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 60 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 61 int PSScavenge::_consecutive_skipped_scavenges = 0; 62 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 63 CardTableExtension* PSScavenge::_card_table = NULL; 64 bool PSScavenge::_survivor_overflow = false; 65 uint PSScavenge::_tenuring_threshold = 0; 66 HeapWord* PSScavenge::_young_generation_boundary = NULL; 67 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 68 elapsedTimer PSScavenge::_accumulated_time; 69 STWGCTimer PSScavenge::_gc_timer; 70 ParallelScavengeTracer PSScavenge::_gc_tracer; 71 CollectorCounters* PSScavenge::_counters = NULL; 72 73 // Define before use 74 class PSIsAliveClosure: public BoolObjectClosure { 75 public: 76 bool do_object_b(oop p) { 77 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 78 } 79 }; 80 81 PSIsAliveClosure PSScavenge::_is_alive_closure; 82 83 class PSKeepAliveClosure: public OopClosure { 84 protected: 85 MutableSpace* _to_space; 86 PSPromotionManager* _promotion_manager; 87 88 public: 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 }; 109 110 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 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 class CreateThreadRootsTasksClosure : public ThreadClosure { 245 246 private: 247 GCTaskQueue* _queue; 248 249 public: 250 251 CreateThreadRootsTasksClosure(GCTaskQueue* q) : _queue(q) { 252 } 253 254 void do_thread(Thread* thread) { 255 if (thread->is_Java_thread()) { 256 _queue->enqueue(new ThreadRootsTask((JavaThread*) thread)); 257 } else if (thread->is_VM_thread()) { 258 _queue->enqueue(new ThreadRootsTask((VMThread*) thread)); 259 } 260 } 261 262 }; 263 264 // This method contains no policy. You should probably 265 // be calling invoke() instead. 266 bool PSScavenge::invoke_no_policy() { 267 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 268 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 269 270 _gc_timer.register_gc_start(); 271 272 TimeStamp scavenge_entry; 273 TimeStamp scavenge_midpoint; 274 TimeStamp scavenge_exit; 275 276 scavenge_entry.update(); 277 278 if (GCLocker::check_active_before_gc()) { 279 return false; 280 } 281 282 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 283 GCCause::Cause gc_cause = heap->gc_cause(); 284 285 // Check for potential problems. 286 if (!should_attempt_scavenge()) { 287 return false; 288 } 289 290 GCIdMark gc_id_mark; 291 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 292 293 bool promotion_failure_occurred = false; 294 295 PSYoungGen* young_gen = heap->young_gen(); 296 PSOldGen* old_gen = heap->old_gen(); 297 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 298 299 heap->increment_total_collections(); 300 301 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) { 302 // Gather the feedback data for eden occupancy. 303 young_gen->eden_space()->accumulate_statistics(); 304 } 305 306 heap->print_heap_before_gc(); 307 heap->trace_heap_before_gc(&_gc_tracer); 308 309 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 310 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 311 312 // Fill in TLABs 313 heap->accumulate_statistics_all_tlabs(); 314 heap->ensure_parsability(true); // retire TLABs 315 316 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 317 HandleMark hm; // Discard invalid handles created during verification 318 Universe::verify("Before GC"); 319 } 320 321 { 322 ResourceMark rm; 323 HandleMark hm; 324 325 GCTraceCPUTime tcpu; 326 GCTraceTime(Info, gc) tm("Pause Young", NULL, gc_cause, true); 327 TraceCollectorStats tcs(counters()); 328 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 329 330 if (TraceYoungGenTime) accumulated_time()->start(); 331 332 // Let the size policy know we're starting 333 size_policy->minor_collection_begin(); 334 335 // Verify the object start arrays. 336 if (VerifyObjectStartArray && 337 VerifyBeforeGC) { 338 old_gen->verify_object_start_array(); 339 } 340 341 // Verify no unmarked old->young roots 342 if (VerifyRememberedSets) { 343 CardTableExtension::verify_all_young_refs_imprecise(); 344 } 345 346 assert(young_gen->to_space()->is_empty(), 347 "Attempt to scavenge with live objects in to_space"); 348 young_gen->to_space()->clear(SpaceDecorator::Mangle); 349 350 save_to_space_top_before_gc(); 351 352 #if defined(COMPILER2) || INCLUDE_JVMCI 353 DerivedPointerTable::clear(); 354 #endif 355 356 reference_processor()->enable_discovery(); 357 reference_processor()->setup_policy(false); 358 359 PreGCValues pre_gc_values(heap); 360 361 // Reset our survivor overflow. 362 set_survivor_overflow(false); 363 364 // We need to save the old top values before 365 // creating the promotion_manager. We pass the top 366 // values to the card_table, to prevent it from 367 // straying into the promotion labs. 368 HeapWord* old_top = old_gen->object_space()->top(); 369 370 // Release all previously held resources 371 gc_task_manager()->release_all_resources(); 372 373 // Set the number of GC threads to be used in this collection 374 gc_task_manager()->set_active_gang(); 375 gc_task_manager()->task_idle_workers(); 376 // Get the active number of workers here and use that value 377 // throughout the methods. 