Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/parNew/parNewGeneration.cpp @ 679:cea947c8a988
6819891: ParNew: Fix work queue overflow code to deal correctly with +UseCompressedOops
Summary: When using compressed oops, rather than chaining the overflowed grey objects' pre-images through their klass words, we use GC-worker thread-local overflow stacks.
Reviewed-by: jcoomes, jmasa
| author | ysr |
|---|---|
| date | Sat, 28 Mar 2009 15:47:29 -0700 |
| parents | 0fbdb4381b99 |
| children | becb17ad5e51 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 579 | 2 * Copyright 2001-2009 Sun Microsystems, Inc. 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 * | |
| 19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
| 20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
| 21 * have any questions. | |
| 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_, | |
| 37 size_t desired_plab_sz_, | |
| 38 ParallelTaskTerminator& term_) : | |
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39 _to_space(to_space_), _old_gen(old_gen_), _young_gen(gen_), _thread_num(thread_num_), |
| 0 | 40 _work_queue(work_queue_set_->queue(thread_num_)), _to_space_full(false), |
| 41 _ageTable(false), // false ==> not the global age table, no perf data. | |
| 42 _to_space_alloc_buffer(desired_plab_sz_), | |
| 43 _to_space_closure(gen_, this), _old_gen_closure(gen_, this), | |
| 44 _to_space_root_closure(gen_, this), _old_gen_root_closure(gen_, this), | |
| 45 _older_gen_closure(gen_, this), | |
| 46 _evacuate_followers(this, &_to_space_closure, &_old_gen_closure, | |
| 47 &_to_space_root_closure, gen_, &_old_gen_root_closure, | |
| 48 work_queue_set_, &term_), | |
| 49 _is_alive_closure(gen_), _scan_weak_ref_closure(gen_, this), | |
| 50 _keep_alive_closure(&_scan_weak_ref_closure), | |
| 51 _pushes(0), _pops(0), _steals(0), _steal_attempts(0), _term_attempts(0), | |
| 52 _strong_roots_time(0.0), _term_time(0.0) | |
| 53 { | |
| 54 _survivor_chunk_array = | |
| 55 (ChunkArray*) old_gen()->get_data_recorder(thread_num()); | |
| 56 _hash_seed = 17; // Might want to take time-based random value. | |
| 57 _start = os::elapsedTime(); | |
| 58 _old_gen_closure.set_generation(old_gen_); | |
| 59 _old_gen_root_closure.set_generation(old_gen_); | |
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60 if (UseCompressedOops) { |
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61 _overflow_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(512, true); |
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62 } else { |
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63 _overflow_stack = NULL; |
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64 } |
| 0 | 65 } |
| 66 #ifdef _MSC_VER | |
| 67 #pragma warning( pop ) | |
| 68 #endif | |
| 69 | |
| 70 void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, | |
| 71 size_t plab_word_size) { | |
| 72 ChunkArray* sca = survivor_chunk_array(); | |
| 73 if (sca != NULL) { | |
| 74 // A non-null SCA implies that we want the PLAB data recorded. | |
| 75 sca->record_sample(plab_start, plab_word_size); | |
| 76 } | |
| 77 } | |
| 78 | |
| 79 bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { | |
| 80 return new_obj->is_objArray() && | |
| 81 arrayOop(new_obj)->length() > ParGCArrayScanChunk && | |
| 82 new_obj != old_obj; | |
| 83 } | |
| 84 | |
| 85 void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { | |
| 86 assert(old->is_objArray(), "must be obj array"); | |
| 87 assert(old->is_forwarded(), "must be forwarded"); | |
| 88 assert(Universe::heap()->is_in_reserved(old), "must be in heap."); | |
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89 assert(!old_gen()->is_in(old), "must be in young generation."); |
| 0 | 90 |
| 91 objArrayOop obj = objArrayOop(old->forwardee()); | |
| 92 // Process ParGCArrayScanChunk elements now | |
| 93 // and push the remainder back onto queue | |
| 94 int start = arrayOop(old)->length(); | |
| 95 int end = obj->length(); | |
| 96 int remainder = end - start; | |
| 97 assert(start <= end, "just checking"); | |
| 98 if (remainder > 2 * ParGCArrayScanChunk) { | |
| 99 // Test above combines last partial chunk with a full chunk | |
| 100 end = start + ParGCArrayScanChunk; | |
| 101 arrayOop(old)->set_length(end); | |
| 102 // Push remainder. | |
| 103 bool ok = work_queue()->push(old); | |
| 104 assert(ok, "just popped, push must be okay"); | |
| 105 note_push(); | |
| 106 } else { | |
| 107 // Restore length so that it can be used if there | |
| 108 // is a promotion failure and forwarding pointers | |
| 109 // must be removed. | |
| 110 arrayOop(old)->set_length(end); | |
| 111 } | |
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112 |
| 0 | 113 // process our set of indices (include header in first chunk) |
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114 // should make sure end is even (aligned to HeapWord in case of compressed oops) |
| 0 | 115 if ((HeapWord *)obj < young_old_boundary()) { |
| 116 // object is in to_space | |
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117 obj->oop_iterate_range(&_to_space_closure, start, end); |
| 0 | 118 } else { |
| 119 // object is in old generation | |
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120 obj->oop_iterate_range(&_old_gen_closure, start, end); |
| 0 | 121 } |
| 122 } | |
| 123 | |
| 124 | |
| 125 void ParScanThreadState::trim_queues(int max_size) { | |
| 126 ObjToScanQueue* queue = work_queue(); | |
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127 do { |
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128 while (queue->size() > (juint)max_size) { |
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129 oop obj_to_scan; |
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130 if (queue->pop_local(obj_to_scan)) { |
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131 note_pop(); |
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132 if ((HeapWord *)obj_to_scan < young_old_boundary()) { |
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133 if (obj_to_scan->is_objArray() && |
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134 obj_to_scan->is_forwarded() && |
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135 obj_to_scan->forwardee() != obj_to_scan) { |
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136 scan_partial_array_and_push_remainder(obj_to_scan); |
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137 } else { |
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138 // object is in to_space |
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139 obj_to_scan->oop_iterate(&_to_space_closure); |
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140 } |
| 0 | 141 } else { |
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142 // object is in old generation |
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143 obj_to_scan->oop_iterate(&_old_gen_closure); |
| 0 | 144 } |
| 145 } | |
| 146 } | |
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147 // For the case of compressed oops, we have a private, non-shared |
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148 // overflow stack, so we eagerly drain it so as to more evenly |
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149 // distribute load early. Note: this may be good to do in |
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150 // general rather than delay for the final stealing phase. |
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151 // If applicable, we'll transfer a set of objects over to our |
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152 // work queue, allowing them to be stolen and draining our |
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153 // private overflow stack. |
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154 } while (ParGCTrimOverflow && young_gen()->take_from_overflow_list(this)); |
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155 } |
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156 |
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157 bool ParScanThreadState::take_from_overflow_stack() { |
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158 assert(UseCompressedOops, "Else should not call"); |
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159 assert(young_gen()->overflow_list() == NULL, "Error"); |
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160 ObjToScanQueue* queue = work_queue(); |
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161 GrowableArray<oop>* of_stack = overflow_stack(); |
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162 uint num_overflow_elems = of_stack->length(); |
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163 uint num_take_elems = MIN2(MIN2((queue->max_elems() - queue->size())/4, |
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164 (juint)ParGCDesiredObjsFromOverflowList), |
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165 num_overflow_elems); |
