1 /* 2 * Copyright (c) 2002, 2015, 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.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.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 "oops/oop.inline.hpp" 50 #include "runtime/biasedLocking.hpp" 51 #include "runtime/fprofiler.hpp" 52 #include "runtime/handles.inline.hpp" 53 #include "runtime/threadCritical.hpp" 54 #include "runtime/vmThread.hpp" 55 #include "runtime/vm_operations.hpp" 56 #include "services/memoryService.hpp" 57 #include "utilities/stack.inline.hpp" 58 59 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 60 int PSScavenge::_consecutive_skipped_scavenges = 0; 61 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 62 CardTableExtension* PSScavenge::_card_table = NULL; 63 bool PSScavenge::_survivor_overflow = false; 64 uint PSScavenge::_tenuring_threshold = 0; 65 HeapWord* PSScavenge::_young_generation_boundary = NULL; 66 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 67 elapsedTimer PSScavenge::_accumulated_time; 68 STWGCTimer PSScavenge::_gc_timer; 69 ParallelScavengeTracer PSScavenge::_gc_tracer; 70 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack; 71 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack; 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_null(*p), "expected non-null ref"); 99 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 100 "expected an oop while scanning weak refs"); 101 102 // Weak refs may be visited more than once. 103 if (PSScavenge::should_scavenge(p, _to_space)) { 104 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p); 105 } 106 } 107 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 108 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 109 }; 110 111 class PSEvacuateFollowersClosure: public VoidClosure { 112 private: 113 PSPromotionManager* _promotion_manager; 114 public: 115 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 116 117 virtual void do_void() { 118 assert(_promotion_manager != NULL, "Sanity"); 119 _promotion_manager->drain_stacks(true); 120 guarantee(_promotion_manager->stacks_empty(), 121 "stacks should be empty at this point"); 122 } 123 }; 124 125 class PSPromotionFailedClosure : public ObjectClosure { 126 virtual void do_object(oop obj) { 127 if (obj->is_forwarded()) { 128 obj->init_mark(); 129 } 130 } 131 }; 132 133 class PSRefProcTaskProxy: public GCTask { 134 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 135 ProcessTask & _rp_task; 136 uint _work_id; 137 public: 138 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 139 : _rp_task(rp_task), 140 _work_id(work_id) 141 { } 142 143 private: 144 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 145 virtual void do_it(GCTaskManager* manager, uint which); 146 }; 147 148 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 149 { 150 PSPromotionManager* promotion_manager = 151 PSPromotionManager::gc_thread_promotion_manager(which); 152 assert(promotion_manager != NULL, "sanity check"); 153 PSKeepAliveClosure keep_alive(promotion_manager); 154 PSEvacuateFollowersClosure evac_followers(promotion_manager); 155 PSIsAliveClosure is_alive; 156 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 157 } 158 159 class PSRefEnqueueTaskProxy: public GCTask { 160 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 161 EnqueueTask& _enq_task; 162 uint _work_id; 163 164 public: 165 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 166 : _enq_task(enq_task), 167 _work_id(work_id) 168 { } 169 170 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 171 virtual void do_it(GCTaskManager* manager, uint which) 172 { 173 _enq_task.work(_work_id); 174 } 175 }; 176 177 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 178 virtual void execute(ProcessTask& task); 179 virtual void execute(EnqueueTask& task); 180 }; 181 182 void PSRefProcTaskExecutor::execute(ProcessTask& task) 183 { 184 GCTaskQueue* q = GCTaskQueue::create(); 185 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 186 for(uint i=0; i < manager->active_workers(); i++) { 187 q->enqueue(new PSRefProcTaskProxy(task, i)); 188 } 189 ParallelTaskTerminator terminator(manager->active_workers(), 190 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 191 if (task.marks_oops_alive() && manager->active_workers() > 1) { 192 for (uint j = 0; j < manager->active_workers(); j++) { 193 q->enqueue(new StealTask(&terminator)); 194 } 195 } 196 manager->execute_and_wait(q); 197 } 198 199 200 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 201 { 202 GCTaskQueue* q = GCTaskQueue::create(); 203 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 204 for(uint i=0; i < manager->active_workers(); i++) { 205 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 206 } 207 manager->execute_and_wait(q); 208 } 209 210 // This method contains all heap specific policy for invoking scavenge. 