | 279 void flush(); |
| 280 private: | |
| 281 ParallelTaskTerminator& _term; | |
| 282 ParNewGeneration& _gen; | |
| 283 Generation& _next_gen; | |
| 284 // staticstics | |
| 285 int _pushes; | |
| 286 int _pops; | |
| 287 int _steals; | |
| 288 }; | |
| 289 | |
| 290 | |
| 291 ParScanThreadStateSet::ParScanThreadStateSet( | |
| 292 int num_threads, Space& to_space, ParNewGeneration& gen, | |
| 293 Generation& old_gen, ObjToScanQueueSet& queue_set, | |
| 695 | 294 GrowableArray<oop>** overflow_stack_set_, |
| 0 | 295 size_t desired_plab_sz, ParallelTaskTerminator& term) |
| 296 : ResourceArray(sizeof(ParScanThreadState), num_threads), | |
| 297 _gen(gen), _next_gen(old_gen), _term(term), | |
| 298 _pushes(0), _pops(0), _steals(0) | |
| 299 { | |
| 300 assert(num_threads > 0, "sanity check!"); | |
| 301 // Initialize states. | |
| 302 for (int i = 0; i < num_threads; ++i) { | |
| 303 new ((ParScanThreadState*)_data + i) | |
| 304 ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, | |
| 695 | 305 overflow_stack_set_, desired_plab_sz, term); |
| 0 | 306 } |
| 307 } | |
| 308 | |
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309 inline ParScanThreadState& ParScanThreadStateSet::thread_state(int i) |
| 0 | 310 { |
| 311 assert(i >= 0 && i < length(), "sanity check!"); | |
| 312 return ((ParScanThreadState*)_data)[i]; | |
| 313 } | |
| 314 | |
| 315 | |
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316 void ParScanThreadStateSet::reset(bool promotion_failed) |
| 0 | 317 { |
| 318 _term.reset_for_reuse(); | |
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319 if (promotion_failed) { |
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320 for (int i = 0; i < length(); ++i) { |
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321 thread_state(i).print_and_clear_promotion_failure_size(); |
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322 } |
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323 } |
| 0 | 324 } |
| 325 | |
| 326 void ParScanThreadStateSet::flush() | |
| 327 { | |
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328 // Work in this loop should be kept as lightweight as |
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329 // possible since this might otherwise become a bottleneck |
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330 // to scaling. Should we add heavy-weight work into this |
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331 // loop, consider parallelizing the loop into the worker threads. |
| 0 | 332 for (int i = 0; i < length(); ++i) { |
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333 ParScanThreadState& par_scan_state = thread_state(i); |
| 0 | 334 |
| 335 // Flush stats related to To-space PLAB activity and | |
| 336 // retire the last buffer. | |
| 337 par_scan_state.to_space_alloc_buffer()-> | |
| 338 flush_stats_and_retire(_gen.plab_stats(), | |
| 339 false /* !retain */); | |
| 340 | |
| 341 // Every thread has its own age table. We need to merge | |
| 342 // them all into one. | |
| 343 ageTable *local_table = par_scan_state.age_table(); | |
| 344 _gen.age_table()->merge(local_table); | |
| 345 | |
| 346 // Inform old gen that we're done. | |
| 347 _next_gen.par_promote_alloc_done(i); | |
| 348 _next_gen.par_oop_since_save_marks_iterate_done(i); | |
| 349 | |
| 350 // Flush stats related to work queue activity (push/pop/steal) | |
| 351 // This could conceivably become a bottleneck; if so, we'll put the | |
| 352 // stat's gathering under the flag. | |
| 353 if (PAR_STATS_ENABLED) { | |
| 354 _pushes += par_scan_state.pushes(); | |
| 355 _pops += par_scan_state.pops(); | |
| 356 _steals += par_scan_state.steals(); | |
| 357 if (ParallelGCVerbose) { | |
| 358 gclog_or_tty->print("Thread %d complete:\n" | |
| 359 " Pushes: %7d Pops: %7d Steals %7d (in %d attempts)\n", | |
| 360 i, par_scan_state.pushes(), par_scan_state.pops(), | |
| 361 par_scan_state.steals(), par_scan_state.steal_attempts()); | |
| 362 if (par_scan_state.overflow_pushes() > 0 || | |
| 363 par_scan_state.overflow_refills() > 0) { | |
| 364 gclog_or_tty->print(" Overflow pushes: %7d " | |
| 365 "Overflow refills: %7d for %d objs.\n", | |
| 366 par_scan_state.overflow_pushes(), | |
| 367 par_scan_state.overflow_refills(), | |
| 368 par_scan_state.overflow_refill_objs()); | |
| 369 } | |
| 370 | |
| 371 double elapsed = par_scan_state.elapsed(); | |
| 372 double strong_roots = par_scan_state.strong_roots_time(); | |
| 373 double term = par_scan_state.term_time(); | |
| 374 gclog_or_tty->print( | |
| 375 " Elapsed: %7.2f ms.\n" | |
| 376 " Strong roots: %7.2f ms (%6.2f%%)\n" | |
| 377 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n", | |
| 378 elapsed * 1000.0, | |
| 379 strong_roots * 1000.0, (strong_roots*100.0/elapsed), | |
| 380 term * 1000.0, (term*100.0/elapsed), | |
| 381 par_scan_state.term_attempts()); | |
| 382 } | |
| 383 } | |
| 384 } | |
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385 if (UseConcMarkSweepGC && ParallelGCThreads > 0) { |
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386 // We need to call this even when ResizeOldPLAB is disabled |
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387 // so as to avoid breaking some asserts. While we may be able |
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388 // to avoid this by reorganizing the code a bit, I am loathe |
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389 // to do that unless we find cases where ergo leads to bad |
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390 // performance. |
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391 CFLS_LAB::compute_desired_plab_size(); |
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392 } |
| 0 | 393 } |
| 394 | |
| 395 ParScanClosure::ParScanClosure(ParNewGeneration* g, | |
| 396 ParScanThreadState* par_scan_state) : | |
| 397 OopsInGenClosure(g), _par_scan_state(par_scan_state), _g(g) | |
| 398 { | |
| 399 assert(_g->level() == 0, "Optimized for youngest generation"); | |
| 400 _boundary = _g->reserved().end(); | |
| 401 } | |
| 402 | |
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403 void ParScanWithBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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404 void ParScanWithBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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405 |
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406 void ParScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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407 void ParScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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408 |
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409 void ParRootScanWithBarrierTwoGensClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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410 void ParRootScanWithBarrierTwoGensClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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411 |
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412 void ParRootScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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413 void ParRootScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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414 |
| 0 | 415 ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
| 416 ParScanThreadState* par_scan_state) | |
| 417 : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) | |
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418 {} |
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419 |
