1/* 2 * Copyright (c) 2002, 2016, 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/cardTableExtension.hpp" 29#include "gc/parallel/gcTaskManager.hpp" 30#include "gc/parallel/parallelScavengeHeap.hpp" 31#include "gc/parallel/psAdaptiveSizePolicy.hpp" 32#include "gc/parallel/psMarkSweep.hpp" 33#include "gc/parallel/psParallelCompact.inline.hpp" 34#include "gc/parallel/psScavenge.inline.hpp" 35#include "gc/parallel/psTasks.hpp" 36#include "gc/shared/collectorPolicy.hpp" 37#include "gc/shared/gcCause.hpp" 38#include "gc/shared/gcHeapSummary.hpp" 39#include "gc/shared/gcId.hpp" 40#include "gc/shared/gcLocker.inline.hpp" 41#include "gc/shared/gcTimer.hpp" 42#include "gc/shared/gcTrace.hpp" 43#include "gc/shared/gcTraceTime.inline.hpp" 44#include "gc/shared/isGCActiveMark.hpp" 45#include "gc/shared/referencePolicy.hpp" 46#include "gc/shared/referenceProcessor.hpp" 47#include "gc/shared/spaceDecorator.hpp" 48#include "memory/resourceArea.hpp" 49#include "logging/log.hpp" 50#include "oops/oop.inline.hpp" 51#include "runtime/biasedLocking.hpp" 52#include "runtime/fprofiler.hpp" 53#include "runtime/handles.inline.hpp" 54#include "runtime/threadCritical.hpp" 55#include "runtime/vmThread.hpp" 56#include "runtime/vm_operations.hpp" 57#include "services/memoryService.hpp" 58#include "utilities/stack.inline.hpp" 59 60HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 61int PSScavenge::_consecutive_skipped_scavenges = 0; 62ReferenceProcessor* PSScavenge::_ref_processor = NULL; 63CardTableExtension* PSScavenge::_card_table = NULL; 64bool PSScavenge::_survivor_overflow = false; 65uint PSScavenge::_tenuring_threshold = 0; 66HeapWord* PSScavenge::_young_generation_boundary = NULL; 67uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 68elapsedTimer PSScavenge::_accumulated_time; 69STWGCTimer PSScavenge::_gc_timer; 70ParallelScavengeTracer PSScavenge::_gc_tracer; 71CollectorCounters* PSScavenge::_counters = NULL; 72 73// Define before use 74class PSIsAliveClosure: public BoolObjectClosure { 75public: 76 bool do_object_b(oop p) { 77 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 78 } 79}; 80 81PSIsAliveClosure PSScavenge::_is_alive_closure; 82 83class PSKeepAliveClosure: public OopClosure { 84protected: 85 MutableSpace* _to_space; 86 PSPromotionManager* _promotion_manager; 87 88public: 89 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 90 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 91 _to_space = heap->young_gen()->to_space(); 92 93 assert(_promotion_manager != NULL, "Sanity"); 94 } 95 96 template <class T> void do_oop_work(T* p) { 97 assert (!oopDesc::is_null(*p), "expected non-null ref"); 98 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 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 110class 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 124class PSRefProcTaskProxy: public GCTask { 125 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 126 ProcessTask & _rp_task; 127 uint _work_id; 128public: 129 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 130 : _rp_task(rp_task), 131 _work_id(work_id) 132 { } 133 134private: 135 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 136 virtual void do_it(GCTaskManager* manager, uint which); 137}; 138 139void 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 150class PSRefEnqueueTaskProxy: public GCTask { 151 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 152 EnqueueTask& _enq_task; 153 uint _work_id; 154 155public: 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 168class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 169 virtual void execute(ProcessTask& task); 170 virtual void execute(EnqueueTask& task); 171}; 172 173void 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 191void 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! 209bool 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 CollectorPolicy* cp = heap->collector_policy(); 232 const bool clear_all_softrefs = cp->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 = PSMarkSweep::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. 246bool 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(false /* not full GC */,gc_cause); 309 310 if (TraceYoungGenTime) accumulated_time()->start(); 311 312 // Let the size policy know we're starting 313 size_policy->minor_collection_begin(); 314 315 // Verify the object start arrays. 316 if (VerifyObjectStartArray && 317 VerifyBeforeGC) { 318 old_gen->verify_object_start_array(); 319 } 320 321 // Verify no unmarked old->young roots 322 if (VerifyRememberedSets) { 323 CardTableExtension::verify_all_young_refs_imprecise(); 324 } 325 326 assert(young_gen->to_space()->is_empty(), 327 "Attempt to scavenge with live objects in to_space"); 328 young_gen->to_space()->clear(SpaceDecorator::Mangle); 329 330 save_to_space_top_before_gc(); 331 332#if defined(COMPILER2) || INCLUDE_JVMCI 333 DerivedPointerTable::clear(); 334#endif 335 336 reference_processor()->enable_discovery(); 337 reference_processor()->setup_policy(false); 338 339 PreGCValues pre_gc_values(heap); 340 341 // Reset our survivor overflow. 