1 /* 2 * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "code/codeCache.hpp" 28 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" 29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" 30 #include "gc_implementation/parallelScavenge/generationSizer.hpp" 31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 33 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 34 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" 35 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp" 36 #include "gc_implementation/parallelScavenge/psTasks.hpp" 37 #include "gc_implementation/shared/isGCActiveMark.hpp" 38 #include "gc_implementation/shared/spaceDecorator.hpp" 39 #include "gc_interface/gcCause.hpp" 40 #include "memory/collectorPolicy.hpp" 41 #include "memory/gcLocker.inline.hpp" 42 #include "memory/referencePolicy.hpp" 43 #include "memory/referenceProcessor.hpp" 44 #include "memory/resourceArea.hpp" 45 #include "oops/oop.inline.hpp" 46 #include "oops/oop.psgc.inline.hpp" 47 #include "runtime/biasedLocking.hpp" 48 #include "runtime/fprofiler.hpp" 49 #include "runtime/handles.inline.hpp" 50 #include "runtime/threadCritical.hpp" 51 #include "runtime/vmThread.hpp" 52 #include "runtime/vm_operations.hpp" 53 #include "services/memoryService.hpp" 54 #include "utilities/stack.inline.hpp" 55 56 57 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 58 int PSScavenge::_consecutive_skipped_scavenges = 0; 59 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 60 CardTableExtension* PSScavenge::_card_table = NULL; 61 bool PSScavenge::_survivor_overflow = false; 62 uint PSScavenge::_tenuring_threshold = 0; 63 HeapWord* PSScavenge::_young_generation_boundary = NULL; 64 elapsedTimer PSScavenge::_accumulated_time; 65 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack; 66 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack; 67 CollectorCounters* PSScavenge::_counters = NULL; 68 bool PSScavenge::_promotion_failed = false; 69 70 // Define before use 71 class PSIsAliveClosure: public BoolObjectClosure { 72 public: 73 bool do_object_b(oop p) { 74 return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded(); 75 } 76 }; 77 78 PSIsAliveClosure PSScavenge::_is_alive_closure; 79 80 class PSKeepAliveClosure: public OopClosure { 81 protected: 82 MutableSpace* _to_space; 83 PSPromotionManager* _promotion_manager; 84 85 public: 86 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 87 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 88 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 89 _to_space = heap->young_gen()->to_space(); 90 91 assert(_promotion_manager != NULL, "Sanity"); 92 } 93 94 template <class T> void do_oop_work(T* p) { 95 assert (!oopDesc::is_null(*p), "expected non-null ref"); 96 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 97 "expected an oop while scanning weak refs"); 98 99 // Weak refs may be visited more than once. 100 if (PSScavenge::should_scavenge(p, _to_space)) { 101 PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p); 102 } 103 } 104 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 105 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 106 }; 107 108 class PSEvacuateFollowersClosure: public VoidClosure { 109 private: 110 PSPromotionManager* _promotion_manager; 111 public: 112 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 113 114 virtual void do_void() { 115 assert(_promotion_manager != NULL, "Sanity"); 116 _promotion_manager->drain_stacks(true); 117 guarantee(_promotion_manager->stacks_empty(), 118 "stacks should be empty at this point"); 119 } 120 }; 121 122 class PSPromotionFailedClosure : public ObjectClosure { 123 virtual void do_object(oop obj) { 124 if (obj->is_forwarded()) { 125 obj->init_mark(); 126 } 127 } 128 }; 129 130 class PSRefProcTaskProxy: public GCTask { 131 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 132 ProcessTask & _rp_task; 133 uint _work_id; 134 public: 135 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 136 : _rp_task(rp_task), 137 _work_id(work_id) 138 { } 139 140 private: 141 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 142 virtual void do_it(GCTaskManager* manager, uint which); 143 }; 144 145 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 146 { 147 PSPromotionManager* promotion_manager = 148 PSPromotionManager::gc_thread_promotion_manager(which); 149 assert(promotion_manager != NULL, "sanity check"); 150 PSKeepAliveClosure keep_alive(promotion_manager); 151 PSEvacuateFollowersClosure evac_followers(promotion_manager); 152 PSIsAliveClosure is_alive; 153 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 154 } 155 156 class PSRefEnqueueTaskProxy: public GCTask { 