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420 void ParScanWeakRefClosure::do_oop(oop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
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421 void ParScanWeakRefClosure::do_oop(narrowOop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
| 0 | 422 |
| 423 #ifdef WIN32 | |
| 424 #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ | |
| 425 #endif | |
| 426 | |
| 427 ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( | |
| 428 ParScanThreadState* par_scan_state_, | |
| 429 ParScanWithoutBarrierClosure* to_space_closure_, | |
| 430 ParScanWithBarrierClosure* old_gen_closure_, | |
| 431 ParRootScanWithoutBarrierClosure* to_space_root_closure_, | |
| 432 ParNewGeneration* par_gen_, | |
| 433 ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, | |
| 434 ObjToScanQueueSet* task_queues_, | |
| 435 ParallelTaskTerminator* terminator_) : | |
| 436 | |
| 437 _par_scan_state(par_scan_state_), | |
| 438 _to_space_closure(to_space_closure_), | |
| 439 _old_gen_closure(old_gen_closure_), | |
| 440 _to_space_root_closure(to_space_root_closure_), | |
| 441 _old_gen_root_closure(old_gen_root_closure_), | |
| 442 _par_gen(par_gen_), | |
| 443 _task_queues(task_queues_), | |
| 444 _terminator(terminator_) | |
| 445 {} | |
| 446 | |
| 447 void ParEvacuateFollowersClosure::do_void() { | |
| 448 ObjToScanQueue* work_q = par_scan_state()->work_queue(); | |
| 449 | |
| 450 while (true) { | |
| 451 | |
| 452 // Scan to-space and old-gen objs until we run out of both. | |
| 453 oop obj_to_scan; | |
| 454 par_scan_state()->trim_queues(0); | |
| 455 | |
| 456 // We have no local work, attempt to steal from other threads. | |
| 457 | |
| 458 // attempt to steal work from promoted. | |
| 459 par_scan_state()->note_steal_attempt(); | |
| 460 if (task_queues()->steal(par_scan_state()->thread_num(), | |
| 461 par_scan_state()->hash_seed(), | |
| 462 obj_to_scan)) { | |
| 463 par_scan_state()->note_steal(); | |
| 464 bool res = work_q->push(obj_to_scan); | |
| 465 assert(res, "Empty queue should have room for a push."); | |
| 466 | |
| 467 par_scan_state()->note_push(); | |
| 468 // if successful, goto Start. | |
| 469 continue; | |
| 470 | |
| 471 // try global overflow list. | |
| 472 } else if (par_gen()->take_from_overflow_list(par_scan_state())) { | |
| 473 continue; | |
| 474 } | |
| 475 | |
| 476 // Otherwise, offer termination. | |
| 477 par_scan_state()->start_term_time(); | |
| 478 if (terminator()->offer_termination()) break; | |
| 479 par_scan_state()->end_term_time(); | |
| 480 } | |
| 534 | 481 assert(par_gen()->_overflow_list == NULL && par_gen()->_num_par_pushes == 0, |
| 482 "Broken overflow list?"); | |
| 0 | 483 // Finish the last termination pause. |
| 484 par_scan_state()->end_term_time(); | |
| 485 } | |
| 486 | |
| 487 ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, | |
| 488 HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : | |
| 489 AbstractGangTask("ParNewGeneration collection"), | |
| 490 _gen(gen), _next_gen(next_gen), | |
| 491 _young_old_boundary(young_old_boundary), | |
| 492 _state_set(state_set) | |
| 493 {} | |
| 494 | |
| 495 void ParNewGenTask::work(int i) { | |
| 496 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 497 // Since this is being done in a separate thread, need new resource | |
| 498 // and handle marks. | |
| 499 ResourceMark rm; | |
| 500 HandleMark hm; | |
| 501 // We would need multiple old-gen queues otherwise. | |
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502 assert(gch->n_gens() == 2, "Par young collection currently only works with one older gen."); |
| 0 | 503 |
| 504 Generation* old_gen = gch->next_gen(_gen); | |
| 505 | |
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506 ParScanThreadState& par_scan_state = _state_set->thread_state(i); |
| 0 | 507 par_scan_state.set_young_old_boundary(_young_old_boundary); |
| 508 | |
| 509 par_scan_state.start_strong_roots(); | |
| 510 gch->gen_process_strong_roots(_gen->level(), | |
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511 true, // Process younger gens, if any, |
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512 // as strong roots. |
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513 false, // no scope; this is parallel code |
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514 false, // not collecting perm generation. |
| 0 | 515 SharedHeap::SO_AllClasses, |
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516 &par_scan_state.to_space_root_closure(), |
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517 true, // walk *all* scavengable nmethods |
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518 &par_scan_state.older_gen_closure()); |
| 0 | 519 par_scan_state.end_strong_roots(); |
| 520 | |
| 521 // "evacuate followers". | |
| 522 par_scan_state.evacuate_followers_closure().do_void(); | |
| 523 } | |
| 524 | |
| 525 #ifdef _MSC_VER | |
| 526 #pragma warning( push ) | |
| 527 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
| 528 #endif | |
| 529 ParNewGeneration:: | |
| 530 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) | |
| 531 : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), | |
| 532 _overflow_list(NULL), | |
| 533 _is_alive_closure(this), | |
| 534 _plab_stats(YoungPLABSize, PLABWeight) | |
| 535 { | |
| 534 | 536 NOT_PRODUCT(_overflow_counter = ParGCWorkQueueOverflowInterval;) |
| 537 NOT_PRODUCT(_num_par_pushes = 0;) | |
| 0 | 538 _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
| 539 guarantee(_task_queues != NULL, "task_queues allocation failure."); | |
| 540 | |
| 541 for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { | |
| 1665 | 542 ObjToScanQueue *q = new ObjToScanQueue(); |
| 543 guarantee(q != NULL, "work_queue Allocation failure."); | |
| 544 _task_queues->register_queue(i1, q); | |
| 0 | 545 } |
| 546 | |
| 547 for (uint i2 = 0; i2 < ParallelGCThreads; i2++) | |
| 548 _task_queues->queue(i2)->initialize(); | |
| 549 | |
| 695 | 550 _overflow_stacks = NEW_C_HEAP_ARRAY(GrowableArray<oop>*, ParallelGCThreads); |
| 551 guarantee(_overflow_stacks != NULL, "Overflow stack set allocation failure"); | |
| 552 for (uint i = 0; i < ParallelGCThreads; i++) { | |
| 553 if (ParGCUseLocalOverflow) { | |
| 554 _overflow_stacks[i] = new (ResourceObj::C_HEAP) GrowableArray<oop>(512, true); | |
| 555 guarantee(_overflow_stacks[i] != NULL, "Overflow Stack allocation failure."); | |
| 556 } else { | |
| 557 _overflow_stacks[i] = NULL; | |
| 558 } | |
| 559 } | |
| 560 | |
| 0 | 561 if (UsePerfData) { |
| 562 EXCEPTION_MARK; | |
| 563 ResourceMark rm; | |
| 564 | |
| 565 const char* cname = | |
| 566 PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); | |
| 567 PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, | |
| 568 ParallelGCThreads, CHECK); | |
| 569 } | |
| 570 } | |
| 571 #ifdef _MSC_VER | |
| 572 #pragma warning( pop ) | |
| 573 #endif | |
| 574 | |
| 575 // ParNewGeneration:: | |
| 576 ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : | |
| 577 DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} | |
| 578 | |
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579 template <class T> |
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580 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop_work(T* p) { |
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581 #ifdef ASSERT |
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582 { |
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583 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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584 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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585 // We never expect to see a null reference being processed |