342 set_survivor_overflow(false); 343 344 // We need to save the old top values before 345 // creating the promotion_manager. We pass the top 346 // values to the card_table, to prevent it from 347 // straying into the promotion labs. 348 HeapWord* old_top = old_gen->object_space()->top(); 349 350 // Release all previously held resources 351 gc_task_manager()->release_all_resources(); 352 353 // Set the number of GC threads to be used in this collection 354 gc_task_manager()->set_active_gang(); 355 gc_task_manager()->task_idle_workers(); 356 // Get the active number of workers here and use that value 357 // throughout the methods. 358 uint active_workers = gc_task_manager()->active_workers(); 359 360 PSPromotionManager::pre_scavenge(); 361 362 // We'll use the promotion manager again later. 363 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 364 { 365 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer); 366 ParallelScavengeHeap::ParStrongRootsScope psrs; 367 368 GCTaskQueue* q = GCTaskQueue::create(); 369 370 if (!old_gen->object_space()->is_empty()) { 371 // There are only old-to-young pointers if there are objects 372 // in the old gen. 373 uint stripe_total = active_workers; 374 for(uint i=0; i < stripe_total; i++) { 375 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 376 } 377 } 378 379 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 380 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 381 // We scan the thread roots in parallel 382 Threads::create_thread_roots_tasks(q); 383 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 384 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 385 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 386 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 387 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 388 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 389 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 390 391 ParallelTaskTerminator terminator( 392 active_workers, 393 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 394 // If active_workers can exceed 1, add a StrealTask. 395 // PSPromotionManager::drain_stacks_depth() does not fully drain its 396 // stacks and expects a StealTask to complete the draining if 397 // ParallelGCThreads is > 1. 398 if (gc_task_manager()->workers() > 1) { 399 for (uint j = 0; j < active_workers; j++) { 400 q->enqueue(new StealTask(&terminator)); 401 } 402 } 403 404 gc_task_manager()->execute_and_wait(q); 405 } 406 407 scavenge_midpoint.update(); 408 409 // Process reference objects discovered during scavenge 410 { 411 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 412 413 reference_processor()->setup_policy(false); // not always_clear 414 reference_processor()->set_active_mt_degree(active_workers); 415 PSKeepAliveClosure keep_alive(promotion_manager); 416 PSEvacuateFollowersClosure evac_followers(promotion_manager); 417 ReferenceProcessorStats stats; 418 if (reference_processor()->processing_is_mt()) { 419 PSRefProcTaskExecutor task_executor; 420 stats = reference_processor()->process_discovered_references( 421 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 422 &_gc_timer); 423 } else { 424 stats = reference_processor()->process_discovered_references( 425 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); 426 } 427 428 _gc_tracer.report_gc_reference_stats(stats); 429 430 // Enqueue reference objects discovered during scavenge. 431 if (reference_processor()->processing_is_mt()) { 432 PSRefProcTaskExecutor task_executor; 433 reference_processor()->enqueue_discovered_references(&task_executor); 434 } else { 435 reference_processor()->enqueue_discovered_references(NULL); 436 } 437 } 438 439 { 440 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer); 441 // Unlink any dead interned Strings and process the remaining live ones. 442 PSScavengeRootsClosure root_closure(promotion_manager); 443 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 444 } 445 446 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 447 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 448 if (promotion_failure_occurred) { 449 clean_up_failed_promotion(); 450 log_info(gc, promotion)("Promotion failed"); 451 } 452 453 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 454 455 // Let the size policy know we're done. Note that we count promotion 456 // failure cleanup time as part of the collection (otherwise, we're 457 // implicitly saying it's mutator time). 458 size_policy->minor_collection_end(gc_cause); 459 460 if (!promotion_failure_occurred) { 461 // Swap the survivor spaces. 