Mercurial > hg > graal-compiler
annotate src/share/vm/gc_implementation/parNew/parNewGeneration.cpp @ 579:0fbdb4381b99
6814575: Update copyright year
Summary: Update copyright for files that have been modified in 2009, up to 03/09
Reviewed-by: katleman, tbell, ohair
| author | xdono |
|---|---|
| date | Mon, 09 Mar 2009 13:28:46 -0700 |
| parents | 5cfd8d19e546 |
| children | cea947c8a988 |
| 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_) : | |
| 39 _to_space(to_space_), _old_gen(old_gen_), _thread_num(thread_num_), | |
| 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_); | |
| 60 } | |
| 61 #ifdef _MSC_VER | |
| 62 #pragma warning( pop ) | |
| 63 #endif | |
| 64 | |
| 65 void ParScanThreadState::record_survivor_plab(HeapWord* plab_start, | |
| 66 size_t plab_word_size) { | |
| 67 ChunkArray* sca = survivor_chunk_array(); | |
| 68 if (sca != NULL) { | |
| 69 // A non-null SCA implies that we want the PLAB data recorded. | |
| 70 sca->record_sample(plab_start, plab_word_size); | |
| 71 } | |
| 72 } | |
| 73 | |
| 74 bool ParScanThreadState::should_be_partially_scanned(oop new_obj, oop old_obj) const { | |
| 75 return new_obj->is_objArray() && | |
| 76 arrayOop(new_obj)->length() > ParGCArrayScanChunk && | |
| 77 new_obj != old_obj; | |
| 78 } | |
| 79 | |
| 80 void ParScanThreadState::scan_partial_array_and_push_remainder(oop old) { | |
| 81 assert(old->is_objArray(), "must be obj array"); | |
| 82 assert(old->is_forwarded(), "must be forwarded"); | |
| 83 assert(Universe::heap()->is_in_reserved(old), "must be in heap."); | |
| 84 assert(!_old_gen->is_in(old), "must be in young generation."); | |
| 85 | |
| 86 objArrayOop obj = objArrayOop(old->forwardee()); | |
| 87 // Process ParGCArrayScanChunk elements now | |
| 88 // and push the remainder back onto queue | |
| 89 int start = arrayOop(old)->length(); | |
| 90 int end = obj->length(); | |
| 91 int remainder = end - start; | |
| 92 assert(start <= end, "just checking"); | |
| 93 if (remainder > 2 * ParGCArrayScanChunk) { | |
| 94 // Test above combines last partial chunk with a full chunk | |
| 95 end = start + ParGCArrayScanChunk; | |
| 96 arrayOop(old)->set_length(end); | |
| 97 // Push remainder. | |
| 98 bool ok = work_queue()->push(old); | |
| 99 assert(ok, "just popped, push must be okay"); | |
| 100 note_push(); | |
| 101 } else { | |
| 102 // Restore length so that it can be used if there | |
| 103 // is a promotion failure and forwarding pointers | |
| 104 // must be removed. | |
| 105 arrayOop(old)->set_length(end); | |
| 106 } | |
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107 |
| 0 | 108 // process our set of indices (include header in first chunk) |
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109 // should make sure end is even (aligned to HeapWord in case of compressed oops) |
| 0 | 110 if ((HeapWord *)obj < young_old_boundary()) { |
| 111 // object is in to_space | |
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112 obj->oop_iterate_range(&_to_space_closure, start, end); |
| 0 | 113 } else { |
| 114 // object is in old generation | |
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115 obj->oop_iterate_range(&_old_gen_closure, start, end); |
| 0 | 116 } |
| 117 } | |
| 118 | |
| 119 | |
| 120 void ParScanThreadState::trim_queues(int max_size) { | |
| 121 ObjToScanQueue* queue = work_queue(); | |
| 122 while (queue->size() > (juint)max_size) { | |
| 123 oop obj_to_scan; | |
| 124 if (queue->pop_local(obj_to_scan)) { | |
| 125 note_pop(); | |
| 126 | |
| 127 if ((HeapWord *)obj_to_scan < young_old_boundary()) { | |
| 128 if (obj_to_scan->is_objArray() && | |
| 129 obj_to_scan->is_forwarded() && | |
| 130 obj_to_scan->forwardee() != obj_to_scan) { | |
| 131 scan_partial_array_and_push_remainder(obj_to_scan); | |
| 132 } else { | |
| 133 // object is in to_space | |
| 134 obj_to_scan->oop_iterate(&_to_space_closure); | |
| 135 } | |
| 136 } else { | |
| 137 // object is in old generation | |
| 138 obj_to_scan->oop_iterate(&_old_gen_closure); | |
| 139 } | |
| 140 } | |
| 141 } | |
| 142 } | |
| 143 | |
| 144 HeapWord* ParScanThreadState::alloc_in_to_space_slow(size_t word_sz) { | |
| 145 | |
| 146 // Otherwise, if the object is small enough, try to reallocate the | |
| 147 // buffer. | |
| 148 HeapWord* obj = NULL; | |
| 149 if (!_to_space_full) { | |
| 150 ParGCAllocBuffer* const plab = to_space_alloc_buffer(); | |
| 151 Space* const sp = to_space(); | |
| 152 if (word_sz * 100 < | |
| 153 ParallelGCBufferWastePct * plab->word_sz()) { | |
| 154 // Is small enough; abandon this buffer and start a new one. | |
| 155 plab->retire(false, false); | |
| 156 size_t buf_size = plab->word_sz(); | |
| 157 HeapWord* buf_space = sp->par_allocate(buf_size); | |
| 158 if (buf_space == NULL) { | |
| 159 const size_t min_bytes = | |
| 160 ParGCAllocBuffer::min_size() << LogHeapWordSize; | |
| 161 size_t free_bytes = sp->free(); | |
| 162 while(buf_space == NULL && free_bytes >= min_bytes) { | |
| 163 buf_size = free_bytes >> LogHeapWordSize; | |
| 164 assert(buf_size == (size_t)align_object_size(buf_size), | |
| 165 "Invariant"); | |
| 166 buf_space = sp->par_allocate(buf_size); | |
| 167 free_bytes = sp->free(); | |
| 168 } | |
| 169 } | |
| 170 if (buf_space != NULL) { | |
| 171 plab->set_word_size(buf_size); | |
| 172 plab->set_buf(buf_space); | |
| 173 record_survivor_plab(buf_space, buf_size); | |
| 174 obj = plab->allocate(word_sz); | |
| 175 // Note that we cannot compare buf_size < word_sz below | |
| 176 // because of AlignmentReserve (see ParGCAllocBuffer::allocate()). | |
| 177 assert(obj != NULL || plab->words_remaining() < word_sz, | |
| 178 "Else should have been able to allocate"); | |
| 179 // It's conceivable that we may be able to use the | |
| 180 // buffer we just grabbed for subsequent small requests | |
| 181 // even if not for this one. | |
| 182 } else { | |
| 183 // We're used up. | |
| 184 _to_space_full = true; | |
| 185 } | |
| 186 | |
| 187 } else { | |
| 188 // Too large; allocate the object individually. | |
| 189 obj = sp->par_allocate(word_sz); | |
| 190 } | |
| 191 } | |
| 192 return obj; | |
| 193 } | |
| 194 | |
| 195 | |
| 196 void ParScanThreadState::undo_alloc_in_to_space(HeapWord* obj, | |
| 197 size_t word_sz) { | |
| 198 // Is the alloc in the current alloc buffer? | |
| 199 if (to_space_alloc_buffer()->contains(obj)) { | |
| 200 assert(to_space_alloc_buffer()->contains(obj + word_sz - 1), | |
| 201 "Should contain whole object."); | |
| 202 to_space_alloc_buffer()->undo_allocation(obj, word_sz); | |
| 203 } else { | |
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204 CollectedHeap::fill_with_object(obj, word_sz); |
| 0 | 205 } |
| 206 } | |
| 207 | |
| 208 class ParScanThreadStateSet: private ResourceArray { | |
| 209 public: | |
| 210 // Initializes states for the specified number of threads; | |
| 211 ParScanThreadStateSet(int num_threads, | |
| 212 Space& to_space, | |
| 213 ParNewGeneration& gen, | |
| 214 Generation& old_gen, | |
| 215 ObjToScanQueueSet& queue_set, | |
| 216 size_t desired_plab_sz, | |
| 217 ParallelTaskTerminator& term); | |
| 218 inline ParScanThreadState& thread_sate(int i); | |
| 219 int pushes() { return _pushes; } | |
| 220 int pops() { return _pops; } | |
| 221 int steals() { return _steals; } | |
| 222 void reset(); | |
| 223 void flush(); | |
| 224 private: | |
| 225 ParallelTaskTerminator& _term; | |
| 226 ParNewGeneration& _gen; | |
| 227 Generation& _next_gen; | |
| 228 // staticstics | |