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586 // as a weak reference. |
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587 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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588 } |
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589 #endif // ASSERT |
| 0 | 590 |
| 591 _par_cl->do_oop_nv(p); | |
| 592 | |
| 593 if (Universe::heap()->is_in_reserved(p)) { | |
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594 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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595 _rs->write_ref_field_gc_par(p, obj); |
| 0 | 596 } |
| 597 } | |
| 598 | |
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599 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(oop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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600 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(narrowOop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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601 |
| 0 | 602 // ParNewGeneration:: |
| 603 KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : | |
| 604 DefNewGeneration::KeepAliveClosure(cl) {} | |
| 605 | |
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606 template <class T> |
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607 void /*ParNewGeneration::*/KeepAliveClosure::do_oop_work(T* p) { |
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608 #ifdef ASSERT |
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609 { |
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610 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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611 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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612 // We never expect to see a null reference being processed |
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613 // as a weak reference. |
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614 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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615 } |
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616 #endif // ASSERT |
| 0 | 617 |
| 618 _cl->do_oop_nv(p); | |
| 619 | |
| 620 if (Universe::heap()->is_in_reserved(p)) { | |
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621 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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622 _rs->write_ref_field_gc_par(p, obj); |
| 0 | 623 } |
| 624 } | |
| 625 | |
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626 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(oop* p) { KeepAliveClosure::do_oop_work(p); } |
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627 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(narrowOop* p) { KeepAliveClosure::do_oop_work(p); } |
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628 |
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629 template <class T> void ScanClosureWithParBarrier::do_oop_work(T* p) { |
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630 T heap_oop = oopDesc::load_heap_oop(p); |
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631 if (!oopDesc::is_null(heap_oop)) { |
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632 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
| 0 | 633 if ((HeapWord*)obj < _boundary) { |
| 634 assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); | |
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635 oop new_obj = obj->is_forwarded() |
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636 ? obj->forwardee() |
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637 : _g->DefNewGeneration::copy_to_survivor_space(obj); |
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638 oopDesc::encode_store_heap_oop_not_null(p, new_obj); |
| 0 | 639 } |
| 640 if (_gc_barrier) { | |
| 641 // If p points to a younger generation, mark the card. | |
| 642 if ((HeapWord*)obj < _gen_boundary) { | |
| 643 _rs->write_ref_field_gc_par(p, obj); | |
| 644 } | |
| 645 } | |
| 646 } | |
| 647 } | |
| 648 | |
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649 void ScanClosureWithParBarrier::do_oop(oop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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650 void ScanClosureWithParBarrier::do_oop(narrowOop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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651 |
| 0 | 652 class ParNewRefProcTaskProxy: public AbstractGangTask { |
| 653 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; | |
| 654 public: | |
| 655 ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, | |
| 656 Generation& next_gen, | |
| 657 HeapWord* young_old_boundary, | |
| 658 ParScanThreadStateSet& state_set); | |
| 659 | |
| 660 private: | |
| 661 virtual void work(int i); | |
| 662 | |
| 663 private: | |
| 664 ParNewGeneration& _gen; | |
| 665 ProcessTask& _task; | |
| 666 Generation& _next_gen; | |
| 667 HeapWord* _young_old_boundary; | |
| 668 ParScanThreadStateSet& _state_set; | |
| 669 }; | |
| 670 | |
| 671 ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( | |
| 672 ProcessTask& task, ParNewGeneration& gen, | |
| 673 Generation& next_gen, | |
| 674 HeapWord* young_old_boundary, | |
| 675 ParScanThreadStateSet& state_set) | |
| 676 : AbstractGangTask("ParNewGeneration parallel reference processing"), | |
| 677 _gen(gen), | |
| 678 _task(task), | |
| 679 _next_gen(next_gen), | |
| 680 _young_old_boundary(young_old_boundary), | |
| 681 _state_set(state_set) | |
| 682 { | |
| 683 } | |
| 684 | |
| 685 void ParNewRefProcTaskProxy::work(int i) | |
| 686 { | |
| 687 ResourceMark rm; | |
| 688 HandleMark hm; | |
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689 ParScanThreadState& par_scan_state = _state_set.thread_state(i); |
| 0 | 690 par_scan_state.set_young_old_boundary(_young_old_boundary); |
| 691 _task.work(i, par_scan_state.is_alive_closure(), | |
| 692 par_scan_state.keep_alive_closure(), | |
| 693 par_scan_state.evacuate_followers_closure()); | |
| 694 } | |
| 695 | |
| 696 class ParNewRefEnqueueTaskProxy: public AbstractGangTask { | |
| 697 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 698 EnqueueTask& _task; | |
| 699 | |
| 700 public: | |
| 701 ParNewRefEnqueueTaskProxy(EnqueueTask& task) | |
| 702 : AbstractGangTask("ParNewGeneration parallel reference enqueue"), | |
| 703 _task(task) | |
| 704 { } | |
| 705 | |
| 706 virtual void work(int i) | |
| 707 { | |
| 708 _task.work(i); | |
| 709 } | |
| 710 }; | |
| 711 | |
| 712 | |
| 713 void ParNewRefProcTaskExecutor::execute(ProcessTask& task) | |
| 714 { | |
| 715 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 716 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 717 "not a generational heap"); | |
| 718 WorkGang* workers = gch->workers(); | |
| 719 assert(workers != NULL, "Need parallel worker threads."); | |
| 720 ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), | |
| 721 _generation.reserved().end(), _state_set); | |
| 722 workers->run_task(&rp_task); | |
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723 _state_set.reset(_generation.promotion_failed()); |
| 0 | 724 } |
| 725 | |
| 726 void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 727 { | |
| 728 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 729 WorkGang* workers = gch->workers(); | |
| 730 assert(workers != NULL, "Need parallel worker threads."); | |
| 731 ParNewRefEnqueueTaskProxy enq_task(task); | |
