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/psMarkSweepProxy.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/referenceProcessorPhaseTimes.hpp" 47 #include "gc/shared/spaceDecorator.hpp" 48 #include "gc/shared/weakProcessor.hpp" 49 #include "memory/resourceArea.hpp" 50 #include "logging/log.hpp" 51 #include "oops/access.inline.hpp" 52 #include "oops/compressedOops.inline.hpp" 53 #include "oops/oop.inline.hpp" 54 #include "runtime/biasedLocking.hpp" 55 #include "runtime/handles.inline.hpp" 56 #include "runtime/threadCritical.hpp" 57 #include "runtime/vmThread.hpp" 58 #include "runtime/vm_operations.hpp" 59 #include "services/memoryService.hpp" 60 #include "utilities/stack.inline.hpp" 61 62 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 63 int PSScavenge::_consecutive_skipped_scavenges = 0; 64 SpanSubjectToDiscoveryClosure PSScavenge::_span_based_discoverer; 65 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 66 PSCardTable* PSScavenge::_card_table = NULL; 67 bool PSScavenge::_survivor_overflow = false; 68 uint PSScavenge::_tenuring_threshold = 0; 69 HeapWord* PSScavenge::_young_generation_boundary = NULL; 70 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 71 elapsedTimer PSScavenge::_accumulated_time; 72 STWGCTimer PSScavenge::_gc_timer; 73 ParallelScavengeTracer PSScavenge::_gc_tracer; 74 CollectorCounters* PSScavenge::_counters = NULL; 75 76 // Define before use 77 class PSIsAliveClosure: public BoolObjectClosure { 78 public: 79 bool do_object_b(oop p) { 80 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 81 } 82 }; 83 84 PSIsAliveClosure PSScavenge::_is_alive_closure; 85 86 class PSKeepAliveClosure: public OopClosure { 87 protected: 88 MutableSpace* _to_space; 89 PSPromotionManager* _promotion_manager; 90 91 public: 92 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 93 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 94 _to_space = heap->young_gen()->to_space(); 95 96 assert(_promotion_manager != NULL, "Sanity"); 97 } 98 99 template <class T> void do_oop_work(T* p) { 100 assert (oopDesc::is_oop(RawAccess<IS_NOT_NULL>::oop_load(p)), 101 "expected an oop while scanning weak refs"); 102 103 // Weak refs may be visited more than once. 104 if (PSScavenge::should_scavenge(p, _to_space)) { 105 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p); 106 } 107 } 108 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 109 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 110 }; 111 112 class PSEvacuateFollowersClosure: public VoidClosure { 113 private: 114 PSPromotionManager* _promotion_manager; 115 public: 116 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 117 118 virtual void do_void() { 119 assert(_promotion_manager != NULL, "Sanity"); 120 _promotion_manager->drain_stacks(true); 121 guarantee(_promotion_manager->stacks_empty(), 122 "stacks should be empty at this point"); 123 } 124 }; 125 126 class PSRefProcTaskProxy: public GCTask { 127 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 128 ProcessTask & _rp_task; 129 uint _work_id; 130 public: 131 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 132 : _rp_task(rp_task), 133 _work_id(work_id) 134 { } 135 136 private: 137 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 138 virtual void do_it(GCTaskManager* manager, uint which); 139 }; 140 141 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 142 { 143 PSPromotionManager* promotion_manager = 144 PSPromotionManager::gc_thread_promotion_manager(which); 145 assert(promotion_manager != NULL, "sanity check"); 146 PSKeepAliveClosure keep_alive(promotion_manager); 147 PSEvacuateFollowersClosure evac_followers(promotion_manager); 148 PSIsAliveClosure is_alive; 149 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 150 } 151 152 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 153 virtual void execute(ProcessTask& task, uint ergo_workers); 154 }; 155 156 void PSRefProcTaskExecutor::execute(ProcessTask& task, uint ergo_workers) 157 { 158 GCTaskQueue* q = GCTaskQueue::create(); 159 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 160 uint active_workers = manager->active_workers(); 161 162 assert(active_workers == ergo_workers, 163 "Ergonomically chosen workers (%u) must be equal to active workers (%u)", 164 ergo_workers, active_workers); 165 166 for(uint i=0; i < active_workers; i++) { 167 q->enqueue(new PSRefProcTaskProxy(task, i)); 168 } 169 ParallelTaskTerminator terminator(active_workers, 170 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 171 if (task.marks_oops_alive() && active_workers > 1) { 172 for (uint j = 0; j < active_workers; j++) { 173 q->enqueue(new StealTask(&terminator)); 174 } 175 } 176 manager->execute_and_wait(q); 177 } 178 179 // This method contains all heap specific policy for invoking scavenge. 180 // PSScavenge::invoke_no_policy() will do nothing but attempt to 181 // scavenge. It will not clean up after failed promotions, bail out if 182 // we've exceeded policy time limits, or any other special behavior. 