1 /* 2 * Copyright (c) 2002, 2014, 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/symbolTable.hpp" 27 #include "code/codeCache.hpp" 28 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" 29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" 30 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" 31 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" 32 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" 33 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" 34 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp" 35 #include "gc_implementation/parallelScavenge/psTasks.hpp" 36 #include "gc_implementation/shared/gcHeapSummary.hpp" 37 #include "gc_implementation/shared/gcTimer.hpp" 38 #include "gc_implementation/shared/gcTrace.hpp" 39 #include "gc_implementation/shared/gcTraceTime.hpp" 40 #include "gc_implementation/shared/isGCActiveMark.hpp" 41 #include "gc_implementation/shared/spaceDecorator.hpp" 42 #include "gc_interface/gcCause.hpp" 43 #include "memory/collectorPolicy.hpp" 44 #include "memory/gcLocker.inline.hpp" 45 #include "memory/referencePolicy.hpp" 46 #include "memory/referenceProcessor.hpp" 47 #include "memory/resourceArea.hpp" 48 #include "oops/oop.inline.hpp" 49 #include "oops/oop.psgc.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 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 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack; 72 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack; 73 CollectorCounters* PSScavenge::_counters = NULL; 74 75 // Define before use 76 class PSIsAliveClosure: public BoolObjectClosure { 77 public: 78 bool do_object_b(oop p) { 79 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 80 } 81 }; 82 83 PSIsAliveClosure PSScavenge::_is_alive_closure; 84 85 class PSKeepAliveClosure: public OopClosure { 86 protected: 87 MutableSpace* _to_space; 88 PSPromotionManager* _promotion_manager; 89 90 public: 91 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 92 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 93 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 94 _to_space = heap->young_gen()->to_space(); 95 96 assert(_promotion_manager != NULL, "Sanity"); 97 } 98 99 template <class T> void do_oop_work(T* p) { 100 assert (!oopDesc::is_null(*p), "expected non-null ref"); 101 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 102 "expected an oop while scanning weak refs"); 103 104 // Weak refs may be visited more than once. 105 if (PSScavenge::should_scavenge(p, _to_space)) { 106 PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p); 107 } 108 } 109 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 110 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 111 }; 112 113 class PSEvacuateFollowersClosure: public VoidClosure { 114 private: 115 PSPromotionManager* _promotion_manager; 116 public: 117 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 118 119 virtual void do_void() { 120 assert(_promotion_manager != NULL, "Sanity"); 121 _promotion_manager->drain_stacks(true); 122 guarantee(_promotion_manager->stacks_empty(), 123 "stacks should be empty at this point"); 124 } 125 }; 126 127 class PSPromotionFailedClosure : public ObjectClosure { 128 virtual void do_object(oop obj) { 129 if (obj->is_forwarded()) { 130 obj->init_mark(); 131 } 132 } 133 }; 134 135 class PSRefProcTaskProxy: public GCTask { 136 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 137 ProcessTask & _rp_task; 138 uint _work_id; 139 public: 140 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 141 : _rp_task(rp_task), 142 _work_id(work_id) 143 { } 144 145 private: 146 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 147 virtual void do_it(GCTaskManager* manager, uint which); 148 }; 149 150 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 151 { 152 PSPromotionManager* promotion_manager = 153 PSPromotionManager::gc_thread_promotion_manager(which); 154 assert(promotion_manager != NULL, "sanity check"); 155 PSKeepAliveClosure keep_alive(promotion_manager); 156 PSEvacuateFollowersClosure evac_followers(promotion_manager); 157 PSIsAliveClosure is_alive; 158 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 159 } 160 161 class PSRefEnqueueTaskProxy: public GCTask { 162 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 163 EnqueueTask& _enq_task; 164 uint _work_id; 165 166 public: 167 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 168 : _enq_task(enq_task), 169 _work_id(work_id) 170 { } 171 172 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 173 virtual void do_it(GCTaskManager* manager, uint which) 174 { 175 _enq_task.work(_work_id); 176 } 177 }; 178 179 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 180 virtual void execute(ProcessTask& task); 181 virtual void execute(EnqueueTask& task); 182 }; 183 184 void PSRefProcTaskExecutor::execute(ProcessTask& task) 185 { 186 GCTaskQueue* q = GCTaskQueue::create(); 187 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 188 for(uint i=0; i < manager->active_workers(); i++) { 189 q->enqueue(new PSRefProcTaskProxy(task, i)); 190 } 191 ParallelTaskTerminator terminator(manager->active_workers(), 192 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 193 if (task.marks_oops_alive() && manager->active_workers() > 1) { 194 for (uint j = 0; j < manager->active_workers(); j++) { 195 q->enqueue(new StealTask(&terminator)); 196 } 197 } 198 manager->execute_and_wait(q); 199 } 200 201 202 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 203 { 204 GCTaskQueue* q = GCTaskQueue::create(); 205 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 206 for(uint i=0; i < manager->active_workers(); i++) { 207 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 208 } 209 manager->execute_and_wait(q); 210 } 211 212 // This method contains all heap specific policy for invoking scavenge. 