157 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 158 EnqueueTask& _enq_task; 159 uint _work_id; 160 161 public: 162 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 163 : _enq_task(enq_task), 164 _work_id(work_id) 165 { } 166 167 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 168 virtual void do_it(GCTaskManager* manager, uint which) 169 { 170 _enq_task.work(_work_id); 171 } 172 }; 173 174 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 175 virtual void execute(ProcessTask& task); 176 virtual void execute(EnqueueTask& task); 177 }; 178 179 void PSRefProcTaskExecutor::execute(ProcessTask& task) 180 { 181 GCTaskQueue* q = GCTaskQueue::create(); 182 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 183 for(uint i=0; i < manager->active_workers(); i++) { 184 q->enqueue(new PSRefProcTaskProxy(task, i)); 185 } 186 ParallelTaskTerminator terminator(manager->active_workers(), 187 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 188 if (task.marks_oops_alive() && manager->active_workers() > 1) { 189 for (uint j = 0; j < manager->active_workers(); j++) { 190 q->enqueue(new StealTask(&terminator)); 191 } 192 } 193 manager->execute_and_wait(q); 194 } 195 196 197 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 198 { 199 GCTaskQueue* q = GCTaskQueue::create(); 200 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 201 for(uint i=0; i < manager->active_workers(); i++) { 202 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 203 } 204 manager->execute_and_wait(q); 205 } 206 207 // This method contains all heap specific policy for invoking scavenge. 208 // PSScavenge::invoke_no_policy() will do nothing but attempt to 209 // scavenge. It will not clean up after failed promotions, bail out if 210 // we've exceeded policy time limits, or any other special behavior. 211 // All such policy should be placed here. 212 // 213 // Note that this method should only be called from the vm_thread while 214 // at a safepoint! 215 bool PSScavenge::invoke() { 216 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 217 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 218 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 219 220 ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap(); 221 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 222 223 PSAdaptiveSizePolicy* policy = heap->size_policy(); 224 IsGCActiveMark mark; 225 226 const bool scavenge_done = PSScavenge::invoke_no_policy(); 227 const bool need_full_gc = !scavenge_done || 228 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 229 bool full_gc_done = false; 230 231 if (UsePerfData) { 232 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 233 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 234 counters->update_full_follows_scavenge(ffs_val); 235 } 236 237 if (need_full_gc) { 238 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 239 CollectorPolicy* cp = heap->collector_policy(); 240 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 241 242 if (UseParallelOldGC) { 243 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 244 } else { 245 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 246 } 247 } 248 249 return full_gc_done; 250 } 251 252 // This method contains no policy. You should probably 253 // be calling invoke() instead. 254 bool PSScavenge::invoke_no_policy() { 255 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 256 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 257 258 assert(_preserved_mark_stack.is_empty(), "should be empty"); 259 assert(_preserved_oop_stack.is_empty(), "should be empty"); 260 261 TimeStamp scavenge_entry; 262 TimeStamp scavenge_midpoint; 263 TimeStamp scavenge_exit; 264 265 scavenge_entry.update(); 266 267 if (GC_locker::check_active_before_gc()) { 268 return false; 269 } 270 271 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 272 GCCause::Cause gc_cause = heap->gc_cause(); 273 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 274 275 // Check for potential problems. 276 if (!should_attempt_scavenge()) { 277 return false; 278 } 279 280 bool promotion_failure_occurred = false; 281 282 PSYoungGen* young_gen = heap->young_gen(); 283 PSOldGen* old_gen = heap->old_gen(); 284 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 285 heap->increment_total_collections(); 286 287 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 288 289 if ((gc_cause != GCCause::_java_lang_system_gc) || 290 UseAdaptiveSizePolicyWithSystemGC) { 291 // Gather the feedback data for eden occupancy. 