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 if (ZapUnusedHeapArea) { 301 // Save information needed to minimize mangling 302 heap->record_gen_tops_before_GC(); 303 } 304 305 heap->print_heap_before_gc(); 306 heap->trace_heap_before_gc(&_gc_tracer); 307 308 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 309 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 310 311 size_t prev_used = heap->used(); 312 313 // Fill in TLABs 314 heap->accumulate_statistics_all_tlabs(); 315 heap->ensure_parsability(true); // retire TLABs 316 317 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 318 HandleMark hm; // Discard invalid handles created during verification 319 Universe::verify(" VerifyBeforeGC:"); 320 } 321 322 { 323 ResourceMark rm; 324 HandleMark hm; 325 326 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 327 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); 328 TraceCollectorStats tcs(counters()); 329 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 330 331 if (TraceYoungGenTime) accumulated_time()->start(); 332 333 // Let the size policy know we're starting 334 size_policy->minor_collection_begin(); 335 336 // Verify the object start arrays. 337 if (VerifyObjectStartArray && 338 VerifyBeforeGC) { 339 old_gen->verify_object_start_array(); 340 } 341 342 // Verify no unmarked old->young roots 343 if (VerifyRememberedSets) { 344 CardTableExtension::verify_all_young_refs_imprecise(); 345 } 346 347 if (!ScavengeWithObjectsInToSpace) { 348 assert(young_gen->to_space()->is_empty(), 349 "Attempt to scavenge with live objects in to_space"); 350 young_gen->to_space()->clear(SpaceDecorator::Mangle); 351 } else if (ZapUnusedHeapArea) { 352 young_gen->to_space()->mangle_unused_area(); 353 } 354 save_to_space_top_before_gc(); 355 356 COMPILER2_PRESENT(DerivedPointerTable::clear()); 357 358 reference_processor()->enable_discovery(); 359 reference_processor()->setup_policy(false); 360 361 // We track how much was promoted to the next generation for 362 // the AdaptiveSizePolicy. 363 size_t old_gen_used_before = old_gen->used_in_bytes(); 364 365 // For PrintGCDetails 366 size_t young_gen_used_before = young_gen->used_in_bytes(); 367 368 // Reset our survivor overflow. 369 set_survivor_overflow(false); 370 371 // We need to save the old top values before 372 // creating the promotion_manager. We pass the top 373 // values to the card_table, to prevent it from 374 // straying into the promotion labs. 375 HeapWord* old_top = old_gen->object_space()->top(); 376 377 // Release all previously held resources 378 gc_task_manager()->release_all_resources(); 379 380 // Set the number of GC threads to be used in this collection 381 gc_task_manager()->set_active_gang(); 382 gc_task_manager()->task_idle_workers(); 383 // Get the active number of workers here and use that value 384 // throughout the methods. 385 uint active_workers = gc_task_manager()->active_workers(); 386 387 PSPromotionManager::pre_scavenge(); 388 389 // We'll use the promotion manager again later. 390 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 391 { 392 GCTraceTime tm("Scavenge", false, false, &_gc_timer); 393 ParallelScavengeHeap::ParStrongRootsScope psrs; 394 395 GCTaskQueue* q = GCTaskQueue::create(); 396 397 if (!old_gen->object_space()->is_empty()) { 398 // There are only old-to-young pointers if there are objects 399 // in the old gen. 400 uint stripe_total = active_workers; 401 for(uint i=0; i < stripe_total; i++) { 402 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 403 } 404 } 405 406 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 407 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 408 // We scan the thread roots in parallel 409 Threads::create_thread_roots_tasks(q); 410 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 411 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 412 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 413 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 414 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 415 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 416 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 417 418 ParallelTaskTerminator terminator( 419 active_workers, 420 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 421 if (active_workers > 1) { 422 for (uint j = 0; j < active_workers; j++) { 423 q->enqueue(new StealTask(&terminator)); 424 } 425 } 426 427 gc_task_manager()->execute_and_wait(q); 428 } 429 430 scavenge_midpoint.update(); 431 432 // Process reference objects discovered during scavenge 433 { 434 GCTraceTime tm("References", false, false, &_gc_timer); 435 436 reference_processor()->setup_policy(false); // not always_clear 437 reference_processor()->set_active_mt_degree(active_workers); 438 PSKeepAliveClosure keep_alive(promotion_manager); 439 PSEvacuateFollowersClosure evac_followers(promotion_manager); 440 ReferenceProcessorStats stats; 441 if (reference_processor()->processing_is_mt()) { 442 PSRefProcTaskExecutor task_executor; 443 stats = reference_processor()->process_discovered_references( 444 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 445 &_gc_timer); 446 } else { 447 stats = reference_processor()->process_discovered_references( 448 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); 449 } 450 451 _gc_tracer.report_gc_reference_stats(stats); 452 453 // Enqueue reference objects discovered during scavenge. 