1 /* 2 * Copyright (c) 2002, 2019, 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 "aot/aotLoader.hpp" 27 #include "classfile/classLoaderDataGraph.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "code/codeCache.hpp" 30 #include "gc/parallel/parallelScavengeHeap.hpp" 31 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 32 #include "gc/parallel/psClosure.inline.hpp" 33 #include "gc/parallel/psCompactionManager.hpp" 34 #include "gc/parallel/psMarkSweepProxy.hpp" 35 #include "gc/parallel/psParallelCompact.inline.hpp" 36 #include "gc/parallel/psPromotionManager.inline.hpp" 37 #include "gc/parallel/psRootType.inline.hpp" 38 #include "gc/parallel/psScavenge.inline.hpp" 39 #include "gc/shared/gcCause.hpp" 40 #include "gc/shared/gcHeapSummary.hpp" 41 #include "gc/shared/gcId.hpp" 42 #include "gc/shared/gcLocker.hpp" 43 #include "gc/shared/gcTimer.hpp" 44 #include "gc/shared/gcTrace.hpp" 45 #include "gc/shared/gcTraceTime.inline.hpp" 46 #include "gc/shared/isGCActiveMark.hpp" 47 #include "gc/shared/referencePolicy.hpp" 48 #include "gc/shared/referenceProcessor.hpp" 49 #include "gc/shared/referenceProcessorPhaseTimes.hpp" 50 #include "gc/shared/scavengableNMethods.hpp" 51 #include "gc/shared/spaceDecorator.hpp" 52 #include "gc/shared/weakProcessor.hpp" 53 #include "gc/shared/workerPolicy.hpp" 54 #include "gc/shared/workgroup.hpp" 55 #if INCLUDE_JVMCI 56 #include "jvmci/jvmci.hpp" 57 #endif 58 #include "memory/resourceArea.hpp" 59 #include "memory/universe.hpp" 60 #include "logging/log.hpp" 61 #include "oops/access.inline.hpp" 62 #include "oops/compressedOops.inline.hpp" 63 #include "oops/oop.inline.hpp" 64 #include "runtime/biasedLocking.hpp" 65 #include "runtime/handles.inline.hpp" 66 #include "runtime/threadCritical.hpp" 67 #include "runtime/vmThread.hpp" 68 #include "runtime/vmOperations.hpp" 69 #include "services/management.hpp" 70 #include "services/memoryService.hpp" 71 #include "utilities/stack.inline.hpp" 72 73 74 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 75 int PSScavenge::_consecutive_skipped_scavenges = 0; 76 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer; 77 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 78 PSCardTable* PSScavenge::_card_table = NULL; 79 bool PSScavenge::_survivor_overflow = false; 80 uint PSScavenge::_tenuring_threshold = 0; 81 HeapWord* PSScavenge::_young_generation_boundary = NULL; 82 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 83 elapsedTimer PSScavenge::_accumulated_time; 84 STWGCTimer PSScavenge::_gc_timer; 85 ParallelScavengeTracer PSScavenge::_gc_tracer; 86 CollectorCounters* PSScavenge::_counters = NULL; 87 88 void scavenge_roots_task(Parallel::RootType::Value root_type, uint which) { 89 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc"); 90 91 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(which); 92 PSScavengeRootsClosure roots_closure(pm); 93 PSPromoteRootsClosure roots_to_old_closure(pm); 94 95 switch (root_type) { 96 case Parallel::RootType::universe: 97 Universe::oops_do(&roots_closure); 98 break; 99 100 case Parallel::RootType::jni_handles: 101 JNIHandles::oops_do(&roots_closure); 102 break; 103 104 case Parallel::RootType::object_synchronizer: 105 ObjectSynchronizer::oops_do(&roots_closure); 106 break; 107 108 case Parallel::RootType::system_dictionary: 109 SystemDictionary::oops_do(&roots_closure); 110 break; 111 112 case Parallel::RootType::class_loader_data: 113 { 114 PSScavengeCLDClosure cld_closure(pm); 115 ClassLoaderDataGraph::cld_do(&cld_closure); 116 } 117 break; 118 119 case Parallel::RootType::management: 120 Management::oops_do(&roots_closure); 121 break; 122 123 case Parallel::RootType::jvmti: 124 JvmtiExport::oops_do(&roots_closure); 125 break; 126 127 case Parallel::RootType::code_cache: 128 { 129 MarkingCodeBlobClosure code_closure(&roots_to_old_closure, CodeBlobToOopClosure::FixRelocations); 130 ScavengableNMethods::nmethods_do(&code_closure); 131 AOTLoader::oops_do(&roots_closure); 132 } 133 break; 134 135 #if INCLUDE_JVMCI 136 case Parallel::RootType::jvmci: 137 JVMCI::oops_do(&roots_closure); 138 break; 139 #endif 140 141 case Parallel::RootType::sentinel: 142 DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds 143 fatal("Bad enumeration value: %u", root_type); 144 break; 145 } 146 147 // Do the real work 148 pm->drain_stacks(false); 149 } 150 151 void steal_task(ParallelTaskTerminator& terminator, uint