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166 // Transfer the most recent num_take_elems from the overflow |
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167 // stack to our work queue. |
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168 for (size_t i = 0; i != num_take_elems; i++) { |
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169 oop cur = of_stack->pop(); |
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170 oop obj_to_push = cur->forwardee(); |
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171 assert(Universe::heap()->is_in_reserved(cur), "Should be in heap"); |
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172 assert(!old_gen()->is_in_reserved(cur), "Should be in young gen"); |
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173 assert(Universe::heap()->is_in_reserved(obj_to_push), "Should be in heap"); |
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174 if (should_be_partially_scanned(obj_to_push, cur)) { |
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175 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
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176 obj_to_push = cur; |
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177 } |
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178 bool ok = queue->push(obj_to_push); |
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179 assert(ok, "Should have succeeded"); |
| 0 | 180 } |
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181 assert(young_gen()->overflow_list() == NULL, "Error"); |
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182 return num_take_elems > 0; // was something transferred? |
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183 } |
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184 |
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185 void ParScanThreadState::push_on_overflow_stack(oop p) { |
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186 assert(UseCompressedOops, "Else should not call"); |
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187 overflow_stack()->push(p); |
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188 assert(young_gen()->overflow_list() == NULL, "Error"); |
| 0 | 189 } |
| 190 | |
| 191 HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { | |
| 192 | |
| 193 // Otherwise, if the object is small enough, try to reallocate the | |
| 194 // buffer. | |
| 195 HeapWord* obj = NULL; | |
| 196 if (!_to_space_full) { | |
| 197 ParGCAllocBuffer* const plab = to_space_alloc_buffer(); | |
| 198 Space* const sp = to_space(); | |
| 199 if (word_sz * 100 < | |
| 200 ParallelGCBufferWastePct * plab->word_sz()) { | |
| 201 // Is small enough; abandon this buffer and start a new one. | |
| 202 plab->retire(false, false); | |
| 203 size_t buf_size = plab->word_sz(); | |
| 204 HeapWord* buf_space = sp->par_allocate(buf_size); | |
| 205 if (buf_space == NULL) { | |
| 206 const size_t min_bytes = | |
| 207 ParGCAllocBuffer::min_size() << LogHeapWordSize; | |
| 208 size_t free_bytes = sp->free(); | |
| 209 while(buf_space == NULL && free_bytes >= min_bytes) { | |
| 210 buf_size = free_bytes >> LogHeapWordSize; | |
| 211 assert(buf_size == (size_t)align_object_size(buf_size), | |
| 212 "Invariant"); | |
| 213 buf_space = sp->par_allocate(buf_size); | |
| 214 free_bytes = sp->free(); | |
| 215 } | |
| 216 } | |
| 217 if (buf_space != NULL) { | |
| 218 plab->set_word_size(buf_size); | |
| 219 plab->set_buf(buf_space); | |
| 220 record_survivor_plab(buf_space, buf_size); | |
| 221 obj = plab->allocate(word_sz); | |
| 222 // Note that we cannot compare buf_size < word_sz below | |
| 223 // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). | |
| 224 assert(obj != NULL || plab->words_remaining() < word_sz, | |
| 225 "Else should have been able to allocate"); | |
| 226 // It's conceivable that we may be able to use the | |
| 227 // buffer we just grabbed for subsequent small requests | |
| 228 // even if not for this one. | |
| 229 } else { | |
| 230 // We're used up. | |
| 231 _to_space_full = true; | |
| 232 } | |
| 233 | |
| 234 } else { | |
| 235 // Too large; allocate the object individually. | |
| 236 obj = sp->par_allocate(word_sz); | |
| 237 } | |
| 238 } | |
| 239 return obj; | |
| 240 } | |
| 241 | |
| 242 | |
| 243 void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, | |
| 244 size_t word_sz) { | |
| 245 // Is the alloc in the current alloc buffer? | |
| 246 if (to_space_alloc_buffer()->contains(obj)) { | |
| 247 assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), | |
| 248 "Should contain whole object."); | |
| 249 to_space_alloc_buffer()->undo_allocation(obj, word_sz); | |
| 250 } else { | |
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251 CollectedHeap::fill_with_object(obj, word_sz); |
| 0 | 252 } |
| 253 } | |
| 254 | |
| 255 class ParScanThreadStateSet: private ResourceArray { | |
| 256 public: | |
| 257 // Initializes states for the specified number of threads; | |
| 258 ParScanThreadStateSet(int num_threads, | |
| 259 Space& to_space, | |
| 260 ParNewGeneration& gen, | |
| 261 Generation& old_gen, | |
| 262 ObjToScanQueueSet& queue_set, | |
| 263 size_t desired_plab_sz, | |
| 264 ParallelTaskTerminator& term); | |
| 265 inline ParScanThreadState& thread_sate(int i); | |
| 266 int pushes() { return _pushes; } | |
| 267 int pops() { return _pops; } | |
| 268 int steals() { return _steals; } | |
| 269 void reset(); | |
| 270 void flush(); | |
| 271 private: | |
| 272 ParallelTaskTerminator& _term; | |
| 273 ParNewGeneration& _gen; | |
| 274 Generation& _next_gen; | |
| 275 // staticstics | |
| 276 int _pushes; | |
| 277 int _pops; | |
| 278 int _steals; | |
| 279 }; | |
| 280 | |
| 281 | |
| 282 ParScanThreadStateSet::ParScanThreadStateSet( | |
| 283 int num_threads, Space& to_space, ParNewGeneration& gen, | |
| 284 Generation& old_gen, ObjToScanQueueSet& queue_set, | |
| 285 size_t desired_plab_sz, ParallelTaskTerminator& term) | |
| 286 : ResourceArray(sizeof(ParScanThreadState), num_threads), | |
| 287 _gen(gen), _next_gen(old_gen), _term(term), | |
| 288 _pushes(0), _pops(0), _steals(0) | |
| 289 { | |
| 290 assert(num_threads > 0, "sanity check!"); | |
| 291 // Initialize states. | |
| 292 for (int i = 0; i < num_threads; ++i) { | |
| 293 new ((ParScanThreadState*)_data + i) | |
| 294 ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, | |
| 295 desired_plab_sz, term); | |
| 296 } | |
| 297 } | |
| 298 | |
| 299 inline ParScanThreadState& ParScanThreadStateSet::thread_sate(int i) | |
| 300 { | |
| 301 assert(i >= 0 && i < length(), "sanity check!"); | |
| 302 return ((ParScanThreadState*)_data)[i]; | |
| 303 } | |
| 304 | |
| 305 | |
| 306 void ParScanThreadStateSet::reset() | |
| 307 { | |
| 308 _term.reset_for_reuse(); | |
| 309 } | |
| 310 | |
| 311 void ParScanThreadStateSet::flush() | |
| 312 { | |
| 313 for (int i = 0; i < length(); ++i) { | |
| 314 ParScanThreadState& par_scan_state = thread_sate(i); | |
| 315 | |
| 316 // Flush stats related to To-space PLAB activity and | |
| 317 // retire the last buffer. | |
| 318 par_scan_state.to_space_alloc_buffer()-> | |
| 319 flush_stats_and_retire(_gen.plab_stats(), | |
| 320 false /* !retain */); | |
| 321 | |
| 322 // Every thread has its own age table. We need to merge | |
| 323 // them all into one. | |
| 324 ageTable *local_table = par_scan_state.age_table(); | |
| 325 _gen.age_table()->merge(local_table); | |
| 326 | |
| 327 // Inform old gen that we're done. | |
| 328 _next_gen.par_promote_alloc_done(i); | |
| 329 _next_gen.par_oop_since_save_marks_iterate_done(i); | |
| 330 | |
| 331 // Flush stats related to work queue activity (push/pop/steal) | |
| 332 // This could conceivably become a bottleneck; if so, we'll put the | |
| 333 // stat's gathering under the flag. | |
| 334 if (PAR_STATS_ENABLED) { | |
| 335 _pushes += par_scan_state.pushes(); | |
| 336 _pops += par_scan_state.pops(); | |
| 337 _steals += par_scan_state.steals(); | |
| 338 if (ParallelGCVerbose) { | |
| 339 gclog_or_tty->print("Thread %d complete:\n" | |
| 340 " Pushes: %7d Pops: %7d Steals %7d (in %d attempts)\n", | |
| 341 i, par_scan_state.pushes(), par_scan_state.pops(), | |
| 342 par_scan_state.steals(), par_scan_state.steal_attempts()); | |
| 343 if (par_scan_state.overflow_pushes() > 0 || | |
| 344 par_scan_state.overflow_refills() > 0) { | |
| 345 gclog_or_tty->print(" Overflow pushes: %7d " | |
| 346 "Overflow refills: %7d for %d objs.\n", | |
| 347 par_scan_state.overflow_pushes(), | |
| 348 par_scan_state.overflow_refills(), | |
| 349 par_scan_state.overflow_refill_objs()); | |
| 350 } | |
| 351 | |
| 352 double elapsed = par_scan_state.elapsed(); | |
| 353 double strong_roots = par_scan_state.strong_roots_time(); | |
| 354 double term = par_scan_state.term_time(); | |
| 355 gclog_or_tty->print( | |
| 356 " Elapsed: %7.2f ms.\n" | |
| 357 " Strong roots: %7.2f ms (%6.2f%%)\n" | |