211 // PSScavenge::invoke_no_policy() will do nothing but attempt to 212 // scavenge. It will not clean up after failed promotions, bail out if 213 // we've exceeded policy time limits, or any other special behavior. 214 // All such policy should be placed here. 215 // 216 // Note that this method should only be called from the vm_thread while 217 // at a safepoint! 218 bool PSScavenge::invoke() { 219 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 220 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 221 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 222 223 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap(); 224 PSAdaptiveSizePolicy* policy = heap->size_policy(); 225 IsGCActiveMark mark; 226 227 const bool scavenge_done = PSScavenge::invoke_no_policy(); 228 const bool need_full_gc = !scavenge_done || 229 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 230 bool full_gc_done = false; 231 232 if (UsePerfData) { 233 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 234 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 235 counters->update_full_follows_scavenge(ffs_val); 236 } 237 238 if (need_full_gc) { 239 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 240 CollectorPolicy* cp = heap->collector_policy(); 241 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 242 243 if (UseParallelOldGC) { 244 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 245 } else { 246 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 247 } 248 } 249 250 return full_gc_done; 251 } 252 253 // This method contains no policy. You should probably 254 // be calling invoke() instead. 255 bool PSScavenge::invoke_no_policy() { 256 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 257 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 258 259 assert(_preserved_mark_stack.is_empty(), "should be empty"); 260 assert(_preserved_oop_stack.is_empty(), "should be empty"); 261 262 _gc_timer.register_gc_start(); 263 264 TimeStamp scavenge_entry; 265 TimeStamp scavenge_midpoint; 266 TimeStamp scavenge_exit; 267 268 scavenge_entry.update(); 269 270 if (GC_locker::check_active_before_gc()) { 271 return false; 272 } 273 274 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 275 GCCause::Cause gc_cause = heap->gc_cause(); 276 277 // Check for potential problems. 278 if (!should_attempt_scavenge()) { 279 return false; 280 } 281 282 GCIdMark gc_id_mark; 283 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 284 285 bool promotion_failure_occurred = false; 286 287 PSYoungGen* young_gen = heap->young_gen(); 288 PSOldGen* old_gen = heap->old_gen(); 289 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 290 291 heap->increment_total_collections(); 292 293 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 294 295 if (AdaptiveSizePolicy::should_update_eden_stats(gc_cause)) { 296 // Gather the feedback data for eden occupancy. 297 young_gen->eden_space()->accumulate_statistics(); 298 } 299 300 heap->print_heap_before_gc(); 301 heap->trace_heap_before_gc(&_gc_tracer); 302 303 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 304 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 305 306 size_t prev_used = heap->used(); 307 308 // Fill in TLABs 309 heap->accumulate_statistics_all_tlabs(); 310 heap->ensure_parsability(true); // retire TLABs 311 312 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 313 HandleMark hm; // Discard invalid handles created during verification 314 Universe::verify(" VerifyBeforeGC:"); 315 } 316 317 { 318 ResourceMark rm; 319 HandleMark hm; 320 321 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 322 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); 323 TraceCollectorStats tcs(counters()); 324 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 325 326 if (TraceYoungGenTime) accumulated_time()->start(); 327 328 // Let the size policy know we're starting 329 size_policy->minor_collection_begin(); 330 331 // Verify the object start arrays. 