454 if (reference_processor()->processing_is_mt()) { 455 PSRefProcTaskExecutor task_executor; 456 reference_processor()->enqueue_discovered_references(&task_executor); 457 } else { 458 reference_processor()->enqueue_discovered_references(NULL); 459 } 460 } 461 462 { 463 GCTraceTime tm("StringTable", false, false, &_gc_timer); 464 // Unlink any dead interned Strings and process the remaining live ones. 465 PSScavengeRootsClosure root_closure(promotion_manager); 466 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 467 } 468 469 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 470 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 471 if (promotion_failure_occurred) { 472 clean_up_failed_promotion(); 473 if (PrintGC) { 474 gclog_or_tty->print("--"); 475 } 476 } 477 478 // Let the size policy know we're done. Note that we count promotion 479 // failure cleanup time as part of the collection (otherwise, we're 480 // implicitly saying it's mutator time). 481 size_policy->minor_collection_end(gc_cause); 482 483 if (!promotion_failure_occurred) { 484 // Swap the survivor spaces. 485 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 486 young_gen->from_space()->clear(SpaceDecorator::Mangle); 487 young_gen->swap_spaces(); 488 489 size_t survived = young_gen->from_space()->used_in_bytes(); 490 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 491 size_policy->update_averages(_survivor_overflow, survived, promoted); 492 493 // A successful scavenge should restart the GC time limit count which is 494 // for full GC's. 495 size_policy->reset_gc_overhead_limit_count(); 496 if (UseAdaptiveSizePolicy) { 497 // Calculate the new survivor size and tenuring threshold 498 499 if (PrintAdaptiveSizePolicy) { 500 gclog_or_tty->print("AdaptiveSizeStart: "); 501 gclog_or_tty->stamp(); 502 gclog_or_tty->print_cr(" collection: %d ", 503 heap->total_collections()); 504 505 if (Verbose) { 506 gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT 507 " young_gen_capacity: " SIZE_FORMAT, 508 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 509 } 510 } 511 512 513 if (UsePerfData) { 514 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 515 counters->update_old_eden_size( 516 size_policy->calculated_eden_size_in_bytes()); 517 counters->update_old_promo_size( 518 size_policy->calculated_promo_size_in_bytes()); 519 counters->update_old_capacity(old_gen->capacity_in_bytes()); 520 counters->update_young_capacity(young_gen->capacity_in_bytes()); 521 counters->update_survived(survived); 522 counters->update_promoted(promoted); 523 counters->update_survivor_overflowed(_survivor_overflow); 524 } 525 526 size_t max_young_size = young_gen->max_size(); 527 528 // Deciding a free ratio in the young generation is tricky, so if 529 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 530 // that the old generation size may have been limited because of them) we 531 // should then limit our young generation size using NewRatio to have it 532 // follow the old generation size. 533 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 534 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 535 } 536 537 size_t survivor_limit = 538 size_policy->max_survivor_size(max_young_size); 539 _tenuring_threshold = 540 size_policy->compute_survivor_space_size_and_threshold( 541 _survivor_overflow, 542 _tenuring_threshold, 543 survivor_limit); 544 545 if (PrintTenuringDistribution) { 546 gclog_or_tty->cr(); 547 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u" 548 " (max threshold " UINTX_FORMAT ")", 549 size_policy->calculated_survivor_size_in_bytes(), 550 _tenuring_threshold, MaxTenuringThreshold); 551 } 552 553 if (UsePerfData) { 554 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 555 counters->update_tenuring_threshold(_tenuring_threshold); 556 counters->update_survivor_size_counters(); 557 } 558 559 // Do call at minor collections? 560 // Don't check if the size_policy is ready at this 561 // level. Let the size_policy check that internally. 