213 // PSScavenge::invoke_no_policy() will do nothing but attempt to 214 // scavenge. It will not clean up after failed promotions, bail out if 215 // we've exceeded policy time limits, or any other special behavior. 216 // All such policy should be placed here. 217 // 218 // Note that this method should only be called from the vm_thread while 219 // at a safepoint! 220 bool PSScavenge::invoke() { 221 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 222 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 223 assert(!Universe::heap()->is_gc_active(), "not reentrant"); 224 225 ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap(); 226 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 227 228 PSAdaptiveSizePolicy* policy = heap->size_policy(); 229 IsGCActiveMark mark; 230 231 const bool scavenge_done = PSScavenge::invoke_no_policy(); 232 const bool need_full_gc = !scavenge_done || 233 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 234 bool full_gc_done = false; 235 236 if (UsePerfData) { 237 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 238 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 239 counters->update_full_follows_scavenge(ffs_val); 240 } 241 242 if (need_full_gc) { 243 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 244 CollectorPolicy* cp = heap->collector_policy(); 245 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 246 247 if (UseParallelOldGC) { 248 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 249 } else { 250 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 251 } 252 } 253 254 return full_gc_done; 255 } 256 257 // This method contains no policy. You should probably 258 // be calling invoke() instead. 259 bool PSScavenge::invoke_no_policy() { 260 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 261 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 262 263 assert(_preserved_mark_stack.is_empty(), "should be empty"); 264 assert(_preserved_oop_stack.is_empty(), "should be empty"); 265 266 _gc_timer.register_gc_start(); 267 268 TimeStamp scavenge_entry; 269 TimeStamp scavenge_midpoint; 270 TimeStamp scavenge_exit; 271 272 scavenge_entry.update(); 273 274 if (GC_locker::check_active_before_gc()) { 275 return false; 276 } 277 278 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 279 GCCause::Cause gc_cause = heap->gc_cause(); 280 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 281 282 // Check for potential problems. 283 if (!should_attempt_scavenge()) { 284 return false; 285 } 286 287 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 288 289 bool promotion_failure_occurred = false; 290 291 PSYoungGen* young_gen = heap->young_gen(); 292 PSOldGen* old_gen = heap->old_gen(); 293 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 294 295 heap->increment_total_collections(); 296 297 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 298 299 if ((gc_cause != GCCause::_java_lang_system_gc) || 300 UseAdaptiveSizePolicyWithSystemGC) { 301 // Gather the feedback data for eden occupancy. 302 young_gen->eden_space()->accumulate_statistics(); 303 } 304 305 if (ZapUnusedHeapArea) { 306 // Save information needed to minimize mangling 307 heap->record_gen_tops_before_GC(); 308 } 309 310 heap->print_heap_before_gc(); 311 heap->trace_heap_before_gc(&_gc_tracer); 312 313 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 314 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 315 316 size_t prev_used = heap->used(); 317 318 // Fill in TLABs 319 heap->accumulate_statistics_all_tlabs(); 320 heap->ensure_parsability(true); // retire TLABs 321 322 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 323 HandleMark hm; // Discard invalid handles created during verification 324 Universe::verify(" VerifyBeforeGC:"); 325 } 326 327 { 328 ResourceMark rm; 329 HandleMark hm; 330 331 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 332 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 333 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL); 334 TraceCollectorStats tcs(counters()); 335 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 336 337 if (TraceGen0Time) accumulated_time()->start(); 338 339 // Let the size policy know we're starting 340 size_policy->minor_collection_begin(); 341 342 // Verify the object start arrays. 343 if (VerifyObjectStartArray && 344 VerifyBeforeGC) { 345 old_gen->verify_object_start_array(); 346 } 347 348 // Verify no unmarked old->young roots 349 if (VerifyRememberedSets) { 350 CardTableExtension::verify_all_young_refs_imprecise(); 351 } 352 353 if (!ScavengeWithObjectsInToSpace) { 354 assert(young_gen->to_space()->is_empty(), 355 "Attempt to scavenge with live objects in to_space"); 356 young_gen->to_space()->clear(SpaceDecorator::Mangle); 357 } else if (ZapUnusedHeapArea) { 358 young_gen->to_space()->mangle_unused_area(); 359 } 360 save_to_space_top_before_gc(); 361 362 COMPILER2_PRESENT(DerivedPointerTable::clear()); 363 364 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 365 reference_processor()->setup_policy(false); 366 367 // We track how much was promoted to the next generation for 368 // the AdaptiveSizePolicy. 