332 if (VerifyObjectStartArray && 333 VerifyBeforeGC) { 334 old_gen->verify_object_start_array(); 335 } 336 337 // Verify no unmarked old->young roots 338 if (VerifyRememberedSets) { 339 CardTableExtension::verify_all_young_refs_imprecise(); 340 } 341 342 assert(young_gen->to_space()->is_empty(), 343 "Attempt to scavenge with live objects in to_space"); 344 young_gen->to_space()->clear(SpaceDecorator::Mangle); 345 346 save_to_space_top_before_gc(); 347 348 #if defined(COMPILER2) || INCLUDE_JVMCI 349 DerivedPointerTable::clear(); 350 #endif 351 352 reference_processor()->enable_discovery(); 353 reference_processor()->setup_policy(false); 354 355 // We track how much was promoted to the next generation for 356 // the AdaptiveSizePolicy. 357 size_t old_gen_used_before = old_gen->used_in_bytes(); 358 359 // For PrintGCDetails 360 size_t young_gen_used_before = young_gen->used_in_bytes(); 361 362 // Reset our survivor overflow. 363 set_survivor_overflow(false); 364 365 // We need to save the old top values before 366 // creating the promotion_manager. We pass the top 367 // values to the card_table, to prevent it from 368 // straying into the promotion labs. 369 HeapWord* old_top = old_gen->object_space()->top(); 370 371 // Release all previously held resources 372 gc_task_manager()->release_all_resources(); 373 374 // Set the number of GC threads to be used in this collection 375 gc_task_manager()->set_active_gang(); 376 gc_task_manager()->task_idle_workers(); 377 // Get the active number of workers here and use that value 378 // throughout the methods. 379 uint active_workers = gc_task_manager()->active_workers(); 380 381 PSPromotionManager::pre_scavenge(); 382 383 // We'll use the promotion manager again later. 384 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 385 { 386 GCTraceTime tm("Scavenge", false, false, &_gc_timer); 387 ParallelScavengeHeap::ParStrongRootsScope psrs; 388 389 GCTaskQueue* q = GCTaskQueue::create(); 390 391 if (!old_gen->object_space()->is_empty()) { 392 // There are only old-to-young pointers if there are objects 393 // in the old gen. 394 uint stripe_total = active_workers; 395 for(uint i=0; i < stripe_total; i++) { 396 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 397 } 398 } 399 400 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 401 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 402 // We scan the thread roots in parallel 403 Threads::create_thread_roots_tasks(q); 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 > 1) { 416 for (uint j = 0; j < active_workers; j++) { 417 q->enqueue(new StealTask(&terminator)); 418 } 419 } 420 421 gc_task_manager()->execute_and_wait(q); 422 } 423 424 scavenge_midpoint.update(); 425 426 // Process reference objects discovered during scavenge 427 { 428 GCTraceTime tm("References", false, false, &_gc_timer); 429 430 reference_processor()->setup_policy(false); // not always_clear 431 reference_processor()->set_active_mt_degree(active_workers); 432 PSKeepAliveClosure keep_alive(promotion_manager); 433 PSEvacuateFollowersClosure evac_followers(promotion_manager); 434 ReferenceProcessorStats stats; 435 if (reference_processor()->processing_is_mt()) { 436 PSRefProcTaskExecutor task_executor; 437 stats = reference_processor()->process_discovered_references( 438 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 439 &_gc_timer); 440 } else { 441 stats = reference_processor()->process_discovered_references( 442 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); 443 } 444 445 _gc_tracer.report_gc_reference_stats(stats); 446 447 // Enqueue reference objects discovered during scavenge. 448 if (reference_processor()->processing_is_mt()) { 449 PSRefProcTaskExecutor task_executor; 450 reference_processor()->enqueue_discovered_references(&task_executor); 451 } else { 452 reference_processor()->enqueue_discovered_references(NULL); 453 } 454 } 455 456 { 457 GCTraceTime tm("StringTable", false, false, &_gc_timer); 458 // Unlink any dead interned Strings and process the remaining live ones. 459 PSScavengeRootsClosure root_closure(promotion_manager); 460 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 461 } 462 463 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 464 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 465 if (promotion_failure_occurred) { 466 clean_up_failed_promotion(); 467 if (PrintGC) { 468 gclog_or_tty->print("--"); 469 } 470 } 471 472 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 473 474 // Let the size policy know we're done. Note that we count promotion 475 // failure cleanup time as part of the collection (otherwise, we're 476 // implicitly saying it's mutator time). 