| 358 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n", | |
| 359 elapsed * 1000.0, | |
| 360 strong_roots * 1000.0, (strong_roots*100.0/elapsed), | |
| 361 term * 1000.0, (term*100.0/elapsed), | |
| 362 par_scan_state.term_attempts()); | |
| 363 } | |
| 364 } | |
| 365 } | |
| 366 } | |
| 367 | |
| 368 ParScanClosure::ParScanClosure(ParNewGeneration* g, | |
| 369 ParScanThreadState* par_scan_state) : | |
| 370 OopsInGenClosure(g), _par_scan_state(par_scan_state), _g(g) | |
| 371 { | |
| 372 assert(_g->level() == 0, "Optimized for youngest generation"); | |
| 373 _boundary = _g->reserved().end(); | |
| 374 } | |
| 375 | |
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376 void ParScanWithBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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377 void ParScanWithBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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378 |
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379 void ParScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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380 void ParScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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381 |
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382 void ParRootScanWithBarrierTwoGensClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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383 void ParRootScanWithBarrierTwoGensClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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384 |
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385 void ParRootScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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386 void ParRootScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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387 |
| 0 | 388 ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
| 389 ParScanThreadState* par_scan_state) | |
| 390 : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) | |
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391 {} |
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392 |
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393 void ParScanWeakRefClosure::do_oop(oop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
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394 void ParScanWeakRefClosure::do_oop(narrowOop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
| 0 | 395 |
| 396 #ifdef WIN32 | |
| 397 #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ | |
| 398 #endif | |
| 399 | |
| 400 ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( | |
| 401 ParScanThreadState* par_scan_state_, | |
| 402 ParScanWithoutBarrierClosure* to_space_closure_, | |
| 403 ParScanWithBarrierClosure* old_gen_closure_, | |
| 404 ParRootScanWithoutBarrierClosure* to_space_root_closure_, | |
| 405 ParNewGeneration* par_gen_, | |
| 406 ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, | |
| 407 ObjToScanQueueSet* task_queues_, | |
| 408 ParallelTaskTerminator* terminator_) : | |
| 409 | |
| 410 _par_scan_state(par_scan_state_), | |
| 411 _to_space_closure(to_space_closure_), | |
| 412 _old_gen_closure(old_gen_closure_), | |
| 413 _to_space_root_closure(to_space_root_closure_), | |
| 414 _old_gen_root_closure(old_gen_root_closure_), | |
| 415 _par_gen(par_gen_), | |
| 416 _task_queues(task_queues_), | |
| 417 _terminator(terminator_) | |
| 418 {} | |
| 419 | |
| 420 void ParEvacuateFollowersClosure::do_void() { | |
| 421 ObjToScanQueue* work_q = par_scan_state()->work_queue(); | |
| 422 | |
| 423 while (true) { | |
| 424 | |
| 425 // Scan to-space and old-gen objs until we run out of both. | |
| 426 oop obj_to_scan; | |
| 427 par_scan_state()->trim_queues(0); | |
| 428 | |
| 429 // We have no local work, attempt to steal from other threads. | |
| 430 | |
| 431 // attempt to steal work from promoted. | |
| 432 par_scan_state()->note_steal_attempt(); | |
| 433 if (task_queues()->steal(par_scan_state()->thread_num(), | |
| 434 par_scan_state()->hash_seed(), | |
| 435 obj_to_scan)) { | |
| 436 par_scan_state()->note_steal(); | |
| 437 bool res = work_q->push(obj_to_scan); | |
| 438 assert(res, "Empty queue should have room for a push."); | |
| 439 | |
| 440 par_scan_state()->note_push(); | |
| 441 // if successful, goto Start. | |
| 442 continue; | |
| 443 | |
| 444 // try global overflow list. | |
| 445 } else if (par_gen()->take_from_overflow_list(par_scan_state())) { | |
| 446 continue; | |
| 447 } | |
| 448 | |
| 449 // Otherwise, offer termination. | |
| 450 par_scan_state()->start_term_time(); | |
| 451 if (terminator()->offer_termination()) break; | |
| 452 par_scan_state()->end_term_time(); | |
| 453 } | |
| 534 | 454 assert(par_gen()->_overflow_list == NULL && par_gen()->_num_par_pushes == 0, |
| 455 "Broken overflow list?"); | |
| 0 | 456 // Finish the last termination pause. |
| 457 par_scan_state()->end_term_time(); | |
| 458 } | |
| 459 | |
| 460 ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, | |
| 461 HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : | |
| 462 AbstractGangTask("ParNewGeneration collection"), | |
| 463 _gen(gen), _next_gen(next_gen), | |
| 464 _young_old_boundary(young_old_boundary), | |
| 465 _state_set(state_set) | |
| 466 {} | |
| 467 | |
| 468 void ParNewGenTask::work(int i) { | |
| 469 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 470 // Since this is being done in a separate thread, need new resource | |
| 471 // and handle marks. | |
| 472 ResourceMark rm; | |
| 473 HandleMark hm; | |
| 474 // We would need multiple old-gen queues otherwise. | |
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475 assert(gch->n_gens() == 2, "Par young collection currently only works with one older gen."); |
| 0 | 476 |
| 477 Generation* old_gen = gch->next_gen(_gen); | |
| 478 | |
| 479 ParScanThreadState& par_scan_state = _state_set->thread_sate(i); | |
| 480 par_scan_state.set_young_old_boundary(_young_old_boundary); | |
| 481 | |
| 482 par_scan_state.start_strong_roots(); | |
| 483 gch->gen_process_strong_roots(_gen->level(), | |
| 484 true, // Process younger gens, if any, | |
| 485 // as strong roots. | |
| 486 false,// not collecting perm generation. | |
| 487 SharedHeap::SO_AllClasses, | |
| 488 &par_scan_state.older_gen_closure(), | |
| 489 &par_scan_state.to_space_root_closure()); | |
| 490 par_scan_state.end_strong_roots(); | |
| 491 | |
| 492 // "evacuate followers". | |
| 493 par_scan_state.evacuate_followers_closure().do_void(); | |
| 494 } | |
| 495 | |
| 496 #ifdef _MSC_VER | |
| 497 #pragma warning( push ) | |
| 498 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
| 499 #endif | |
| 500 ParNewGeneration:: | |
| 501 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) | |
| 502 : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), | |
| 503 _overflow_list(NULL), | |
| 504 _is_alive_closure(this), | |
| 505 _plab_stats(YoungPLABSize, PLABWeight) | |
| 506 { | |
| 534 | 507 NOT_PRODUCT(_overflow_counter = ParGCWorkQueueOverflowInterval;) |
| 508 NOT_PRODUCT(_num_par_pushes = 0;) | |
| 0 | 509 _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
| 510 guarantee(_task_queues != NULL, "task_queues allocation failure."); | |
| 511 | |
| 512 for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { | |
| 513 ObjToScanQueuePadded *q_padded = new ObjToScanQueuePadded(); | |
| 514 guarantee(q_padded != NULL, "work_queue Allocation failure."); | |
| 515 | |
| 516 _task_queues->register_queue(i1, &q_padded->work_queue); | |
| 517 } | |
| 518 | |
| 519 for (uint i2 = 0; i2 < ParallelGCThreads; i2++) | |
| 520 _task_queues->queue(i2)->initialize(); | |
| 521 | |
| 522 if (UsePerfData) { | |
| 523 EXCEPTION_MARK; | |
| 524 ResourceMark rm; | |
| 525 | |
| 526 const char* cname = | |
| 527 PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); | |
| 528 PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, | |
| 529 ParallelGCThreads, CHECK); | |
| 530 } | |
| 531 } | |
| 532 #ifdef _MSC_VER | |
| 533 #pragma warning( pop ) | |
| 534 #endif | |
| 535 | |
| 536 // ParNewGeneration:: | |
| 537 ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : | |
| 538 DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} | |
| 539 | |
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540 template <class T> |
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541 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop_work(T* p) { |
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542 #ifdef ASSERT |
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543 { |
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544 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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545 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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546 // We never expect to see a null reference being processed |
