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/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 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 64 PSCardTable* PSScavenge::_card_table = NULL; 65 bool PSScavenge::_survivor_overflow = false; 66 uint PSScavenge::_tenuring_threshold = 0; 67 HeapWord* PSScavenge::_young_generation_boundary = NULL; 68 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 69 elapsedTimer PSScavenge::_accumulated_time; 70 STWGCTimer PSScavenge::_gc_timer; 71 ParallelScavengeTracer PSScavenge::_gc_tracer; 72 CollectorCounters* PSScavenge::_counters = NULL; 73 74 // Define before use 75 class PSIsAliveClosure: public BoolObjectClosure { 76 public: 77 bool do_object_b(oop p) { 78 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 79 } 80 }; 81 82 PSIsAliveClosure PSScavenge::_is_alive_closure; 83 84 class PSKeepAliveClosure: public OopClosure { 85 protected: 86 MutableSpace* _to_space; 87 PSPromotionManager* _promotion_manager; 88 89 public: 90 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 91 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 92 _to_space = heap->young_gen()->to_space(); 93 94 assert(_promotion_manager != NULL, "Sanity"); 95 } 96 97 template <class T> void do_oop_work(T* p) { 98 assert (oopDesc::is_oop(RawAccess<OOP_NOT_NULL>::oop_load(p)), 99 "expected an oop while scanning weak refs"); 100 101 // Weak refs may be visited more than once. 102 if (PSScavenge::should_scavenge(p, _to_space)) { 103 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p); 104 } 105 } 106 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 107 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 108 }; 109 110 class PSEvacuateFollowersClosure: public VoidClosure { 111 private: 112 PSPromotionManager* _promotion_manager; 113 public: 114 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 115 116 virtual void do_void() { 117 assert(_promotion_manager != NULL, "Sanity"); 118 _promotion_manager->drain_stacks(true); 119 guarantee(_promotion_manager->stacks_empty(), 120 "stacks should be empty at this point"); 121 } 122 }; 123 124 class PSRefProcTaskProxy: public GCTask { 125 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 126 ProcessTask & _rp_task; 127 uint _work_id; 128 public: 129 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 130 : _rp_task(rp_task), 131 _work_id(work_id) 132 { } 133 134 private: 135 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 136 virtual void do_it(GCTaskManager* manager, uint which); 137 }; 138 139 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 140 { 141 PSPromotionManager* promotion_manager = 142 PSPromotionManager::gc_thread_promotion_manager(which); 143 assert(promotion_manager != NULL, "sanity check"); 144 PSKeepAliveClosure keep_alive(promotion_manager); 145 PSEvacuateFollowersClosure evac_followers(promotion_manager); 146 PSIsAliveClosure is_alive; 147 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 148 } 149 150 class PSRefEnqueueTaskProxy: public GCTask { 151 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 152 EnqueueTask& _enq_task; 153 uint _work_id; 154 155 public: 156 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 157 : _enq_task(enq_task), 158 _work_id(work_id) 159 { } 160 161 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 162 virtual void do_it(GCTaskManager* manager, uint which) 163 { 164 _enq_task.work(_work_id); 165 } 166 }; 167 168 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 169 virtual void execute(ProcessTask& task); 170 virtual void execute(EnqueueTask& task); 171 }; 172 173 void PSRefProcTaskExecutor::execute(ProcessTask& task) 174 { 175 GCTaskQueue* q = GCTaskQueue::create(); 176 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 177 for(uint i=0; i < manager->active_workers(); i++) { 178 q->enqueue(new PSRefProcTaskProxy(task, i)); 179 } 180 ParallelTaskTerminator terminator(manager->active_workers(), 181 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 182 if (task.marks_oops_alive() && manager->active_workers() > 1) { 183 for (uint j = 0; j < manager->active_workers(); j++) { 184 q->enqueue(new StealTask(&terminator)); 185 } 186 } 187 manager->execute_and_wait(q); 188 } 189 190 191 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 192 { 193 GCTaskQueue* q = GCTaskQueue::create(); 194 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 195 for(uint i=0; i < manager->active_workers(); i++) { 196 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 197 } 198 manager->execute_and_wait(q); 199 } 200 201 // This method contains all heap specific policy for invoking scavenge. 202 // PSScavenge::invoke_no_policy() will do nothing but attempt to 203 // scavenge. It will not clean up after failed promotions, bail out if 204 // we've exceeded policy time limits, or any other special behavior. 