worker_id) { 152 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc"); 153 154 PSPromotionManager* pm = 155 PSPromotionManager::gc_thread_promotion_manager(worker_id); 156 pm->drain_stacks(true); 157 guarantee(pm->stacks_empty(), 158 "stacks should be empty at this point"); 159 160 while (true) { 161 StarTask p; 162 if (PSPromotionManager::steal_depth(worker_id, p)) { 163 TASKQUEUE_STATS_ONLY(pm->record_steal(p)); 164 pm->process_popped_location_depth(p); 165 pm->drain_stacks_depth(true); 166 } else { 167 if (terminator.offer_termination()) { 168 break; 169 } 170 } 171 } 172 guarantee(pm->stacks_empty(), "stacks should be empty at this point"); 173 } 174 175 // Define before use 176 class PSIsAliveClosure: public BoolObjectClosure { 177 public: 178 bool do_object_b(oop p) { 179 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 180 } 181 }; 182 183 PSIsAliveClosure PSScavenge::_is_alive_closure; 184 185 class PSKeepAliveClosure: public OopClosure { 186 protected: 187 MutableSpace* _to_space; 188 PSPromotionManager* _promotion_manager; 189 190 public: 191 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 192 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 193 _to_space = heap->young_gen()->to_space(); 194 195 assert(_promotion_manager != NULL, "Sanity"); 196 } 197 198 template <class T> void do_oop_work(T* p) { 199 assert (oopDesc::is_oop(RawAccess<IS_NOT_NULL>::oop_load(p)), 200 "expected an oop while scanning weak refs"); 201 202 // Weak refs may be visited more than once. 203 if (PSScavenge::should_scavenge(p, _to_space)) { 204 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p); 205 } 206 } 207 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 208 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 209 }; 210 211 class PSEvacuateFollowersClosure: public VoidClosure { 212 private: 213 PSPromotionManager* _promotion_manager; 214 public: 215 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 216 217 virtual void do_void() { 218 assert(_promotion_manager != NULL, "Sanity"); 219 _promotion_manager->drain_stacks(true); 220 guarantee(_promotion_manager->stacks_empty(), 221 "stacks should be empty at this point"); 222 } 223 }; 224 225 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 226 virtual void execute(ProcessTask& process_task, uint ergo_workers); 227 }; 228 229 class PSRefProcTask : public AbstractGangTask { 230 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 231 TaskTerminator _terminator; 232 ProcessTask& _task; 233 uint _active_workers; 234 235 public: 236 PSRefProcTask(ProcessTask& task, uint active_workers) 237 : AbstractGangTask("PSRefProcTask"), 238 _terminator(active_workers, PSPromotionManager::stack_array_depth()), 239 _task(task), 240 _active_workers(active_workers) { 241 } 242 243 virtual void work(uint worker_id) { 244 PSPromotionManager* promotion_manager = 245 PSPromotionManager::gc_thread_promotion_manager(worker_id); 246 assert(promotion_manager != NULL, "sanity check"); 247 PSKeepAliveClosure keep_alive(promotion_manager); 248 PSEvacuateFollowersClosure evac_followers(promotion_manager); 249 PSIsAliveClosure is_alive; 250 _task.work(worker_id, is_alive, keep_alive, evac_followers); 251 252 if (_task.marks_oops_alive() && _active_workers > 1) { 253 steal_task(*_terminator.terminator(), worker_id); 254 } 255 } 256 }; 257 258 void PSRefProcTaskExecutor::execute(ProcessTask& process_task, uint ergo_workers) { 259 PSRefProcTask task(process_task, ergo_workers); 260 ParallelScavengeHeap::heap()->workers().run_task(&task); 261 } 262 263 // This method contains all heap specific policy for invoking scavenge. 264 // PSScavenge::invoke_no_policy() will do nothing but attempt to 265 // scavenge. It will not clean up after failed promotions, bail out if 266 // we've exceeded policy time limits, or any other special behavior. 267 // All such policy should be placed here. 268 // 269 // Note that this method should only be called from the vm_thread while 270 // at a safepoint! 