378 uint active_workers = gc_task_manager()->active_workers(); 379 380 PSPromotionManager::pre_scavenge(); 381 382 // We'll use the promotion manager again later. 383 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 384 { 385 GCTraceTime(Debug, gc, phases) tm("Scavenge", &_gc_timer); 386 ParallelScavengeHeap::ParStrongRootsScope psrs; 387 388 GCTaskQueue* q = GCTaskQueue::create(); 389 390 if (!old_gen->object_space()->is_empty()) { 391 // There are only old-to-young pointers if there are objects 392 // in the old gen. 393 uint stripe_total = active_workers; 394 for(uint i=0; i < stripe_total; i++) { 395 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 396 } 397 } 398 399 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 400 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 401 // We scan the thread roots in parallel 402 CreateThreadRootsTasksClosure cl(q); 403 Threads::threads_do(&cl); 404 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 405 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 406 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 407 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 408 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 409 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 410 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 411 412 ParallelTaskTerminator terminator( 413 active_workers, 414 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 415 // If active_workers can exceed 1, add a StrealTask. 416 // PSPromotionManager::drain_stacks_depth() does not fully drain its 417 // stacks and expects a StealTask to complete the draining if 418 // ParallelGCThreads is > 1. 419 if (gc_task_manager()->workers() > 1) { 420 for (uint j = 0; j < active_workers; j++) { 421 q->enqueue(new StealTask(&terminator)); 422 } 423 } 424 425 gc_task_manager()->execute_and_wait(q); 426 } 427 428 scavenge_midpoint.update(); 429 430 // Process reference objects discovered during scavenge 431 { 432 GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer); 433 434 reference_processor()->setup_policy(false); // not always_clear 435 reference_processor()->set_active_mt_degree(active_workers); 436 PSKeepAliveClosure keep_alive(promotion_manager); 437 PSEvacuateFollowersClosure evac_followers(promotion_manager); 438 ReferenceProcessorStats stats; 439 if (reference_processor()->processing_is_mt()) { 440 PSRefProcTaskExecutor task_executor; 441 stats = reference_processor()->process_discovered_references( 442 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 443 &_gc_timer); 444 } else { 445 stats = reference_processor()->process_discovered_references( 446 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); 447 } 448 449 _gc_tracer.report_gc_reference_stats(stats); 450 451 // Enqueue reference objects discovered during scavenge. 452 if (reference_processor()->processing_is_mt()) { 453 PSRefProcTaskExecutor task_executor; 454 reference_processor()->enqueue_discovered_references(&task_executor); 455 } else { 456 reference_processor()->enqueue_discovered_references(NULL); 457 } 458 } 459 460 { 461 GCTraceTime(Debug, gc, phases) tm("Scrub String Table", &_gc_timer); 462 // Unlink any dead interned Strings and process the remaining live ones. 463 PSScavengeRootsClosure root_closure(promotion_manager); 464 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 465 } 466 467 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 468 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 469 if (promotion_failure_occurred) { 470 clean_up_failed_promotion(); 471 log_info(gc, promotion)("Promotion failed"); 472 } 473 474 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 475 476 // Let the size policy know we're done. Note that we count promotion 477 // failure cleanup time as part of the collection (otherwise, we're 478 // implicitly saying it's mutator time). 479 size_policy->minor_collection_end(gc_cause); 480 481 if (!promotion_failure_occurred) { 482 // Swap the survivor spaces. 483 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 484 young_gen->from_space()->clear(SpaceDecorator::Mangle); 485 young_gen->swap_spaces(); 486 487 size_t survived = young_gen->from_space()->used_in_bytes(); 488 size_t promoted = old_gen->used_in_bytes() - pre_gc_values.old_gen_used(); 489 size_policy->update_averages(_survivor_overflow, survived, promoted); 490 491 // A successful scavenge should restart the GC time limit count which is 492 // for full GC's. 493 size_policy->reset_gc_overhead_limit_count(); 494 if (UseAdaptiveSizePolicy) { 495 // Calculate the new survivor size and tenuring threshold 496 497 log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections()); 498 log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT, 499 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 500 501 if (UsePerfData) { 502 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 503 counters->update_old_eden_size( 504 