183 // All such policy should be placed here. 184 // 185 // Note that this method should only be called from the vm_thread while 186 // at a safepoint! 187 bool PSScavenge::invoke() { 188 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 189 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 190 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 191 192 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap(); 193 PSAdaptiveSizePolicy* policy = heap->size_policy(); 194 IsGCActiveMark mark; 195 196 const bool scavenge_done = PSScavenge::invoke_no_policy(); 197 const bool need_full_gc = !scavenge_done || 198 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 199 bool full_gc_done = false; 200 201 if (UsePerfData) { 202 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 203 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 204 counters->update_full_follows_scavenge(ffs_val); 205 } 206 207 if (need_full_gc) { 208 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 209 SoftRefPolicy* srp = heap->soft_ref_policy(); 210 const bool clear_all_softrefs = srp->should_clear_all_soft_refs(); 211 212 if (UseParallelOldGC) { 213 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 214 } else { 215 full_gc_done = PSMarkSweepProxy::invoke_no_policy(clear_all_softrefs); 216 } 217 } 218 219 return full_gc_done; 220 } 221 222 class PSAddThreadRootsTaskClosure : public ThreadClosure { 223 private: 224 GCTaskQueue* _q; 225 226 public: 227 PSAddThreadRootsTaskClosure(GCTaskQueue* q) : _q(q) { } 228 void do_thread(Thread* t) { 229 _q->enqueue(new ThreadRootsTask(t)); 230 } 231 }; 232 233 // This method contains no policy. You should probably 234 // be calling invoke() instead. 235 bool PSScavenge::invoke_no_policy() { 236 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 237 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 238 239 _gc_timer.register_gc_start(); 240 241 TimeStamp scavenge_entry; 242 TimeStamp scavenge_midpoint; 243 TimeStamp scavenge_exit; 244 245 scavenge_entry.update(); 246 247 if (GCLocker::check_active_before_gc()) { 248 return false; 249 } 250 251 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 252 GCCause::Cause gc_cause = heap->gc_cause(); 253 254 // Check for potential problems. 255 if (!should_attempt_scavenge()) { 256 return false; 257 } 258 259 GCIdMark gc_id_mark; 260 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 261 262 bool promotion_failure_occurred = false; 263 264 PSYoungGen* young_gen = heap->young_gen(); 265 PSOldGen* old_gen = heap->old_gen(); 266 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 267 268 heap->increment_total_collections(); 269 270 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) { 271 // Gather the feedback data for eden occupancy. 272 young_gen->eden_space()->accumulate_statistics(); 273 } 274 275 heap->print_heap_before_gc(); 276 heap->trace_heap_before_gc(&_gc_tracer); 277 278 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 279 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 280 281 // Fill in TLABs 282 heap->accumulate_statistics_all_tlabs(); 283 heap->ensure_parsability(true); // retire TLABs 284 285 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 286 HandleMark hm; // Discard invalid handles created during verification 287 Universe::verify("Before GC"); 288 } 289 290 { 291 ResourceMark rm; 292 HandleMark hm; 293 294 GCTraceCPUTime tcpu; 295 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true); 296 TraceCollectorStats tcs(counters()); 297 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause); 298 299 if (log_is_enabled(Debug, gc, heap, exit)) { 300 accumulated_time()->start(); 301 } 302 303 // Let the size policy know we're starting 304 size_policy->minor_collection_begin(); 305 306 // Verify the object start arrays. 307 if (VerifyObjectStartArray && 308 VerifyBeforeGC) { 309 old_gen->verify_object_start_array(); 310 } 311 312 // Verify no unmarked old->young roots 313 if (VerifyRememberedSets) { 314 heap->card_table()->verify_all_young_refs_imprecise(); 315 } 316 317 assert(young_gen->to_space()->is_empty(), 318 "Attempt to scavenge with live objects in to_space"); 319 young_gen->to_space()->clear(SpaceDecorator::Mangle); 320 321 save_to_space_top_before_gc(); 322 323 #if COMPILER2_OR_JVMCI 324 DerivedPointerTable::clear(); 325 #endif 326 327 reference_processor()->enable_discovery(); 328 reference_processor()->setup_policy(false); 329 330 PreGCValues pre_gc_values(heap); 331 332 // Reset our survivor overflow. 333 set_survivor_overflow(false); 334 335 // We need to save the old top values before 336 // creating the promotion_manager. We pass the top 337 // values to the card_table, to prevent it from 338 // straying into the promotion labs. 339 HeapWord* old_top = old_gen->object_space()->top(); 340 341 // Release all previously held resources 342 gc_task_manager()->release_all_resources(); 343 344 // Set the number of GC threads to be used in this collection 345 gc_task_manager()->set_active_gang(); 346 gc_task_manager()->task_idle_workers(); 347 // Get the active number of workers here and use that value 348 // throughout the methods. 