205 // All such policy should be placed here. 206 // 207 // Note that this method should only be called from the vm_thread while 208 // at a safepoint! 209 bool PSScavenge::invoke() { 210 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 211 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 212 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 213 214 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap(); 215 PSAdaptiveSizePolicy* policy = heap->size_policy(); 216 IsGCActiveMark mark; 217 218 const bool scavenge_done = PSScavenge::invoke_no_policy(); 219 const bool need_full_gc = !scavenge_done || 220 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 221 bool full_gc_done = false; 222 223 if (UsePerfData) { 224 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 225 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 226 counters->update_full_follows_scavenge(ffs_val); 227 } 228 229 if (need_full_gc) { 230 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 231 SoftRefPolicy* srp = heap->soft_ref_policy(); 232 const bool clear_all_softrefs = srp->should_clear_all_soft_refs(); 233 234 if (UseParallelOldGC) { 235 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 236 } else { 237 full_gc_done = PSMarkSweepProxy::invoke_no_policy(clear_all_softrefs); 238 } 239 } 240 241 return full_gc_done; 242 } 243 244 // This method contains no policy. You should probably 245 // be calling invoke() instead. 246 bool PSScavenge::invoke_no_policy() { 247 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 248 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 249 250 _gc_timer.register_gc_start(); 251 252 TimeStamp scavenge_entry; 253 TimeStamp scavenge_midpoint; 254 TimeStamp scavenge_exit; 255 256 scavenge_entry.update(); 257 258 if (GCLocker::check_active_before_gc()) { 259 return false; 260 } 261 262 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 263 GCCause::Cause gc_cause = heap->gc_cause(); 264 265 // Check for potential problems. 266 if (!should_attempt_scavenge()) { 267 return false; 268 } 269 270 GCIdMark gc_id_mark; 271 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 272 273 bool promotion_failure_occurred = false; 274 275 PSYoungGen* young_gen = heap->young_gen(); 276 PSOldGen* old_gen = heap->old_gen(); 277 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 278 279 heap->increment_total_collections(); 280 281 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) { 282 // Gather the feedback data for eden occupancy. 283 young_gen->eden_space()->accumulate_statistics(); 284 } 285 286 heap->print_heap_before_gc(); 287 heap->trace_heap_before_gc(&_gc_tracer); 288 289 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 290 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 291 292 // Fill in TLABs 293 heap->accumulate_statistics_all_tlabs(); 294 heap->ensure_parsability(true); // retire TLABs 295 296 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 297 HandleMark hm; // Discard invalid handles created during verification 298 Universe::verify("Before GC"); 299 } 300 301 { 302 ResourceMark rm; 303 HandleMark hm; 304 305 GCTraceCPUTime tcpu; 306 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true); 307 TraceCollectorStats tcs(counters()); 308 TraceMemoryManagerStats tms(heap->young_gc_manager(), gc_cause); 309 310 if (log_is_enabled(Debug, gc, heap, exit)) { 311 accumulated_time()->start(); 312 } 313 314 // Let the size policy know we're starting 315 size_policy->minor_collection_begin(); 316 317 // Verify the object start arrays. 318 if (VerifyObjectStartArray && 319 VerifyBeforeGC) { 320 old_gen->verify_object_start_array(); 321 } 322 323 // Verify no unmarked old->young roots 324 if (VerifyRememberedSets) { 325 heap->card_table()->verify_all_young_refs_imprecise(); 326 } 327 328 assert(young_gen->to_space()->is_empty(), 329 "Attempt to scavenge with live objects in to_space"); 330 young_gen->to_space()->clear(SpaceDecorator::Mangle); 331 332 save_to_space_top_before_gc(); 333 334 #if COMPILER2_OR_JVMCI 335 DerivedPointerTable::clear(); 336 #endif 337 338 reference_processor()->enable_discovery(); 339 reference_processor()->setup_policy(false); 340 341 PreGCValues pre_gc_values(heap); 342 343 // Reset our survivor overflow. 344 set_survivor_overflow(false); 345 346 // We need to save the old top values before 347 // creating the promotion_manager. We pass the top 348 // values to the card_table, to prevent it from 349 // straying into the promotion labs. 350 HeapWord* old_top = old_gen->object_space()->top(); 351 352 // Release all previously held resources 353 gc_task_manager()->release_all_resources(); 354 355 // Set the number of GC threads to be used in this collection 356 gc_task_manager()->set_active_gang(); 357 gc_task_manager()->task_idle_workers(); 358 // Get the active number of workers here and use that value 359 // throughout the methods. 