292 young_gen->eden_space()->accumulate_statistics(); 293 } 294 295 if (ZapUnusedHeapArea) { 296 // Save information needed to minimize mangling 297 heap->record_gen_tops_before_GC(); 298 } 299 300 heap->print_heap_before_gc(); 301 302 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 303 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 304 305 size_t prev_used = heap->used(); 306 assert(promotion_failed() == false, "Sanity"); 307 308 // Fill in TLABs 309 heap->accumulate_statistics_all_tlabs(); 310 heap->ensure_parsability(true); // retire TLABs 311 312 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 313 HandleMark hm; // Discard invalid handles created during verification 314 Universe::verify(" VerifyBeforeGC:"); 315 } 316 317 { 318 ResourceMark rm; 319 HandleMark hm; 320 321 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 322 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 323 TraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty); 324 TraceCollectorStats tcs(counters()); 325 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 326 327 if (TraceGen0Time) accumulated_time()->start(); 328 329 // Let the size policy know we're starting 330 size_policy->minor_collection_begin(); 331 332 // Verify the object start arrays. 333 if (VerifyObjectStartArray && 334 VerifyBeforeGC) { 335 old_gen->verify_object_start_array(); 336 } 337 338 // Verify no unmarked old->young roots 339 if (VerifyRememberedSets) { 340 CardTableExtension::verify_all_young_refs_imprecise(); 341 } 342 343 if (!ScavengeWithObjectsInToSpace) { 344 assert(young_gen->to_space()->is_empty(), 345 "Attempt to scavenge with live objects in to_space"); 346 young_gen->to_space()->clear(SpaceDecorator::Mangle); 347 } else if (ZapUnusedHeapArea) { 348 young_gen->to_space()->mangle_unused_area(); 349 } 350 save_to_space_top_before_gc(); 351 352 COMPILER2_PRESENT(DerivedPointerTable::clear()); 353 354 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 355 reference_processor()->setup_policy(false); 356 357 // We track how much was promoted to the next generation for 358 // the AdaptiveSizePolicy. 359 size_t old_gen_used_before = old_gen->used_in_bytes(); 360 361 // For PrintGCDetails 362 size_t young_gen_used_before = young_gen->used_in_bytes(); 363 364 // Reset our survivor overflow. 365 set_survivor_overflow(false); 366 367 // We need to save the old top values before 368 // creating the promotion_manager. We pass the top 369 // values to the card_table, to prevent it from 370 // straying into the promotion labs. 371 HeapWord* old_top = old_gen->object_space()->top(); 372 373 // Release all previously held resources 374 gc_task_manager()->release_all_resources(); 375 376 // Set the number of GC threads to be used in this collection 377 gc_task_manager()->set_active_gang(); 378 gc_task_manager()->task_idle_workers(); 379 // Get the active number of workers here and use that value 380 // throughout the methods. 381 uint active_workers = gc_task_manager()->active_workers(); 382 heap->set_par_threads(active_workers); 383 384 PSPromotionManager::pre_scavenge(); 385 386 // We'll use the promotion manager again later. 387 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 388 { 389 // TraceTime("Roots"); 390 ParallelScavengeHeap::ParStrongRootsScope psrs; 391 392 GCTaskQueue* q = GCTaskQueue::create(); 393 394 if (!old_gen->object_space()->is_empty()) { 395 // There are only old-to-young pointers if there are objects 396 // in the old gen. 397 uint stripe_total = active_workers; 398 for(uint i=0; i < stripe_total; i++) { 399 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 400 } 401 } 402 403 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 404 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 405 // We scan the thread roots in parallel 406 Threads::create_thread_roots_tasks(q); 407 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 408 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 409 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 410 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 411 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 412 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 413 414 ParallelTaskTerminator terminator( 415 active_workers, 416 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 417 if (active_workers > 1) { 418 for (uint j = 0; j < active_workers; j++) { 419 q->enqueue(new StealTask(&terminator)); 420 } 421 } 422 423 gc_task_manager()->execute_and_wait(q); 424 } 425 426 scavenge_midpoint.update(); 427 428 // Process reference objects discovered during scavenge 429 { 430 reference_processor()->setup_policy(false); // not always_clear 431 reference_processor()->set_active_mt_degree(active_workers); 432 PSKeepAliveClosure keep_alive(promotion_manager); 433 PSEvacuateFollowersClosure evac_followers(promotion_manager); 434 if (reference_processor()->processing_is_mt()) { 435 PSRefProcTaskExecutor task_executor; 436 reference_processor()->process_discovered_references( 437 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor); 438 } else { 439 reference_processor()->process_discovered_references( 440 &_is_alive_closure, &keep_alive, &evac_followers, NULL); 441 } 442 } 443 444 // Enqueue reference objects discovered during scavenge. 