1 /* 2 * Copyright (c) 2002, 2018, 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/stringTable.hpp" 27 #include "code/codeCache.hpp" 28 #include "gc/parallel/gcTaskManager.hpp" 29 #include "gc/parallel/parallelScavengeHeap.hpp" 30 #include "gc/parallel/psAdaptiveSizePolicy.hpp" 31 #include "gc/parallel/psMarkSweep.hpp" 32 #include "gc/parallel/psParallelCompact.inline.hpp" 33 #include "gc/parallel/psScavenge.inline.hpp" 34 #include "gc/parallel/psTasks.hpp" 35 #include "gc/shared/collectorPolicy.hpp" 36 #include "gc/shared/gcCause.hpp" 37 #include "gc/shared/gcHeapSummary.hpp" 38 #include "gc/shared/gcId.hpp" 39 #include "gc/shared/gcLocker.hpp" 40 #include "gc/shared/gcTimer.hpp" 41 #include "gc/shared/gcTrace.hpp" 42 #include "gc/shared/gcTraceTime.inline.hpp" 43 #include "gc/shared/isGCActiveMark.hpp" 44 #include "gc/shared/referencePolicy.hpp" 45 #include "gc/shared/referenceProcessor.hpp" 46 #include "gc/shared/spaceDecorator.hpp" 47 #include "gc/shared/weakProcessor.hpp" 48 #include "memory/resourceArea.hpp" 49 #include "logging/log.hpp" 50 #include "oops/access.inline.hpp" 51 #include "oops/compressedOops.inline.hpp" 52 #include "oops/oop.inline.hpp" 53 #include "runtime/biasedLocking.hpp" 54 #include "runtime/handles.inline.hpp" 55 #include "runtime/threadCritical.hpp" 56 #include "runtime/vmThread.hpp" 57 #include "runtime/vm_operations.hpp" 58 #include "services/memoryService.hpp" 59 #include "utilities/stack.inline.hpp" 60 61 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 62 int PSScavenge::_consecutive_skipped_scavenges = 0; 63 SpanSubjectToDiscoveryClosure PSScavenge::_span_discoverer; 64 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 65 PSCardTable* PSScavenge::_card_table = NULL; 66 bool PSScavenge::_survivor_overflow = false; 67 uint PSScavenge::_tenuring_threshold = 0; 68 HeapWord* PSScavenge::_young_generation_boundary = NULL; 69 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 70 elapsedTimer PSScavenge::_accumulated_time; 71 STWGCTimer PSScavenge::_gc_timer; 72 ParallelScavengeTracer PSScavenge::_gc_tracer; 73 CollectorCounters* PSScavenge::_counters = NULL; 74 75 // Define before use 76 class PSIsAliveClosure: public BoolObjectClosure { 77 public: 78 bool do_object_b(oop p) { 79 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 80 } 81 }; 82 83 PSIsAliveClosure PSScavenge::_is_alive_closure; 84 85 class PSKeepAliveClosure: public OopClosure { 86 protected: 87 MutableSpace* _to_space; 88 PSPromotionManager* _promotion_manager; 89 90 public: 91 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 92 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 93 _to_space = heap->young_gen()->to_space(); 94 95 assert(_promotion_manager != NULL, "Sanity"); 96 } 97 98 template <class T> void do_oop_work(T* p) { 99 assert (oopDesc::is_oop(RawAccess<OOP_NOT_NULL>::oop_load(p)), 100 "expected an oop while scanning weak refs"); 101 102 // Weak refs may be visited more than once. 103 if (PSScavenge::should_scavenge(p, _to_space)) { 104 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p); 105 } 106 } 107 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 108 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 109 }; 110 111 class PSEvacuateFollowersClosure: public VoidClosure { 112 private: 113 PSPromotionManager* _promotion_manager; 114 public: 115 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 116 117 virtual void do_void() { 118 assert(_promotion_manager != NULL, "Sanity"); 119 _promotion_manager->drain_stacks(true); 120 guarantee(_promotion_manager->stacks_empty(), 121 "stacks should be empty at this point"); 122 } 123 }; 124 125 class PSRefProcTaskProxy: public GCTask { 126 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 127 ProcessTask & _rp_task; 128 uint _work_id; 129 public: 130 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 131 : _rp_task(rp_task), 132 _work_id(work_id) 133 { } 134 135 private: 136 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 137 virtual void do_it(GCTaskManager* manager, uint which); 138 }; 139 140 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 141 { 142 PSPromotionManager* promotion_manager = 143 PSPromotionManager::gc_thread_promotion_manager(which); 144 assert(promotion_manager != NULL, "sanity check"); 145 PSKeepAliveClosure keep_alive(promotion_manager); 146 PSEvacuateFollowersClosure