477 size_policy->minor_collection_end(gc_cause); 478 479 if (!promotion_failure_occurred) { 480 // Swap the survivor spaces. 481 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 482 young_gen->from_space()->clear(SpaceDecorator::Mangle); 483 young_gen->swap_spaces(); 484 485 size_t survived = young_gen->from_space()->used_in_bytes(); 486 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 487 size_policy->update_averages(_survivor_overflow, survived, promoted); 488 489 // A successful scavenge should restart the GC time limit count which is 490 // for full GC's. 491 size_policy->reset_gc_overhead_limit_count(); 492 if (UseAdaptiveSizePolicy) { 493 // Calculate the new survivor size and tenuring threshold 494 495 if (PrintAdaptiveSizePolicy) { 496 gclog_or_tty->print("AdaptiveSizeStart: "); 497 gclog_or_tty->stamp(); 498 gclog_or_tty->print_cr(" collection: %d ", 499 heap->total_collections()); 500 501 if (Verbose) { 502 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT 503 " young_gen_capacity: " SIZE_FORMAT, 504 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 505 } 506 } 507 508 509 if (UsePerfData) { 510 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 511 counters->update_old_eden_size( 512 size_policy->calculated_eden_size_in_bytes()); 513 counters->update_old_promo_size( 514 size_policy->calculated_promo_size_in_bytes()); 515 counters->update_old_capacity(old_gen->capacity_in_bytes()); 516 counters->update_young_capacity(young_gen->capacity_in_bytes()); 517 counters->update_survived(survived); 518 counters->update_promoted(promoted); 519 counters->update_survivor_overflowed(_survivor_overflow); 520 } 521 522 size_t max_young_size = young_gen->max_size(); 523 524 // Deciding a free ratio in the young generation is tricky, so if 525 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 526 // that the old generation size may have been limited because of them) we 527 // should then limit our young generation size using NewRatio to have it 528 // follow the old generation size. 529 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 530 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 531 } 532 533 size_t survivor_limit = 534 size_policy->max_survivor_size(max_young_size); 535 _tenuring_threshold = 536 size_policy->compute_survivor_space_size_and_threshold( 537 _survivor_overflow, 538 _tenuring_threshold, 539 survivor_limit); 540 541 if (PrintTenuringDistribution) { 542 gclog_or_tty->cr(); 543 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u" 544 " (max threshold " UINTX_FORMAT ")", 545 size_policy->calculated_survivor_size_in_bytes(), 546 _tenuring_threshold, MaxTenuringThreshold); 547 } 548 549 if (UsePerfData) { 550 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 551 counters->update_tenuring_threshold(_tenuring_threshold); 552 counters->update_survivor_size_counters(); 553 } 554 555 // Do call at minor collections? 556 // Don't check if the size_policy is ready at this 557 // level. Let the size_policy check that internally. 558 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 559 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 560 // Calculate optimal free space amounts 561 assert(young_gen->max_size() > 562 young_gen->from_space()->capacity_in_bytes() + 563 young_gen->to_space()->capacity_in_bytes(), 564 "Sizes of space in young gen are out-of-bounds"); 565 566 size_t young_live = young_gen->used_in_bytes(); 567 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 568 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 569 size_t max_old_gen_size = old_gen->max_gen_size(); 570 size_t max_eden_size = max_young_size - 571 young_gen->from_space()->capacity_in_bytes() - 572 young_gen->to_space()->capacity_in_bytes(); 573 574 // Used for diagnostics 575 size_policy->clear_generation_free_space_flags(); 576 577 size_policy->compute_eden_space_size(young_live, 578 eden_live, 579 cur_eden, 580 max_eden_size, 581 false /* not full gc*/); 582 583 size_policy->check_gc_overhead_limit(young_live, 584 eden_live, 585 max_old_gen_size, 586 max_eden_size, 587 false /* not full gc*/, 588 gc_cause, 589 heap->collector_policy()); 590 591 size_policy->decay_supplemental_growth(false /* not full gc*/); 592 } 593 // Resize the young generation at every collection 594 // even if new sizes have not been calculated. This is 595 // to allow resizes that may have been inhibited by the 596 // relative location of the "to" and "from" spaces. 