| 732 workers->run_task(&enq_task); | |
| 733 } | |
| 734 | |
| 735 void ParNewRefProcTaskExecutor::set_single_threaded_mode() | |
| 736 { | |
| 737 _state_set.flush(); | |
| 738 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 739 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 740 gch->save_marks(); | |
| 741 } | |
| 742 | |
| 743 ScanClosureWithParBarrier:: | |
| 744 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : | |
| 745 ScanClosure(g, gc_barrier) {} | |
| 746 | |
| 747 EvacuateFollowersClosureGeneral:: | |
| 748 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, | |
| 749 OopsInGenClosure* cur, | |
| 750 OopsInGenClosure* older) : | |
| 751 _gch(gch), _level(level), | |
| 752 _scan_cur_or_nonheap(cur), _scan_older(older) | |
| 753 {} | |
| 754 | |
| 755 void EvacuateFollowersClosureGeneral::do_void() { | |
| 756 do { | |
| 757 // Beware: this call will lead to closure applications via virtual | |
| 758 // calls. | |
| 759 _gch->oop_since_save_marks_iterate(_level, | |
| 760 _scan_cur_or_nonheap, | |
| 761 _scan_older); | |
| 762 } while (!_gch->no_allocs_since_save_marks(_level)); | |
| 763 } | |
| 764 | |
| 765 | |
| 766 bool ParNewGeneration::_avoid_promotion_undo = false; | |
| 767 | |
| 768 void ParNewGeneration::adjust_desired_tenuring_threshold() { | |
| 769 // Set the desired survivor size to half the real survivor space | |
| 770 _tenuring_threshold = | |
| 771 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); | |
| 772 } | |
| 773 | |
| 774 // A Generation that does parallel young-gen collection. | |
| 775 | |
| 776 void ParNewGeneration::collect(bool full, | |
| 777 bool clear_all_soft_refs, | |
| 778 size_t size, | |
| 779 bool is_tlab) { | |
| 780 assert(full || size > 0, "otherwise we don't want to collect"); | |
| 781 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 782 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 783 "not a CMS generational heap"); | |
| 784 AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); | |
| 785 WorkGang* workers = gch->workers(); | |
| 786 _next_gen = gch->next_gen(this); | |
| 787 assert(_next_gen != NULL, | |
| 788 "This must be the youngest gen, and not the only gen"); | |
| 789 assert(gch->n_gens() == 2, | |
| 790 "Par collection currently only works with single older gen."); | |
| 791 // Do we have to avoid promotion_undo? | |
| 792 if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { | |
| 793 set_avoid_promotion_undo(true); | |
| 794 } | |
| 795 | |
| 796 // If the next generation is too full to accomodate worst-case promotion | |
| 797 // from this generation, pass on collection; let the next generation | |
| 798 // do it. | |
| 799 if (!collection_attempt_is_safe()) { | |
| 800 gch->set_incremental_collection_will_fail(); | |
| 801 return; | |
| 802 } | |
| 803 assert(to()->is_empty(), "Else not collection_attempt_is_safe"); | |
| 804 | |
| 805 init_assuming_no_promotion_failure(); | |
| 806 | |
| 807 if (UseAdaptiveSizePolicy) { | |
| 808 set_survivor_overflow(false); | |
| 809 size_policy->minor_collection_begin(); | |
| 810 } | |
| 811 | |
| 812 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); | |
| 813 // Capture heap used before collection (for printing). | |
| 814 size_t gch_prev_used = gch->used(); | |
| 815 | |
| 816 SpecializationStats::clear(); | |
| 817 | |
| 818 age_table()->clear(); | |
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819 to()->clear(SpaceDecorator::Mangle); |
| 0 | 820 |
| 821 gch->save_marks(); | |
| 822 assert(workers != NULL, "Need parallel worker threads."); | |
| 823 ParallelTaskTerminator _term(workers->total_workers(), task_queues()); | |
| 824 ParScanThreadStateSet thread_state_set(workers->total_workers(), | |
| 825 *to(), *this, *_next_gen, *task_queues(), | |
| 695 | 826 _overflow_stacks, desired_plab_sz(), _term); |
| 0 | 827 |
| 828 ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); | |
| 829 int n_workers = workers->total_workers(); | |
| 830 gch->set_par_threads(n_workers); | |
| 831 gch->rem_set()->prepare_for_younger_refs_iterate(true); | |
| 832 // It turns out that even when we're using 1 thread, doing the work in a | |
| 833 // separate thread causes wide variance in run times. We can't help this | |
| 834 // in the multi-threaded case, but we special-case n=1 here to get | |
| 835 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 836 if (n_workers > 1) { | |
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837 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 838 workers->run_task(&tsk); |
| 839 } else { | |
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840 GenCollectedHeap::StrongRootsScope srs(gch); |
| 0 | 841 tsk.work(0); |
| 842 } | |
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843 thread_state_set.reset(promotion_failed()); |
| 0 | 844 |
| 845 if (PAR_STATS_ENABLED && ParallelGCVerbose) { | |
| 846 gclog_or_tty->print("Thread totals:\n" | |
| 847 " Pushes: %7d Pops: %7d Steals %7d (sum = %7d).\n", | |
| 848 thread_state_set.pushes(), thread_state_set.pops(), | |
| 849 thread_state_set.steals(), | |
| 850 thread_state_set.pops()+thread_state_set.steals()); | |
| 851 } | |
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852 assert(thread_state_set.pushes() == thread_state_set.pops() |
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853 + thread_state_set.steals(), |
| 0 | 854 "Or else the queues are leaky."); |
| 855 | |
| 856 // Process (weak) reference objects found during scavenge. | |
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857 ReferenceProcessor* rp = ref_processor(); |
| 0 | 858 IsAliveClosure is_alive(this); |
| 859 ScanWeakRefClosure scan_weak_ref(this); | |
| 860 KeepAliveClosure keep_alive(&scan_weak_ref); | |
| 861 ScanClosure scan_without_gc_barrier(this, false); | |
| 862 ScanClosureWithParBarrier scan_with_gc_barrier(this, true); | |
| 863 set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); | |
| 864 EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, | |
| 865 &scan_without_gc_barrier, &scan_with_gc_barrier); | |
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866 rp->setup_policy(clear_all_soft_refs); |
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867 if (rp->processing_is_mt()) { |
| 0 | 868 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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869 rp->process_discovered_references(&is_alive, &keep_alive, |
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870 &evacuate_followers, &task_executor); |
| 0 | 871 } else { |
| 872 thread_state_set.flush(); | |
| 873 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 874 gch->save_marks(); | |
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875 rp->process_discovered_references(&is_alive, &keep_alive, |
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876 &evacuate_followers, NULL); |
| 0 | 877 } |
| 878 if (!promotion_failed()) { | |
| 879 // Swap the survivor spaces. | |
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880 eden()->clear(SpaceDecorator::Mangle); |
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881 from()->clear(SpaceDecorator::Mangle); |
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882 if (ZapUnusedHeapArea) { |
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883 // This is now done here because of the piece-meal mangling which |
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884 // can check for valid mangling at intermediate points in the |
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885 // collection(s). When a minor collection fails to collect |
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886 // sufficient space resizing of the young generation can occur |