| 229 int _pushes; | |
| 230 int _pops; | |
| 231 int _steals; | |
| 232 }; | |
| 233 | |
| 234 | |
| 235 ParScanThreadStateSet::ParScanThreadStateSet( | |
| 236 int num_threads, Space& to_space, ParNewGeneration& gen, | |
| 237 Generation& old_gen, ObjToScanQueueSet& queue_set, | |
| 238 size_t desired_plab_sz, ParallelTaskTerminator& term) | |
| 239 : ResourceArray(sizeof(ParScanThreadState), num_threads), | |
| 240 _gen(gen), _next_gen(old_gen), _term(term), | |
| 241 _pushes(0), _pops(0), _steals(0) | |
| 242 { | |
| 243 assert(num_threads > 0, "sanity check!"); | |
| 244 // Initialize states. | |
| 245 for (int i = 0; i < num_threads; ++i) { | |
| 246 new ((ParScanThreadState*)_data + i) | |
| 247 ParScanThreadState(&to_space, &gen, &old_gen, i, &queue_set, | |
| 248 desired_plab_sz, term); | |
| 249 } | |
| 250 } | |
| 251 | |
| 252 inline ParScanThreadState& ParScanThreadStateSet::thread_sate(int i) | |
| 253 { | |
| 254 assert(i >= 0 && i < length(), "sanity check!"); | |
| 255 return ((ParScanThreadState*)_data)[i]; | |
| 256 } | |
| 257 | |
| 258 | |
| 259 void ParScanThreadStateSet::reset() | |
| 260 { | |
| 261 _term.reset_for_reuse(); | |
| 262 } | |
| 263 | |
| 264 void ParScanThreadStateSet::flush() | |
| 265 { | |
| 266 for (int i = 0; i < length(); ++i) { | |
| 267 ParScanThreadState& par_scan_state = thread_sate(i); | |
| 268 | |
| 269 // Flush stats related to To-space PLAB activity and | |
| 270 // retire the last buffer. | |
| 271 par_scan_state.to_space_alloc_buffer()-> | |
| 272 flush_stats_and_retire(_gen.plab_stats(), | |
| 273 false /* !retain */); | |
| 274 | |
| 275 // Every thread has its own age table. We need to merge | |
| 276 // them all into one. | |
| 277 ageTable *local_table = par_scan_state.age_table(); | |
| 278 _gen.age_table()->merge(local_table); | |
| 279 | |
| 280 // Inform old gen that we're done. | |
| 281 _next_gen.par_promote_alloc_done(i); | |
| 282 _next_gen.par_oop_since_save_marks_iterate_done(i); | |
| 283 | |
| 284 // Flush stats related to work queue activity (push/pop/steal) | |
| 285 // This could conceivably become a bottleneck; if so, we'll put the | |
| 286 // stat's gathering under the flag. | |
| 287 if (PAR_STATS_ENABLED) { | |
| 288 _pushes += par_scan_state.pushes(); | |
| 289 _pops += par_scan_state.pops(); | |
| 290 _steals += par_scan_state.steals(); | |
| 291 if (ParallelGCVerbose) { | |
| 292 gclog_or_tty->print("Thread %d complete:\n" | |
| 293 " Pushes: %7d Pops: %7d Steals %7d (in %d attempts)\n", | |
| 294 i, par_scan_state.pushes(), par_scan_state.pops(), | |
| 295 par_scan_state.steals(), par_scan_state.steal_attempts()); | |
| 296 if (par_scan_state.overflow_pushes() > 0 || | |
| 297 par_scan_state.overflow_refills() > 0) { | |
| 298 gclog_or_tty->print(" Overflow pushes: %7d " | |
| 299 "Overflow refills: %7d for %d objs.\n", | |
| 300 par_scan_state.overflow_pushes(), | |
| 301 par_scan_state.overflow_refills(), | |
| 302 par_scan_state.overflow_refill_objs()); | |
| 303 } | |
| 304 | |
| 305 double elapsed = par_scan_state.elapsed(); | |
| 306 double strong_roots = par_scan_state.strong_roots_time(); | |
| 307 double term = par_scan_state.term_time(); | |
| 308 gclog_or_tty->print( | |
| 309 " Elapsed: %7.2f ms.\n" | |
| 310 " Strong roots: %7.2f ms (%6.2f%%)\n" | |
| 311 " Termination: %7.2f ms (%6.2f%%) (in %d entries)\n", | |
| 312 elapsed * 1000.0, | |
| 313 strong_roots * 1000.0, (strong_roots*100.0/elapsed), | |
| 314 term * 1000.0, (term*100.0/elapsed), | |
| 315 par_scan_state.term_attempts()); | |
| 316 } | |
| 317 } | |
| 318 } | |
| 319 } | |
| 320 | |
| 321 ParScanClosure::ParScanClosure(ParNewGeneration* g, | |
| 322 ParScanThreadState* par_scan_state) : | |
| 323 OopsInGenClosure(g), _par_scan_state(par_scan_state), _g(g) | |
| 324 { | |
| 325 assert(_g->level() == 0, "Optimized for youngest generation"); | |
| 326 _boundary = _g->reserved().end(); | |
| 327 } | |
| 328 | |
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329 void ParScanWithBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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330 void ParScanWithBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, false); } |
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331 |
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332 void ParScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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333 void ParScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, false); } |
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334 |
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335 void ParRootScanWithBarrierTwoGensClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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336 void ParRootScanWithBarrierTwoGensClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, true, true); } |
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337 |
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338 void ParRootScanWithoutBarrierClosure::do_oop(oop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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339 void ParRootScanWithoutBarrierClosure::do_oop(narrowOop* p) { ParScanClosure::do_oop_work(p, false, true); } |
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340 |
| 0 | 341 ParScanWeakRefClosure::ParScanWeakRefClosure(ParNewGeneration* g, |
| 342 ParScanThreadState* par_scan_state) | |
| 343 : ScanWeakRefClosure(g), _par_scan_state(par_scan_state) | |
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344 {} |
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345 |
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346 void ParScanWeakRefClosure::do_oop(oop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
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347 void ParScanWeakRefClosure::do_oop(narrowOop* p) { ParScanWeakRefClosure::do_oop_work(p); } |
| 0 | 348 |
| 349 #ifdef WIN32 | |
| 350 #pragma warning(disable: 4786) /* identifier was truncated to '255' characters in the browser information */ | |
| 351 #endif | |
| 352 | |
| 353 ParEvacuateFollowersClosure::ParEvacuateFollowersClosure( | |
| 354 ParScanThreadState* par_scan_state_, | |
| 355 ParScanWithoutBarrierClosure* to_space_closure_, | |
| 356 ParScanWithBarrierClosure* old_gen_closure_, | |
| 357 ParRootScanWithoutBarrierClosure* to_space_root_closure_, | |
| 358 ParNewGeneration* par_gen_, | |
| 359 ParRootScanWithBarrierTwoGensClosure* old_gen_root_closure_, | |
| 360 ObjToScanQueueSet* task_queues_, | |
| 361 ParallelTaskTerminator* terminator_) : | |
| 362 | |
| 363 _par_scan_state(par_scan_state_), | |
| 364 _to_space_closure(to_space_closure_), | |
| 365 _old_gen_closure(old_gen_closure_), | |
| 366 _to_space_root_closure(to_space_root_closure_), | |
| 367 _old_gen_root_closure(old_gen_root_closure_), | |
| 368 _par_gen(par_gen_), | |
| 369 _task_queues(task_queues_), | |
| 370 _terminator(terminator_) | |
| 371 {} | |
| 372 | |
| 373 void ParEvacuateFollowersClosure::do_void() { | |
| 374 ObjToScanQueue* work_q = par_scan_state()->work_queue(); | |
| 375 | |
| 376 while (true) { | |
| 377 | |
| 378 // Scan to-space and old-gen objs until we run out of both. | |
| 379 oop obj_to_scan; | |
| 380 par_scan_state()->trim_queues(0); | |
| 381 | |
| 382 // We have no local work, attempt to steal from other threads. | |
| 383 | |
| 384 // attempt to steal work from promoted. | |