597 598 // Resizing the old gen at young collections can cause increases 599 // that don't feed back to the generation sizing policy until 600 // a full collection. Don't resize the old gen here. 601 602 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 603 size_policy->calculated_survivor_size_in_bytes()); 604 605 if (PrintAdaptiveSizePolicy) { 606 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 607 heap->total_collections()); 608 } 609 } 610 611 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 612 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 613 // Also update() will case adaptive NUMA chunk resizing. 614 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 615 young_gen->eden_space()->update(); 616 617 heap->gc_policy_counters()->update_counters(); 618 619 heap->resize_all_tlabs(); 620 621 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 622 } 623 624 #if defined(COMPILER2) || INCLUDE_JVMCI 625 DerivedPointerTable::update_pointers(); 626 #endif 627 628 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 629 630 { 631 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer); 632 633 CodeCache::prune_scavenge_root_nmethods(); 634 } 635 636 // Re-verify object start arrays 637 if (VerifyObjectStartArray && 638 VerifyAfterGC) { 639 old_gen->verify_object_start_array(); 640 } 641 642 // Verify all old -> young cards are now precise 643 if (VerifyRememberedSets) { 644 // Precise verification will give false positives. Until this is fixed, 645 // use imprecise verification. 646 // CardTableExtension::verify_all_young_refs_precise(); 647 CardTableExtension::verify_all_young_refs_imprecise(); 648 } 649 650 if (TraceYoungGenTime) accumulated_time()->stop(); 651 652 if (PrintGC) { 653 if (PrintGCDetails) { 654 // Don't print a GC timestamp here. This is after the GC so 655 // would be confusing. 656 young_gen->print_used_change(young_gen_used_before); 657 } 658 heap->print_heap_change(prev_used); 659 } 660 661 // Track memory usage and detect low memory 662 MemoryService::track_memory_usage(); 663 heap->update_counters(); 664 665 gc_task_manager()->release_idle_workers(); 666 } 667 668 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 669 HandleMark hm; // Discard invalid handles created during verification 670 Universe::verify(" VerifyAfterGC:"); 671 } 672 673 heap->print_heap_after_gc(); 674 heap->trace_heap_after_gc(&_gc_tracer); 675 676 scavenge_exit.update(); 677 678 if (PrintGCTaskTimeStamps) { 679 tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 680 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 681 scavenge_exit.ticks()); 682 gc_task_manager()->print_task_time_stamps(); 683 } 684 685 #ifdef TRACESPINNING 686 ParallelTaskTerminator::print_termination_counts(); 687 #endif 688 689 690 _gc_timer.register_gc_end(); 691 692 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 693 694 return !promotion_failure_occurred; 695 } 696 697 // This method iterates over all objects in the young generation, 698 // unforwarding markOops. It then restores any preserved mark oops, 699 // and clears the _preserved_mark_stack. 700 void PSScavenge::clean_up_failed_promotion() { 701 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 702 PSYoungGen* young_gen = heap->young_gen(); 703 704 { 705 ResourceMark rm; 706 707 // Unforward all pointers in the young gen. 708 PSPromotionFailedClosure unforward_closure; 709 young_gen->object_iterate(&unforward_closure); 710 711 if (PrintGC && Verbose) { 712 gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size()); 713 } 714 715 // Restore any saved marks. 716 while (!_preserved_oop_stack.is_empty()) { 717 oop obj = _preserved_oop_stack.pop(); 718 markOop mark = _preserved_mark_stack.pop(); 719 obj->set_mark(mark); 720 } 721 722 // Clear the preserved mark and oop stack caches. 