evac_followers(promotion_manager); 147 PSIsAliveClosure is_alive; 148 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 149 } 150 151 class PSRefEnqueueTaskProxy: public GCTask { 152 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 153 EnqueueTask& _enq_task; 154 uint _work_id; 155 156 public: 157 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 158 : _enq_task(enq_task), 159 _work_id(work_id) 160 { } 161 162 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 163 virtual void do_it(GCTaskManager* manager, uint which) 164 { 165 _enq_task.work(_work_id); 166 } 167 }; 168 169 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 170 virtual void execute(ProcessTask& task); 171 virtual void execute(EnqueueTask& task); 172 }; 173 174 void PSRefProcTaskExecutor::execute(ProcessTask& task) 175 { 176 GCTaskQueue* q = GCTaskQueue::create(); 177 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 178 for(uint i=0; i < manager->active_workers(); i++) { 179 q->enqueue(new PSRefProcTaskProxy(task, i)); 180 } 181 ParallelTaskTerminator terminator(manager->active_workers(), 182 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 183 if (task.marks_oops_alive() && manager->active_workers() > 1) { 184 for (uint j = 0; j < manager->active_workers(); j++) { 185 q->enqueue(new StealTask(&terminator)); 186 } 187 } 188 manager->execute_and_wait(q); 189 } 190 191 192 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 193 { 194 GCTaskQueue* q = GCTaskQueue::create(); 195 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 196 for(uint i=0; i < manager->active_workers(); i++) { 197 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 198 } 199 manager->execute_and_wait(q); 200 } 201 202 // This method contains all heap specific policy for invoking scavenge. 203 // PSScavenge::invoke_no_policy() will do nothing but attempt to 204 // scavenge. It will not clean up after failed promotions, bail out if 205 // we've exceeded policy time limits, or any other special behavior. 206 // All such policy should be placed here. 207 // 208 // Note that this method should only be called from the vm_thread while 209 // at a safepoint! 210 bool PSScavenge::invoke() { 211 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 212 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 213 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 214 215 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap(); 216 PSAdaptiveSizePolicy* policy = heap->size_policy(); 217 IsGCActiveMark mark; 218 219 const bool scavenge_done = PSScavenge::invoke_no_policy(); 220 const bool need_full_gc = !scavenge_done || 221 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 222 bool full_gc_done = false; 223 224 if (UsePerfData) { 225 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 226 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 227 counters->update_full_follows_scavenge(ffs_val); 228 } 229 230 if (need_full_gc) { 231 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 232 SoftRefPolicy* srp = heap->soft_ref_policy(); 233 const bool clear_all_softrefs = srp->should_clear_all_soft_refs(); 234 235 if (UseParallelOldGC) { 236 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 237 } else { 238 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 239 } 240 } 241 242 return full_gc_done; 243 } 244 245 // This method contains no policy. You should probably 246 // be calling invoke() instead. 247 bool PSScavenge::invoke_no_policy() { 248 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 249 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 250 251 _gc_timer.register_gc_start(); 252 253 TimeStamp scavenge_entry; 254 TimeStamp scavenge_midpoint; 255 TimeStamp scavenge_exit; 256 257 scavenge_entry.update(); 258 259 if (GCLocker::check_active_before_gc()) { 260 return false; 261 } 262 263 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 264 GCCause::Cause gc_cause = heap->gc_cause(); 265 266 // Check for potential problems. 267 if (!should_attempt_scavenge()) { 268 return false; 269 } 270 271 GCIdMark gc_id_mark; 272 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 273 274 bool promotion_failure_occurred = false; 275 276 PSYoungGen* young_gen = heap->young_gen(); 277 PSOldGen* old_gen = heap->old_gen(); 278 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 279 280 heap->increment_total_collections(); 281 282 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) { 283 // Gather the feedback data for eden occupancy. 