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547 // as a weak reference. |
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548 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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549 } |
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550 #endif // ASSERT |
| 0 | 551 |
| 552 _par_cl->do_oop_nv(p); | |
| 553 | |
| 554 if (Universe::heap()->is_in_reserved(p)) { | |
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555 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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556 _rs->write_ref_field_gc_par(p, obj); |
| 0 | 557 } |
| 558 } | |
| 559 | |
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560 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(oop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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561 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(narrowOop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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562 |
| 0 | 563 // ParNewGeneration:: |
| 564 KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : | |
| 565 DefNewGeneration::KeepAliveClosure(cl) {} | |
| 566 | |
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567 template <class T> |
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568 void /*ParNewGeneration::*/KeepAliveClosure::do_oop_work(T* p) { |
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569 #ifdef ASSERT |
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570 { |
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571 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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572 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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573 // We never expect to see a null reference being processed |
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574 // as a weak reference. |
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575 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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576 } |
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577 #endif // ASSERT |
| 0 | 578 |
| 579 _cl->do_oop_nv(p); | |
| 580 | |
| 581 if (Universe::heap()->is_in_reserved(p)) { | |
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582 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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583 _rs->write_ref_field_gc_par(p, obj); |
| 0 | 584 } |
| 585 } | |
| 586 | |
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587 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(oop* p) { KeepAliveClosure::do_oop_work(p); } |
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588 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(narrowOop* p) { KeepAliveClosure::do_oop_work(p); } |
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589 |
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590 template <class T> void ScanClosureWithParBarrier::do_oop_work(T* p) { |
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591 T heap_oop = oopDesc::load_heap_oop(p); |
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592 if (!oopDesc::is_null(heap_oop)) { |
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593 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
| 0 | 594 if ((HeapWord*)obj < _boundary) { |
| 595 assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); | |
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596 oop new_obj = obj->is_forwarded() |
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597 ? obj->forwardee() |
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598 : _g->DefNewGeneration::copy_to_survivor_space(obj); |
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599 oopDesc::encode_store_heap_oop_not_null(p, new_obj); |
| 0 | 600 } |
| 601 if (_gc_barrier) { | |
| 602 // If p points to a younger generation, mark the card. | |
| 603 if ((HeapWord*)obj < _gen_boundary) { | |
| 604 _rs->write_ref_field_gc_par(p, obj); | |
| 605 } | |
| 606 } | |
| 607 } | |
| 608 } | |
| 609 | |
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610 void ScanClosureWithParBarrier::do_oop(oop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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611 void ScanClosureWithParBarrier::do_oop(narrowOop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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612 |
| 0 | 613 class ParNewRefProcTaskProxy: public AbstractGangTask { |
| 614 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; | |
| 615 public: | |
| 616 ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, | |
| 617 Generation& next_gen, | |
| 618 HeapWord* young_old_boundary, | |
| 619 ParScanThreadStateSet& state_set); | |
| 620 | |
| 621 private: | |
| 622 virtual void work(int i); | |
| 623 | |
| 624 private: | |
| 625 ParNewGeneration& _gen; | |
| 626 ProcessTask& _task; | |
| 627 Generation& _next_gen; | |
| 628 HeapWord* _young_old_boundary; | |
| 629 ParScanThreadStateSet& _state_set; | |
| 630 }; | |
| 631 | |
| 632 ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( | |
| 633 ProcessTask& task, ParNewGeneration& gen, | |
| 634 Generation& next_gen, | |
| 635 HeapWord* young_old_boundary, | |
| 636 ParScanThreadStateSet& state_set) | |
| 637 : AbstractGangTask("ParNewGeneration parallel reference processing"), | |
| 638 _gen(gen), | |
| 639 _task(task), | |
| 640 _next_gen(next_gen), | |
| 641 _young_old_boundary(young_old_boundary), | |
| 642 _state_set(state_set) | |
| 643 { | |
| 644 } | |
| 645 | |
| 646 void ParNewRefProcTaskProxy::work(int i) | |
| 647 { | |
| 648 ResourceMark rm; | |
| 649 HandleMark hm; | |
| 650 ParScanThreadState& par_scan_state = _state_set.thread_sate(i); | |
| 651 par_scan_state.set_young_old_boundary(_young_old_boundary); | |
| 652 _task.work(i, par_scan_state.is_alive_closure(), | |
| 653 par_scan_state.keep_alive_closure(), | |
| 654 par_scan_state.evacuate_followers_closure()); | |
| 655 } | |
| 656 | |
| 657 class ParNewRefEnqueueTaskProxy: public AbstractGangTask { | |
| 658 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 659 EnqueueTask& _task; | |
| 660 | |
| 661 public: | |
| 662 ParNewRefEnqueueTaskProxy(EnqueueTask& task) | |
| 663 : AbstractGangTask("ParNewGeneration parallel reference enqueue"), | |
| 664 _task(task) | |
| 665 { } | |
| 666 | |
| 667 virtual void work(int i) | |
| 668 { | |
| 669 _task.work(i); | |
| 670 } | |
| 671 }; | |
| 672 | |
| 673 | |
| 674 void ParNewRefProcTaskExecutor::execute(ProcessTask& task) | |
| 675 { | |
| 676 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 677 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 678 "not a generational heap"); | |
| 679 WorkGang* workers = gch->workers(); | |
| 680 assert(workers != NULL, "Need parallel worker threads."); | |
| 681 ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), | |
| 682 _generation.reserved().end(), _state_set); | |
| 683 workers->run_task(&rp_task); | |
| 684 _state_set.reset(); | |
| 685 } | |
| 686 | |
| 687 void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 688 { | |
| 689 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 690 WorkGang* workers = gch->workers(); | |
| 691 assert(workers != NULL, "Need parallel worker threads."); | |
| 692 ParNewRefEnqueueTaskProxy enq_task(task); | |
| 693 workers->run_task(&enq_task); | |
| 694 } | |
| 695 | |
| 696 void ParNewRefProcTaskExecutor::set_single_threaded_mode() | |
| 697 { | |
| 698 _state_set.flush(); | |
| 699 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 700 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 701 gch->save_marks(); | |
| 702 } | |
| 703 | |
| 704 ScanClosureWithParBarrier:: | |
| 705 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : | |
| 706 ScanClosure(g, gc_barrier) {} | |
| 707 | |
| 708 EvacuateFollowersClosureGeneral:: | |
| 709 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, | |
| 710 OopsInGenClosure* cur, | |
| 711 OopsInGenClosure* older) : | |
| 712 _gch(gch), _level(level), | |
| 713 _scan_cur_or_nonheap(cur), _scan_older(older) | |
| 714 {} | |
| 715 | |
| 716 void EvacuateFollowersClosureGeneral::do_void() { | |
| 717 do { | |
| 718 // Beware: this call will lead to closure applications via virtual | |
| 719 // calls. | |
| 720 _gch->oop_since_save_marks_iterate(_level, | |
| 721 _scan_cur_or_nonheap, | |
| 722 _scan_older); | |
| 723 } while (!_gch->no_allocs_since_save_marks(_level)); | |
| 724 } | |
| 725 | |
| 726 | |
| 727 bool ParNewGeneration::_avoid_promotion_undo = false; | |
| 728 | |
| 729 void ParNewGeneration::adjust_desired_tenuring_threshold() { | |
| 730 // Set the desired survivor size to half the real survivor space | |
| 731 _tenuring_threshold = | |