349 uint active_workers = gc_task_manager()->active_workers(); 350 351 PSPromotionManager::pre_scavenge(); 352 353 // We'll use the promotion manager again later. 354 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 355 { 356 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer); 357 ParallelScavengeHeap::ParStrongRootsScope psrs; 358 359 GCTaskQueue* q = GCTaskQueue::create(); 360 361 if (!old_gen->object_space()->is_empty()) { 362 // There are only old-to-young pointers if there are objects 363 // in the old gen. 364 uint stripe_total = active_workers; 365 for(uint i=0; i < stripe_total; i++) { 366 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 367 } 368 } 369 370 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 371 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 372 // We scan the thread roots in parallel 373 PSAddThreadRootsTaskClosure cl(q); 374 Threads::java_threads_and_vm_thread_do(&cl); 375 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 376 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 377 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 378 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 379 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 380 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 381 382 ParallelTaskTerminator terminator( 383 active_workers, 384 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 385 // If active_workers can exceed 1, add a StrealTask. 386 // PSPromotionManager::drain_stacks_depth() does not fully drain its 387 // stacks and expects a StealTask to complete the draining if 388 // ParallelGCThreads is > 1. 389 if (gc_task_manager()->workers() > 1) { 390 for (uint j = 0; j < active_workers; j++) { 391 q->enqueue(new StealTask(&terminator)); 392 } 393 } 394 395 gc_task_manager()->execute_and_wait(q); 396 } 397 398 scavenge_midpoint.update(); 399 400 // Process reference objects discovered during scavenge 401 { 402 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 403 404 reference_processor()->setup_policy(false); // not always_clear 405 reference_processor()->set_active_mt_degree(active_workers); 406 PSKeepAliveClosure keep_alive(promotion_manager); 407 PSEvacuateFollowersClosure evac_followers(promotion_manager); 408 ReferenceProcessorStats stats; 409 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->max_num_queues()); 410 if (reference_processor()->processing_is_mt()) { 411 PSRefProcTaskExecutor task_executor; 412 stats = reference_processor()->process_discovered_references( 413 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 414 &pt); 415 } else { 416 stats = reference_processor()->process_discovered_references( 417 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt); 418 } 419 420 _gc_tracer.report_gc_reference_stats(stats); 421 pt.print_all_references(); 422 } 423 424 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 425 426 PSScavengeRootsClosure root_closure(promotion_manager); 427 428 { 429 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 430 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure); 431 } 432 433 { 434 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer); 435 // Unlink any dead interned Strings and process the remaining live ones. 436 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 437 } 438 439 // Verify that usage of root_closure didn't copy any objects. 440 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 441 442 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 443 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 444 if (promotion_failure_occurred) { 445 clean_up_failed_promotion(); 446 log_info(gc, promotion)("Promotion failed"); 447 } 448 449 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 450 451 // Let the size policy know we're done. Note that we count promotion 452 // failure cleanup time as part of the collection (otherwise, we're 453 // implicitly saying it's mutator time). 454 size_policy->minor_collection_end(gc_cause); 455 456 if (!promotion_failure_occurred) { 457 // Swap the survivor spaces. 458 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 459 young_gen->from_space()->clear(SpaceDecorator::Mangle); 460 young_gen->swap_spaces(); 461 462 size_t survived = young_gen->from_space()->used_in_bytes(); 463 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used(); 464 size_policy->update_averages(_survivor_overflow, survived, promoted); 465 466 // A successful scavenge should restart the GC time limit count which is 467 // for full GC's. 468 size_policy->reset_gc_overhead_limit_count(); 469 if (UseAdaptiveSizePolicy) { 470 // Calculate the new survivor size and tenuring threshold 471 472 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 473 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 474 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 475 476 if (UsePerfData) { 477 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 