284 young_gen->eden_space()->accumulate_statistics(); 285 } 286 287 heap->print_heap_before_gc(); 288 heap->trace_heap_before_gc(&_gc_tracer); 289 290 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 291 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 292 293 // Fill in TLABs 294 heap->accumulate_statistics_all_tlabs(); 295 heap->ensure_parsability(true); // retire TLABs 296 297 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 298 HandleMark hm; // Discard invalid handles created during verification 299 Universe::verify("Before GC"); 300 } 301 302 { 303 ResourceMark rm; 304 HandleMark hm; 305 306 GCTraceCPUTime tcpu; 307 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true); 308 TraceCollectorStats tcs(counters()); 309 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause); 310 311 if (log_is_enabled(Debug, gc, heap, exit)) { 312 accumulated_time()->start(); 313 } 314 315 // Let the size policy know we're starting 316 size_policy->minor_collection_begin(); 317 318 // Verify the object start arrays. 319 if (VerifyObjectStartArray && 320 VerifyBeforeGC) { 321 old_gen->verify_object_start_array(); 322 } 323 324 // Verify no unmarked old->young roots 325 if (VerifyRememberedSets) { 326 heap->card_table()->verify_all_young_refs_imprecise(); 327 } 328 329 assert(young_gen->to_space()->is_empty(), 330 "Attempt to scavenge with live objects in to_space"); 331 young_gen->to_space()->clear(SpaceDecorator::Mangle); 332 333 save_to_space_top_before_gc(); 334 335 #if COMPILER2_OR_JVMCI 336 DerivedPointerTable::clear(); 337 #endif 338 339 reference_processor()->enable_discovery(); 340 reference_processor()->setup_policy(false); 341 342 PreGCValues pre_gc_values(heap); 343 344 // Reset our survivor overflow. 345 set_survivor_overflow(false); 346 347 // We need to save the old top values before 348 // creating the promotion_manager. We pass the top 349 // values to the card_table, to prevent it from 350 // straying into the promotion labs. 351 HeapWord* old_top = old_gen->object_space()->top(); 352 353 // Release all previously held resources 354 gc_task_manager()->release_all_resources(); 355 356 // Set the number of GC threads to be used in this collection 357 gc_task_manager()->set_active_gang(); 358 gc_task_manager()->task_idle_workers(); 359 // Get the active number of workers here and use that value 360 // throughout the methods. 361 uint active_workers = gc_task_manager()->active_workers(); 362 363 PSPromotionManager::pre_scavenge(); 364 365 // We'll use the promotion manager again later. 366 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 367 { 368 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer); 369 ParallelScavengeHeap::ParStrongRootsScope psrs; 370 371 GCTaskQueue* q = GCTaskQueue::create(); 372 373 if (!old_gen->object_space()->is_empty()) { 374 // There are only old-to-young pointers if there are objects 375 // in the old gen. 376 uint stripe_total = active_workers; 377 for(uint i=0; i < stripe_total; i++) { 378 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 379 } 380 } 381 382 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 383 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 384 // We scan the thread roots in parallel 385 Threads::create_thread_roots_tasks(q); 386 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 387 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 388 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 389 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 390 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 391 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 392 393 ParallelTaskTerminator terminator( 394 active_workers, 395 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 396 // If active_workers can exceed 1, add a StrealTask. 397 // PSPromotionManager::drain_stacks_depth() does not fully drain its 398 // stacks and expects a StealTask to complete the draining if 399 // ParallelGCThreads is > 1. 