| 732 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); | |
| 733 } | |
| 734 | |
| 735 // A Generation that does parallel young-gen collection. | |
| 736 | |
| 737 void ParNewGeneration::collect(bool full, | |
| 738 bool clear_all_soft_refs, | |
| 739 size_t size, | |
| 740 bool is_tlab) { | |
| 741 assert(full || size > 0, "otherwise we don't want to collect"); | |
| 742 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 743 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 744 "not a CMS generational heap"); | |
| 745 AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); | |
| 746 WorkGang* workers = gch->workers(); | |
| 747 _next_gen = gch->next_gen(this); | |
| 748 assert(_next_gen != NULL, | |
| 749 "This must be the youngest gen, and not the only gen"); | |
| 750 assert(gch->n_gens() == 2, | |
| 751 "Par collection currently only works with single older gen."); | |
| 752 // Do we have to avoid promotion_undo? | |
| 753 if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { | |
| 754 set_avoid_promotion_undo(true); | |
| 755 } | |
| 756 | |
| 757 // If the next generation is too full to accomodate worst-case promotion | |
| 758 // from this generation, pass on collection; let the next generation | |
| 759 // do it. | |
| 760 if (!collection_attempt_is_safe()) { | |
| 761 gch->set_incremental_collection_will_fail(); | |
| 762 return; | |
| 763 } | |
| 764 assert(to()->is_empty(), "Else not collection_attempt_is_safe"); | |
| 765 | |
| 766 init_assuming_no_promotion_failure(); | |
| 767 | |
| 768 if (UseAdaptiveSizePolicy) { | |
| 769 set_survivor_overflow(false); | |
| 770 size_policy->minor_collection_begin(); | |
| 771 } | |
| 772 | |
| 773 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); | |
| 774 // Capture heap used before collection (for printing). | |
| 775 size_t gch_prev_used = gch->used(); | |
| 776 | |
| 777 SpecializationStats::clear(); | |
| 778 | |
| 779 age_table()->clear(); | |
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780 to()->clear(SpaceDecorator::Mangle); |
| 0 | 781 |
| 782 gch->save_marks(); | |
| 783 assert(workers != NULL, "Need parallel worker threads."); | |
| 784 ParallelTaskTerminator _term(workers->total_workers(), task_queues()); | |
| 785 ParScanThreadStateSet thread_state_set(workers->total_workers(), | |
| 786 *to(), *this, *_next_gen, *task_queues(), | |
| 787 desired_plab_sz(), _term); | |
| 788 | |
| 789 ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); | |
| 790 int n_workers = workers->total_workers(); | |
| 791 gch->set_par_threads(n_workers); | |
| 792 gch->change_strong_roots_parity(); | |
| 793 gch->rem_set()->prepare_for_younger_refs_iterate(true); | |
| 794 // It turns out that even when we're using 1 thread, doing the work in a | |
| 795 // separate thread causes wide variance in run times. We can't help this | |
| 796 // in the multi-threaded case, but we special-case n=1 here to get | |
| 797 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 798 if (n_workers > 1) { | |
| 799 workers->run_task(&tsk); | |
| 800 } else { | |
| 801 tsk.work(0); | |
| 802 } | |
| 803 thread_state_set.reset(); | |
| 804 | |
| 805 if (PAR_STATS_ENABLED && ParallelGCVerbose) { | |
| 806 gclog_or_tty->print("Thread totals:\n" | |
| 807 " Pushes: %7d Pops: %7d Steals %7d (sum = %7d).\n", | |
| 808 thread_state_set.pushes(), thread_state_set.pops(), | |
| 809 thread_state_set.steals(), | |
| 810 thread_state_set.pops()+thread_state_set.steals()); | |
| 811 } | |
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812 assert(thread_state_set.pushes() == thread_state_set.pops() |
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813 + thread_state_set.steals(), |
| 0 | 814 "Or else the queues are leaky."); |
| 815 | |
| 816 // Process (weak) reference objects found during scavenge. | |
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817 ReferenceProcessor* rp = ref_processor(); |
| 0 | 818 IsAliveClosure is_alive(this); |
| 819 ScanWeakRefClosure scan_weak_ref(this); | |
| 820 KeepAliveClosure keep_alive(&scan_weak_ref); | |
| 821 ScanClosure scan_without_gc_barrier(this, false); | |
| 822 ScanClosureWithParBarrier scan_with_gc_barrier(this, true); | |
| 823 set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); | |
| 824 EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, | |
| 825 &scan_without_gc_barrier, &scan_with_gc_barrier); | |
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826 rp->setup_policy(clear_all_soft_refs); |
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827 if (rp->processing_is_mt()) { |
| 0 | 828 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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829 rp->process_discovered_references(&is_alive, &keep_alive, |
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830 &evacuate_followers, &task_executor); |
| 0 | 831 } else { |
| 832 thread_state_set.flush(); | |
| 833 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 834 gch->save_marks(); | |
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835 rp->process_discovered_references(&is_alive, &keep_alive, |
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836 &evacuate_followers, NULL); |
| 0 | 837 } |
| 838 if (!promotion_failed()) { | |
| 839 // Swap the survivor spaces. | |
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840 eden()->clear(SpaceDecorator::Mangle); |
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841 from()->clear(SpaceDecorator::Mangle); |
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842 if (ZapUnusedHeapArea) { |
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843 // This is now done here because of the piece-meal mangling which |
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844 // can check for valid mangling at intermediate points in the |
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845 // collection(s). When a minor collection fails to collect |
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846 // sufficient space resizing of the young generation can occur |
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847 // an redistribute the spaces in the young generation. Mangle |
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848 // here so that unzapped regions don't get distributed to |
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849 // other spaces. |
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850 to()->mangle_unused_area(); |
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851 } |
| 0 | 852 swap_spaces(); |
| 853 | |
| 854 assert(to()->is_empty(), "to space should be empty now"); | |
| 855 } else { | |
| 856 assert(HandlePromotionFailure, | |
| 857 "Should only be here if promotion failure handling is on"); | |
| 858 if (_promo_failure_scan_stack != NULL) { | |
| 859 // Can be non-null because of reference processing. | |
| 860 // Free stack with its elements. | |
| 861 delete _promo_failure_scan_stack; | |
| 862 _promo_failure_scan_stack = NULL; | |
| 863 } | |
| 864 remove_forwarding_pointers(); | |
| 865 if (PrintGCDetails) { | |
| 866 gclog_or_tty->print(" (promotion failed)"); | |
| 867 } | |
| 868 // All the spaces are in play for mark-sweep. | |
| 869 swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. | |
| 870 from()->set_next_compaction_space(to()); | |
| 871 gch->set_incremental_collection_will_fail(); | |
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872 |
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873 // Reset the PromotionFailureALot counters. |
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874 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) |
| 0 | 875 } |
| 876 // set new iteration safe limit for the survivor spaces | |
| 877 from()->set_concurrent_iteration_safe_limit(from()->top()); | |
| 878 to()->set_concurrent_iteration_safe_limit(to()->top()); | |
| 879 | |
| 880 adjust_desired_tenuring_threshold(); | |
| 881 if (ResizePLAB) { | |
| 882 plab_stats()->adjust_desired_plab_sz(); | |
| 883 } | |
| 884 | |
| 885 if (PrintGC && !PrintGCDetails) { | |
| 886 gch->print_heap_change(gch_prev_used); | |
| 887 } | |
| 888 | |
| 889 if (UseAdaptiveSizePolicy) { | |
| 890 size_policy->minor_collection_end(gch->gc_cause()); | |
| 891 size_policy->avg_survived()->sample(from()->used()); | |
| 892 } | |
| 893 | |
| 894 update_time_of_last_gc(os::javaTimeMillis()); | |
| 895 | |
| 896 SpecializationStats::print(); | |
| 897 | |
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898 rp->set_enqueuing_is_done(true); |
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899 if (rp->processing_is_mt()) { |
| 0 | 900 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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901 rp->enqueue_discovered_references(&task_executor); |
| 0 | 902 } else { |
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903 rp->enqueue_discovered_references(NULL); |
| 0 | 904 } |