360 uint active_workers = gc_task_manager()->active_workers(); 361 362 PSPromotionManager::pre_scavenge(); 363 364 // We'll use the promotion manager again later. 365 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 366 { 367 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer); 368 ParallelScavengeHeap::ParStrongRootsScope psrs; 369 370 GCTaskQueue* q = GCTaskQueue::create(); 371 372 if (!old_gen->object_space()->is_empty()) { 373 // There are only old-to-young pointers if there are objects 374 // in the old gen. 375 uint stripe_total = active_workers; 376 for(uint i=0; i < stripe_total; i++) { 377 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 378 } 379 } 380 381 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 382 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 383 // We scan the thread roots in parallel 384 Threads::create_thread_roots_tasks(q); 385 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 386 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 387 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 388 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 389 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 390 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 391 392 ParallelTaskTerminator terminator( 393 active_workers, 394 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 395 // If active_workers can exceed 1, add a StrealTask. 396 // PSPromotionManager::drain_stacks_depth() does not fully drain its 397 // stacks and expects a StealTask to complete the draining if 398 // ParallelGCThreads is > 1. 399 if (gc_task_manager()->workers() > 1) { 400 for (uint j = 0; j < active_workers; j++) { 401 q->enqueue(new StealTask(&terminator)); 402 } 403 } 404 405 gc_task_manager()->execute_and_wait(q); 406 } 407 408 scavenge_midpoint.update(); 409 410 // Process reference objects discovered during scavenge 411 { 412 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 413 414 reference_processor()->setup_policy(false); // not always_clear 415 reference_processor()->set_active_mt_degree(active_workers); 416 PSKeepAliveClosure keep_alive(promotion_manager); 417 PSEvacuateFollowersClosure evac_followers(promotion_manager); 418 ReferenceProcessorStats stats; 419 ReferenceProcessorPhaseTimes pt(&_gc_timer, reference_processor()->num_q()); 420 if (reference_processor()->processing_is_mt()) { 421 PSRefProcTaskExecutor task_executor; 422 stats = reference_processor()->process_discovered_references( 423 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 424 &pt); 425 } else { 426 stats = reference_processor()->process_discovered_references( 427 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &pt); 428 } 429 430 _gc_tracer.report_gc_reference_stats(stats); 431 pt.print_all_references(); 432 433 // Enqueue reference objects discovered during scavenge. 434 if (reference_processor()->processing_is_mt()) { 435 PSRefProcTaskExecutor task_executor; 436 reference_processor()->enqueue_discovered_references(&task_executor, &pt); 437 } else { 438 reference_processor()->enqueue_discovered_references(NULL, &pt); 439 } 440 441 pt.print_enqueue_phase(); 442 } 443 444 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 445 446 PSScavengeRootsClosure root_closure(promotion_manager); 447 448 { 449 GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer); 450 WeakProcessor::weak_oops_do(&_is_alive_closure, &root_closure); 451 } 452 453 { 454 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer); 455 // Unlink any dead interned Strings and process the remaining live ones. 456 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 457 } 458 459 // Verify that usage of root_closure didn't copy any objects. 460 assert(promotion_manager->stacks_empty(),"stacks should be empty at this point"); 461 462 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 463 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 464 if (promotion_failure_occurred) { 465 clean_up_failed_promotion(); 466 log_info(gc, promotion)("Promotion failed"); 467 } 468 469 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 470 471 // Let the size policy know we're done. Note that we count promotion 472 // failure cleanup time as part of the collection (otherwise, we're 473 // implicitly saying it's mutator time). 474 size_policy->minor_collection_end(gc_cause); 475 476 if (!promotion_failure_occurred) { 477 // Swap the survivor spaces. 