400 if (gc_task_manager()->workers() > 1) { 401 for (uint j = 0; j < active_workers; j++) { 402 q->enqueue(new StealTask(&terminator)); 403 } 404 } 405 406 gc_task_manager()->execute_and_wait(q); 407 } 408 409 scavenge_midpoint.update(); 410 411 // Process reference objects discovered during scavenge 412 { 413 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 414 415 reference_processor()->setup_policy(false); // not always_clear 416 reference_processor()->set_active_mt_degree(active_workers); 417 PSKeepAliveClosure keep_alive(promotion_manager); 418 PSEvacuateFollowersClosure evac_followers(promotion_manager); 419 ReferenceProcessorStats stats; 420 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->num_q()); 421 if (reference_processor()->processing_is_mt()) { 422 PSRefProcTaskExecutor task_executor; 423 stats = reference_processor()->process_discovered_references( 424 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 425 &pt); 426 } else { 427 stats = reference_processor()->process_discovered_references( 428 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt); 429 } 430 431 _gc_tracer.report_gc_reference_stats(stats); 432 pt.print_all_references(); 433 434 // Enqueue reference objects discovered during scavenge. 435 if (reference_processor()->processing_is_mt()) { 436 PSRefProcTaskExecutor task_executor; 437 reference_processor()->enqueue_discovered_references(&task_executor, &pt); 438 } else { 439 reference_processor()->enqueue_discovered_references(NULL, &pt); 440 } 441 442 pt.print_enqueue_phase(); 443 } 444 445 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 446 447 PSScavengeRootsClosure root_closure(promotion_manager); 448 449 { 450 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 451 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure); 452 } 453 454 { 455 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer); 456 // Unlink any dead interned Strings and process the remaining live ones. 457 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 458 } 459 460 // Verify that usage of root_closure didn't copy any objects. 461 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 462 463 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 464 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 465 if (promotion_failure_occurred) { 466 clean_up_failed_promotion(); 467 log_info(gc, promotion)("Promotion failed"); 468 } 469 470 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 471 472 // Let the size policy know we're done. Note that we count promotion 473 // failure cleanup time as part of the collection (otherwise, we're 474 // implicitly saying it's mutator time). 475 size_policy->minor_collection_end(gc_cause); 476 477 if (!promotion_failure_occurred) { 478 // Swap the survivor spaces. 479 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 480 young_gen->from_space()->clear(SpaceDecorator::Mangle); 481 young_gen->swap_spaces(); 482 483 size_t survived = young_gen->from_space()->used_in_bytes(); 484 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used(); 485 size_policy->update_averages(_survivor_overflow, survived, promoted); 486 487 // A successful scavenge should restart the GC time limit count which is 488 // for full GC's. 489 size_policy->reset_gc_overhead_limit_count(); 490 if (UseAdaptiveSizePolicy) { 491 // Calculate the new survivor size and tenuring threshold 492 493 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 494 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 495 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 496 497 if (UsePerfData) { 498 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 499 counters->update_old_eden_size( 500 size_policy->calculated_eden_size_in_bytes()); 501 counters->update_old_promo_size( 502 size_policy->calculated_promo_size_in_bytes()); 503 counters->update_old_capacity(old_gen->capacity_in_bytes()); 504 counters->update_young_capacity(young_gen->capacity_in_bytes()); 505 counters->update_survived(survived); 506 counters->update_promoted(promoted); 507 counters->update_survivor_overflowed(_survivor_overflow); 508 } 509 510 size_t max_young_size = young_gen->max_size(); 511 512 // Deciding a free ratio in the young generation is tricky, so if 513 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 514 // that the old generation size may have been limited because of them) we 515 // should then limit our young generation size using NewRatio to have it 516 // follow the old generation size. 517 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 518 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 519 } 520 521 size_t