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905 rp->verify_no_references_recorded(); |
| 0 | 906 } |
| 907 | |
| 908 static int sum; | |
| 909 void ParNewGeneration::waste_some_time() { | |
| 910 for (int i = 0; i < 100; i++) { | |
| 911 sum += i; | |
| 912 } | |
| 913 } | |
| 914 | |
| 915 static const oop ClaimedForwardPtr = oop(0x4); | |
| 916 | |
| 917 // Because of concurrency, there are times where an object for which | |
| 918 // "is_forwarded()" is true contains an "interim" forwarding pointer | |
| 919 // value. Such a value will soon be overwritten with a real value. | |
| 920 // This method requires "obj" to have a forwarding pointer, and waits, if | |
| 921 // necessary for a real one to be inserted, and returns it. | |
| 922 | |
| 923 oop ParNewGeneration::real_forwardee(oop obj) { | |
| 924 oop forward_ptr = obj->forwardee(); | |
| 925 if (forward_ptr != ClaimedForwardPtr) { | |
| 926 return forward_ptr; | |
| 927 } else { | |
| 928 return real_forwardee_slow(obj); | |
| 929 } | |
| 930 } | |
| 931 | |
| 932 oop ParNewGeneration::real_forwardee_slow(oop obj) { | |
| 933 // Spin-read if it is claimed but not yet written by another thread. | |
| 934 oop forward_ptr = obj->forwardee(); | |
| 935 while (forward_ptr == ClaimedForwardPtr) { | |
| 936 waste_some_time(); | |
| 937 assert(obj->is_forwarded(), "precondition"); | |
| 938 forward_ptr = obj->forwardee(); | |
| 939 } | |
| 940 return forward_ptr; | |
| 941 } | |
| 942 | |
| 943 #ifdef ASSERT | |
| 944 bool ParNewGeneration::is_legal_forward_ptr(oop p) { | |
| 945 return | |
| 946 (_avoid_promotion_undo && p == ClaimedForwardPtr) | |
| 947 || Universe::heap()->is_in_reserved(p); | |
| 948 } | |
| 949 #endif | |
| 950 | |
| 951 void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { | |
| 952 if ((m != markOopDesc::prototype()) && | |
| 953 (!UseBiasedLocking || (m != markOopDesc::biased_locking_prototype()))) { | |
| 954 MutexLocker ml(ParGCRareEvent_lock); | |
| 955 DefNewGeneration::preserve_mark_if_necessary(obj, m); | |
| 956 } | |
| 957 } | |
| 958 | |
| 959 // Multiple GC threads may try to promote an object. If the object | |
| 960 // is successfully promoted, a forwarding pointer will be installed in | |
| 961 // the object in the young generation. This method claims the right | |
| 962 // to install the forwarding pointer before it copies the object, | |
| 963 // thus avoiding the need to undo the copy as in | |
| 964 // copy_to_survivor_space_avoiding_with_undo. | |
| 965 | |
| 966 oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( | |
| 967 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
| 968 // In the sequential version, this assert also says that the object is | |
| 969 // not forwarded. That might not be the case here. It is the case that | |
| 970 // the caller observed it to be not forwarded at some time in the past. | |
| 971 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
| 972 | |
| 973 // The sequential code read "old->age()" below. That doesn't work here, | |
| 974 // since the age is in the mark word, and that might be overwritten with | |
| 975 // a forwarding pointer by a parallel thread. So we must save the mark | |
| 976 // word in a local and then analyze it. | |
| 977 oopDesc dummyOld; | |
| 978 dummyOld.set_mark(m); | |
| 979 assert(!dummyOld.is_forwarded(), | |
| 980 "should not be called with forwarding pointer mark word."); | |
| 981 | |
| 982 oop new_obj = NULL; | |
| 983 oop forward_ptr; | |
| 984 | |
| 985 // Try allocating obj in to-space (unless too old) | |
| 986 if (dummyOld.age() < tenuring_threshold()) { | |
| 987 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
| 988 if (new_obj == NULL) { | |
| 989 set_survivor_overflow(true); | |
| 990 } | |
| 991 } | |
| 992 | |
| 993 if (new_obj == NULL) { | |
| 994 // Either to-space is full or we decided to promote | |
| 995 // try allocating obj tenured | |
| 996 | |
| 997 // Attempt to install a null forwarding pointer (atomically), | |
| 998 // to claim the right to install the real forwarding pointer. | |
| 999 forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); | |
| 1000 if (forward_ptr != NULL) { | |
| 1001 // someone else beat us to it. | |
| 1002 return real_forwardee(old); | |
| 1003 } | |
| 1004 | |
| 1005 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
| 1006 old, m, sz); | |
| 1007 | |
| 1008 if (new_obj == NULL) { | |
| 1009 if (!HandlePromotionFailure) { | |
| 1010 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag | |
| 1011 // is incorrectly set. In any case, its seriously wrong to be here! | |
| 1012 vm_exit_out_of_memory(sz*wordSize, "promotion"); | |
| 1013 } | |
| 1014 // promotion failed, forward to self | |
| 1015 _promotion_failed = true; | |
| 1016 new_obj = old; | |
| 1017 | |
| 1018 preserve_mark_if_necessary(old, m); | |
| 1019 } | |
| 1020 | |
| 1021 old->forward_to(new_obj); | |
| 1022 forward_ptr = NULL; | |
| 1023 } else { | |
| 1024 // Is in to-space; do copying ourselves. | |
| 1025 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
| 1026 forward_ptr = old->forward_to_atomic(new_obj); | |
| 1027 // Restore the mark word copied above. | |
| 1028 new_obj->set_mark(m); | |
| 1029 // Increment age if obj still in new generation | |
| 1030 new_obj->incr_age(); | |
| 1031 par_scan_state->age_table()->add(new_obj, sz); | |
| 1032 } | |
| 1033 assert(new_obj != NULL, "just checking"); | |
| 1034 | |
| 1035 if (forward_ptr == NULL) { | |
| 1036 oop obj_to_push = new_obj; | |
| 1037 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
| 1038 // Length field used as index of next element to be scanned. | |
| 1039 // Real length can be obtained from real_forwardee() | |
| 1040 arrayOop(old)->set_length(0); | |
| 1041 obj_to_push = old; | |
| 1042 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
| 1043 "push forwarded object"); | |
| 1044 } | |
| 1045 // Push it on one of the queues of to-be-scanned objects. | |
| 534 | 1046 bool simulate_overflow = false; |
| 1047 NOT_PRODUCT( | |
| 1048 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
| 1049 // simulate a stack overflow | |
| 1050 simulate_overflow = true; | |
| 1051 } | |
| 1052 ) | |
| 1053 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
| 0 | 1054 // Add stats for overflow pushes. |
| 1055 if (Verbose && PrintGCDetails) { | |
| 1056 gclog_or_tty->print("queue overflow!\n"); | |
| 1057 } | |
| 534 | 1058 push_on_overflow_list(old, par_scan_state); |
| 0 | 1059 par_scan_state->note_overflow_push(); |
| 1060 } | |
| 1061 par_scan_state->note_push(); | |
| 1062 | |
| 1063 return new_obj; | |
| 1064 } | |
| 1065 | |
| 1066 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
| 1067 // allocate it? | |
| 1068 if (is_in_reserved(new_obj)) { | |
| 1069 // Must be in to_space. | |
| 1070 assert(to()->is_in_reserved(new_obj), "Checking"); | |
| 1071 if (forward_ptr == ClaimedForwardPtr) { | |
| 1072 // Wait to get the real forwarding pointer value. | |
| 1073 forward_ptr = real_forwardee(old); | |
| 1074 } | |
| 1075 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
| 1076 } | |
| 1077 | |
| 1078 return forward_ptr; | |
| 1079 } | |
| 1080 | |
| 1081 | |
| 1082 // Multiple GC threads may try to promote the same object. If two | |
| 1083 // or more GC threads copy the object, only one wins the race to install | |
| 1084 // the forwarding pointer. The other threads have to undo their copy. | |
| 1085 | |
| 1086 oop ParNewGeneration::copy_to_survivor_space_with_undo( | |
| 1087 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
| 1088 | |
| 1089 // In the sequential version, this assert also says that the object is | |
| 1090 // not forwarded. That might not be the case here. It is the case that | |
| 1091 // the caller observed it to be not forwarded at some time in the past. | |
| 1092 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
| 1093 | |
| 1094 // The sequential code read "old->age()" below. That doesn't work here, | |
| 1095 // since the age is in the mark word, and that might be overwritten with | |
| 1096 // a forwarding pointer by a parallel thread. So we must save the mark | |
| 1097 // word here, install it in a local oopDesc, and then analyze it. | |
| 1098 oopDesc dummyOld; | |
| 1099 dummyOld.set_mark(m); | |
| 1100 assert(!dummyOld.is_forwarded(), | |
| 1101 "should not be called with forwarding pointer mark word."); | |
| 1102 | |
| 1103 bool failed_to_promote = false; | |
| 1104 oop new_obj = NULL; | |
| 1105 oop forward_ptr; | |
| 1106 | |
| 1107 // Try allocating obj in to-space (unless too old) | |
| 1108 if (dummyOld.age() < tenuring_threshold()) { | |
| 1109 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
| 1110 if (new_obj == NULL) { | |
| 1111 set_survivor_overflow(true); | |
| 1112 } | |
| 1113 } | |
| 1114 | |
| 1115 if (new_obj == NULL) { | |
| 1116 // Either to-space is full or we decided to promote | |
| 1117 // try allocating obj tenured | |