271 bool PSScavenge::invoke() { 272 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 273 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 274 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 275 276 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap(); 277 PSAdaptiveSizePolicy* policy = heap->size_policy(); 278 IsGCActiveMark mark; 279 280 const bool scavenge_done = PSScavenge::invoke_no_policy(); 281 const bool need_full_gc = !scavenge_done || 282 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 283 bool full_gc_done = false; 284 285 if (UsePerfData) { 286 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 287 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 288 counters->update_full_follows_scavenge(ffs_val); 289 } 290 291 if (need_full_gc) { 292 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 293 SoftRefPolicy* srp = heap->soft_ref_policy(); 294 const bool clear_all_softrefs = srp->should_clear_all_soft_refs(); 295 296 if (UseParallelOldGC) { 297 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 298 } else { 299 full_gc_done = PSMarkSweepProxy::invoke_no_policy(clear_all_softrefs); 300 } 301 } 302 303 return full_gc_done; 304 } 305 306 class PSThreadRootsTaskClosure : public ThreadClosure { 307 uint _worker_id; 308 public: 309 PSThreadRootsTaskClosure(uint worker_id) : _worker_id(worker_id) { } 310 virtual void do_thread(Thread* thread) { 311 assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc"); 312 313 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(_worker_id); 314 PSScavengeRootsClosure roots_closure(pm); 315 MarkingCodeBlobClosure roots_in_blobs(&roots_closure, CodeBlobToOopClosure::FixRelocations); 316 317 thread->oops_do(&roots_closure, &roots_in_blobs); 318 319 // Do the real work 320 pm->drain_stacks(false); 321 } 322 }; 323 // 324 // OldToYoungRootsTask 325 // 326 // This task is used to scan old to young roots in parallel 327 // 328 // A GC thread executing this tasks divides the generation (old gen) 329 // into slices and takes a stripe in the slice as its part of the 330 // work. 331 // 332 // +===============+ slice 0 333 // | stripe 0 | 334 // +---------------+ 335 // | stripe 1 | 336 // +---------------+ 337 // | stripe 2 | 338 // +---------------+ 339 // | stripe 3 | 340 // +===============+ slice 1 341 // | stripe 0 | 342 // +---------------+ 343 // | stripe 1 | 344 // +---------------+ 345 // | stripe 2 | 346 // +---------------+ 347 // | stripe 3 | 348 // +===============+ slice 2 349 // ... 350 // 351 // A task is created for each stripe. In this case there are 4 tasks 352 // created. A GC thread first works on its stripe within slice 0 353 // and then moves to its stripe in the next slice until all stripes 354 // exceed the top of the generation. Note that having fewer GC threads 355 // than stripes works because all the tasks are executed so all stripes 356 // will be covered. In this example if 4 tasks have been created to cover 357 // all the stripes and there are only 3 threads, one of the threads will 358 // get the tasks with the 4th stripe. However, there is a dependence in 359 // PSCardTable::scavenge_contents_parallel() on the number 360 // of tasks created. In scavenge_contents_parallel the distance 361 // to the next stripe is calculated based on the number of tasks. 362 // If the stripe width is ssize, a task's next stripe is at 363 // ssize * number_of_tasks (= slice_stride). In this case after 364 // finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1 365 // by adding slice_stride to the start of stripe 0 in slice 0 to get 366 // to the start of stride 0 in slice 1. 367 368 class ScavengeRootsTask : public AbstractGangTask { 369 StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do 370 EnumClaimer<Parallel::RootType::Value> _enum_claimer; 371 PSOldGen* _old_gen; 372 HeapWord* _gen_top; 373 uint _active_workers; 374 bool _is_empty; 375 TaskTerminator _terminator; 376 377 public: 378 ScavengeRootsTask( 379 PSOldGen* old_gen, 380 HeapWord* gen_top, 381 uint active_workers, 382 bool is_empty) 383 : AbstractGangTask("ScavengeRootsTask"), 384 _strong_roots_scope(active_workers), 385 _enum_claimer(Parallel::RootType::sentinel), 386 _old_gen(old_gen), 387 _gen_top(gen_top), 388 _active_workers(active_workers), 389 _is_empty(is_empty), 390 _terminator(active_workers, PSPromotionManager::vm_thread_promotion_manager()->stack_array_depth()) { 391 } 392 393 virtual void work(uint worker_id) { 394 ResourceMark rm; 395 396 if (!_is_empty) { 397 // There are only old-to-young pointers if there are objects 398 // in the old gen. 399 400 // There are not old-to-young pointers if the old gen is empty. 401 assert(!