size_policy->calculated_eden_size_in_bytes()); 505 counters->update_old_promo_size( 506 size_policy->calculated_promo_size_in_bytes()); 507 counters->update_old_capacity(old_gen->capacity_in_bytes()); 508 counters->update_young_capacity(young_gen->capacity_in_bytes()); 509 counters->update_survived(survived); 510 counters->update_promoted(promoted); 511 counters->update_survivor_overflowed(_survivor_overflow); 512 } 513 514 size_t max_young_size = young_gen->max_size(); 515 516 // Deciding a free ratio in the young generation is tricky, so if 517 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 518 // that the old generation size may have been limited because of them) we 519 // should then limit our young generation size using NewRatio to have it 520 // follow the old generation size. 521 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 522 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 523 } 524 525 size_t survivor_limit = 526 size_policy->max_survivor_size(max_young_size); 527 _tenuring_threshold = 528 size_policy->compute_survivor_space_size_and_threshold( 529 _survivor_overflow, 530 _tenuring_threshold, 531 survivor_limit); 532 533 log_debug(gc, age)("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max threshold " UINTX_FORMAT ")", 534 size_policy->calculated_survivor_size_in_bytes(), 535 _tenuring_threshold, MaxTenuringThreshold); 536 537 if (UsePerfData) { 538 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 539 counters->update_tenuring_threshold(_tenuring_threshold); 540 counters->update_survivor_size_counters(); 541 } 542 543 // Do call at minor collections? 544 // Don't check if the size_policy is ready at this 545 // level. Let the size_policy check that internally. 546 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 547 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 548 // Calculate optimal free space amounts 549 assert(young_gen->max_size() > 550 young_gen->from_space()->capacity_in_bytes() + 551 young_gen->to_space()->capacity_in_bytes(), 552 "Sizes of space in young gen are out-of-bounds"); 553 554 size_t young_live = young_gen->used_in_bytes(); 555 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 556 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 557 size_t max_old_gen_size = old_gen->max_gen_size(); 558 size_t max_eden_size = max_young_size - 559 young_gen->from_space()->capacity_in_bytes() - 560 young_gen->to_space()->capacity_in_bytes(); 561 562 // Used for diagnostics 563 size_policy->clear_generation_free_space_flags(); 564 565 size_policy->compute_eden_space_size(young_live, 566 eden_live, 567 cur_eden, 568 max_eden_size, 569 false /* not full gc*/); 570 571 size_policy->check_gc_overhead_limit(young_live, 572 eden_live, 573 max_old_gen_size, 574 max_eden_size, 575 false /* not full gc*/, 576 gc_cause, 577 heap->collector_policy()); 578 579 size_policy->decay_supplemental_growth(false /* not full gc*/); 580 } 581 // Resize the young generation at every collection 582 // even if new sizes have not been calculated. This is 583 // to allow resizes that may have been inhibited by the 584 // relative location of the "to" and "from" spaces. 585 586 // Resizing the old gen at young collections can cause increases 587 // that don't feed back to the generation sizing policy until 588 // a full collection. Don't resize the old gen here. 589 590 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 591 size_policy->calculated_survivor_size_in_bytes()); 592 593 log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections()); 594 } 595 596 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 597 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 598 // Also update() will case adaptive NUMA chunk resizing. 599 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 600 young_gen->eden_space()->update(); 601 602 heap->gc_policy_counters()->update_counters(); 603 604 heap->resize_all_tlabs(); 605 606 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 607 } 608 609 #if defined(COMPILER2) || INCLUDE_JVMCI 610 DerivedPointerTable::update_pointers(); 611 #endif 612 613 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 614 615 // Re-verify object start arrays 616 if (VerifyObjectStartArray && 617 VerifyAfterGC) { 618 old_gen->verify_object_start_array(); 619 } 620 621 // Verify all old -> young cards are now precise 622 if (VerifyRememberedSets) { 623 // Precise verification will give false positives. Until this is fixed, 624 // use imprecise verification. 