562 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 563 (AdaptiveSizePolicy::should_update_eden_stats(gc_cause))) { 564 // Calculate optimal free space amounts 565 assert(young_gen->max_size() > 566 young_gen->from_space()->capacity_in_bytes() + 567 young_gen->to_space()->capacity_in_bytes(), 568 "Sizes of space in young gen are out-of-bounds"); 569 570 size_t young_live = young_gen->used_in_bytes(); 571 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 572 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 573 size_t max_old_gen_size = old_gen->max_gen_size(); 574 size_t max_eden_size = max_young_size - 575 young_gen->from_space()->capacity_in_bytes() - 576 young_gen->to_space()->capacity_in_bytes(); 577 578 // Used for diagnostics 579 size_policy->clear_generation_free_space_flags(); 580 581 size_policy->compute_eden_space_size(young_live, 582 eden_live, 583 cur_eden, 584 max_eden_size, 585 false /* not full gc*/); 586 587 size_policy->check_gc_overhead_limit(young_live, 588 eden_live, 589 max_old_gen_size, 590 max_eden_size, 591 false /* not full gc*/, 592 gc_cause, 593 heap->collector_policy()); 594 595 size_policy->decay_supplemental_growth(false /* not full gc*/); 596 } 597 // Resize the young generation at every collection 598 // even if new sizes have not been calculated. This is 599 // to allow resizes that may have been inhibited by the 600 // relative location of the "to" and "from" spaces. 601 602 // Resizing the old gen at young collections can cause increases 603 // that don't feed back to the generation sizing policy until 604 // a full collection. Don't resize the old gen here. 605 606 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 607 size_policy->calculated_survivor_size_in_bytes()); 608 609 if (PrintAdaptiveSizePolicy) { 610 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 611 heap->total_collections()); 612 } 613 } 614 615 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 616 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 617 // Also update() will case adaptive NUMA chunk resizing. 618 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 619 young_gen->eden_space()->update(); 620 621 heap->gc_policy_counters()->update_counters(); 622 623 heap->resize_all_tlabs(); 624 625 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 626 } 627 628 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 629 630 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 631 632 { 633 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer); 634 635 CodeCache::prune_scavenge_root_nmethods(); 636 } 637 638 // Re-verify object start arrays 639 if (VerifyObjectStartArray && 640 VerifyAfterGC) { 641 old_gen->verify_object_start_array(); 642 } 643 644 // Verify all old -> young cards are now precise 645 if (VerifyRememberedSets) { 646 // Precise verification will give false positives. Until this is fixed, 647 // use imprecise verification. 648 // CardTableExtension::verify_all_young_refs_precise(); 649 CardTableExtension::verify_all_young_refs_imprecise(); 650 } 651 652 if (TraceYoungGenTime) accumulated_time()->stop(); 653 654 if (PrintGC) { 655 if (PrintGCDetails) { 656 // Don't print a GC timestamp here. This is after the GC so 657 // would be confusing. 658 young_gen->print_used_change(young_gen_used_before); 659 } 660 heap->print_heap_change(prev_used); 661 } 662 663 // Track memory usage and detect low memory 664 MemoryService::track_memory_usage(); 665 heap->update_counters(); 666 667 gc_task_manager()->release_idle_workers(); 668 } 669 670 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 671 HandleMark hm; // Discard invalid handles created during verification 672 Universe::verify(" VerifyAfterGC:"); 673 } 674 675 heap->print_heap_after_gc(); 676 heap->trace_heap_after_gc(&_gc_tracer); 677 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 678 679 if (ZapUnusedHeapArea) { 680 young_gen->eden_space()->check_mangled_unused_area_complete(); 681 young_gen->from_space()->check_mangled_unused_area_complete(); 682 young_gen->to_space()->check_mangled_unused_area_complete(); 683 } 684 685 scavenge_exit.update(); 686 687 if (PrintGCTaskTimeStamps) { 688 tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 689 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 690 scavenge_exit.ticks()); 691 gc_task_manager()->print_task_time_stamps(); 692 } 693 694 #ifdef TRACESPINNING 695 ParallelTaskTerminator::print_termination_counts(); 696 #endif 697 698 699 _gc_timer.register_gc_end(); 700 701 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 702 703 return !promotion_failure_occurred; 704 } 705 706 // This method iterates over all objects in the young generation, 707 // unforwarding markOops. It then restores any preserved mark oops, 708 // and clears the _preserved_mark_stack. 709 void PSScavenge::clean_up_failed_promotion() { 710 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 711 PSYoungGen* young_gen = heap->young_gen(); 712 713 { 714 ResourceMark rm; 715 716 // Unforward all pointers in the young gen. 717 PSPromotionFailedClosure unforward_closure; 718 young_gen->object_iterate(&unforward_closure); 719 720 if (PrintGC && Verbose) { 721 gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size()); 722 } 723 724 // Restore any saved marks. 