survivor_limit = 522 size_policy->max_survivor_size(max_young_size); 523 _tenuring_threshold = 524 size_policy->compute_survivor_space_size_and_threshold( 525 _survivor_overflow, 526 _tenuring_threshold, 527 survivor_limit); 528 529 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")", 530 size_policy->calculated_survivor_size_in_bytes(), 531 _tenuring_threshold, MaxTenuringThreshold); 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 (UseAdaptiveGenerationSizePolicyAtMinorCollection && 543 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 544 // Calculate optimal free space amounts 545 assert(young_gen->max_size() > 546 young_gen->from_space()->capacity_in_bytes() + 547 young_gen->to_space()->capacity_in_bytes(), 548 "Sizes of space in young gen are out-of-bounds"); 549 550 size_t young_live = young_gen->used_in_bytes(); 551 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 552 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 553 size_t max_old_gen_size = old_gen->max_gen_size(); 554 size_t max_eden_size = max_young_size - 555 young_gen->from_space()->capacity_in_bytes() - 556 young_gen->to_space()->capacity_in_bytes(); 557 558 // Used for diagnostics 559 size_policy->clear_generation_free_space_flags(); 560 561 size_policy->compute_eden_space_size(young_live, 562 eden_live, 563 cur_eden, 564 max_eden_size, 565 false /* not full gc*/); 566 567 size_policy->check_gc_overhead_limit(young_live, 568 eden_live, 569 max_old_gen_size, 570 max_eden_size, 571 false /* not full gc*/, 572 gc_cause, 573 heap->soft_ref_policy()); 574 575 size_policy->decay_supplemental_growth(false /* not full gc*/); 576 } 577 // Resize the young generation at every collection 578 // even if new sizes have not been calculated. This is 579 // to allow resizes that may have been inhibited by the 580 // relative location of the "to" and "from" spaces. 581 582 // Resizing the old gen at young collections can cause increases 583 // that don't feed back to the generation sizing policy until 584 // a full collection. Don't resize the old gen here. 585 586 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 587 size_policy->calculated_survivor_size_in_bytes()); 588 589 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 590 } 591 592 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 593 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 594 // Also update() will case adaptive NUMA chunk resizing. 595 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 596 young_gen->eden_space()->update(); 597 598 heap->gc_policy_counters()->update_counters(); 599 600 heap->resize_all_tlabs(); 601 602 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 603 } 604 605 #if COMPILER2_OR_JVMCI 606 DerivedPointerTable::update_pointers(); 607 #endif 608 609 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 610 611 // Re-verify object start arrays 612 if (VerifyObjectStartArray && 613 VerifyAfterGC) { 614 old_gen->verify_object_start_array(); 615 } 616 617 // Verify all old -> young cards are now precise 618 if (VerifyRememberedSets) { 619 // Precise verification will give false positives. Until this is fixed, 620 // use imprecise verification. 621 // heap->card_table()->verify_all_young_refs_precise(); 622 heap->card_table()->verify_all_young_refs_imprecise(); 623 } 624 625 if (log_is_enabled(Debug, gc, heap, exit)) { 626 accumulated_time()->stop(); 627 } 628 629 young_gen->print_used_change(pre_gc_values.young_gen_used()); 630 old_gen->print_used_change(pre_gc_values.old_gen_used()); 631 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used()); 632 633 // Track memory usage and detect low memory 634 MemoryService::track_memory_usage(); 635 heap->update_counters(); 636 637 gc_task_manager()->release_idle_workers(); 638 } 639 640 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 641 HandleMark hm; // Discard invalid handles created during verification 642 Universe::verify("After GC"); 643 } 644 645 heap->print_heap_after_gc(); 646 heap->trace_heap_after_gc(&_gc_tracer); 647 648 scavenge_exit.update(); 649 650 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 651 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 652 scavenge_exit.ticks()); 653 gc_task_manager()->print_task_time_stamps(); 654 655 #ifdef TRACESPINNING 656 ParallelTaskTerminator::print_termination_counts(); 657 #endif 658 659 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 660 661 _gc_timer.register_gc_end(); 662 663 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 664 665 return !promotion_failure_occurred; 666 } 667 668 // This method iterates over all objects in the young generation, 669 // removing all forwarding references. It then restores any preserved marks. 