_old_gen->object_space()->is_empty(), 402 "Should not be called is there is no work"); 403 assert(_old_gen != NULL, "Sanity"); 404 assert(_old_gen->object_space()->contains(_gen_top) || _gen_top == _old_gen->object_space()->top(), "Sanity"); 405 assert(worker_id < ParallelGCThreads, "Sanity"); 406 407 { 408 PSPromotionManager* pm = PSPromotionManager::gc_thread_promotion_manager(worker_id); 409 PSCardTable* card_table = ParallelScavengeHeap::heap()->card_table(); 410 411 card_table->scavenge_contents_parallel(_old_gen->start_array(), 412 _old_gen->object_space(), 413 _gen_top, 414 pm, 415 worker_id, 416 _active_workers); 417 418 // Do the real work 419 pm->drain_stacks(false); 420 } 421 } 422 423 for (Parallel::RootType::Value root_type; _enum_claimer.try_claim(root_type); /* empty */) { 424 scavenge_roots_task(root_type, worker_id); 425 } 426 427 PSThreadRootsTaskClosure closure(worker_id); 428 Threads::possibly_parallel_threads_do(true /*parallel */, &closure); 429 430 431 // If active_workers can exceed 1, add a StrealTask. 432 // PSPromotionManager::drain_stacks_depth() does not fully drain its 433 // stacks and expects a StealTask to complete the draining if 434 // ParallelGCThreads is > 1. 435 436 if (_active_workers > 1) { 437 steal_task(*_terminator.terminator() , worker_id); 438 } 439 } 440 }; 441 442 // This method contains no policy. You should probably 443 // be calling invoke() instead. 444 bool PSScavenge::invoke_no_policy() { 445 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 446 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 447 448 _gc_timer.register_gc_start(); 449 450 TimeStamp scavenge_entry; 451 TimeStamp scavenge_midpoint; 452 TimeStamp scavenge_exit; 453 454 scavenge_entry.update(); 455 456 if (GCLocker::check_active_before_gc()) { 457 return false; 458 } 459 460 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 461 GCCause::Cause gc_cause = heap->gc_cause(); 462 463 // Check for potential problems. 464 if (!should_attempt_scavenge()) { 465 return false; 466 } 467 468 GCIdMark gc_id_mark; 469 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 470 471 bool promotion_failure_occurred = false; 472 473 PSYoungGen* young_gen = heap->young_gen(); 474 PSOldGen* old_gen = heap->old_gen(); 475 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 476 477 heap->increment_total_collections(); 478 479 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) { 480 // Gather the feedback data for eden occupancy. 481 young_gen->eden_space()->accumulate_statistics(); 482 } 483 484 heap->print_heap_before_gc(); 485 heap->trace_heap_before_gc(&_gc_tracer); 486 487 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 488 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 489 490 // Fill in TLABs 491 heap->ensure_parsability(true); // retire TLABs 492 493 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 494 HandleMark hm; // Discard invalid handles created during verification 495 Universe::verify("Before GC"); 496 } 497 498 { 499 ResourceMark rm; 500 HandleMark hm; 501 502 GCTraceCPUTime tcpu; 503 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true); 504 TraceCollectorStats tcs(counters()); 505 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause); 506 507 if (log_is_enabled(Debug, gc, heap, exit)) { 508 accumulated_time()->start(); 509 } 510 511 // Let the size policy know we're starting 512 size_policy->minor_collection_begin(); 513 514 // Verify the object start arrays. 515 if (VerifyObjectStartArray && 516 VerifyBeforeGC) { 517 old_gen->verify_object_start_array(); 518 } 519 520 // Verify no unmarked old->young roots 521 if (VerifyRememberedSets) { 522 heap->card_table()->verify_all_young_refs_imprecise(); 523 } 524 525 assert(young_gen->to_space()->is_empty(), 526 "Attempt to scavenge with live objects in to_space"); 527 young_gen->to_space()->clear(SpaceDecorator::Mangle); 528 529 save_to_space_top_before_gc(); 530 531 #if COMPILER2_OR_JVMCI 532 DerivedPointerTable::clear(); 533 #endif 534 535 reference_processor()->enable_discovery(); 536 reference_processor()->setup_policy(false); 537 538 PreGCValues pre_gc_values(heap); 539 540 // Reset our survivor overflow. 541 set_survivor_overflow(false); 542 543 // We need to save the old top values before 544 // creating the promotion_manager. We pass the top 545 // values to the card_table, to prevent it from 546 // straying into the promotion labs. 547 HeapWord* old_top = old_gen->object_space()->top(); 548 549 uint active_workers = ParallelScavengeHeap::heap()->workers().update_active_workers(WorkerPolicy::calc_active_workers( 550 ParallelScavengeHeap::heap()->workers().total_workers(), 551 ParallelScavengeHeap::heap()->workers().active_workers(), 552 Threads::number_of_non_daemon_threads())); 553 554 PSPromotionManager::pre_scavenge(); 555 556 // We'll use the promotion manager again later. 