| 385 par_scan_state()->note_steal_attempt(); | |
| 386 if (task_queues()->steal(par_scan_state()->thread_num(), | |
| 387 par_scan_state()->hash_seed(), | |
| 388 obj_to_scan)) { | |
| 389 par_scan_state()->note_steal(); | |
| 390 bool res = work_q->push(obj_to_scan); | |
| 391 assert(res, "Empty queue should have room for a push."); | |
| 392 | |
| 393 par_scan_state()->note_push(); | |
| 394 // if successful, goto Start. | |
| 395 continue; | |
| 396 | |
| 397 // try global overflow list. | |
| 398 } else if (par_gen()->take_from_overflow_list(par_scan_state())) { | |
| 399 continue; | |
| 400 } | |
| 401 | |
| 402 // Otherwise, offer termination. | |
| 403 par_scan_state()->start_term_time(); | |
| 404 if (terminator()->offer_termination()) break; | |
| 405 par_scan_state()->end_term_time(); | |
| 406 } | |
| 534 | 407 assert(par_gen()->_overflow_list == NULL && par_gen()->_num_par_pushes == 0, |
| 408 "Broken overflow list?"); | |
| 0 | 409 // Finish the last termination pause. |
| 410 par_scan_state()->end_term_time(); | |
| 411 } | |
| 412 | |
| 413 ParNewGenTask::ParNewGenTask(ParNewGeneration* gen, Generation* next_gen, | |
| 414 HeapWord* young_old_boundary, ParScanThreadStateSet* state_set) : | |
| 415 AbstractGangTask("ParNewGeneration collection"), | |
| 416 _gen(gen), _next_gen(next_gen), | |
| 417 _young_old_boundary(young_old_boundary), | |
| 418 _state_set(state_set) | |
| 419 {} | |
| 420 | |
| 421 void ParNewGenTask::work(int i) { | |
| 422 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 423 // Since this is being done in a separate thread, need new resource | |
| 424 // and handle marks. | |
| 425 ResourceMark rm; | |
| 426 HandleMark hm; | |
| 427 // We would need multiple old-gen queues otherwise. | |
| 428 guarantee(gch->n_gens() == 2, | |
| 429 "Par young collection currently only works with one older gen."); | |
| 430 | |
| 431 Generation* old_gen = gch->next_gen(_gen); | |
| 432 | |
| 433 ParScanThreadState& par_scan_state = _state_set->thread_sate(i); | |
| 434 par_scan_state.set_young_old_boundary(_young_old_boundary); | |
| 435 | |
| 436 par_scan_state.start_strong_roots(); | |
| 437 gch->gen_process_strong_roots(_gen->level(), | |
| 438 true, // Process younger gens, if any, | |
| 439 // as strong roots. | |
| 440 false,// not collecting perm generation. | |
| 441 SharedHeap::SO_AllClasses, | |
| 442 &par_scan_state.older_gen_closure(), | |
| 443 &par_scan_state.to_space_root_closure()); | |
| 444 par_scan_state.end_strong_roots(); | |
| 445 | |
| 446 // "evacuate followers". | |
| 447 par_scan_state.evacuate_followers_closure().do_void(); | |
| 448 } | |
| 449 | |
| 450 #ifdef _MSC_VER | |
| 451 #pragma warning( push ) | |
| 452 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list | |
| 453 #endif | |
| 454 ParNewGeneration:: | |
| 455 ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level) | |
| 456 : DefNewGeneration(rs, initial_byte_size, level, "PCopy"), | |
| 457 _overflow_list(NULL), | |
| 458 _is_alive_closure(this), | |
| 459 _plab_stats(YoungPLABSize, PLABWeight) | |
| 460 { | |
| 534 | 461 NOT_PRODUCT(_overflow_counter = ParGCWorkQueueOverflowInterval;) |
| 462 NOT_PRODUCT(_num_par_pushes = 0;) | |
| 0 | 463 _task_queues = new ObjToScanQueueSet(ParallelGCThreads); |
| 464 guarantee(_task_queues != NULL, "task_queues allocation failure."); | |
| 465 | |
| 466 for (uint i1 = 0; i1 < ParallelGCThreads; i1++) { | |
| 467 ObjToScanQueuePadded *q_padded = new ObjToScanQueuePadded(); | |
| 468 guarantee(q_padded != NULL, "work_queue Allocation failure."); | |
| 469 | |
| 470 _task_queues->register_queue(i1, &q_padded->work_queue); | |
| 471 } | |
| 472 | |
| 473 for (uint i2 = 0; i2 < ParallelGCThreads; i2++) | |
| 474 _task_queues->queue(i2)->initialize(); | |
| 475 | |
| 476 if (UsePerfData) { | |
| 477 EXCEPTION_MARK; | |
| 478 ResourceMark rm; | |
| 479 | |
| 480 const char* cname = | |
| 481 PerfDataManager::counter_name(_gen_counters->name_space(), "threads"); | |
| 482 PerfDataManager::create_constant(SUN_GC, cname, PerfData::U_None, | |
| 483 ParallelGCThreads, CHECK); | |
| 484 } | |
| 485 } | |
| 486 #ifdef _MSC_VER | |
| 487 #pragma warning( pop ) | |
| 488 #endif | |
| 489 | |
| 490 // ParNewGeneration:: | |
| 491 ParKeepAliveClosure::ParKeepAliveClosure(ParScanWeakRefClosure* cl) : | |
| 492 DefNewGeneration::KeepAliveClosure(cl), _par_cl(cl) {} | |
| 493 | |
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494 template <class T> |
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495 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop_work(T* p) { |
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496 #ifdef ASSERT |
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497 { |
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498 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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499 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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500 // We never expect to see a null reference being processed |
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501 // as a weak reference. |
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502 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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503 } |
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504 #endif // ASSERT |
| 0 | 505 |
| 506 _par_cl->do_oop_nv(p); | |
| 507 | |
| 508 if (Universe::heap()->is_in_reserved(p)) { | |
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509 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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510 _rs->write_ref_field_gc_par(p, obj); |
| 0 | 511 } |
| 512 } | |
| 513 | |
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514 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(oop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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515 void /*ParNewGeneration::*/ParKeepAliveClosure::do_oop(narrowOop* p) { ParKeepAliveClosure::do_oop_work(p); } |
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516 |
| 0 | 517 // ParNewGeneration:: |
| 518 KeepAliveClosure::KeepAliveClosure(ScanWeakRefClosure* cl) : | |
| 519 DefNewGeneration::KeepAliveClosure(cl) {} | |
| 520 | |
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521 template <class T> |
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522 void /*ParNewGeneration::*/KeepAliveClosure::do_oop_work(T* p) { |
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523 #ifdef ASSERT |
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524 { |
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525 assert(!oopDesc::is_null(*p), "expected non-null ref"); |
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526 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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527 // We never expect to see a null reference being processed |
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528 // as a weak reference. |
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529 assert(obj->is_oop(), "expected an oop while scanning weak refs"); |
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530 } |
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531 #endif // ASSERT |
| 0 | 532 |
| 533 _cl->do_oop_nv(p); | |
| 534 | |
| 535 if (Universe::heap()->is_in_reserved(p)) { | |
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536 oop obj = oopDesc::load_decode_heap_oop_not_null(p); |