670 void PSScavenge::clean_up_failed_promotion() { 671 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 672 PSYoungGen* young_gen = heap->young_gen(); 673 674 RemoveForwardedPointerClosure remove_fwd_ptr_closure; 675 young_gen->object_iterate(&remove_fwd_ptr_closure); 676 677 PSPromotionManager::restore_preserved_marks(); 678 679 // Reset the PromotionFailureALot counters. 680 NOT_PRODUCT(heap->reset_promotion_should_fail();) 681 } 682 683 bool PSScavenge::should_attempt_scavenge() { 684 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 685 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 686 687 if (UsePerfData) { 688 counters->update_scavenge_skipped(not_skipped); 689 } 690 691 PSYoungGen* young_gen = heap->young_gen(); 692 PSOldGen* old_gen = heap->old_gen(); 693 694 // Do not attempt to promote unless to_space is empty 695 if (!young_gen->to_space()->is_empty()) { 696 _consecutive_skipped_scavenges++; 697 if (UsePerfData) { 698 counters->update_scavenge_skipped(to_space_not_empty); 699 } 700 return false; 701 } 702 703 // Test to see if the scavenge will likely fail. 704 PSAdaptiveSizePolicy* policy = heap->size_policy(); 705 706 // A similar test is done in the policy's should_full_GC(). If this is 707 // changed, decide if that test should also be changed. 708 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 709 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 710 bool result = promotion_estimate < old_gen->free_in_bytes(); 711 712 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, 713 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(), 714 (size_t) policy->padded_average_promoted_in_bytes(), 715 old_gen->free_in_bytes()); 716 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { 717 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 718 } 719 720 if (result) { 721 _consecutive_skipped_scavenges = 0; 722 } else { 723 _consecutive_skipped_scavenges++; 724 if (UsePerfData) { 725 counters->update_scavenge_skipped(promoted_too_large); 726 } 727 } 728 return result; 729 } 730 731 // Used to add tasks 732 GCTaskManager* const PSScavenge::gc_task_manager() { 733 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 734 "shouldn't return NULL"); 735 return ParallelScavengeHeap::gc_task_manager(); 736 } 737 738 // Adaptive size policy support. When the young generation/old generation 739 // boundary moves, _young_generation_boundary must be reset 740 void PSScavenge::set_young_generation_boundary(HeapWord* v) { 741 _young_generation_boundary = v; 742 if (UseCompressedOops) { 743 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v); 744 } 745 } 746 747 void PSScavenge::initialize() { 748 // Arguments must have been parsed 749 750 if (AlwaysTenure || NeverTenure) { 751 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 752 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 753 _tenuring_threshold = MaxTenuringThreshold; 754 } else { 755 // We want to smooth out our startup times for the AdaptiveSizePolicy 756 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 757 MaxTenuringThreshold; 758 } 759 760 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 761 PSYoungGen* young_gen = heap->young_gen(); 762 PSOldGen* old_gen = heap->old_gen(); 763 764 // Set boundary between young_gen and old_gen 765 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 766 "old above young"); 767 set_young_generation_boundary(young_gen->eden_space()->bottom()); 768 769 // Initialize ref handling object for scavenging. 770 _span_discoverer.set_span(young_gen->reserved()); 771 _ref_processor = 772 new ReferenceProcessor(&_span_discoverer, // span 773 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 774 ParallelGCThreads, // mt processing degree 775 true, // mt discovery 776 ParallelGCThreads, // mt discovery degree 777 true, // atomic_discovery 778 NULL); // header provides liveness info 779 780 // Cache the cardtable 781 _card_table = heap->card_table(); 782 783 _counters = new CollectorCounters("PSScavenge", 0); 784 }