478 counters->update_old_eden_size( 479 size_policy->calculated_eden_size_in_bytes()); 480 counters->update_old_promo_size( 481 size_policy->calculated_promo_size_in_bytes()); 482 counters->update_old_capacity(old_gen->capacity_in_bytes()); 483 counters->update_young_capacity(young_gen->capacity_in_bytes()); 484 counters->update_survived(survived); 485 counters->update_promoted(promoted); 486 counters->update_survivor_overflowed(_survivor_overflow); 487 } 488 489 size_t max_young_size = young_gen->max_size(); 490 491 // Deciding a free ratio in the young generation is tricky, so if 492 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 493 // that the old generation size may have been limited because of them) we 494 // should then limit our young generation size using NewRatio to have it 495 // follow the old generation size. 496 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 497 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 498 } 499 500 size_t survivor_limit = 501 size_policy->max_survivor_size(max_young_size); 502 _tenuring_threshold = 503 size_policy->compute_survivor_space_size_and_threshold( 504 _survivor_overflow, 505 _tenuring_threshold, 506 survivor_limit); 507 508 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")", 509 size_policy->calculated_survivor_size_in_bytes(), 510 _tenuring_threshold, MaxTenuringThreshold); 511 512 if (UsePerfData) { 513 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 514 counters->update_tenuring_threshold(_tenuring_threshold); 515 counters->update_survivor_size_counters(); 516 } 517 518 // Do call at minor collections? 519 // Don't check if the size_policy is ready at this 520 // level. Let the size_policy check that internally. 521 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 522 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 523 // Calculate optimal free space amounts 524 assert(young_gen->max_size() > 525 young_gen->from_space()->capacity_in_bytes() + 526 young_gen->to_space()->capacity_in_bytes(), 527 "Sizes of space in young gen are out-of-bounds"); 528 529 size_t young_live = young_gen->used_in_bytes(); 530 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 531 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 532 size_t max_old_gen_size = old_gen->max_gen_size(); 533 size_t max_eden_size = max_young_size - 534 young_gen->from_space()->capacity_in_bytes() - 535 young_gen->to_space()->capacity_in_bytes(); 536 537 // Used for diagnostics 538 size_policy->clear_generation_free_space_flags(); 539 540 size_policy->compute_eden_space_size(young_live, 541 eden_live, 542 cur_eden, 543 max_eden_size, 544 false /* not full gc*/); 545 546 size_policy->check_gc_overhead_limit(young_live, 547 eden_live, 548 max_old_gen_size, 549 max_eden_size, 550 false /* not full gc*/, 551 gc_cause, 552 heap->soft_ref_policy()); 553 554 size_policy->decay_supplemental_growth(false /* not full gc*/); 555 } 556 // Resize the young generation at every collection 557 // even if new sizes have not been calculated. This is 558 // to allow resizes that may have been inhibited by the 559 // relative location of the "to" and "from" spaces. 560 561 // Resizing the old gen at young collections can cause increases 562 // that don't feed back to the generation sizing policy until 563 // a full collection. Don't resize the old gen here. 564 565 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 566 size_policy->calculated_survivor_size_in_bytes()); 567 568 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 569 } 570 571 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 572 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 573 // Also update() will case adaptive NUMA chunk resizing. 574 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 575 young_gen->eden_space()->update(); 576 577 heap->gc_policy_counters()->update_counters(); 578 579 heap->resize_all_tlabs(); 580 581 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 582 } 583 584 #if COMPILER2_OR_JVMCI 585 DerivedPointerTable::update_pointers(); 586 #endif 587 588 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 589 590 // Re-verify object start arrays 591 if (VerifyObjectStartArray && 592 VerifyAfterGC) { 593 old_gen->verify_object_start_array(); 594 } 595 596 // Verify all old -> young cards are now precise 597 if (VerifyRememberedSets) { 598 // Precise verification will give false positives. Until this is fixed, 599 // use imprecise verification. 