445 if (reference_processor()->processing_is_mt()) { 446 PSRefProcTaskExecutor task_executor; 447 reference_processor()->enqueue_discovered_references(&task_executor); 448 } else { 449 reference_processor()->enqueue_discovered_references(NULL); 450 } 451 452 // Unlink any dead interned Strings 453 StringTable::unlink(&_is_alive_closure); 454 // Process the remaining live ones 455 PSScavengeRootsClosure root_closure(promotion_manager); 456 StringTable::oops_do(&root_closure); 457 458 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 459 PSPromotionManager::post_scavenge(); 460 461 promotion_failure_occurred = promotion_failed(); 462 if (promotion_failure_occurred) { 463 clean_up_failed_promotion(); 464 if (PrintGC) { 465 gclog_or_tty->print("--"); 466 } 467 } 468 469 // Let the size policy know we're done. Note that we count promotion 470 // failure cleanup time as part of the collection (otherwise, we're 471 // implicitly saying it's mutator time). 472 size_policy->minor_collection_end(gc_cause); 473 474 if (!promotion_failure_occurred) { 475 // Swap the survivor spaces. 476 477 478 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 479 young_gen->from_space()->clear(SpaceDecorator::Mangle); 480 young_gen->swap_spaces(); 481 482 size_t survived = young_gen->from_space()->used_in_bytes(); 483 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 484 size_policy->update_averages(_survivor_overflow, survived, promoted); 485 486 // A successful scavenge should restart the GC time limit count which is 487 // for full GC's. 488 size_policy->reset_gc_overhead_limit_count(); 489 if (UseAdaptiveSizePolicy) { 490 // Calculate the new survivor size and tenuring threshold 491 492 if (PrintAdaptiveSizePolicy) { 493 gclog_or_tty->print("AdaptiveSizeStart: "); 494 gclog_or_tty->stamp(); 495 gclog_or_tty->print_cr(" collection: %d ", 496 heap->total_collections()); 497 498 if (Verbose) { 499 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d", 500 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 501 } 502 } 503 504 505 if (UsePerfData) { 506 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 507 counters->update_old_eden_size( 508 size_policy->calculated_eden_size_in_bytes()); 509 counters->update_old_promo_size( 510 size_policy->calculated_promo_size_in_bytes()); 511 counters->update_old_capacity(old_gen->capacity_in_bytes()); 512 counters->update_young_capacity(young_gen->capacity_in_bytes()); 513 counters->update_survived(survived); 514 counters->update_promoted(promoted); 515 counters->update_survivor_overflowed(_survivor_overflow); 516 } 517 518 size_t survivor_limit = 519 size_policy->max_survivor_size(young_gen->max_size()); 520 _tenuring_threshold = 521 size_policy->compute_survivor_space_size_and_threshold( 522 _survivor_overflow, 523 _tenuring_threshold, 524 survivor_limit); 525 526 if (PrintTenuringDistribution) { 527 gclog_or_tty->cr(); 528 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max %u)", 529 size_policy->calculated_survivor_size_in_bytes(), 530 _tenuring_threshold, MaxTenuringThreshold); 531 } 532 533 if (UsePerfData) { 534 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 535 counters->update_tenuring_threshold(_tenuring_threshold); 536 counters->update_survivor_size_counters(); 537 } 538 539 // Do call at minor collections? 540 // Don't check if the size_policy is ready at this 541 // level. Let the size_policy check that internally. 542 if (UseAdaptiveSizePolicy && 543 UseAdaptiveGenerationSizePolicyAtMinorCollection && 544 ((gc_cause != GCCause::_java_lang_system_gc) || 545 UseAdaptiveSizePolicyWithSystemGC)) { 546 547 // Calculate optimial free space amounts 548 assert(young_gen->max_size() > 549 young_gen->from_space()->capacity_in_bytes() + 550 young_gen->to_space()->capacity_in_bytes(), 551 "Sizes of space in young gen are out-of-bounds"); 552 553 size_t young_live = young_gen->used_in_bytes(); 554 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 555 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 556 size_t max_old_gen_size = old_gen->max_gen_size(); 557 size_t max_eden_size = young_gen->max_size() - 558 young_gen->from_space()->capacity_in_bytes() - 559 