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887 // an redistribute the spaces in the young generation. Mangle |
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888 // here so that unzapped regions don't get distributed to |
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889 // other spaces. |
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890 to()->mangle_unused_area(); |
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891 } |
| 0 | 892 swap_spaces(); |
| 893 | |
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894 // A successful scavenge should restart the GC time limit count which is |
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895 // for full GC's. |
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896 size_policy->reset_gc_overhead_limit_count(); |
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897 |
| 0 | 898 assert(to()->is_empty(), "to space should be empty now"); |
| 899 } else { | |
| 900 assert(HandlePromotionFailure, | |
| 901 "Should only be here if promotion failure handling is on"); | |
| 902 if (_promo_failure_scan_stack != NULL) { | |
| 903 // Can be non-null because of reference processing. | |
| 904 // Free stack with its elements. | |
| 905 delete _promo_failure_scan_stack; | |
| 906 _promo_failure_scan_stack = NULL; | |
| 907 } | |
| 908 remove_forwarding_pointers(); | |
| 909 if (PrintGCDetails) { | |
| 910 gclog_or_tty->print(" (promotion failed)"); | |
| 911 } | |
| 912 // All the spaces are in play for mark-sweep. | |
| 913 swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. | |
| 914 from()->set_next_compaction_space(to()); | |
| 915 gch->set_incremental_collection_will_fail(); | |
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916 // Inform the next generation that a promotion failure occurred. |
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917 _next_gen->promotion_failure_occurred(); |
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918 |
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919 // Reset the PromotionFailureALot counters. |
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920 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) |
| 0 | 921 } |
| 922 // set new iteration safe limit for the survivor spaces | |
| 923 from()->set_concurrent_iteration_safe_limit(from()->top()); | |
| 924 to()->set_concurrent_iteration_safe_limit(to()->top()); | |
| 925 | |
| 926 adjust_desired_tenuring_threshold(); | |
| 927 if (ResizePLAB) { | |
| 928 plab_stats()->adjust_desired_plab_sz(); | |
| 929 } | |
| 930 | |
| 931 if (PrintGC && !PrintGCDetails) { | |
| 932 gch->print_heap_change(gch_prev_used); | |
| 933 } | |
| 934 | |
| 935 if (UseAdaptiveSizePolicy) { | |
| 936 size_policy->minor_collection_end(gch->gc_cause()); | |
| 937 size_policy->avg_survived()->sample(from()->used()); | |
| 938 } | |
| 939 | |
| 940 update_time_of_last_gc(os::javaTimeMillis()); | |
| 941 | |
| 942 SpecializationStats::print(); | |
| 943 | |
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944 rp->set_enqueuing_is_done(true); |
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945 if (rp->processing_is_mt()) { |
| 0 | 946 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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947 rp->enqueue_discovered_references(&task_executor); |
| 0 | 948 } else { |
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949 rp->enqueue_discovered_references(NULL); |
| 0 | 950 } |
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951 rp->verify_no_references_recorded(); |
| 0 | 952 } |
| 953 | |
| 954 static int sum; | |
| 955 void ParNewGeneration::waste_some_time() { | |
| 956 for (int i = 0; i < 100; i++) { | |
| 957 sum += i; | |
| 958 } | |
| 959 } | |
| 960 | |
| 961 static const oop ClaimedForwardPtr = oop(0x4); | |
| 962 | |
| 963 // Because of concurrency, there are times where an object for which | |
| 964 // "is_forwarded()" is true contains an "interim" forwarding pointer | |
| 965 // value. Such a value will soon be overwritten with a real value. | |
| 966 // This method requires "obj" to have a forwarding pointer, and waits, if | |
| 967 // necessary for a real one to be inserted, and returns it. | |
| 968 | |
| 969 oop ParNewGeneration::real_forwardee(oop obj) { | |
| 970 oop forward_ptr = obj->forwardee(); | |
| 971 if (forward_ptr != ClaimedForwardPtr) { | |
| 972 return forward_ptr; | |
| 973 } else { | |
| 974 return real_forwardee_slow(obj); | |
| 975 } | |
| 976 } | |
| 977 | |
| 978 oop ParNewGeneration::real_forwardee_slow(oop obj) { | |
| 979 // Spin-read if it is claimed but not yet written by another thread. | |
| 980 oop forward_ptr = obj->forwardee(); | |
| 981 while (forward_ptr == ClaimedForwardPtr) { | |
| 982 waste_some_time(); | |
| 983 assert(obj->is_forwarded(), "precondition"); | |
| 984 forward_ptr = obj->forwardee(); | |
| 985 } | |
| 986 return forward_ptr; | |
| 987 } | |
| 988 | |
| 989 #ifdef ASSERT | |
| 990 bool ParNewGeneration::is_legal_forward_ptr(oop p) { | |
| 991 return | |
| 992 (_avoid_promotion_undo && p == ClaimedForwardPtr) | |
| 993 || Universe::heap()->is_in_reserved(p); | |
| 994 } | |
| 995 #endif | |
| 996 | |
| 997 void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { | |
| 998 if ((m != markOopDesc::prototype()) && | |
| 999 (!UseBiasedLocking || (m != markOopDesc::biased_locking_prototype()))) { | |
| 1000 MutexLocker ml(ParGCRareEvent_lock); | |
| 1001 DefNewGeneration::preserve_mark_if_necessary(obj, m); | |
| 1002 } | |
| 1003 } | |
| 1004 | |
| 1005 // Multiple GC threads may try to promote an object. If the object | |
| 1006 // is successfully promoted, a forwarding pointer will be installed in | |
| 1007 // the object in the young generation. This method claims the right | |
| 1008 // to install the forwarding pointer before it copies the object, | |
| 1009 // thus avoiding the need to undo the copy as in | |
| 1010 // copy_to_survivor_space_avoiding_with_undo. | |
| 1011 | |
| 1012 oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( | |
| 1013 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
| 1014 // In the sequential version, this assert also says that the object is | |
| 1015 // not forwarded. That might not be the case here. It is the case that | |
| 1016 // the caller observed it to be not forwarded at some time in the past. | |
| 1017 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
| 1018 | |
| 1019 // The sequential code read "old->age()" below. That doesn't work here, | |
| 1020 // since the age is in the mark word, and that might be overwritten with | |
| 1021 // a forwarding pointer by a parallel thread. So we must save the mark | |
| 1022 // word in a local and then analyze it. | |
| 1023 oopDesc dummyOld; | |
| 1024 dummyOld.set_mark(m); | |
| 1025 assert(!dummyOld.is_forwarded(), | |
| 1026 "should not be called with forwarding pointer mark word."); | |
| 1027 | |
| 1028 oop new_obj = NULL; | |
| 1029 oop forward_ptr; | |
| 1030 | |
| 1031 // Try allocating obj in to-space (unless too old) | |
| 1032 if (dummyOld.age() < tenuring_threshold()) { | |
| 1033 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
| 1034 if (new_obj == NULL) { | |
| 1035 set_survivor_overflow(true); | |
| 1036 } | |
| 1037 } | |
| 1038 | |
| 1039 if (new_obj == NULL) { | |
| 1040 // Either to-space is full or we decided to promote | |
| 1041 // try allocating obj tenured | |
| 1042 | |
| 1043 // Attempt to install a null forwarding pointer (atomically), | |
| 1044 // to claim the right to install the real forwarding pointer. | |
| 1045 forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); | |