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537 _rs->write_ref_field_gc_par(p, obj); |
| 0 | 538 } |
| 539 } | |
| 540 | |
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541 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(oop* p) { KeepAliveClosure::do_oop_work(p); } |
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542 void /*ParNewGeneration::*/KeepAliveClosure::do_oop(narrowOop* p) { KeepAliveClosure::do_oop_work(p); } |
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543 |
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544 template <class T> void ScanClosureWithParBarrier::do_oop_work(T* p) { |
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545 T heap_oop = oopDesc::load_heap_oop(p); |
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546 if (!oopDesc::is_null(heap_oop)) { |
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547 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop); |
| 0 | 548 if ((HeapWord*)obj < _boundary) { |
| 549 assert(!_g->to()->is_in_reserved(obj), "Scanning field twice?"); | |
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550 oop new_obj = obj->is_forwarded() |
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551 ? obj->forwardee() |
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552 : _g->DefNewGeneration::copy_to_survivor_space(obj); |
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553 oopDesc::encode_store_heap_oop_not_null(p, new_obj); |
| 0 | 554 } |
| 555 if (_gc_barrier) { | |
| 556 // If p points to a younger generation, mark the card. | |
| 557 if ((HeapWord*)obj < _gen_boundary) { | |
| 558 _rs->write_ref_field_gc_par(p, obj); | |
| 559 } | |
| 560 } | |
| 561 } | |
| 562 } | |
| 563 | |
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564 void ScanClosureWithParBarrier::do_oop(oop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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565 void ScanClosureWithParBarrier::do_oop(narrowOop* p) { ScanClosureWithParBarrier::do_oop_work(p); } |
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566 |
| 0 | 567 class ParNewRefProcTaskProxy: public AbstractGangTask { |
| 568 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; | |
| 569 public: | |
| 570 ParNewRefProcTaskProxy(ProcessTask& task, ParNewGeneration& gen, | |
| 571 Generation& next_gen, | |
| 572 HeapWord* young_old_boundary, | |
| 573 ParScanThreadStateSet& state_set); | |
| 574 | |
| 575 private: | |
| 576 virtual void work(int i); | |
| 577 | |
| 578 private: | |
| 579 ParNewGeneration& _gen; | |
| 580 ProcessTask& _task; | |
| 581 Generation& _next_gen; | |
| 582 HeapWord* _young_old_boundary; | |
| 583 ParScanThreadStateSet& _state_set; | |
| 584 }; | |
| 585 | |
| 586 ParNewRefProcTaskProxy::ParNewRefProcTaskProxy( | |
| 587 ProcessTask& task, ParNewGeneration& gen, | |
| 588 Generation& next_gen, | |
| 589 HeapWord* young_old_boundary, | |
| 590 ParScanThreadStateSet& state_set) | |
| 591 : AbstractGangTask("ParNewGeneration parallel reference processing"), | |
| 592 _gen(gen), | |
| 593 _task(task), | |
| 594 _next_gen(next_gen), | |
| 595 _young_old_boundary(young_old_boundary), | |
| 596 _state_set(state_set) | |
| 597 { | |
| 598 } | |
| 599 | |
| 600 void ParNewRefProcTaskProxy::work(int i) | |
| 601 { | |
| 602 ResourceMark rm; | |
| 603 HandleMark hm; | |
| 604 ParScanThreadState& par_scan_state = _state_set.thread_sate(i); | |
| 605 par_scan_state.set_young_old_boundary(_young_old_boundary); | |
| 606 _task.work(i, par_scan_state.is_alive_closure(), | |
| 607 par_scan_state.keep_alive_closure(), | |
| 608 par_scan_state.evacuate_followers_closure()); | |
| 609 } | |
| 610 | |
| 611 class ParNewRefEnqueueTaskProxy: public AbstractGangTask { | |
| 612 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; | |
| 613 EnqueueTask& _task; | |
| 614 | |
| 615 public: | |
| 616 ParNewRefEnqueueTaskProxy(EnqueueTask& task) | |
| 617 : AbstractGangTask("ParNewGeneration parallel reference enqueue"), | |
| 618 _task(task) | |
| 619 { } | |
| 620 | |
| 621 virtual void work(int i) | |
| 622 { | |
| 623 _task.work(i); | |
| 624 } | |
| 625 }; | |
| 626 | |
| 627 | |
| 628 void ParNewRefProcTaskExecutor::execute(ProcessTask& task) | |
| 629 { | |
| 630 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 631 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 632 "not a generational heap"); | |
| 633 WorkGang* workers = gch->workers(); | |
| 634 assert(workers != NULL, "Need parallel worker threads."); | |
| 635 ParNewRefProcTaskProxy rp_task(task, _generation, *_generation.next_gen(), | |
| 636 _generation.reserved().end(), _state_set); | |
| 637 workers->run_task(&rp_task); | |
| 638 _state_set.reset(); | |
| 639 } | |
| 640 | |
| 641 void ParNewRefProcTaskExecutor::execute(EnqueueTask& task) | |
| 642 { | |
| 643 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 644 WorkGang* workers = gch->workers(); | |
| 645 assert(workers != NULL, "Need parallel worker threads."); | |
| 646 ParNewRefEnqueueTaskProxy enq_task(task); | |
| 647 workers->run_task(&enq_task); | |
| 648 } | |
| 649 | |
| 650 void ParNewRefProcTaskExecutor::set_single_threaded_mode() | |
| 651 { | |
| 652 _state_set.flush(); | |
| 653 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 654 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 655 gch->save_marks(); | |
| 656 } | |
| 657 | |
| 658 ScanClosureWithParBarrier:: | |
| 659 ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier) : | |
| 660 ScanClosure(g, gc_barrier) {} | |
| 661 | |
| 662 EvacuateFollowersClosureGeneral:: | |
| 663 EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level, | |
| 664 OopsInGenClosure* cur, | |
| 665 OopsInGenClosure* older) : | |
| 666 _gch(gch), _level(level), | |
| 667 _scan_cur_or_nonheap(cur), _scan_older(older) | |
| 668 {} | |
| 669 | |
| 670 void EvacuateFollowersClosureGeneral::do_void() { | |
| 671 do { | |
| 672 // Beware: this call will lead to closure applications via virtual | |
| 673 // calls. | |
| 674 _gch->oop_since_save_marks_iterate(_level, | |
| 675 _scan_cur_or_nonheap, | |
| 676 _scan_older); | |
| 677 } while (!_gch->no_allocs_since_save_marks(_level)); | |
| 678 } | |
| 679 | |
| 680 | |
| 681 bool ParNewGeneration::_avoid_promotion_undo = false; | |
| 682 | |
| 683 void ParNewGeneration::adjust_desired_tenuring_threshold() { | |
| 684 // Set the desired survivor size to half the real survivor space | |
| 685 _tenuring_threshold = | |
| 686 age_table()->compute_tenuring_threshold(to()->capacity()/HeapWordSize); | |
| 687 } | |
| 688 | |
| 689 // A Generation that does parallel young-gen collection. | |
| 690 | |
| 691 void ParNewGeneration::collect(bool full, | |
| 692 bool clear_all_soft_refs, | |
| 693 size_t size, | |
| 694 bool is_tlab) { | |
| 695 assert(full || size > 0, "otherwise we don't want to collect"); | |
| 696 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
| 697 assert(gch->kind() == CollectedHeap::GenCollectedHeap, | |
| 698 "not a CMS generational heap"); | |
| 699 AdaptiveSizePolicy* size_policy = gch->gen_policy()->size_policy(); | |
| 700 WorkGang* workers = gch->workers(); | |
| 701 _next_gen = gch->next_gen(this); | |
| 702 assert(_next_gen != NULL, | |
| 703 "This must be the youngest gen, and not the only gen"); | |
| 704 assert(gch->n_gens() == 2, | |
| 705 "Par collection currently only works with single older gen."); | |