young_gen->to_space()->capacity_in_bytes(); 560 561 // Used for diagnostics 562 size_policy->clear_generation_free_space_flags(); 563 564 size_policy->compute_eden_space_size(young_live, 565 eden_live, 566 cur_eden, 567 max_eden_size, 568 false /* not full gc*/); 569 570 size_policy->check_gc_overhead_limit(young_live, 571 eden_live, 572 max_old_gen_size, 573 max_eden_size, 574 false /* not full gc*/, 575 gc_cause, 576 heap->collector_policy()); 577 578 size_policy->decay_supplemental_growth(false /* not full gc*/); 579 } 580 // Resize the young generation at every collection 581 // even if new sizes have not been calculated. This is 582 // to allow resizes that may have been inhibited by the 583 // relative location of the "to" and "from" spaces. 584 585 // Resizing the old gen at minor collects can cause increases 586 // that don't feed back to the generation sizing policy until 587 // a major collection. Don't resize the old gen here. 588 589 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 590 size_policy->calculated_survivor_size_in_bytes()); 591 592 if (PrintAdaptiveSizePolicy) { 593 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 594 heap->total_collections()); 595 } 596 } 597 598 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 599 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 600 // Also update() will case adaptive NUMA chunk resizing. 601 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 602 young_gen->eden_space()->update(); 603 604 heap->gc_policy_counters()->update_counters(); 605 606 heap->resize_all_tlabs(); 607 608 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 609 } 610 611 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 612 613 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 614 615 CodeCache::prune_scavenge_root_nmethods(); 616 617 // Re-verify object start arrays 618 if (VerifyObjectStartArray && 619 VerifyAfterGC) { 620 old_gen->verify_object_start_array(); 621 } 622 623 // Verify all old -> young cards are now precise 624 if (VerifyRememberedSets) { 625 // Precise verification will give false positives. Until this is fixed, 626 // use imprecise verification. 627 // CardTableExtension::verify_all_young_refs_precise(); 628 CardTableExtension::verify_all_young_refs_imprecise(); 629 } 630 631 if (TraceGen0Time) accumulated_time()->stop(); 632 633 if (PrintGC) { 634 if (PrintGCDetails) { 635 // Don't print a GC timestamp here. This is after the GC so 636 // would be confusing. 637 young_gen->print_used_change(young_gen_used_before); 638 } 639 heap->print_heap_change(prev_used); 640 } 641 642 // Track memory usage and detect low memory 643 MemoryService::track_memory_usage(); 644 heap->update_counters(); 645 646 gc_task_manager()->release_idle_workers(); 647 } 648 649 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 650 HandleMark hm; // Discard invalid handles created during verification 651 Universe::verify(" VerifyAfterGC:"); 652 } 653 654 heap->print_heap_after_gc(); 655 656 if (ZapUnusedHeapArea) { 657 young_gen->eden_space()->check_mangled_unused_area_complete(); 658 young_gen->from_space()->check_mangled_unused_area_complete(); 659 young_gen->to_space()->check_mangled_unused_area_complete(); 660 } 661 662 scavenge_exit.update(); 663 664 if (PrintGCTaskTimeStamps) { 665 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, 666 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 667 scavenge_exit.ticks()); 668 gc_task_manager()->print_task_time_stamps(); 669 } 670 671 #ifdef TRACESPINNING 672 ParallelTaskTerminator::print_termination_counts(); 673 #endif 674 675 return !promotion_failure_occurred; 676 } 677 678 // This method iterates over all objects in the young generation, 679 // unforwarding markOops. It then restores any preserved mark oops, 680 // and clears the _preserved_mark_stack. 681 void PSScavenge::clean_up_failed_promotion() { 682 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 683 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 684 assert(promotion_failed(), "Sanity"); 685 686 PSYoungGen* young_gen = heap->young_gen(); 687 688 { 689 ResourceMark rm; 690 691 // Unforward all pointers in the young gen. 692 PSPromotionFailedClosure unforward_closure; 693 young_gen->object_iterate(&unforward_closure); 694 695 if (PrintGC && Verbose) { 696 gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size()); 697 } 698 699 // Restore any saved marks. 700 while (!_preserved_oop_stack.is_empty()) { 701 oop obj = _preserved_oop_stack.pop(); 702 markOop mark = _preserved_mark_stack.pop(); 703 obj->set_mark(mark); 704 } 705 706 // Clear the preserved mark and oop stack caches. 