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() - pre_gc_values.old_gen_used(); 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 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 493 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 494 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 495 496 if (UsePerfData) { 497 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 498 counters->update_old_eden_size( 499 size_policy->calculated_eden_size_in_bytes()); 500 counters->update_old_promo_size( 501 size_policy->calculated_promo_size_in_bytes()); 502 counters->update_old_capacity(old_gen->capacity_in_bytes()); 503 counters->update_young_capacity(young_gen->capacity_in_bytes()); 504 counters->update_survived(survived); 505 counters->update_promoted(promoted); 506 counters->update_survivor_overflowed(_survivor_overflow); 507 } 508 509 size_t max_young_size = young_gen->max_size(); 510 511 // Deciding a free ratio in the young generation is tricky, so if 512 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 513 // that the old generation size may have been limited because of them) we 514 // should then limit our young generation size using NewRatio to have it 515 // follow the old generation size. 516 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 517 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 518 } 519 520 size_t survivor_limit = 521 size_policy->max_survivor_size(max_young_size); 522 _tenuring_threshold = 523 size_policy->compute_survivor_space_size_and_threshold( 524 _survivor_overflow, 525 _tenuring_threshold, 526 survivor_limit); 527 528 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")", 529 size_policy->calculated_survivor_size_in_bytes(), 530 _tenuring_threshold, MaxTenuringThreshold); 531 532 if (UsePerfData) { 533 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 534 counters->update_tenuring_threshold(_tenuring_threshold); 535 counters->update_survivor_size_counters(); 536 } 537 538 // Do call at minor collections? 539 // Don't check if the size_policy is ready at this 540 // level. Let the size_policy check that internally. 541 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 542 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 543 // Calculate optimal free space amounts 544 assert(young_gen->max_size() > 545 young_gen->from_space()->capacity_in_bytes() + 546 young_gen->to_space()->capacity_in_bytes(), 547 "Sizes of space in young gen are out-of-bounds"); 548 549 size_t young_live = young_gen->used_in_bytes(); 550 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 551 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 552 size_t max_old_gen_size = old_gen->max_gen_size(); 553 size_t max_eden_size = max_young_size - 554 young_gen->from_space()->capacity_in_bytes() - 555 young_gen->to_space()->capacity_in_bytes(); 556 557 // Used for diagnostics 558 size_policy->clear_generation_free_space_flags(); 559 560 size_policy->compute_eden_space_size(young_live, 561 eden_live, 562 cur_eden, 563 max_eden_size, 564 false /* not full gc*/); 565 566 size_policy->check_gc_overhead_limit(young_live, 567 eden_live, 568 max_old_gen_size, 569 max_eden_size, 570 false /* not full gc*/, 571 gc_cause, 572 heap->soft_ref_policy()); 573 574 size_policy->decay_supplemental_growth(false /* not full gc*/); 575 } 576 // Resize the young generation at every collection 577 // even if new sizes have not been calculated. This is 578 // to allow resizes that may have been inhibited by the 579 // relative location of the "to" and "from" spaces. 580 581 // Resizing the old gen at young collections can cause increases 582 // that don't feed back to the generation sizing policy until 583 // a full collection. Don't resize the old gen here. 584 585 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 586 size_policy->calculated_survivor_size_in_bytes()); 587 588 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 589 } 590 591 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 592 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 593 // Also update() will case adaptive NUMA chunk resizing. 594 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 595 young_gen->eden_space()->update(); 596 597 heap->gc_policy_counters()->update_counters(); 598 599 heap->resize_all_tlabs(); 600 601 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 602 } 603 604 #if COMPILER2_OR_JVMCI 605 DerivedPointerTable::update_pointers(); 606 #endif 607 608 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 609 610 // Re-verify object start arrays 611 if (VerifyObjectStartArray && 612 VerifyAfterGC) { 613 old_gen->verify_object_start_array(); 614 } 615 616 // Verify all old -> young cards are now precise 617 if (VerifyRememberedSets) { 618 // Precise verification will give false positives. Until this is fixed, 619 // use imprecise verification. 