| 706 // Do we have to avoid promotion_undo? | |
| 707 if (gch->collector_policy()->is_concurrent_mark_sweep_policy()) { | |
| 708 set_avoid_promotion_undo(true); | |
| 709 } | |
| 710 | |
| 711 // If the next generation is too full to accomodate worst-case promotion | |
| 712 // from this generation, pass on collection; let the next generation | |
| 713 // do it. | |
| 714 if (!collection_attempt_is_safe()) { | |
| 715 gch->set_incremental_collection_will_fail(); | |
| 716 return; | |
| 717 } | |
| 718 assert(to()->is_empty(), "Else not collection_attempt_is_safe"); | |
| 719 | |
| 720 init_assuming_no_promotion_failure(); | |
| 721 | |
| 722 if (UseAdaptiveSizePolicy) { | |
| 723 set_survivor_overflow(false); | |
| 724 size_policy->minor_collection_begin(); | |
| 725 } | |
| 726 | |
| 727 TraceTime t1("GC", PrintGC && !PrintGCDetails, true, gclog_or_tty); | |
| 728 // Capture heap used before collection (for printing). | |
| 729 size_t gch_prev_used = gch->used(); | |
| 730 | |
| 731 SpecializationStats::clear(); | |
| 732 | |
| 733 age_table()->clear(); | |
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734 to()->clear(SpaceDecorator::Mangle); |
| 0 | 735 |
| 736 gch->save_marks(); | |
| 737 assert(workers != NULL, "Need parallel worker threads."); | |
| 738 ParallelTaskTerminator _term(workers->total_workers(), task_queues()); | |
| 739 ParScanThreadStateSet thread_state_set(workers->total_workers(), | |
| 740 *to(), *this, *_next_gen, *task_queues(), | |
| 741 desired_plab_sz(), _term); | |
| 742 | |
| 743 ParNewGenTask tsk(this, _next_gen, reserved().end(), &thread_state_set); | |
| 744 int n_workers = workers->total_workers(); | |
| 745 gch->set_par_threads(n_workers); | |
| 746 gch->change_strong_roots_parity(); | |
| 747 gch->rem_set()->prepare_for_younger_refs_iterate(true); | |
| 748 // It turns out that even when we're using 1 thread, doing the work in a | |
| 749 // separate thread causes wide variance in run times. We can't help this | |
| 750 // in the multi-threaded case, but we special-case n=1 here to get | |
| 751 // repeatable measurements of the 1-thread overhead of the parallel code. | |
| 752 if (n_workers > 1) { | |
| 753 workers->run_task(&tsk); | |
| 754 } else { | |
| 755 tsk.work(0); | |
| 756 } | |
| 757 thread_state_set.reset(); | |
| 758 | |
| 759 if (PAR_STATS_ENABLED && ParallelGCVerbose) { | |
| 760 gclog_or_tty->print("Thread totals:\n" | |
| 761 " Pushes: %7d Pops: %7d Steals %7d (sum = %7d).\n", | |
| 762 thread_state_set.pushes(), thread_state_set.pops(), | |
| 763 thread_state_set.steals(), | |
| 764 thread_state_set.pops()+thread_state_set.steals()); | |
| 765 } | |
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766 assert(thread_state_set.pushes() == thread_state_set.pops() |
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767 + thread_state_set.steals(), |
| 0 | 768 "Or else the queues are leaky."); |
| 769 | |
| 770 // Process (weak) reference objects found during scavenge. | |
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771 ReferenceProcessor* rp = ref_processor(); |
| 0 | 772 IsAliveClosure is_alive(this); |
| 773 ScanWeakRefClosure scan_weak_ref(this); | |
| 774 KeepAliveClosure keep_alive(&scan_weak_ref); | |
| 775 ScanClosure scan_without_gc_barrier(this, false); | |
| 776 ScanClosureWithParBarrier scan_with_gc_barrier(this, true); | |
| 777 set_promo_failure_scan_stack_closure(&scan_without_gc_barrier); | |
| 778 EvacuateFollowersClosureGeneral evacuate_followers(gch, _level, | |
| 779 &scan_without_gc_barrier, &scan_with_gc_barrier); | |
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780 rp->setup_policy(clear_all_soft_refs); |
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781 if (rp->processing_is_mt()) { |
| 0 | 782 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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783 rp->process_discovered_references(&is_alive, &keep_alive, |
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784 &evacuate_followers, &task_executor); |
| 0 | 785 } else { |
| 786 thread_state_set.flush(); | |
| 787 gch->set_par_threads(0); // 0 ==> non-parallel. | |
| 788 gch->save_marks(); | |
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789 rp->process_discovered_references(&is_alive, &keep_alive, |
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790 &evacuate_followers, NULL); |
| 0 | 791 } |
| 792 if (!promotion_failed()) { | |
| 793 // Swap the survivor spaces. | |
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794 eden()->clear(SpaceDecorator::Mangle); |
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795 from()->clear(SpaceDecorator::Mangle); |
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796 if (ZapUnusedHeapArea) { |
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797 // This is now done here because of the piece-meal mangling which |
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798 // can check for valid mangling at intermediate points in the |
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799 // collection(s). When a minor collection fails to collect |
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800 // sufficient space resizing of the young generation can occur |
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801 // an redistribute the spaces in the young generation. Mangle |
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802 // here so that unzapped regions don't get distributed to |
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803 // other spaces. |
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804 to()->mangle_unused_area(); |
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805 } |
| 0 | 806 swap_spaces(); |
| 807 | |
| 808 assert(to()->is_empty(), "to space should be empty now"); | |
| 809 } else { | |
| 810 assert(HandlePromotionFailure, | |
| 811 "Should only be here if promotion failure handling is on"); | |
| 812 if (_promo_failure_scan_stack != NULL) { | |
| 813 // Can be non-null because of reference processing. | |
| 814 // Free stack with its elements. | |
| 815 delete _promo_failure_scan_stack; | |
| 816 _promo_failure_scan_stack = NULL; | |
| 817 } | |
| 818 remove_forwarding_pointers(); | |
| 819 if (PrintGCDetails) { | |
| 820 gclog_or_tty->print(" (promotion failed)"); | |
| 821 } | |
| 822 // All the spaces are in play for mark-sweep. | |
| 823 swap_spaces(); // Make life simpler for CMS || rescan; see 6483690. | |
| 824 from()->set_next_compaction_space(to()); | |
| 825 gch->set_incremental_collection_will_fail(); | |
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826 |
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827 // Reset the PromotionFailureALot counters. |
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828 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) |
| 0 | 829 } |
| 830 // set new iteration safe limit for the survivor spaces | |
| 831 from()->set_concurrent_iteration_safe_limit(from()->top()); | |
| 832 to()->set_concurrent_iteration_safe_limit(to()->top()); | |
| 833 | |
| 834 adjust_desired_tenuring_threshold(); | |
| 835 if (ResizePLAB) { | |
| 836 plab_stats()->adjust_desired_plab_sz(); | |
| 837 } | |
| 838 | |
| 839 if (PrintGC && !PrintGCDetails) { | |
| 840 gch->print_heap_change(gch_prev_used); | |
| 841 } | |
| 842 | |
| 843 if (UseAdaptiveSizePolicy) { | |
| 844 size_policy->minor_collection_end(gch->gc_cause()); | |
| 845 size_policy->avg_survived()->sample(from()->used()); | |
| 846 } | |