462 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 463 young_gen->from_space()->clear(SpaceDecorator::Mangle); 464 young_gen->swap_spaces(); 465 466 size_t survived = young_gen->from_space()->used_in_bytes(); 467 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used(); 468 size_policy->update_averages(_survivor_overflow, survived, promoted); 469 470 // A successful scavenge should restart the GC time limit count which is 471 // for full GC's. 472 size_policy->reset_gc_overhead_limit_count(); 473 if (UseAdaptiveSizePolicy) { 474 // Calculate the new survivor size and tenuring threshold 475 476 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 477 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 478 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 479 480 if (UsePerfData) { 481 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 482 counters->update_old_eden_size( 483 size_policy->calculated_eden_size_in_bytes()); 484 counters->update_old_promo_size( 485 size_policy->calculated_promo_size_in_bytes()); 486 counters->update_old_capacity(old_gen->capacity_in_bytes()); 487 counters->update_young_capacity(young_gen->capacity_in_bytes()); 488 counters->update_survived(survived); 489 counters->update_promoted(promoted); 490 counters->update_survivor_overflowed(_survivor_overflow); 491 } 492 493 size_t max_young_size = young_gen->max_size(); 494 495 // Deciding a free ratio in the young generation is tricky, so if 496 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 497 // that the old generation size may have been limited because of them) we 498 // should then limit our young generation size using NewRatio to have it 499 // follow the old generation size. 500 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 501 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 502 } 503 504 size_t survivor_limit = 505 size_policy->max_survivor_size(max_young_size); 506 _tenuring_threshold = 507 size_policy->compute_survivor_space_size_and_threshold( 508 _survivor_overflow, 509 _tenuring_threshold, 510 survivor_limit); 511 512 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")", 513 size_policy->calculated_survivor_size_in_bytes(), 514 _tenuring_threshold, MaxTenuringThreshold); 515 516 if (UsePerfData) { 517 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 518 counters->update_tenuring_threshold(_tenuring_threshold); 519 counters->update_survivor_size_counters(); 520 } 521 522 // Do call at minor collections? 523 // Don't check if the size_policy is ready at this 524 // level. Let the size_policy check that internally. 525 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 526 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 527 // Calculate optimal free space amounts 528 assert(young_gen->max_size() > 529 young_gen->from_space()->capacity_in_bytes() + 530 young_gen->to_space()->capacity_in_bytes(), 531 "Sizes of space in young gen are out-of-bounds"); 532 533 size_t young_live = young_gen->used_in_bytes(); 534 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 535 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 536 size_t max_old_gen_size = old_gen->max_gen_size(); 537 size_t max_eden_size = max_young_size - 538 young_gen->from_space()->capacity_in_bytes() - 539 young_gen->to_space()->capacity_in_bytes(); 540 541 // Used for diagnostics 542 size_policy->clear_generation_free_space_flags(); 543 544 size_policy->compute_eden_space_size(young_live, 545 eden_live, 546 cur_eden, 547 max_eden_size, 548 false /* not full gc*/); 549 550 size_policy->check_gc_overhead_limit(young_live, 551 eden_live, 552 max_old_gen_size, 553 max_eden_size, 554 false /* not full gc*/, 555 gc_cause, 556 heap->collector_policy()); 557 558 size_policy->decay_supplemental_growth(false /* not full gc*/); 559 } 560 // Resize the young generation at every collection 561 // even if new sizes have not been calculated. This is 562 // to allow resizes that may have been inhibited by the 563 // relative location of the "to" and "from" spaces. 564 565 // Resizing the old gen at young collections can cause increases 566 // that don't feed back to the generation sizing policy until 567 // a full collection. Don't resize the old gen here. 568 569 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 570 size_policy->calculated_survivor_size_in_bytes()); 571 572 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 573 } 574 575 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 576 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 577 // Also update() will case adaptive NUMA chunk resizing. 578 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 579 young_gen->eden_space()->update(); 580 581 heap->gc_policy_counters()->update_counters(); 582 583 heap->resize_all_tlabs(); 584 585 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 586 } 587 588#if defined(COMPILER2) || INCLUDE_JVMCI 589 DerivedPointerTable::update_pointers(); 590#endif 591 592 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 593 594 // Re-verify object start arrays 595 if (VerifyObjectStartArray && 596 VerifyAfterGC) { 597 old_gen->verify_object_start_array(); 598 } 599 600 // Verify all old -> young cards are now precise 601 if (VerifyRememberedSets) { 602 // Precise verification will give false positives. Until this is fixed, 603 // use imprecise verification. 