620 // heap->card_table()->verify_all_young_refs_precise(); 621 heap->card_table()->verify_all_young_refs_imprecise(); 622 } 623 624 if (log_is_enabled(Debug, gc, heap, exit)) { 625 accumulated_time()->stop(); 626 } 627 628 young_gen->print_used_change(pre_gc_values.young_gen_used()); 629 old_gen->print_used_change(pre_gc_values.old_gen_used()); 630 MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used()); 631 632 // Track memory usage and detect low memory 633 MemoryService::track_memory_usage(); 634 heap->update_counters(); 635 636 gc_task_manager()->release_idle_workers(); 637 } 638 639 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 640 HandleMark hm; // Discard invalid handles created during verification 641 Universe::verify("After GC"); 642 } 643 644 heap->print_heap_after_gc(); 645 heap->trace_heap_after_gc(&_gc_tracer); 646 647 scavenge_exit.update(); 648 649 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 650 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 651 scavenge_exit.ticks()); 652 gc_task_manager()->print_task_time_stamps(); 653 654 #ifdef TRACESPINNING 655 ParallelTaskTerminator::print_termination_counts(); 656 #endif 657 658 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 659 660 _gc_timer.register_gc_end(); 661 662 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 663 664 return !promotion_failure_occurred; 665 } 666 667 // This method iterates over all objects in the young generation, 668 // removing all forwarding references. It then restores any preserved marks. 669 void PSScavenge::clean_up_failed_promotion() { 670 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 671 PSYoungGen* young_gen = heap->young_gen(); 672 673 RemoveForwardedPointerClosure remove_fwd_ptr_closure; 674 young_gen->object_iterate(&remove_fwd_ptr_closure); 675 676 PSPromotionManager::restore_preserved_marks(); 677 678 // Reset the PromotionFailureALot counters. 679 NOT_PRODUCT(heap->reset_promotion_should_fail();) 680 } 681 682 bool PSScavenge::should_attempt_scavenge() { 683 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 684 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 685 686 if (UsePerfData) { 687 counters->update_scavenge_skipped(not_skipped); 688 } 689 690 PSYoungGen* young_gen = heap->young_gen(); 691 PSOldGen* old_gen = heap->old_gen(); 692 693 // Do not attempt to promote unless to_space is empty 694 if (!young_gen->to_space()->is_empty()) { 695 _consecutive_skipped_scavenges++; 696 if (UsePerfData) { 697 counters->update_scavenge_skipped(to_space_not_empty); 698 } 699 return false; 700 } 701 702 // Test to see if the scavenge will likely fail. 703 PSAdaptiveSizePolicy* policy = heap->size_policy(); 704 705 // A similar test is done in the policy's should_full_GC(). If this is 706 // changed, decide if that test should also be changed. 707 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 708 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 709 bool result = promotion_estimate < old_gen->free_in_bytes(); 710 711 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, 712 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(), 713 (size_t) policy->padded_average_promoted_in_bytes(), 714 old_gen->free_in_bytes()); 715 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { 716 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 717 } 718 719 if (result) { 720 _consecutive_skipped_scavenges = 0; 721 } else { 722 _consecutive_skipped_scavenges++; 723 if (UsePerfData) { 724 counters->update_scavenge_skipped(promoted_too_large); 725 } 726 } 727 return result; 728 } 729 730 // Used to add tasks 731 GCTaskManager* const PSScavenge::gc_task_manager() { 732 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 733 "shouldn't return NULL"); 734 return ParallelScavengeHeap::gc_task_manager(); 735 } 736 737 // Adaptive size policy support. When the young generation/old generation 738 // boundary moves, _young_generation_boundary must be reset 739 void PSScavenge::set_young_generation_boundary(HeapWord* v) { 740 _young_generation_boundary = v; 741 if (UseCompressedOops) { 742 _young_generation_boundary_compressed = (uintptr_t)CompressedOops::encode((oop)v); 743 } 744 } 745 746 void PSScavenge::initialize() { 747 // Arguments must have been parsed 748 749 if (AlwaysTenure || NeverTenure) { 750 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 751 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 752 _tenuring_threshold = MaxTenuringThreshold; 753 } else { 754 // We want to smooth out our startup times for the AdaptiveSizePolicy 755 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 756 MaxTenuringThreshold; 757 } 758 759 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 760 PSYoungGen* young_gen = heap->young_gen(); 761 PSOldGen* old_gen = heap->old_gen(); 762 763 // Set boundary between young_gen and old_gen 764 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 765 "old above young"); 766 set_young_generation_boundary(young_gen->eden_space()->bottom()); 767 768 // Initialize ref handling object for scavenging. 769 MemRegion mr = young_gen->reserved(); 770 771 _ref_processor = 772 new ReferenceProcessor(mr, // 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 }