725 while (!_preserved_oop_stack.is_empty()) { 726 oop obj = _preserved_oop_stack.pop(); 727 markOop mark = _preserved_mark_stack.pop(); 728 obj->set_mark(mark); 729 } 730 731 // Clear the preserved mark and oop stack caches. 732 _preserved_mark_stack.clear(true); 733 _preserved_oop_stack.clear(true); 734 } 735 736 // Reset the PromotionFailureALot counters. 737 NOT_PRODUCT(heap->reset_promotion_should_fail();) 738 } 739 740 // This method is called whenever an attempt to promote an object 741 // fails. Some markOops will need preservation, some will not. Note 742 // that the entire eden is traversed after a failed promotion, with 743 // all forwarded headers replaced by the default markOop. This means 744 // it is not necessary to preserve most markOops. 745 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 746 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 747 // Should use per-worker private stacks here rather than 748 // locking a common pair of stacks. 749 ThreadCritical tc; 750 _preserved_oop_stack.push(obj); 751 _preserved_mark_stack.push(obj_mark); 752 } 753 } 754 755 bool PSScavenge::should_attempt_scavenge() { 756 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 757 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 758 759 if (UsePerfData) { 760 counters->update_scavenge_skipped(not_skipped); 761 } 762 763 PSYoungGen* young_gen = heap->young_gen(); 764 PSOldGen* old_gen = heap->old_gen(); 765 766 if (!ScavengeWithObjectsInToSpace) { 767 // Do not attempt to promote unless to_space is empty 768 if (!young_gen->to_space()->is_empty()) { 769 _consecutive_skipped_scavenges++; 770 if (UsePerfData) { 771 counters->update_scavenge_skipped(to_space_not_empty); 772 } 773 return false; 774 } 775 } 776 777 // Test to see if the scavenge will likely fail. 778 PSAdaptiveSizePolicy* policy = heap->size_policy(); 779 780 // A similar test is done in the policy's should_full_GC(). If this is 781 // changed, decide if that test should also be changed. 782 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 783 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 784 bool result = promotion_estimate < old_gen->free_in_bytes(); 785 786 if (PrintGCDetails && Verbose) { 787 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 788 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 789 " padded_average_promoted " SIZE_FORMAT 790 " free in old gen " SIZE_FORMAT, 791 (size_t) policy->average_promoted_in_bytes(), 792 (size_t) policy->padded_average_promoted_in_bytes(), 793 old_gen->free_in_bytes()); 794 if (young_gen->used_in_bytes() < 795 (size_t) policy->padded_average_promoted_in_bytes()) { 796 gclog_or_tty->print_cr(" padded_promoted_average is greater" 797 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 798 } 799 } 800 801 if (result) { 802 _consecutive_skipped_scavenges = 0; 803 } else { 804 _consecutive_skipped_scavenges++; 805 if (UsePerfData) { 806 counters->update_scavenge_skipped(promoted_too_large); 807 } 808 } 809 return result; 810 } 811 812 // Used to add tasks 813 GCTaskManager* const PSScavenge::gc_task_manager() { 814 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 815 "shouldn't return NULL"); 816 return ParallelScavengeHeap::gc_task_manager(); 817 } 818 819 void PSScavenge::initialize() { 820 // Arguments must have been parsed 821 822 if (AlwaysTenure || NeverTenure) { 823 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 824 err_msg("MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold)); 825 _tenuring_threshold = MaxTenuringThreshold; 826 } else { 827 // We want to smooth out our startup times for the AdaptiveSizePolicy 828 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 829 MaxTenuringThreshold; 830 } 831 832 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 833 PSYoungGen* young_gen = heap->young_gen(); 834 PSOldGen* old_gen = heap->old_gen(); 835 836 // Set boundary between young_gen and old_gen 837 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 838 "old above young"); 839 set_young_generation_boundary(young_gen->eden_space()->bottom()); 840 841 // Initialize ref handling object for scavenging. 842 MemRegion mr = young_gen->reserved(); 843 844 _ref_processor = 845 new ReferenceProcessor(mr, // span 846 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 847 ParallelGCThreads, // mt processing degree 848 true, // mt discovery 849 ParallelGCThreads, // mt discovery degree 850 true, // atomic_discovery 851 NULL); // header provides liveness info 852 853 // Cache the cardtable 854 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set()); 855 856 _counters = new CollectorCounters("PSScavenge", 0); 857 }