600 // heap->card_table()->verify_all_young_refs_precise(); 601 heap->card_table()->verify_all_young_refs_imprecise(); 602 } 603 604 if (log_is_enabled(Debug, gc, heap, exit)) { 605 accumulated_time()->stop(); 606 } 607 608 young_gen->print_used_change(pre_gc_values.young_gen_used()); 609 old_gen->print_used_change(pre_gc_values.old_gen_used()); 610 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used()); 611 612 // Track memory usage and detect low memory 613 MemoryService::track_memory_usage(); 614 heap->update_counters(); 615 616 gc_task_manager()->release_idle_workers(); 617 } 618 619 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 620 HandleMark hm; // Discard invalid handles created during verification 621 Universe::verify("After GC"); 622 } 623 624 heap->print_heap_after_gc(); 625 heap->trace_heap_after_gc(&_gc_tracer); 626 627 scavenge_exit.update(); 628 629 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 630 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 631 scavenge_exit.ticks()); 632 gc_task_manager()->print_task_time_stamps(); 633 634 #ifdef TRACESPINNING 635 ParallelTaskTerminator::print_termination_counts(); 636 #endif 637 638 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 639 640 _gc_timer.register_gc_end(); 641 642 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 643 644 return !promotion_failure_occurred; 645 } 646 647 // This method iterates over all objects in the young generation, 648 // removing all forwarding references. It then restores any preserved marks. 649 void PSScavenge::clean_up_failed_promotion() { 650 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 651 PSYoungGen* young_gen = heap->young_gen(); 652 653 RemoveForwardedPointerClosure remove_fwd_ptr_closure; 654 young_gen->object_iterate(&remove_fwd_ptr_closure); 655 656 PSPromotionManager::restore_preserved_marks(); 657 658 // Reset the PromotionFailureALot counters. 659 NOT_PRODUCT(heap->reset_promotion_should_fail();) 660 } 661 662 bool PSScavenge::should_attempt_scavenge() { 663 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 664 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 665 666 if (UsePerfData) { 667 counters->update_scavenge_skipped(not_skipped); 668 } 669 670 PSYoungGen* young_gen = heap->young_gen(); 671 PSOldGen* old_gen = heap->old_gen(); 672 673 // Do not attempt to promote unless to_space is empty 674 if (!young_gen->to_space()->is_empty()) { 675 _consecutive_skipped_scavenges++; 676 if (UsePerfData) { 677 counters->update_scavenge_skipped(to_space_not_empty); 678 } 679 return false; 680 } 681 682 // Test to see if the scavenge will likely fail. 683 PSAdaptiveSizePolicy* policy = heap->size_policy(); 684 685 // A similar test is done in the policy's should_full_GC(). If this is 686 // changed, decide if that test should also be changed. 687 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 688 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 689 bool result = promotion_estimate < old_gen->free_in_bytes(); 690 691 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, 692 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(), 693 (size_t) policy->padded_average_promoted_in_bytes(), 694 old_gen->free_in_bytes()); 695 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { 696 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 697 } 698 699 if (result) { 700 _consecutive_skipped_scavenges = 0; 701 } else { 702 _consecutive_skipped_scavenges++; 703 if (UsePerfData) { 704 counters->update_scavenge_skipped(promoted_too_large); 705 } 706 } 707 return result; 708 } 709 710 // Used to add tasks 711 GCTaskManager* const PSScavenge::gc_task_manager() { 712 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 713 "shouldn't return NULL"); 714 return ParallelScavengeHeap::gc_task_manager(); 715 } 716 717 // Adaptive size policy support. When the young generation/old generation 718 // boundary moves, _young_generation_boundary must be reset 719 void PSScavenge::set_young_generation_boundary(HeapWord* v) { 720 _young_generation_boundary = v; 721 if (UseCompressedOops) { 722 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v); 723 } 724 } 725 726 void PSScavenge::initialize() { 727 // Arguments must have been parsed 728 729 if (AlwaysTenure || NeverTenure) { 730 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 731 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 732 _tenuring_threshold = MaxTenuringThreshold; 733 } else { 734 // We want to smooth out our startup times for the AdaptiveSizePolicy 735 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 736 MaxTenuringThreshold; 737 } 738 739 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 740 PSYoungGen* young_gen = heap->young_gen(); 741 PSOldGen* old_gen = heap->old_gen(); 742 743 // Set boundary between young_gen and old_gen 744 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 745 "old above young"); 746 set_young_generation_boundary(young_gen->eden_space()->bottom()); 747 748 // Initialize ref handling object for scavenging. 749 _span_based_discoverer.set_span(young_gen->reserved()); 750 _ref_processor = 751 new ReferenceProcessor(&_span_based_discoverer, 752 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 753 ParallelGCThreads, // mt processing degree 754 true, // mt discovery 755 ParallelGCThreads, // mt discovery degree 756 true, // atomic_discovery 757 NULL, // header provides liveness info 758 false); 759 760 // Cache the cardtable 761 _card_table = heap->card_table(); 762 763 _counters = new CollectorCounters("PSScavenge", 0); 764 }