557 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 558 { 559 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer); 560 561 ScavengeRootsTask task(old_gen, old_top, active_workers, old_gen->object_space()->is_empty()); 562 ParallelScavengeHeap::heap()->workers().run_task(&task); 563 } 564 565 scavenge_midpoint.update(); 566 567 // Process reference objects discovered during scavenge 568 { 569 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 570 571 reference_processor()->setup_policy(false); // not always_clear 572 reference_processor()->set_active_mt_degree(active_workers); 573 PSKeepAliveClosure keep_alive(promotion_manager); 574 PSEvacuateFollowersClosure evac_followers(promotion_manager); 575 ReferenceProcessorStats stats; 576 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues()); 577 if (reference_processor()->processing_is_mt()) { 578 PSRefProcTaskExecutor task_executor; 579 stats = reference_processor()->process_discovered_references( 580 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 581 &pt); 582 } else { 583 stats = reference_processor()->process_discovered_references( 584 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt); 585 } 586 587 _gc_tracer.report_gc_reference_stats(stats); 588 pt.print_all_references(); 589 } 590 591 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 592 593 PSScavengeRootsClosure root_closure(promotion_manager); 594 595 { 596 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 597 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure); 598 } 599 600 // Verify that usage of root_closure didn't copy any objects. 601 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 602 603 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 604 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 605 if (promotion_failure_occurred) { 606 clean_up_failed_promotion(); 607 log_info(gc, promotion)("Promotion failed"); 608 } 609 610 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 611 612 // Let the size policy know we're done. Note that we count promotion 613 // failure cleanup time as part of the collection (otherwise, we're 614 // implicitly saying it's mutator time). 615 size_policy->minor_collection_end(gc_cause); 616 617 if (!promotion_failure_occurred) { 618 // Swap the survivor spaces. 619 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 620 young_gen->from_space()->clear(SpaceDecorator::Mangle); 621 young_gen->swap_spaces(); 622 623 size_t survived = young_gen->from_space()->used_in_bytes(); 624 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used(); 625 size_policy->update_averages(_survivor_overflow, survived, promoted); 626 627 // A successful scavenge should restart the GC time limit count which is 628 // for full GC's. 629 size_policy->reset_gc_overhead_limit_count(); 630 if (UseAdaptiveSizePolicy) { 631 // Calculate the new survivor size and tenuring threshold 632 633 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 634 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 635 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 636 637 if (UsePerfData) { 638 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 639 counters->update_old_eden_size( 640 size_policy->calculated_eden_size_in_bytes()); 641 counters->update_old_promo_size( 642 size_policy->calculated_promo_size_in_bytes()); 643 counters->update_old_capacity(old_gen->capacity_in_bytes()); 644 counters->update_young_capacity(young_gen->capacity_in_bytes()); 645 counters->update_survived(survived); 646 counters->update_promoted(promoted); 647 counters->update_survivor_overflowed(_survivor_overflow); 648 } 649 650 size_t max_young_size = young_gen->max_size(); 651 652 // Deciding a free ratio in the young generation is tricky, so if 653 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 654 // that the old generation size may have been limited because of them) we 655 // should then limit our young generation size using NewRatio to have it 656 // follow the old generation size. 657 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 