| 1046 if (forward_ptr != NULL) { | |
| 1047 // someone else beat us to it. | |
| 1048 return real_forwardee(old); | |
| 1049 } | |
| 1050 | |
| 1051 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
| 1052 old, m, sz); | |
| 1053 | |
| 1054 if (new_obj == NULL) { | |
| 1055 if (!HandlePromotionFailure) { | |
| 1056 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag | |
| 1057 // is incorrectly set. In any case, its seriously wrong to be here! | |
| 1058 vm_exit_out_of_memory(sz*wordSize, "promotion"); | |
| 1059 } | |
| 1060 // promotion failed, forward to self | |
| 1061 _promotion_failed = true; | |
| 1062 new_obj = old; | |
| 1063 | |
| 1064 preserve_mark_if_necessary(old, m); | |
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1066 par_scan_state->log_promotion_failure(sz); |
| 0 | 1067 } |
| 1068 | |
| 1069 old->forward_to(new_obj); | |
| 1070 forward_ptr = NULL; | |
| 1071 } else { | |
| 1072 // Is in to-space; do copying ourselves. | |
| 1073 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
| 1074 forward_ptr = old->forward_to_atomic(new_obj); | |
| 1075 // Restore the mark word copied above. | |
| 1076 new_obj->set_mark(m); | |
| 1077 // Increment age if obj still in new generation | |
| 1078 new_obj->incr_age(); | |
| 1079 par_scan_state->age_table()->add(new_obj, sz); | |
| 1080 } | |
| 1081 assert(new_obj != NULL, "just checking"); | |
| 1082 | |
| 1083 if (forward_ptr == NULL) { | |
| 1084 oop obj_to_push = new_obj; | |
| 1085 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
| 1086 // Length field used as index of next element to be scanned. | |
| 1087 // Real length can be obtained from real_forwardee() | |
| 1088 arrayOop(old)->set_length(0); | |
| 1089 obj_to_push = old; | |
| 1090 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
| 1091 "push forwarded object"); | |
| 1092 } | |
| 1093 // Push it on one of the queues of to-be-scanned objects. | |
| 534 | 1094 bool simulate_overflow = false; |
| 1095 NOT_PRODUCT( | |
| 1096 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
| 1097 // simulate a stack overflow | |
| 1098 simulate_overflow = true; | |
| 1099 } | |
| 1100 ) | |
| 1101 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
| 0 | 1102 // Add stats for overflow pushes. |
| 1103 if (Verbose && PrintGCDetails) { | |
| 1104 gclog_or_tty->print("queue overflow!\n"); | |
| 1105 } | |
| 534 | 1106 push_on_overflow_list(old, par_scan_state); |
| 0 | 1107 par_scan_state->note_overflow_push(); |
| 1108 } | |
| 1109 par_scan_state->note_push(); | |
| 1110 | |
| 1111 return new_obj; | |
| 1112 } | |
| 1113 | |
| 1114 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
| 1115 // allocate it? | |
| 1116 if (is_in_reserved(new_obj)) { | |
| 1117 // Must be in to_space. | |
| 1118 assert(to()->is_in_reserved(new_obj), "Checking"); | |
| 1119 if (forward_ptr == ClaimedForwardPtr) { | |
| 1120 // Wait to get the real forwarding pointer value. | |
| 1121 forward_ptr = real_forwardee(old); | |
| 1122 } | |
| 1123 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
| 1124 } | |
| 1125 | |
| 1126 return forward_ptr; | |
| 1127 } | |
| 1128 | |
| 1129 | |
| 1130 // Multiple GC threads may try to promote the same object. If two | |
| 1131 // or more GC threads copy the object, only one wins the race to install | |
| 1132 // the forwarding pointer. The other threads have to undo their copy. | |
| 1133 | |
| 1134 oop ParNewGeneration::copy_to_survivor_space_with_undo( | |
| 1135 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
| 1136 | |
| 1137 // In the sequential version, this assert also says that the object is | |
| 1138 // not forwarded. That might not be the case here. It is the case that | |
| 1139 // the caller observed it to be not forwarded at some time in the past. | |
| 1140 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
| 1141 | |
| 1142 // The sequential code read "old->age()" below. That doesn't work here, | |
| 1143 // since the age is in the mark word, and that might be overwritten with | |
| 1144 // a forwarding pointer by a parallel thread. So we must save the mark | |
| 1145 // word here, install it in a local oopDesc, and then analyze it. | |
| 1146 oopDesc dummyOld; | |
| 1147 dummyOld.set_mark(m); | |
| 1148 assert(!dummyOld.is_forwarded(), | |
| 1149 "should not be called with forwarding pointer mark word."); | |
| 1150 | |
| 1151 bool failed_to_promote = false; | |
| 1152 oop new_obj = NULL; | |
| 1153 oop forward_ptr; | |
| 1154 | |
| 1155 // Try allocating obj in to-space (unless too old) | |
| 1156 if (dummyOld.age() < tenuring_threshold()) { | |
| 1157 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
| 1158 if (new_obj == NULL) { | |
| 1159 set_survivor_overflow(true); | |
| 1160 } | |
| 1161 } | |
| 1162 | |
| 1163 if (new_obj == NULL) { | |
| 1164 // Either to-space is full or we decided to promote | |
| 1165 // try allocating obj tenured | |
| 1166 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
| 1167 old, m, sz); | |
| 1168 | |
| 1169 if (new_obj == NULL) { | |
| 1170 if (!HandlePromotionFailure) { | |
| 1171 // A failed promotion likely means the MaxLiveObjectEvacuationRatio | |
| 1172 // flag is incorrectly set. In any case, its seriously wrong to be | |
| 1173 // here! | |
| 1174 vm_exit_out_of_memory(sz*wordSize, "promotion"); | |
| 1175 } | |
| 1176 // promotion failed, forward to self | |
| 1177 forward_ptr = old->forward_to_atomic(old); | |
| 1178 new_obj = old; | |
| 1179 | |
| 1180 if (forward_ptr != NULL) { | |
| 1181 return forward_ptr; // someone else succeeded | |
| 1182 } | |
| 1183 | |
| 1184 _promotion_failed = true; | |
| 1185 failed_to_promote = true; | |
| 1186 | |
| 1187 preserve_mark_if_necessary(old, m); | |
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1189 par_scan_state->log_promotion_failure(sz); |
| 0 | 1190 } |
| 1191 } else { | |
| 1192 // Is in to-space; do copying ourselves. | |
| 1193 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
| 1194 // Restore the mark word copied above. | |
| 1195 new_obj->set_mark(m); | |
| 1196 // Increment age if new_obj still in new generation | |
| 1197 new_obj->incr_age(); | |
| 1198 par_scan_state->age_table()->add(new_obj, sz); | |
| 1199 } | |
| 1200 assert(new_obj != NULL, "just checking"); | |
| 1201 | |
| 1202 // Now attempt to install the forwarding pointer (atomically). | |
| 1203 // We have to copy the mark word before overwriting with forwarding | |
| 1204 // ptr, so we can restore it below in the copy. | |
| 1205 if (!failed_to_promote) { | |
| 1206 forward_ptr = old->forward_to_atomic(new_obj); | |
| 1207 } | |
| 1208 | |
| 1209 if (forward_ptr == NULL) { | |
| 1210 oop obj_to_push = new_obj; | |
| 1211 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
| 1212 // Length field used as index of next element to be scanned. | |
| 1213 // Real length can be obtained from real_forwardee() | |
| 1214 arrayOop(old)->set_length(0); | |
| 1215 obj_to_push = old; | |
| 1216 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
| 1217 "push forwarded object"); | |
| 1218 } | |
| 1219 // Push it on one of the queues of to-be-scanned objects. | |
| 534 | 1220 bool simulate_overflow = false; |
| 1221 NOT_PRODUCT( | |
| 1222 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
| 1223 // simulate a stack overflow | |
| 1224 simulate_overflow = true; | |
| 1225 } | |
| 1226 ) | |
| 1227 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
| 0 | 1228 // Add stats for overflow pushes. |
| 534 | 1229 push_on_overflow_list(old, par_scan_state); |
| 0 | 1230 par_scan_state->note_overflow_push(); |
| 1231 } | |
| 1232 par_scan_state->note_push(); | |
| 1233 | |