| 847 | |
| 848 update_time_of_last_gc(os::javaTimeMillis()); | |
| 849 | |
| 850 SpecializationStats::print(); | |
| 851 | |
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852 rp->set_enqueuing_is_done(true); |
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853 if (rp->processing_is_mt()) { |
| 0 | 854 ParNewRefProcTaskExecutor task_executor(*this, thread_state_set); |
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855 rp->enqueue_discovered_references(&task_executor); |
| 0 | 856 } else { |
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857 rp->enqueue_discovered_references(NULL); |
| 0 | 858 } |
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859 rp->verify_no_references_recorded(); |
| 0 | 860 } |
| 861 | |
| 862 static int sum; | |
| 863 void ParNewGeneration::waste_some_time() { | |
| 864 for (int i = 0; i < 100; i++) { | |
| 865 sum += i; | |
| 866 } | |
| 867 } | |
| 868 | |
| 869 static const oop ClaimedForwardPtr = oop(0x4); | |
| 870 | |
| 871 // Because of concurrency, there are times where an object for which | |
| 872 // "is_forwarded()" is true contains an "interim" forwarding pointer | |
| 873 // value. Such a value will soon be overwritten with a real value. | |
| 874 // This method requires "obj" to have a forwarding pointer, and waits, if | |
| 875 // necessary for a real one to be inserted, and returns it. | |
| 876 | |
| 877 oop ParNewGeneration::real_forwardee(oop obj) { | |
| 878 oop forward_ptr = obj->forwardee(); | |
| 879 if (forward_ptr != ClaimedForwardPtr) { | |
| 880 return forward_ptr; | |
| 881 } else { | |
| 882 return real_forwardee_slow(obj); | |
| 883 } | |
| 884 } | |
| 885 | |
| 886 oop ParNewGeneration::real_forwardee_slow(oop obj) { | |
| 887 // Spin-read if it is claimed but not yet written by another thread. | |
| 888 oop forward_ptr = obj->forwardee(); | |
| 889 while (forward_ptr == ClaimedForwardPtr) { | |
| 890 waste_some_time(); | |
| 891 assert(obj->is_forwarded(), "precondition"); | |
| 892 forward_ptr = obj->forwardee(); | |
| 893 } | |
| 894 return forward_ptr; | |
| 895 } | |
| 896 | |
| 897 #ifdef ASSERT | |
| 898 bool ParNewGeneration::is_legal_forward_ptr(oop p) { | |
| 899 return | |
| 900 (_avoid_promotion_undo && p == ClaimedForwardPtr) | |
| 901 || Universe::heap()->is_in_reserved(p); | |
| 902 } | |
| 903 #endif | |
| 904 | |
| 905 void ParNewGeneration::preserve_mark_if_necessary(oop obj, markOop m) { | |
| 906 if ((m != markOopDesc::prototype()) && | |
| 907 (!UseBiasedLocking || (m != markOopDesc::biased_locking_prototype()))) { | |
| 908 MutexLocker ml(ParGCRareEvent_lock); | |
| 909 DefNewGeneration::preserve_mark_if_necessary(obj, m); | |
| 910 } | |
| 911 } | |
| 912 | |
| 913 // Multiple GC threads may try to promote an object. If the object | |
| 914 // is successfully promoted, a forwarding pointer will be installed in | |
| 915 // the object in the young generation. This method claims the right | |
| 916 // to install the forwarding pointer before it copies the object, | |
| 917 // thus avoiding the need to undo the copy as in | |
| 918 // copy_to_survivor_space_avoiding_with_undo. | |
| 919 | |
| 920 oop ParNewGeneration::copy_to_survivor_space_avoiding_promotion_undo( | |
| 921 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
| 922 // In the sequential version, this assert also says that the object is | |
| 923 // not forwarded. That might not be the case here. It is the case that | |
| 924 // the caller observed it to be not forwarded at some time in the past. | |
| 925 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
| 926 | |
| 927 // The sequential code read "old->age()" below. That doesn't work here, | |
| 928 // since the age is in the mark word, and that might be overwritten with | |
| 929 // a forwarding pointer by a parallel thread. So we must save the mark | |
| 930 // word in a local and then analyze it. | |
| 931 oopDesc dummyOld; | |
| 932 dummyOld.set_mark(m); | |
| 933 assert(!dummyOld.is_forwarded(), | |
| 934 "should not be called with forwarding pointer mark word."); | |
| 935 | |
| 936 oop new_obj = NULL; | |
| 937 oop forward_ptr; | |
| 938 | |
| 939 // Try allocating obj in to-space (unless too old) | |
| 940 if (dummyOld.age() < tenuring_threshold()) { | |
| 941 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
| 942 if (new_obj == NULL) { | |
| 943 set_survivor_overflow(true); | |
| 944 } | |
| 945 } | |
| 946 | |
| 947 if (new_obj == NULL) { | |
| 948 // Either to-space is full or we decided to promote | |
| 949 // try allocating obj tenured | |
| 950 | |
| 951 // Attempt to install a null forwarding pointer (atomically), | |
| 952 // to claim the right to install the real forwarding pointer. | |
| 953 forward_ptr = old->forward_to_atomic(ClaimedForwardPtr); | |
| 954 if (forward_ptr != NULL) { | |
| 955 // someone else beat us to it. | |
| 956 return real_forwardee(old); | |
| 957 } | |
| 958 | |
| 959 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
| 960 old, m, sz); | |
| 961 | |
| 962 if (new_obj == NULL) { | |
| 963 if (!HandlePromotionFailure) { | |
| 964 // A failed promotion likely means the MaxLiveObjectEvacuationRatio flag | |
| 965 // is incorrectly set. In any case, its seriously wrong to be here! | |
| 966 vm_exit_out_of_memory(sz*wordSize, "promotion"); | |
| 967 } | |
| 968 // promotion failed, forward to self | |
| 969 _promotion_failed = true; | |
| 970 new_obj = old; | |
| 971 | |
| 972 preserve_mark_if_necessary(old, m); | |
| 973 } | |
| 974 | |
| 975 old->forward_to(new_obj); | |
| 976 forward_ptr = NULL; | |
| 977 } else { | |
| 978 // Is in to-space; do copying ourselves. | |
| 979 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
| 980 forward_ptr = old->forward_to_atomic(new_obj); | |
| 981 // Restore the mark word copied above. | |
| 982 new_obj->set_mark(m); | |
| 983 // Increment age if obj still in new generation | |
| 984 new_obj->incr_age(); | |
| 985 par_scan_state->age_table()->add(new_obj, sz); | |
| 986 } | |
| 987 assert(new_obj != NULL, "just checking"); | |
| 988 | |
| 989 if (forward_ptr == NULL) { | |
| 990 oop obj_to_push = new_obj; | |
| 991 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
| 992 // Length field used as index of next element to be scanned. | |
| 993 // Real length can be obtained from real_forwardee() | |
| 994 arrayOop(old)->set_length(0); | |
| 995 obj_to_push = old; | |
| 996 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
| 997 "push forwarded object"); | |
| 998 } | |
| 999 // Push it on one of the queues of to-be-scanned objects. | |
| 534 | 1000 bool simulate_overflow = false; |
| 1001 NOT_PRODUCT( | |
| 1002 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
| 1003 // simulate a stack overflow | |
| 1004 simulate_overflow = true; | |
| 1005 } | |
| 1006 ) | |
| 1007 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
| 0 | 1008 // Add stats for overflow pushes. |
| 1009 if (Verbose && PrintGCDetails) { | |
| 1010 gclog_or_tty->print("queue overflow!\n"); | |
| 1011 } | |
| 534 | 1012 push_on_overflow_list(old, par_scan_state); |
| 0 | 1013 par_scan_state->note_overflow_push(); |
| 1014 } | |
| 1015 par_scan_state->note_push(); | |
| 1016 | |
| 1017 return new_obj; | |
| 1018 } | |
| 1019 | |
| 1020 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
| 1021 // allocate it? | |
| 1022 if (is_in_reserved(new_obj)) { | |
| 1023 // Must be in to_space. | |
| 1024 assert(to()->is_in_reserved(new_obj), "Checking"); | |