| 1118 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
| 1119 old, m, sz); | |
| 1120 | |
| 1121 if (new_obj == NULL) { | |
| 1122 if (!HandlePromotionFailure) { | |
| 1123 // A failed promotion likely means the MaxLiveObjectEvacuationRatio | |
| 1124 // flag is incorrectly set. In any case, its seriously wrong to be | |
| 1125 // here! | |
| 1126 vm_exit_out_of_memory(sz*wordSize, "promotion"); | |
| 1127 } | |
| 1128 // promotion failed, forward to self | |
| 1129 forward_ptr = old->forward_to_atomic(old); | |
| 1130 new_obj = old; | |
| 1131 | |
| 1132 if (forward_ptr != NULL) { | |
| 1133 return forward_ptr; // someone else succeeded | |
| 1134 } | |
| 1135 | |
| 1136 _promotion_failed = true; | |
| 1137 failed_to_promote = true; | |
| 1138 | |
| 1139 preserve_mark_if_necessary(old, m); | |
| 1140 } | |
| 1141 } else { | |
| 1142 // Is in to-space; do copying ourselves. | |
| 1143 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
| 1144 // Restore the mark word copied above. | |
| 1145 new_obj->set_mark(m); | |
| 1146 // Increment age if new_obj still in new generation | |
| 1147 new_obj->incr_age(); | |
| 1148 par_scan_state->age_table()->add(new_obj, sz); | |
| 1149 } | |
| 1150 assert(new_obj != NULL, "just checking"); | |
| 1151 | |
| 1152 // Now attempt to install the forwarding pointer (atomically). | |
| 1153 // We have to copy the mark word before overwriting with forwarding | |
| 1154 // ptr, so we can restore it below in the copy. | |
| 1155 if (!failed_to_promote) { | |
| 1156 forward_ptr = old->forward_to_atomic(new_obj); | |
| 1157 } | |
| 1158 | |
| 1159 if (forward_ptr == NULL) { | |
| 1160 oop obj_to_push = new_obj; | |
| 1161 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
| 1162 // Length field used as index of next element to be scanned. | |
| 1163 // Real length can be obtained from real_forwardee() | |
| 1164 arrayOop(old)->set_length(0); | |
| 1165 obj_to_push = old; | |
| 1166 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
| 1167 "push forwarded object"); | |
| 1168 } | |
| 1169 // Push it on one of the queues of to-be-scanned objects. | |
| 534 | 1170 bool simulate_overflow = false; |
| 1171 NOT_PRODUCT( | |
| 1172 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
| 1173 // simulate a stack overflow | |
| 1174 simulate_overflow = true; | |
| 1175 } | |
| 1176 ) | |
| 1177 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
| 0 | 1178 // Add stats for overflow pushes. |
| 534 | 1179 push_on_overflow_list(old, par_scan_state); |
| 0 | 1180 par_scan_state->note_overflow_push(); |
| 1181 } | |
| 1182 par_scan_state->note_push(); | |
| 1183 | |
| 1184 return new_obj; | |
| 1185 } | |
| 1186 | |
| 1187 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
| 1188 // allocate it? | |
| 1189 if (is_in_reserved(new_obj)) { | |
| 1190 // Must be in to_space. | |
| 1191 assert(to()->is_in_reserved(new_obj), "Checking"); | |
| 1192 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
| 1193 } else { | |
| 1194 assert(!_avoid_promotion_undo, "Should not be here if avoiding."); | |
| 1195 _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), | |
| 1196 (HeapWord*)new_obj, sz); | |
| 1197 } | |
| 1198 | |
| 1199 return forward_ptr; | |
| 1200 } | |
| 1201 | |
| 534 | 1202 #ifndef PRODUCT |
| 1203 // It's OK to call this multi-threaded; the worst thing | |
| 1204 // that can happen is that we'll get a bunch of closely | |
| 1205 // spaced simulated oveflows, but that's OK, in fact | |
| 1206 // probably good as it would exercise the overflow code | |
| 1207 // under contention. | |
| 1208 bool ParNewGeneration::should_simulate_overflow() { | |
| 1209 if (_overflow_counter-- <= 0) { // just being defensive | |
| 1210 _overflow_counter = ParGCWorkQueueOverflowInterval; | |
| 1211 return true; | |
| 1212 } else { | |
| 1213 return false; | |
| 1214 } | |
| 1215 } | |
| 1216 #endif | |
| 1217 | |
|
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1218 // In case we are using compressed oops, we need to be careful. |
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1219 // If the object being pushed is an object array, then its length |
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1220 // field keeps track of the "grey boundary" at which the next |
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1221 // incremental scan will be done (see ParGCArrayScanChunk). |
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1222 // When using compressed oops, this length field is kept in the |
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1223 // lower 32 bits of the erstwhile klass word and cannot be used |
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1224 // for the overflow chaining pointer (OCP below). As such the OCP |
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1225 // would itself need to be compressed into the top 32-bits in this |
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1226 // case. Unfortunately, see below, in the event that we have a |
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1227 // promotion failure, the node to be pushed on the list can be |
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1228 // outside of the Java heap, so the heap-based pointer compression |
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1229 // would not work (we would have potential aliasing between C-heap |
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1230 // and Java-heap pointers). For this reason, when using compressed |
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1231 // oops, we simply use a worker-thread-local, non-shared overflow |
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1232 // list in the form of a growable array, with a slightly different |
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1233 // overflow stack draining strategy. If/when we start using fat |
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1234 // stacks here, we can go back to using (fat) pointer chains |
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1235 // (although some performance comparisons would be useful since |
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1236 // single global lists have their own performance disadvantages |
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1237 // as we were made painfully aware not long ago, see 6786503). |
| 534 | 1238 #define BUSY (oop(0x1aff1aff)) |
| 1239 void ParNewGeneration::push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state) { | |
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1240 assert(is_in_reserved(from_space_obj), "Should be from this generation"); |
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1241 if (UseCompressedOops) { |
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1242 // In the case of compressed oops, we use a private, not-shared |
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1243 // overflow stack. |
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1244 par_scan_state->push_on_overflow_stack(from_space_obj); |
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1245 } else { |
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1246 // if the object has been forwarded to itself, then we cannot |
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1247 // use the klass pointer for the linked list. Instead we have |
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1248 // to allocate an oopDesc in the C-Heap and use that for the linked list. |
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1249 // XXX This is horribly inefficient when a promotion failure occurs |
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1250 // and should be fixed. XXX FIX ME !!! |
| 534 | 1251 #ifndef PRODUCT |
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1252 Atomic::inc_ptr(&_num_par_pushes); |
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1253 assert(_num_par_pushes > 0, "Tautology"); |
| 534 | 1254 #endif |
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1255 if (from_space_obj->forwardee() == from_space_obj) { |
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1256 oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1); |
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1257 listhead->forward_to(from_space_obj); |
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1258 from_space_obj = listhead; |
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1259 } |
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1260 oop observed_overflow_list = _overflow_list; |
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1261 oop cur_overflow_list; |
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1262 do { |
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1263 cur_overflow_list = observed_overflow_list; |
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1264 if (cur_overflow_list != BUSY) { |