625 // CardTableExtension::verify_all_young_refs_precise(); 626 CardTableExtension::verify_all_young_refs_imprecise(); 627 } 628 629 if (TraceYoungGenTime) accumulated_time()->stop(); 630 631 young_gen->print_used_change(pre_gc_values.young_gen_used()); 632 old_gen->print_used_change(pre_gc_values.old_gen_used()); 633 MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used()); 634 635 // Track memory usage and detect low memory 636 MemoryService::track_memory_usage(); 637 heap->update_counters(); 638 639 gc_task_manager()->release_idle_workers(); 640 } 641 642 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 643 HandleMark hm; // Discard invalid handles created during verification 644 Universe::verify("After GC"); 645 } 646 647 heap->print_heap_after_gc(); 648 heap->trace_heap_after_gc(&_gc_tracer); 649 650 scavenge_exit.update(); 651 652 log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 653 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 654 scavenge_exit.ticks()); 655 gc_task_manager()->print_task_time_stamps(); 656 657 #ifdef TRACESPINNING 658 ParallelTaskTerminator::print_termination_counts(); 659 #endif 660 661 AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections()); 662 663 _gc_timer.register_gc_end(); 664 665 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 666 667 return !promotion_failure_occurred; 668 } 669 670 // This method iterates over all objects in the young generation, 671 // removing all forwarding references. It then restores any preserved marks. 672 void PSScavenge::clean_up_failed_promotion() { 673 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 674 PSYoungGen* young_gen = heap->young_gen(); 675 676 RemoveForwardedPointerClosure remove_fwd_ptr_closure; 677 young_gen->object_iterate(&remove_fwd_ptr_closure); 678 679 PSPromotionManager::restore_preserved_marks(); 680 681 // Reset the PromotionFailureALot counters. 682 NOT_PRODUCT(heap->reset_promotion_should_fail();) 683 } 684 685 bool PSScavenge::should_attempt_scavenge() { 686 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 687 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 688 689 if (UsePerfData) { 690 counters->update_scavenge_skipped(not_skipped); 691 } 692 693 PSYoungGen* young_gen = heap->young_gen(); 694 PSOldGen* old_gen = heap->old_gen(); 695 696 // Do not attempt to promote unless to_space is empty 697 if (!young_gen->to_space()->is_empty()) { 698 _consecutive_skipped_scavenges++; 699 if (UsePerfData) { 700 counters->update_scavenge_skipped(to_space_not_empty); 701 } 702 return false; 703 } 704 705 // Test to see if the scavenge will likely fail. 706 PSAdaptiveSizePolicy* policy = heap->size_policy(); 707 708 // A similar test is done in the policy's should_full_GC(). If this is 709 // changed, decide if that test should also be changed. 710 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 711 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 712 bool result = promotion_estimate < old_gen->free_in_bytes(); 713 714 log_trace(ergo)("%s scavenge: average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, 715 result ? "Do" : "Skip", (size_t) policy->average_promoted_in_bytes(), 716 (size_t) policy->padded_average_promoted_in_bytes(), 717 old_gen->free_in_bytes()); 718 if (young_gen->used_in_bytes() < (size_t) policy->padded_average_promoted_in_bytes()) { 719 log_trace(ergo)(" padded_promoted_average is greater than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 720 } 721 722 if (result) { 723 _consecutive_skipped_scavenges = 0; 724 } else { 725 _consecutive_skipped_scavenges++; 726 if (UsePerfData) { 727 counters->update_scavenge_skipped(promoted_too_large); 728 } 729 } 730 return result; 731 } 732 733 // Used to add tasks 734 GCTaskManager* const PSScavenge::gc_task_manager() { 735 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 736 "shouldn't return NULL"); 737 return ParallelScavengeHeap::gc_task_manager(); 738 } 739 740 // Adaptive size policy support. When the young generation/old generation 741 // boundary moves, _young_generation_boundary must be reset 742 void PSScavenge::set_young_generation_boundary(HeapWord* v) { 743 _young_generation_boundary = v; 744 if (UseCompressedOops) { 745 _young_generation_boundary_compressed = (uintptr_t)oopDesc::encode_heap_oop((oop)v); 746 } 747 } 748 749 void PSScavenge::initialize() { 750 // Arguments must have been parsed 751 752 if (AlwaysTenure || NeverTenure) { 753 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 754 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 755 _tenuring_threshold = MaxTenuringThreshold; 756 } else { 757 // We want to smooth out our startup times for the AdaptiveSizePolicy 758 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 759 MaxTenuringThreshold; 760 } 761 762 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 763 PSYoungGen* young_gen = heap->young_gen(); 764 PSOldGen* old_gen = heap->old_gen(); 765 766 // Set boundary between young_gen and old_gen 767 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 768 "old above young"); 769 set_young_generation_boundary(young_gen->eden_space()->bottom()); 770 771 // Initialize ref handling object for scavenging. 772 MemRegion mr = young_gen->reserved(); 773 774 _ref_processor = 775 new ReferenceProcessor(mr, // span 776 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 777 ParallelGCThreads, // mt processing degree 778 true, // mt discovery 779 ParallelGCThreads, // mt discovery degree 780 true, // atomic_discovery 781 NULL); // header provides liveness info 782 783 // Cache the cardtable 784 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set()); 785 786 _counters = new CollectorCounters("PSScavenge", 0); 787 }