| 1025 if (forward_ptr == ClaimedForwardPtr) { | |
| 1026 // Wait to get the real forwarding pointer value. | |
| 1027 forward_ptr = real_forwardee(old); | |
| 1028 } | |
| 1029 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
| 1030 } | |
| 1031 | |
| 1032 return forward_ptr; | |
| 1033 } | |
| 1034 | |
| 1035 | |
| 1036 // Multiple GC threads may try to promote the same object. If two | |
| 1037 // or more GC threads copy the object, only one wins the race to install | |
| 1038 // the forwarding pointer. The other threads have to undo their copy. | |
| 1039 | |
| 1040 oop ParNewGeneration::copy_to_survivor_space_with_undo( | |
| 1041 ParScanThreadState* par_scan_state, oop old, size_t sz, markOop m) { | |
| 1042 | |
| 1043 // In the sequential version, this assert also says that the object is | |
| 1044 // not forwarded. That might not be the case here. It is the case that | |
| 1045 // the caller observed it to be not forwarded at some time in the past. | |
| 1046 assert(is_in_reserved(old), "shouldn't be scavenging this oop"); | |
| 1047 | |
| 1048 // The sequential code read "old->age()" below. That doesn't work here, | |
| 1049 // since the age is in the mark word, and that might be overwritten with | |
| 1050 // a forwarding pointer by a parallel thread. So we must save the mark | |
| 1051 // word here, install it in a local oopDesc, and then analyze it. | |
| 1052 oopDesc dummyOld; | |
| 1053 dummyOld.set_mark(m); | |
| 1054 assert(!dummyOld.is_forwarded(), | |
| 1055 "should not be called with forwarding pointer mark word."); | |
| 1056 | |
| 1057 bool failed_to_promote = false; | |
| 1058 oop new_obj = NULL; | |
| 1059 oop forward_ptr; | |
| 1060 | |
| 1061 // Try allocating obj in to-space (unless too old) | |
| 1062 if (dummyOld.age() < tenuring_threshold()) { | |
| 1063 new_obj = (oop)par_scan_state->alloc_in_to_space(sz); | |
| 1064 if (new_obj == NULL) { | |
| 1065 set_survivor_overflow(true); | |
| 1066 } | |
| 1067 } | |
| 1068 | |
| 1069 if (new_obj == NULL) { | |
| 1070 // Either to-space is full or we decided to promote | |
| 1071 // try allocating obj tenured | |
| 1072 new_obj = _next_gen->par_promote(par_scan_state->thread_num(), | |
| 1073 old, m, sz); | |
| 1074 | |
| 1075 if (new_obj == NULL) { | |
| 1076 if (!HandlePromotionFailure) { | |
| 1077 // A failed promotion likely means the MaxLiveObjectEvacuationRatio | |
| 1078 // flag is incorrectly set. In any case, its seriously wrong to be | |
| 1079 // here! | |
| 1080 vm_exit_out_of_memory(sz*wordSize, "promotion"); | |
| 1081 } | |
| 1082 // promotion failed, forward to self | |
| 1083 forward_ptr = old->forward_to_atomic(old); | |
| 1084 new_obj = old; | |
| 1085 | |
| 1086 if (forward_ptr != NULL) { | |
| 1087 return forward_ptr; // someone else succeeded | |
| 1088 } | |
| 1089 | |
| 1090 _promotion_failed = true; | |
| 1091 failed_to_promote = true; | |
| 1092 | |
| 1093 preserve_mark_if_necessary(old, m); | |
| 1094 } | |
| 1095 } else { | |
| 1096 // Is in to-space; do copying ourselves. | |
| 1097 Copy::aligned_disjoint_words((HeapWord*)old, (HeapWord*)new_obj, sz); | |
| 1098 // Restore the mark word copied above. | |
| 1099 new_obj->set_mark(m); | |
| 1100 // Increment age if new_obj still in new generation | |
| 1101 new_obj->incr_age(); | |
| 1102 par_scan_state->age_table()->add(new_obj, sz); | |
| 1103 } | |
| 1104 assert(new_obj != NULL, "just checking"); | |
| 1105 | |
| 1106 // Now attempt to install the forwarding pointer (atomically). | |
| 1107 // We have to copy the mark word before overwriting with forwarding | |
| 1108 // ptr, so we can restore it below in the copy. | |
| 1109 if (!failed_to_promote) { | |
| 1110 forward_ptr = old->forward_to_atomic(new_obj); | |
| 1111 } | |
| 1112 | |
| 1113 if (forward_ptr == NULL) { | |
| 1114 oop obj_to_push = new_obj; | |
| 1115 if (par_scan_state->should_be_partially_scanned(obj_to_push, old)) { | |
| 1116 // Length field used as index of next element to be scanned. | |
| 1117 // Real length can be obtained from real_forwardee() | |
| 1118 arrayOop(old)->set_length(0); | |
| 1119 obj_to_push = old; | |
| 1120 assert(obj_to_push->is_forwarded() && obj_to_push->forwardee() != obj_to_push, | |
| 1121 "push forwarded object"); | |
| 1122 } | |
| 1123 // Push it on one of the queues of to-be-scanned objects. | |
| 534 | 1124 bool simulate_overflow = false; |
| 1125 NOT_PRODUCT( | |
| 1126 if (ParGCWorkQueueOverflowALot && should_simulate_overflow()) { | |
| 1127 // simulate a stack overflow | |
| 1128 simulate_overflow = true; | |
| 1129 } | |
| 1130 ) | |
| 1131 if (simulate_overflow || !par_scan_state->work_queue()->push(obj_to_push)) { | |
| 0 | 1132 // Add stats for overflow pushes. |
| 534 | 1133 push_on_overflow_list(old, par_scan_state); |
| 0 | 1134 par_scan_state->note_overflow_push(); |
| 1135 } | |
| 1136 par_scan_state->note_push(); | |
| 1137 | |
| 1138 return new_obj; | |
| 1139 } | |
| 1140 | |
| 1141 // Oops. Someone beat us to it. Undo the allocation. Where did we | |
| 1142 // allocate it? | |
| 1143 if (is_in_reserved(new_obj)) { | |
| 1144 // Must be in to_space. | |
| 1145 assert(to()->is_in_reserved(new_obj), "Checking"); | |
| 1146 par_scan_state->undo_alloc_in_to_space((HeapWord*)new_obj, sz); | |
| 1147 } else { | |
| 1148 assert(!_avoid_promotion_undo, "Should not be here if avoiding."); | |
| 1149 _next_gen->par_promote_alloc_undo(par_scan_state->thread_num(), | |
| 1150 (HeapWord*)new_obj, sz); | |
| 1151 } | |
| 1152 | |
| 1153 return forward_ptr; | |
| 1154 } | |
| 1155 | |
| 534 | 1156 #ifndef PRODUCT |
| 1157 // It's OK to call this multi-threaded; the worst thing | |
| 1158 // that can happen is that we'll get a bunch of closely | |
| 1159 // spaced simulated oveflows, but that's OK, in fact | |
| 1160 // probably good as it would exercise the overflow code | |
| 1161 // under contention. | |
| 1162 bool ParNewGeneration::should_simulate_overflow() { | |
| 1163 if (_overflow_counter-- <= 0) { // just being defensive | |
| 1164 _overflow_counter = ParGCWorkQueueOverflowInterval; | |
| 1165 return true; | |
| 1166 } else { | |
| 1167 return false; | |
| 1168 } | |
| 1169 } | |
| 1170 #endif | |
| 1171 | |
| 1172 #define BUSY (oop(0x1aff1aff)) | |
| 1173 void ParNewGeneration::push_on_overflow_list(oop from_space_obj, ParScanThreadState* par_scan_state) { | |
| 0 | 1174 // if the object has been forwarded to itself, then we cannot |
| 1175 // use the klass pointer for the linked list. Instead we have | |
| 1176 // to allocate an oopDesc in the C-Heap and use that for the linked list. | |
| 534 | 1177 // XXX This is horribly inefficient when a promotion failure occurs |
| 1178 // and should be fixed. XXX FIX ME !!! | |
| 1179 #ifndef PRODUCT | |
| 1180 Atomic::inc_ptr(&_num_par_pushes); | |
| 1181 assert(_num_par_pushes > 0, "Tautology"); | |
| 1182 #endif | |
| 0 | 1183 if (from_space_obj->forwardee() == from_space_obj) { |
| 1184 oopDesc* listhead = NEW_C_HEAP_ARRAY(oopDesc, 1); | |
| 1185 listhead->forward_to(from_space_obj); | |
| 1186 from_space_obj = listhead; | |
| 1187 } | |
| 534 | 1188 oop observed_overflow_list = _overflow_list; |
| 1189 oop cur_overflow_list; | |
| 1190 do { | |
| 1191 cur_overflow_list = observed_overflow_list; | |
| 1192 if (cur_overflow_list != BUSY) { | |
| 1193 from_space_obj->set_klass_to_list_ptr(cur_overflow_list); | |
| 1194 } else { | |
| 1195 from_space_obj->set_klass_to_list_ptr(NULL); | |
| 1196 } | |
| 1197 observed_overflow_list = | |