| 1234 return new_obj; | |
| 1235 } | |
| 1236 | |
| 1237 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
| 1238 // allocate it? | |
| 1239 if (is_in_reserved(new_obj)) { | |
| 1240 // Must be in to_space. | |
| 1241 assert(to()->is_in_reserved(new_obj), "Checking"); | |
| 1242 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
| 1243 } else { | |
| 1244 assert(!_avoid_promotion_undo, "Should not be here if avoiding."); | |
| 1245 _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), | |
| 1246 (HeapWord*)new_obj, sz); | |
| 1247 } | |
| 1248 | |
| 1249 return forward_ptr; | |
| 1250 } | |
| 1251 | |
| 534 | 1252 #ifndef PRODUCT |
| 1253 // It's OK to call this multi-threaded; the worst thing | |
| 1254 // that can happen is that we'll get a bunch of closely | |
| 1255 // spaced simulated oveflows, but that's OK, in fact | |
| 1256 // probably good as it would exercise the overflow code | |
| 1257 // under contention. | |
| 1258 bool ParNewGeneration::should_simulate_overflow() { | |
| 1259 if (_overflow_counter-- <= 0) { // just being defensive | |
| 1260 _overflow_counter = ParGCWorkQueueOverflowInterval; | |
| 1261 return true; | |
| 1262 } else { | |
| 1263 return false; | |
| 1264 } | |
| 1265 } | |
| 1266 #endif | |
| 1267 | |
|
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1268 // In case we are using compressed oops, we need to be careful. |
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1269 // If the object being pushed is an object array, then its length |
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1270 // field keeps track of the "grey boundary" at which the next |
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1271 // incremental scan will be done (see ParGCArrayScanChunk). |
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1272 // When using compressed oops, this length field is kept in the |
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1273 // lower 32 bits of the erstwhile klass word and cannot be used |
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1274 // for the overflow chaining pointer (OCP below). As such the OCP |
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1275 // would itself need to be compressed into the top 32-bits in this |
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1276 // case. Unfortunately, see below, in the event that we have a |
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1277 // promotion failure, the node to be pushed on the list can be |
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1278 // outside of the Java heap, so the heap-based pointer compression |
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1279 // would not work (we would have potential aliasing between C-heap |
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1280 // and Java-heap pointers). For this reason, when using compressed |
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1281 // oops, we simply use a worker-thread-local, non-shared overflow |
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1282 // list in the form of a growable array, with a slightly different |
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1283 // overflow stack draining strategy. If/when we start using fat |
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1284 // stacks here, we can go back to using (fat) pointer chains |
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1285 // (although some performance comparisons would be useful since |
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1286 // single global lists have their own performance disadvantages |
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1287 // as we were made painfully aware not long ago, see 6786503). |
| 534 | 1288 #define BUSY (oop(0x1aff1aff)) |
| 1289 void ParNewGeneration::push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state) { | |
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1290 assert(is_in_reserved(from_space_obj), "Should be from this generation"); |
| 695 | 1291 if (ParGCUseLocalOverflow) { |
|
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1292 // In the case of compressed oops, we use a private, not-shared |
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1293 // overflow stack. |
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1294 par_scan_state->push_on_overflow_stack(from_space_obj); |
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1295 } else { |
| 695 | 1296 assert(!UseCompressedOops, "Error"); |
|
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1297 // if the object has been forwarded to itself, then we cannot |
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1298 // use the klass pointer for the linked list. Instead we have |
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1299 // to allocate an oopDesc in the C-Heap and use that for the linked list. |
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1300 // XXX This is horribly inefficient when a promotion failure occurs |
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1301 // and should be fixed. XXX FIX ME !!! |
| 534 | 1302 #ifndef PRODUCT |
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1303 Atomic::inc_ptr(&_num_par_pushes); |
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1304 assert(_num_par_pushes > 0, "Tautology"); |
| 534 | 1305 #endif |
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1306 if (from_space_obj->forwardee() == from_space_obj) { |
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1307 oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1); |
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1308 listhead->forward_to(from_space_obj); |
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1309 from_space_obj = listhead; |
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1310 } |
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1311 oop observed_overflow_list = _overflow_list; |
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1312 oop cur_overflow_list; |
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1313 do { |
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1314 cur_overflow_list = observed_overflow_list; |
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1315 if (cur_overflow_list != BUSY) { |
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1316 from_space_obj->set_klass_to_list_ptr(cur_overflow_list); |
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1317 } else { |
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1318 from_space_obj->set_klass_to_list_ptr(NULL); |
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1319 } |
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1320 observed_overflow_list = |
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1321 (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
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1322 } while (cur_overflow_list != observed_overflow_list); |
| 0 | 1323 } |
| 1324 } | |
| 1325 | |
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1326 bool ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { |
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1327 bool res; |
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1328 |
| 695 | 1329 if (ParGCUseLocalOverflow) { |
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1330 res = par_scan_state->take_from_overflow_stack(); |
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1331 } else { |
| 695 | 1332 assert(!UseCompressedOops, "Error"); |
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1333 res = take_from_overflow_list_work(par_scan_state); |
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1334 } |