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1265 from_space_obj->set_klass_to_list_ptr(cur_overflow_list); |
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1266 } else { |
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1267 from_space_obj->set_klass_to_list_ptr(NULL); |
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1268 } |
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1269 observed_overflow_list = |
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1270 (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
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1271 } while (cur_overflow_list != observed_overflow_list); |
| 0 | 1272 } |
| 1273 } | |
| 1274 | |
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1275 bool ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { |
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1276 bool res; |
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1277 |
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1278 if (UseCompressedOops) { |
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1279 res = par_scan_state->take_from_overflow_stack(); |
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1280 } else { |
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1281 res = take_from_overflow_list_work(par_scan_state); |
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1282 } |
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1283 return res; |
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1284 } |
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1285 |
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1286 |
| 534 | 1287 // *NOTE*: The overflow list manipulation code here and |
| 1288 // in CMSCollector:: are very similar in shape, | |
| 1289 // except that in the CMS case we thread the objects | |
| 1290 // directly into the list via their mark word, and do | |
| 1291 // not need to deal with special cases below related | |
| 1292 // to chunking of object arrays and promotion failure | |
| 1293 // handling. | |
| 1294 // CR 6797058 has been filed to attempt consolidation of | |
| 1295 // the common code. | |
| 1296 // Because of the common code, if you make any changes in | |
| 1297 // the code below, please check the CMS version to see if | |
| 1298 // similar changes might be needed. | |
| 1299 // See CMSCollector::par_take_from_overflow_list() for | |
| 1300 // more extensive documentation comments. | |
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1301 bool ParNewGeneration::take_from_overflow_list_work(ParScanThreadState* par_scan_state) { |
| 0 | 1302 ObjToScanQueue* work_q = par_scan_state->work_queue(); |
| 1303 // How many to take? | |
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1304 size_t objsFromOverflow = MIN2((size_t)(work_q->max_elems() - work_q->size())/4, |
| 534 | 1305 (size_t)ParGCDesiredObjsFromOverflowList); |
| 0 | 1306 |
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1307 assert(par_scan_state->overflow_stack() == NULL, "Error"); |
| 0 | 1308 if (_overflow_list == NULL) return false; |
| 1309 | |
| 1310 // Otherwise, there was something there; try claiming the list. | |
| 534 | 1311 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 1312 // Trim off a prefix of at most objsFromOverflow items | |
| 1313 Thread* tid = Thread::current(); | |
| 1314 size_t spin_count = (size_t)ParallelGCThreads; | |
| 1315 size_t sleep_time_millis = MAX2((size_t)1, objsFromOverflow/100); | |
| 1316 for (size_t spin = 0; prefix == BUSY && spin < spin_count; spin++) { | |
| 1317 // someone grabbed it before we did ... | |
| 1318 // ... we spin for a short while... | |
| 1319 os::sleep(tid, sleep_time_millis, false); | |
| 1320 if (_overflow_list == NULL) { | |
| 1321 // nothing left to take | |
| 1322 return false; | |
| 1323 } else if (_overflow_list != BUSY) { | |
| 1324 // try and grab the prefix | |
| 1325 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 1326 } | |
| 0 | 1327 } |
| 534 | 1328 if (prefix == NULL || prefix == BUSY) { |
| 1329 // Nothing to take or waited long enough | |
| 1330 if (prefix == NULL) { | |
| 1331 // Write back the NULL in case we overwrote it with BUSY above | |
| 1332 // and it is still the same value. | |
| 1333 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 1334 } | |
| 1335 return false; | |
| 1336 } | |
| 1337 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 1338 size_t i = 1; | |
| 0 | 1339 oop cur = prefix; |
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1340 while (i < objsFromOverflow && cur->klass_or_null() != NULL) { |
| 0 | 1341 i++; cur = oop(cur->klass()); |
| 1342 } | |
| 1343 | |
| 1344 // Reattach remaining (suffix) to overflow list | |
| 534 | 1345 if (cur->klass_or_null() == NULL) { |
| 1346 // Write back the NULL in lieu of the BUSY we wrote | |
| 1347 // above and it is still the same value. | |
| 1348 if (_overflow_list == BUSY) { | |
| 1349 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 0 | 1350 } |
| 534 | 1351 } else { |
| 1352 assert(cur->klass_or_null() != BUSY, "Error"); | |
| 1353 oop suffix = oop(cur->klass()); // suffix will be put back on global list | |
| 1354 cur->set_klass_to_list_ptr(NULL); // break off suffix | |
| 1355 // It's possible that the list is still in the empty(busy) state | |
| 1356 // we left it in a short while ago; in that case we may be | |
| 1357 // able to place back the suffix. | |
| 1358 oop observed_overflow_list = _overflow_list; | |
| 1359 oop cur_overflow_list = observed_overflow_list; | |
| 1360 bool attached = false; | |
| 1361 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 1362 observed_overflow_list = | |
| 1363 (oop) Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
| 1364 if (cur_overflow_list == observed_overflow_list) { | |
| 1365 attached = true; | |
| 1366 break; | |
| 1367 } else cur_overflow_list = observed_overflow_list; | |
| 1368 } | |
| 1369 if (!attached) { | |
| 1370 // Too bad, someone else got in in between; we'll need to do a splice. | |
| 1371 // Find the last item of suffix list | |
| 1372 oop last = suffix; | |
| 1373 while (last->klass_or_null() != NULL) { | |
| 1374 last = oop(last->klass()); | |
| 1375 } | |
| 1376 // Atomically prepend suffix to current overflow list | |
| 1377 observed_overflow_list = _overflow_list; | |
| 1378 do { | |
| 1379 cur_overflow_list = observed_overflow_list; | |
| 1380 if (cur_overflow_list != BUSY) { | |
| 1381 // Do the splice ... | |
| 1382 last->set_klass_to_list_ptr(cur_overflow_list); | |
| 1383 } else { // cur_overflow_list == BUSY | |
| 1384 last->set_klass_to_list_ptr(NULL); | |
| 1385 } | |
| 1386 observed_overflow_list = | |
| 1387 (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
| 1388 } while (cur_overflow_list != observed_overflow_list); | |
| 0 | 1389 } |
| 1390 } | |
| 1391 | |
| 1392 // Push objects on prefix list onto this thread's work queue | |
| 534 | 1393 assert(prefix != NULL && prefix != BUSY, "program logic"); |
| 0 | 1394 cur = prefix; |
| 534 | 1395 ssize_t n = 0; |
| 0 | 1396 while (cur != NULL) { |
| 1397 oop obj_to_push = cur->forwardee(); | |
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1398 oop next = oop(cur->klass_or_null()); |
| 0 | 1399 cur->set_klass(obj_to_push->klass()); |
| 534 | 1400 // This may be an array object that is self-forwarded. In that case, the list pointer |
| 1401 // space, cur, is not in the Java heap, but rather in the C-heap and should be freed. | |
| 1402 if (!is_in_reserved(cur)) { | |
| 1403 // This can become a scaling bottleneck when there is work queue overflow coincident | |
| 1404 // with promotion failure. | |
| 1405 oopDesc* f = cur; | |
| 1406 FREE_C_HEAP_ARRAY(oopDesc, f); | |
| 1407 } else if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { | |
| 0 | 1408 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
| 534 | 1409 obj_to_push = cur; |
| 0 | 1410 } |
| 534 | 1411 bool ok = work_q->push(obj_to_push); |
| 1412 assert(ok, "Should have succeeded"); | |
| 0 | 1413 cur = next; |
| 1414 n++; | |
| 1415 } | |
| 1416 par_scan_state->note_overflow_refill(n); | |
| 534 | 1417 #ifndef PRODUCT |
| 1418 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 1419 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 1420 #endif | |
| 0 | 1421 return true; |
| 1422 } | |
| 534 | 1423 #undef BUSY |
| 0 | 1424 |
| 1425 void ParNewGeneration::ref_processor_init() | |
| 1426 { | |
| 1427 if (_ref_processor == NULL) { | |
| 1428 // Allocate and initialize a reference processor | |
| 1429 _ref_processor = ReferenceProcessor::create_ref_processor( | |
| 1430 _reserved, // span | |
| 1431 refs_discovery_is_atomic(), // atomic_discovery | |
| 1432 refs_discovery_is_mt(), // mt_discovery | |
| 1433 NULL, // is_alive_non_header | |
| 1434 ParallelGCThreads, | |
| 1435 ParallelRefProcEnabled); | |
| 1436 } | |
| 1437 } | |
| 1438 | |
| 1439 const char* ParNewGeneration::name() const { | |
| 1440 return "par new generation"; | |
| 1441 } |