| 0 | 1198 (oop)Atomic::cmpxchg_ptr(from_space_obj, &_overflow_list, cur_overflow_list); |
| 534 | 1199 } while (cur_overflow_list != observed_overflow_list); |
| 0 | 1200 } |
| 1201 | |
| 534 | 1202 // *NOTE*: The overflow list manipulation code here and |
| 1203 // in CMSCollector:: are very similar in shape, | |
| 1204 // except that in the CMS case we thread the objects | |
| 1205 // directly into the list via their mark word, and do | |
| 1206 // not need to deal with special cases below related | |
| 1207 // to chunking of object arrays and promotion failure | |
| 1208 // handling. | |
| 1209 // CR 6797058 has been filed to attempt consolidation of | |
| 1210 // the common code. | |
| 1211 // Because of the common code, if you make any changes in | |
| 1212 // the code below, please check the CMS version to see if | |
| 1213 // similar changes might be needed. | |
| 1214 // See CMSCollector::par_take_from_overflow_list() for | |
| 1215 // more extensive documentation comments. | |
| 0 | 1216 bool |
| 1217 ParNewGeneration::take_from_overflow_list(ParScanThreadState* par_scan_state) { | |
| 1218 ObjToScanQueue* work_q = par_scan_state->work_queue(); | |
| 534 | 1219 assert(work_q->size() == 0, "Should first empty local work queue"); |
| 0 | 1220 // How many to take? |
| 534 | 1221 size_t objsFromOverflow = MIN2((size_t)work_q->max_elems()/4, |
| 1222 (size_t)ParGCDesiredObjsFromOverflowList); | |
| 0 | 1223 |
| 1224 if (_overflow_list == NULL) return false; | |
| 1225 | |
| 1226 // Otherwise, there was something there; try claiming the list. | |
| 534 | 1227 oop prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); |
| 1228 // Trim off a prefix of at most objsFromOverflow items | |
| 1229 Thread* tid = Thread::current(); | |
| 1230 size_t spin_count = (size_t)ParallelGCThreads; | |
| 1231 size_t sleep_time_millis = MAX2((size_t)1, objsFromOverflow/100); | |
| 1232 for (size_t spin = 0; prefix == BUSY && spin < spin_count; spin++) { | |
| 1233 // someone grabbed it before we did ... | |
| 1234 // ... we spin for a short while... | |
| 1235 os::sleep(tid, sleep_time_millis, false); | |
| 1236 if (_overflow_list == NULL) { | |
| 1237 // nothing left to take | |
| 1238 return false; | |
| 1239 } else if (_overflow_list != BUSY) { | |
| 1240 // try and grab the prefix | |
| 1241 prefix = (oop)Atomic::xchg_ptr(BUSY, &_overflow_list); | |
| 1242 } | |
| 0 | 1243 } |
| 534 | 1244 if (prefix == NULL || prefix == BUSY) { |
| 1245 // Nothing to take or waited long enough | |
| 1246 if (prefix == NULL) { | |
| 1247 // Write back the NULL in case we overwrote it with BUSY above | |
| 1248 // and it is still the same value. | |
| 1249 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 1250 } | |
| 1251 return false; | |
| 1252 } | |
| 1253 assert(prefix != NULL && prefix != BUSY, "Error"); | |
| 1254 size_t i = 1; | |
| 0 | 1255 oop cur = prefix; |
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1256 while (i < objsFromOverflow && cur->klass_or_null() != NULL) { |
| 0 | 1257 i++; cur = oop(cur->klass()); |
| 1258 } | |
| 1259 | |
| 1260 // Reattach remaining (suffix) to overflow list | |
| 534 | 1261 if (cur->klass_or_null() == NULL) { |
| 1262 // Write back the NULL in lieu of the BUSY we wrote | |
| 1263 // above and it is still the same value. | |
| 1264 if (_overflow_list == BUSY) { | |
| 1265 (void) Atomic::cmpxchg_ptr(NULL, &_overflow_list, BUSY); | |
| 0 | 1266 } |
| 534 | 1267 } else { |
| 1268 assert(cur->klass_or_null() != BUSY, "Error"); | |
| 1269 oop suffix = oop(cur->klass()); // suffix will be put back on global list | |
| 1270 cur->set_klass_to_list_ptr(NULL); // break off suffix | |
| 1271 // It's possible that the list is still in the empty(busy) state | |
| 1272 // we left it in a short while ago; in that case we may be | |
| 1273 // able to place back the suffix. | |
| 1274 oop observed_overflow_list = _overflow_list; | |
| 1275 oop cur_overflow_list = observed_overflow_list; | |
| 1276 bool attached = false; | |
| 1277 while (observed_overflow_list == BUSY || observed_overflow_list == NULL) { | |
| 1278 observed_overflow_list = | |
| 1279 (oop) Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
| 1280 if (cur_overflow_list == observed_overflow_list) { | |
| 1281 attached = true; | |
| 1282 break; | |
| 1283 } else cur_overflow_list = observed_overflow_list; | |
| 1284 } | |
| 1285 if (!attached) { | |
| 1286 // Too bad, someone else got in in between; we'll need to do a splice. | |
| 1287 // Find the last item of suffix list | |
| 1288 oop last = suffix; | |
| 1289 while (last->klass_or_null() != NULL) { | |
| 1290 last = oop(last->klass()); | |
| 1291 } | |
| 1292 // Atomically prepend suffix to current overflow list | |
| 1293 observed_overflow_list = _overflow_list; | |
| 1294 do { | |
| 1295 cur_overflow_list = observed_overflow_list; | |
| 1296 if (cur_overflow_list != BUSY) { | |
| 1297 // Do the splice ... | |
| 1298 last->set_klass_to_list_ptr(cur_overflow_list); | |
| 1299 } else { // cur_overflow_list == BUSY | |
| 1300 last->set_klass_to_list_ptr(NULL); | |
| 1301 } | |
| 1302 observed_overflow_list = | |
| 1303 (oop)Atomic::cmpxchg_ptr(suffix, &_overflow_list, cur_overflow_list); | |
| 1304 } while (cur_overflow_list != observed_overflow_list); | |
| 0 | 1305 } |
| 1306 } | |
| 1307 | |
| 1308 // Push objects on prefix list onto this thread's work queue | |
| 534 | 1309 assert(prefix != NULL && prefix != BUSY, "program logic"); |
| 0 | 1310 cur = prefix; |
| 534 | 1311 ssize_t n = 0; |
| 0 | 1312 while (cur != NULL) { |
| 1313 oop obj_to_push = cur->forwardee(); | |
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1314 oop next = oop(cur->klass_or_null()); |
| 0 | 1315 cur->set_klass(obj_to_push->klass()); |
| 534 | 1316 // This may be an array object that is self-forwarded. In that case, the list pointer |
| 1317 // space, cur, is not in the Java heap, but rather in the C-heap and should be freed. | |
| 1318 if (!is_in_reserved(cur)) { | |
| 1319 // This can become a scaling bottleneck when there is work queue overflow coincident | |
| 1320 // with promotion failure. | |
| 1321 oopDesc* f = cur; | |
| 1322 FREE_C_HEAP_ARRAY(oopDesc, f); | |
| 1323 } else if (par_scan_state->should_be_partially_scanned(obj_to_push, cur)) { | |
| 0 | 1324 assert(arrayOop(cur)->length() == 0, "entire array remaining to be scanned"); |
| 534 | 1325 obj_to_push = cur; |
| 0 | 1326 } |
| 534 | 1327 bool ok = work_q->push(obj_to_push); |
| 1328 assert(ok, "Should have succeeded"); | |
| 0 | 1329 cur = next; |
| 1330 n++; | |
| 1331 } | |
| 1332 par_scan_state->note_overflow_refill(n); | |
| 534 | 1333 #ifndef PRODUCT |
| 1334 assert(_num_par_pushes >= n, "Too many pops?"); | |
| 1335 Atomic::add_ptr(-(intptr_t)n, &_num_par_pushes); | |
| 1336 #endif | |
| 0 | 1337 return true; |
| 1338 } | |
| 534 | 1339 #undef BUSY |
| 0 | 1340 |
| 1341 void ParNewGeneration::ref_processor_init() | |
| 1342 { | |
| 1343 if (_ref_processor == NULL) { | |
| 1344 // Allocate and initialize a reference processor | |
| 1345 _ref_processor = ReferenceProcessor::create_ref_processor( | |
| 1346 _reserved, // span | |
| 1347 refs_discovery_is_atomic(), // atomic_discovery | |
| 1348 refs_discovery_is_mt(), // mt_discovery | |
| 1349 NULL, // is_alive_non_header | |
| 1350 ParallelGCThreads, | |
| 1351 ParallelRefProcEnabled); | |
| 1352 } | |
| 1353 } | |
| 1354 | |
| 1355 const char* ParNewGeneration::name() const { | |
| 1356 return "par new generation"; | |
| 1357 } |