707 _preserved_mark_stack.clear(true); 708 _preserved_oop_stack.clear(true); 709 _promotion_failed = false; 710 } 711 712 // Reset the PromotionFailureALot counters. 713 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 714 } 715 716 // This method is called whenever an attempt to promote an object 717 // fails. Some markOops will need preservation, some will not. Note 718 // that the entire eden is traversed after a failed promotion, with 719 // all forwarded headers replaced by the default markOop. This means 720 // it is not neccessary to preserve most markOops. 721 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 722 _promotion_failed = true; 723 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 724 // Should use per-worker private stakcs hetre rather than 725 // locking a common pair of stacks. 726 ThreadCritical tc; 727 _preserved_oop_stack.push(obj); 728 _preserved_mark_stack.push(obj_mark); 729 } 730 } 731 732 bool PSScavenge::should_attempt_scavenge() { 733 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 734 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 735 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 736 737 if (UsePerfData) { 738 counters->update_scavenge_skipped(not_skipped); 739 } 740 741 PSYoungGen* young_gen = heap->young_gen(); 742 PSOldGen* old_gen = heap->old_gen(); 743 744 if (!ScavengeWithObjectsInToSpace) { 745 // Do not attempt to promote unless to_space is empty 746 if (!young_gen->to_space()->is_empty()) { 747 _consecutive_skipped_scavenges++; 748 if (UsePerfData) { 749 counters->update_scavenge_skipped(to_space_not_empty); 750 } 751 return false; 752 } 753 } 754 755 // Test to see if the scavenge will likely fail. 756 PSAdaptiveSizePolicy* policy = heap->size_policy(); 757 758 // A similar test is done in the policy's should_full_GC(). If this is 759 // changed, decide if that test should also be changed. 760 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 761 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 762 bool result = promotion_estimate < old_gen->free_in_bytes(); 763 764 if (PrintGCDetails && Verbose) { 765 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 766 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 767 " padded_average_promoted " SIZE_FORMAT 768 " free in old gen " SIZE_FORMAT, 769 (size_t) policy->average_promoted_in_bytes(), 770 (size_t) policy->padded_average_promoted_in_bytes(), 771 old_gen->free_in_bytes()); 772 if (young_gen->used_in_bytes() < 773 (size_t) policy->padded_average_promoted_in_bytes()) { 774 gclog_or_tty->print_cr(" padded_promoted_average is greater" 775 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 776 } 777 } 778 779 if (result) { 780 _consecutive_skipped_scavenges = 0; 781 } else { 782 _consecutive_skipped_scavenges++; 783 if (UsePerfData) { 784 counters->update_scavenge_skipped(promoted_too_large); 785 } 786 } 787 return result; 788 } 789 790 // Used to add tasks 791 GCTaskManager* const PSScavenge::gc_task_manager() { 792 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 793 "shouldn't return NULL"); 794 return ParallelScavengeHeap::gc_task_manager(); 795 } 796 797 void PSScavenge::initialize() { 798 // Arguments must have been parsed 799 800 if (AlwaysTenure) { 801 _tenuring_threshold = 0; 802 } else if (NeverTenure) { 803 _tenuring_threshold = markOopDesc::max_age + 1; 804 } else { 805 // We want to smooth out our startup times for the AdaptiveSizePolicy 806 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 807 MaxTenuringThreshold; 808 } 809 810 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 811 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 812 813 PSYoungGen* young_gen = heap->young_gen(); 814 PSOldGen* old_gen = heap->old_gen(); 815 816 // Set boundary between young_gen and old_gen 817 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 818 "old above young"); 819 _young_generation_boundary = young_gen->eden_space()->bottom(); 820 821 // Initialize ref handling object for scavenging. 822 MemRegion mr = young_gen->reserved(); 823 824 _ref_processor = 825 new ReferenceProcessor(mr, // span 826 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 827 (int) ParallelGCThreads, // mt processing degree 828 true, // mt discovery 829 (int) ParallelGCThreads, // mt discovery degree 830 true, // atomic_discovery 831 NULL, // header provides liveness info 832 false); // next field updates do not need write barrier 833 834 // Cache the cardtable 835 BarrierSet* bs = Universe::heap()->barrier_set(); 836 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); 837 _card_table = (CardTableExtension*)bs; 838 839 _counters = new CollectorCounters("PSScavenge", 0); 840 }