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1335 return res; |
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1336 } |
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1337 |
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1338 |
| 534 | 1339 // *NOTE*: The overflow list manipulation code here and |
| 1340 // in CMSCollector:: are very similar in shape, | |
| 1341 // except that in the CMS case we thread the objects | |
| 1342 // directly into the list via their mark word, and do | |
| 1343 // not need to deal with special cases below related | |
| 1344 // to chunking of object arrays and promotion failure | |
| 1345 // handling. | |
| 1346 // CR 6797058 has been filed to attempt consolidation of | |
| 1347 // the common code. | |
| 1348 // Because of the common code, if you make any changes in | |
| 1349 // the code below, please check the CMS version to see if | |
| 1350 // similar changes might be needed. | |
| 1351 // See CMSCollector::par_take_from_overflow_list() for | |
| 1352 // more extensive documentation comments. | |
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1353 bool ParNewGeneration::take_from_overflow_list_work(ParScanThreadState* par_scan_state) { |
| 0 | 1354 ObjToScanQueue* work_q = par_scan_state->work_queue(); |
| 1355 // How many to take? | |
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1356 size_t objsFromOverflow = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 534 | 1357 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 1358 |
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1359 assert(par_scan_state->overflow_stack() == NULL, "Error"); |
| 695 | 1360 assert(!UseCompressedOops, "Error"); |
| 0 | 1361 if (_overflow_list == NULL) return false; |
| 1362 | |
| 1363 // Otherwise, there was something there; try claiming the list. | |
| 534 | 1364 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 1365 // Trim off a prefix of at most objsFromOverflow items | |
| 1366 Thread* tid = Thread::current(); | |
| 1367 size_t spin_count = (size_t)ParallelGCThreads; | |
| 1368 size_t sleep_time_millis = MAX2((size_t)1, objsFromOverflow/100); | |
| 1369 for (size_t spin = 0; prefix == BUSY && spin < spin_count; spin++) { | |
| 1370 // someone grabbed it before we did ... | |
| 1371 // ... we spin for a short while... | |
| 1372 os::sleep(tid, sleep_time_millis, false); | |
| 1373 if (_overflow_list == NULL) { | |
| 1374 // nothing left to take | |
| 1375 return false; | |
| 1376 } else if (_overflow_list != BUSY) { | |
| 1377 // try and grab the prefix | |
| 1378 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 1379 } | |
| 0 | 1380 } |
| 534 | 1381 if (prefix == NULL || prefix == BUSY) { |
| 1382 // Nothing to take or waited long enough | |
| 1383 if (prefix == NULL) { | |
| 1384 // Write back the NULL in case we overwrote it with BUSY above | |
| 1385 // and it is still the same value. | |
| 1386 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 1387 } | |
| 1388 return false; | |
| 1389 } | |
| 1390 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 1391 size_t i = 1; | |
| 0 | 1392 oop cur = prefix; |
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1393 while (i < objsFromOverflow && cur->klass_or_null() != NULL) { |
| 0 | 1394 i++; cur = oop(cur->klass()); |
| 1395 } | |
| 1396 | |
| 1397 // Reattach remaining (suffix) to overflow list | |
| 534 | 1398 if (cur->klass_or_null() == NULL) { |
| 1399 // Write back the NULL in lieu of the BUSY we wrote | |
| 1400 // above and it is still the same value. | |
| 1401 if (_overflow_list == BUSY) { | |
| 1402 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 0 | 1403 } |
| 534 | 1404 } else { |
| 1405 assert(cur->klass_or_null() != BUSY, "Error"); | |
| 1406 oop suffix = oop(cur->klass()); // suffix will be put back on global list | |
| 1407 cur->set_klass_to_list_ptr(NULL); // break off suffix | |
| 1408 // It's possible that the list is still in the empty(busy) state | |
| 1409 // we left it in a short while ago; in that case we may be | |
| 1410 // able to place back the suffix. | |
| 1411 oop observed_overflow_list = _overflow_list; | |
| 1412 oop cur_overflow_list = observed_overflow_list; | |
| 1413 bool attached = false; | |
| 1414 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 1415 observed_overflow_list = | |
| 1416 (oop) Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
| 1417 if (cur_overflow_list == observed_overflow_list) { | |
| 1418 attached = true; | |
| 1419 break; | |
| 1420 } else cur_overflow_list = observed_overflow_list; | |
| 1421 } | |
| 1422 if (!attached) { | |
| 1423 // Too bad, someone else got in in between; we'll need to do a splice. | |
| 1424 // Find the last item of suffix list | |
| 1425 oop last = suffix; | |
| 1426 while (last->klass_or_null() != NULL) { | |
| 1427 last = oop(last->klass()); | |
| 1428 } | |
| 1429 // Atomically prepend suffix to current overflow list | |
| 1430 observed_overflow_list = _overflow_list; | |
| 1431 do { | |
| 1432 cur_overflow_list = observed_overflow_list; | |
| 1433 if (cur_overflow_list != BUSY) { | |
| 1434 // Do the splice ... | |
| 1435 last->set_klass_to_list_ptr(cur_overflow_list); | |
| 1436 } else { // cur_overflow_list == BUSY | |
| 1437 last->set_klass_to_list_ptr(NULL); | |
| 1438 } | |
| 1439 observed_overflow_list = | |
| 1440 (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
| 1441 } while (cur_overflow_list != observed_overflow_list); | |
| 0 | 1442 } |
| 1443 } | |
| 1444 | |
| 1445 // Push objects on prefix list onto this thread's work queue | |
| 534 | 1446 assert(prefix != NULL && prefix != BUSY, "program logic"); |
| 0 | 1447 cur = prefix; |
| 534 | 1448 ssize_t n = 0; |
| 0 | 1449 while (cur != NULL) { |
| 1450 oop obj_to_push = cur->forwardee(); | |
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1451 oop next = oop(cur->klass_or_null()); |
| 0 | 1452 cur->set_klass(obj_to_push->klass()); |
| 534 | 1453 // This may be an array object that is self-forwarded. In that case, the list pointer |
| 1454 // space, cur, is not in the Java heap, but rather in the C-heap and should be freed. | |
| 1455 if (!is_in_reserved(cur)) { | |
| 1456 // This can become a scaling bottleneck when there is work queue overflow coincident | |
| 1457 // with promotion failure. | |
| 1458 oopDesc* f = cur; | |
| 1459 FREE_C_HEAP_ARRAY(oopDesc, f); | |
| 1460 } else if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { | |
| 0 | 1461 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
| 534 | 1462 obj_to_push = cur; |
| 0 | 1463 } |
| 534 | 1464 bool ok = work_q->push(obj_to_push); |
| 1465 assert(ok, "Should have succeeded"); | |
| 0 | 1466 cur = next; |
| 1467 n++; | |
| 1468 } | |
| 1469 par_scan_state->note_overflow_refill(n); | |
| 534 | 1470 #ifndef PRODUCT |
| 1471 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 1472 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 1473 #endif | |
| 0 | 1474 return true; |
| 1475 } | |
| 534 | 1476 #undef BUSY |
| 0 | 1477 |
| 1478 void ParNewGeneration::ref_processor_init() | |
| 1479 { | |
| 1480 if (_ref_processor == NULL) { | |
| 1481 // Allocate and initialize a reference processor | |
| 1482 _ref_processor = ReferenceProcessor::create_ref_processor( | |
| 1483 _reserved, // span | |
| 1484 refs_discovery_is_atomic(), // atomic_discovery | |
| 1485 refs_discovery_is_mt(), // mt_discovery | |
| 1486 NULL, // is_alive_non_header | |
| 1487 ParallelGCThreads, | |
| 1488 ParallelRefProcEnabled); | |
| 1489 } | |
| 1490 } | |
| 1491 | |
| 1492 const char* ParNewGeneration::name() const { | |
| 1493 return "par new generation"; | |
| 1494 } |