604 // CardTableExtension::verify_all_young_refs_precise(); 605 CardTableExtension::verify_all_young_refs_imprecise(); 606 } 607 608 if (TraceYoungGenTime) accumulated_time()->stop(); 609 610 young_gen->print_used_change(pre_gc_values.young_gen_used()); 611 old_gen->print_used_change(pre_gc_values.old_gen_used()); 612 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used()); 613 614 // Track memory usage and detect low memory 615 MemoryService::track_memory_usage(); 616 heap->update_counters(); 617 618 gc_task_manager()->release_idle_workers(); 619 } 620 621 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 622 HandleMark hm; // Discard invalid handles created during verification 623 Universe::verify("After GC"); 624 } 625 626 heap->print_heap_after_gc(); 627 heap->trace_heap_after_gc(&_gc_tracer); 628 629 scavenge_exit.update(); 630 631 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 632 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 633 scavenge_exit.ticks()); 634 gc_task_manager()->print_task_time_stamps(); 635 636#ifdef TRACESPINNING 637 ParallelTaskTerminator::print_termination_counts(); 638#endif 639 640 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 641 642 _gc_timer.register_gc_end(); 643 644 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 645 646 return !promotion_failure_occurred; 647} 648 649// This method iterates over all objects in the young generation, 650// removing all forwarding references. It then restores any preserved marks. 651void PSScavenge::clean_up_failed_promotion() { 652 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 653 PSYoungGen* young_gen = heap->young_gen(); 654 655 RemoveForwardedPointerClosure remove_fwd_ptr_closure; 656 young_gen->object_iterate(&remove_fwd_ptr_closure); 657 658 PSPromotionManager::restore_preserved_marks(); 659 660 // Reset the PromotionFailureALot counters. 661 NOT_PRODUCT(heap->reset_promotion_should_fail();) 662} 663 664bool PSScavenge::should_attempt_scavenge() { 665 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 666 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 667 668 if (UsePerfData) { 669 counters->update_scavenge_skipped(not_skipped); 670 } 671 672 PSYoungGen* young_gen = heap->young_gen(); 673 PSOldGen* old_gen = heap->old_gen(); 674 675 // Do not attempt to promote unless to_space is empty 676 if (!young_gen->to_space()->is_empty()) { 677 _consecutive_skipped_scavenges++; 678 if (UsePerfData) { 679 counters->update_scavenge_skipped(to_space_not_empty); 680 } 681 return false; 682 } 683 684 // Test to see if the scavenge will likely fail. 685 PSAdaptiveSizePolicy* policy = heap->size_policy(); 686 687 // A similar test is done in the policy's should_full_GC(). If this is 688 // changed, decide if that test should also be changed. 689 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 690 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 691 bool result = promotion_estimate < old_gen->free_in_bytes(); 692 693 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, 694 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(), 695 (size_t) policy->padded_average_promoted_in_bytes(), 696 old_gen->free_in_bytes()); 697 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { 698 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 699 } 700 701 if (result) { 702 _consecutive_skipped_scavenges = 0; 703 } else { 704 _consecutive_skipped_scavenges++; 705 if (UsePerfData) { 706 counters->update_scavenge_skipped(promoted_too_large); 707 } 708 } 709 return result; 710} 711 712 // Used to add tasks 713GCTaskManager* const PSScavenge::gc_task_manager() { 714 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 715 "shouldn't return NULL"); 716 return ParallelScavengeHeap::gc_task_manager(); 717} 718 719// Adaptive size policy support. When the young generation/old generation 720// boundary moves, _young_generation_boundary must be reset 721void PSScavenge::set_young_generation_boundary(HeapWord* v) { 722 _young_generation_boundary = v; 723 if (UseCompressedOops) { 724 _young_generation_boundary_compressed = (uintptr_t)oopDesc::encode_heap_oop((oop)v); 725 } 726} 727 728void PSScavenge::initialize() { 729 // Arguments must have been parsed 730 731 if (AlwaysTenure || NeverTenure) { 732 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 733 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 734 _tenuring_threshold = MaxTenuringThreshold; 735 } else { 736 // We want to smooth out our startup times for the AdaptiveSizePolicy 737 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 738 MaxTenuringThreshold; 739 } 740 741 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 742 PSYoungGen* young_gen = heap->young_gen(); 743 PSOldGen* old_gen = heap->old_gen(); 744 745 // Set boundary between young_gen and old_gen 746 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 747 "old above young"); 748 set_young_generation_boundary(young_gen->eden_space()->bottom()); 749 750 // Initialize ref handling object for scavenging. 751 MemRegion mr = young_gen->reserved(); 752 753 _ref_processor = 754 new ReferenceProcessor(mr, // span 755 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 756 ParallelGCThreads, // mt processing degree 757 true, // mt discovery 758 ParallelGCThreads, // mt discovery degree 759 true, // atomic_discovery 760 NULL); // header provides liveness info 761 762 // Cache the cardtable 763 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set()); 764 765 _counters = new CollectorCounters("PSScavenge", 0); 766} 767