658 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 659 } 660 661 size_t survivor_limit = 662 size_policy->max_survivor_size(max_young_size); 663 _tenuring_threshold = 664 size_policy->compute_survivor_space_size_and_threshold( 665 _survivor_overflow, 666 _tenuring_threshold, 667 survivor_limit); 668 669 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")", 670 size_policy->calculated_survivor_size_in_bytes(), 671 _tenuring_threshold, MaxTenuringThreshold); 672 673 if (UsePerfData) { 674 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 675 counters->update_tenuring_threshold(_tenuring_threshold); 676 counters->update_survivor_size_counters(); 677 } 678 679 // Do call at minor collections? 680 // Don't check if the size_policy is ready at this 681 // level. Let the size_policy check that internally. 682 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 683 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 684 // Calculate optimal free space amounts 685 assert(young_gen->max_size() > 686 young_gen->from_space()->capacity_in_bytes() + 687 young_gen->to_space()->capacity_in_bytes(), 688 "Sizes of space in young gen are out-of-bounds"); 689 690 size_t young_live = young_gen->used_in_bytes(); 691 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 692 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 693 size_t max_old_gen_size = old_gen->max_gen_size(); 694 size_t max_eden_size = max_young_size - 695 young_gen->from_space()->capacity_in_bytes() - 696 young_gen->to_space()->capacity_in_bytes(); 697 698 // Used for diagnostics 699 size_policy->clear_generation_free_space_flags(); 700 701 size_policy->compute_eden_space_size(young_live, 702 eden_live, 703 cur_eden, 704 max_eden_size, 705 false /* not full gc*/); 706 707 size_policy->check_gc_overhead_limit(eden_live, 708 max_old_gen_size, 709 max_eden_size, 710 false /* not full gc*/, 711 gc_cause, 712 heap->soft_ref_policy()); 713 714 size_policy->decay_supplemental_growth(false /* not full gc*/); 715 } 716 // Resize the young generation at every collection 717 // even if new sizes have not been calculated. This is 718 // to allow resizes that may have been inhibited by the 719 // relative location of the "to" and "from" spaces. 720 721 // Resizing the old gen at young collections can cause increases 722 // that don't feed back to the generation sizing policy until 723 // a full collection. Don't resize the old gen here. 724 725 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 726 size_policy->calculated_survivor_size_in_bytes()); 727 728 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 729 } 730 731 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 732 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 733 // Also update() will case adaptive NUMA chunk resizing. 734 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 735 young_gen->eden_space()->update(); 736 737 heap->gc_policy_counters()->update_counters(); 738 739 heap->resize_all_tlabs(); 740 741 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 742 } 743 744 #if COMPILER2_OR_JVMCI 745 DerivedPointerTable::update_pointers(); 746 #endif 747 748 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 749 750 // Re-verify object start arrays 751 if (VerifyObjectStartArray && 752 VerifyAfterGC) { 753 old_gen->verify_object_start_array(); 754 } 755 756 // Verify all old -> young cards are now precise 757 if (VerifyRememberedSets) { 758 // Precise verification will give false positives. Until this is fixed, 759 // use imprecise verification. 760 // heap->card_table()->verify_all_young_refs_precise(); 761 heap->card_table()->verify_all_young_refs_imprecise(); 762 } 763 764 if (log_is_enabled(Debug, gc, heap, exit)) { 765 accumulated_time()->stop(); 766 } 767 768 young_gen->print_used_change(pre_gc_values.young_gen_used()); 769 old_gen->print_used_change(pre_gc_values.old_gen_used()); 770 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used()); 771 772 // Track memory usage and detect low memory 773 MemoryService::track_memory_usage(); 774 heap->update_counters(); 775 } 776 777 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 778 HandleMark hm; // Discard invalid handles created during verification 779 Universe::verify("After GC"); 780 } 781 782 heap->print_heap_after_gc(); 783 heap->trace_heap_after_gc(&_gc_tracer); 784 785 scavenge_exit.update(); 786 787 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 788 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 789 scavenge_exit.ticks()); 790 791 #ifdef TRACESPINNING 792 ParallelTaskTerminator::print_termination_counts(); 793 #endif 794 795 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 796 797 _gc_timer.register_gc_end(); 798 799 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 800 801 return !promotion_failure_occurred; 802 } 803 804 // This method iterates over all objects in the young generation, 805 // removing all forwarding references. It then restores any preserved marks. 