723 _preserved_mark_stack.clear(true); 724 _preserved_oop_stack.clear(true); 725 } 726 727 // Reset the PromotionFailureALot counters. 728 NOT_PRODUCT(heap->reset_promotion_should_fail();) 729 } 730 731 // This method is called whenever an attempt to promote an object 732 // fails. Some markOops will need preservation, some will not. Note 733 // that the entire eden is traversed after a failed promotion, with 734 // all forwarded headers replaced by the default markOop. This means 735 // it is not necessary to preserve most markOops. 736 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 737 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 738 // Should use per-worker private stacks here rather than 739 // locking a common pair of stacks. 740 ThreadCritical tc; 741 _preserved_oop_stack.push(obj); 742 _preserved_mark_stack.push(obj_mark); 743 } 744 } 745 746 bool PSScavenge::should_attempt_scavenge() { 747 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 748 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 749 750 if (UsePerfData) { 751 counters->update_scavenge_skipped(not_skipped); 752 } 753 754 PSYoungGen* young_gen = heap->young_gen(); 755 PSOldGen* old_gen = heap->old_gen(); 756 757 // Do not attempt to promote unless to_space is empty 758 if (!young_gen->to_space()->is_empty()) { 759 _consecutive_skipped_scavenges++; 760 if (UsePerfData) { 761 counters->update_scavenge_skipped(to_space_not_empty); 762 } 763 return false; 764 } 765 766 // Test to see if the scavenge will likely fail. 767 PSAdaptiveSizePolicy* policy = heap->size_policy(); 768 769 // A similar test is done in the policy's should_full_GC(). If this is 770 // changed, decide if that test should also be changed. 771 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 772 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 773 bool result = promotion_estimate < old_gen->free_in_bytes(); 774 775 if (PrintGCDetails && Verbose) { 776 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 777 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 778 " padded_average_promoted " SIZE_FORMAT 779 " free in old gen " SIZE_FORMAT, 780 (size_t) policy->average_promoted_in_bytes(), 781 (size_t) policy->padded_average_promoted_in_bytes(), 782 old_gen->free_in_bytes()); 783 if (young_gen->used_in_bytes() < 784 (size_t) policy->padded_average_promoted_in_bytes()) { 785 gclog_or_tty->print_cr(" padded_promoted_average is greater" 786 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 787 } 788 } 789 790 if (result) { 791 _consecutive_skipped_scavenges = 0; 792 } else { 793 _consecutive_skipped_scavenges++; 794 if (UsePerfData) { 795 counters->update_scavenge_skipped(promoted_too_large); 796 } 797 } 798 return result; 799 } 800 801 // Used to add tasks 802 GCTaskManager* const PSScavenge::gc_task_manager() { 803 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 804 "shouldn't return NULL"); 805 return ParallelScavengeHeap::gc_task_manager(); 806 } 807 808 void PSScavenge::initialize() { 809 // Arguments must have been parsed 810 811 if (AlwaysTenure || NeverTenure) { 812 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 813 "MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold); 814 _tenuring_threshold = MaxTenuringThreshold; 815 } else { 816 // We want to smooth out our startup times for the AdaptiveSizePolicy 817 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 818 MaxTenuringThreshold; 819 } 820 821 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 822 PSYoungGen* young_gen = heap->young_gen(); 823 PSOldGen* old_gen = heap->old_gen(); 824 825 // Set boundary between young_gen and old_gen 826 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 827 "old above young"); 828 set_young_generation_boundary(young_gen->eden_space()->bottom()); 829 830 // Initialize ref handling object for scavenging. 831 MemRegion mr = young_gen->reserved(); 832 833 _ref_processor = 834 new ReferenceProcessor(mr, // span 835 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 836 ParallelGCThreads, // mt processing degree 837 true, // mt discovery 838 ParallelGCThreads, // mt discovery degree 839 true, // atomic_discovery 840 NULL); // header provides liveness info 841 842 // Cache the cardtable 843 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set()); 844 845 _counters = new CollectorCounters("PSScavenge", 0); 846 }