806 void PSScavenge::clean_up_failed_promotion() { 807 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 808 PSYoungGen* young_gen = heap->young_gen(); 809 810 RemoveForwardedPointerClosure remove_fwd_ptr_closure; 811 young_gen->object_iterate(&remove_fwd_ptr_closure); 812 813 PSPromotionManager::restore_preserved_marks(); 814 815 // Reset the PromotionFailureALot counters. 816 NOT_PRODUCT(heap->reset_promotion_should_fail();) 817 } 818 819 bool PSScavenge::should_attempt_scavenge() { 820 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 821 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 822 823 if (UsePerfData) { 824 counters->update_scavenge_skipped(not_skipped); 825 } 826 827 PSYoungGen* young_gen = heap->young_gen(); 828 PSOldGen* old_gen = heap->old_gen(); 829 830 // Do not attempt to promote unless to_space is empty 831 if (!young_gen->to_space()->is_empty()) { 832 _consecutive_skipped_scavenges++; 833 if (UsePerfData) { 834 counters->update_scavenge_skipped(to_space_not_empty); 835 } 836 return false; 837 } 838 839 // Test to see if the scavenge will likely fail. 840 PSAdaptiveSizePolicy* policy = heap->size_policy(); 841 842 // A similar test is done in the policy's should_full_GC(). If this is 843 // changed, decide if that test should also be changed. 844 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 845 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 846 bool result = promotion_estimate < old_gen->free_in_bytes(); 847 848 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, 849 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(), 850 (size_t) policy->padded_average_promoted_in_bytes(), 851 old_gen->free_in_bytes()); 852 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { 853 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 854 } 855 856 if (result) { 857 _consecutive_skipped_scavenges = 0; 858 } else { 859 _consecutive_skipped_scavenges++; 860 if (UsePerfData) { 861 counters->update_scavenge_skipped(promoted_too_large); 862 } 863 } 864 return result; 865 } 866 867 // Adaptive size policy support. When the young generation/old generation 868 // boundary moves, _young_generation_boundary must be reset 869 void PSScavenge::set_young_generation_boundary(HeapWord* v) { 870 _young_generation_boundary = v; 871 if (UseCompressedOops) { 872 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v); 873 } 874 } 875 876 void PSScavenge::initialize() { 877 // Arguments must have been parsed 878 879 if (AlwaysTenure || NeverTenure) { 880 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 881 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 882 _tenuring_threshold = MaxTenuringThreshold; 883 } else { 884 // We want to smooth out our startup times for the AdaptiveSizePolicy 885 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 886 MaxTenuringThreshold; 887 } 888 889 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 890 PSYoungGen* young_gen = heap->young_gen(); 891 PSOldGen* old_gen = heap->old_gen(); 892 893 // Set boundary between young_gen and old_gen 894 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 895 "old above young"); 896 set_young_generation_boundary(young_gen->eden_space()->bottom()); 897 898 // Initialize ref handling object for scavenging. 899 _span_based_discoverer.set_span(young_gen->reserved()); 900 _ref_processor = 901 new ReferenceProcessor(&_span_based_discoverer, 902 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 903 ParallelGCThreads, // mt processing degree 904 true, // mt discovery 905 ParallelGCThreads, // mt discovery degree 906 true, // atomic_discovery 907 NULL, // header provides liveness info 908 false); 909 910 // Cache the cardtable 911 _card_table = heap->card_table(); 912 913 _counters = new CollectorCounters("Parallel young collection pauses", 0); 914 }