369 size_t old_gen_used_before = old_gen->used_in_bytes(); 370 371 // For PrintGCDetails 372 size_t young_gen_used_before = young_gen->used_in_bytes(); 373 374 // Reset our survivor overflow. 375 set_survivor_overflow(false); 376 377 // We need to save the old top values before 378 // creating the promotion_manager. We pass the top 379 // values to the card_table, to prevent it from 380 // straying into the promotion labs. 381 HeapWord* old_top = old_gen->object_space()->top(); 382 383 // Release all previously held resources 384 gc_task_manager()->release_all_resources(); 385 386 // Set the number of GC threads to be used in this collection 387 gc_task_manager()->set_active_gang(); 388 gc_task_manager()->task_idle_workers(); 389 // Get the active number of workers here and use that value 390 // throughout the methods. 391 uint active_workers = gc_task_manager()->active_workers(); 392 heap->set_par_threads(active_workers); 393 394 PSPromotionManager::pre_scavenge(); 395 396 // We'll use the promotion manager again later. 397 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 398 { 399 GCTraceTime tm("Scavenge", false, false, &_gc_timer); 400 ParallelScavengeHeap::ParStrongRootsScope psrs; 401 402 GCTaskQueue* q = GCTaskQueue::create(); 403 404 if (!old_gen->object_space()->is_empty()) { 405 // There are only old-to-young pointers if there are objects 406 // in the old gen. 407 uint stripe_total = active_workers; 408 for(uint i=0; i < stripe_total; i++) { 409 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 410 } 411 } 412 413 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 414 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 415 // We scan the thread roots in parallel 416 Threads::create_thread_roots_tasks(q); 417 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 418 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 419 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 420 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 421 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data)); 422 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 423 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 424 425 ParallelTaskTerminator terminator( 426 active_workers, 427 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 428 if (active_workers > 1) { 429 for (uint j = 0; j < active_workers; j++) { 430 q->enqueue(new StealTask(&terminator)); 431 } 432 } 433 434 gc_task_manager()->execute_and_wait(q); 435 } 436 437 scavenge_midpoint.update(); 438 439 // Process reference objects discovered during scavenge 440 { 441 GCTraceTime tm("References", false, false, &_gc_timer); 442 443 reference_processor()->setup_policy(false); // not always_clear 444 reference_processor()->set_active_mt_degree(active_workers); 445 PSKeepAliveClosure keep_alive(promotion_manager); 446 PSEvacuateFollowersClosure evac_followers(promotion_manager); 447 ReferenceProcessorStats stats; 448 if (reference_processor()->processing_is_mt()) { 449 PSRefProcTaskExecutor task_executor; 450 stats = reference_processor()->process_discovered_references( 451 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor, 452 &_gc_timer); 453 } else { 454 stats = reference_processor()->process_discovered_references( 455 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer); 456 } 457 458 _gc_tracer.report_gc_reference_stats(stats); 459 460 // Enqueue reference objects discovered during scavenge. 461 if (reference_processor()->processing_is_mt()) { 462 PSRefProcTaskExecutor task_executor; 463 reference_processor()->enqueue_discovered_references(&task_executor); 464 } else { 465 reference_processor()->enqueue_discovered_references(NULL); 466 } 467 } 468 469 { 470 GCTraceTime tm("StringTable", false, false, &_gc_timer); 471 // Unlink any dead interned Strings and process the remaining live ones. 472 PSScavengeRootsClosure root_closure(promotion_manager); 473 StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure); 474 } 475 476 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 477 promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer); 478 if (promotion_failure_occurred) { 479 clean_up_failed_promotion(); 480 if (PrintGC) { 481 gclog_or_tty->print("--"); 482 } 483 } 484 485 // Let the size policy know we're done. Note that we count promotion 486 // failure cleanup time as part of the collection (otherwise, we're 487 // implicitly saying it's mutator time). 488 size_policy->minor_collection_end(gc_cause); 489 490 if (!promotion_failure_occurred) { 491 // Swap the survivor spaces. 492 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 493 young_gen->from_space()->clear(SpaceDecorator::Mangle); 494 young_gen->swap_spaces(); 495 496 size_t survived = young_gen->from_space()->used_in_bytes(); 497 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 498 size_policy->update_averages(_survivor_overflow, survived, promoted); 499 500 // A successful scavenge should restart the GC time limit count which is 501 // for full GC's. 502 size_policy->reset_gc_overhead_limit_count(); 503 if (UseAdaptiveSizePolicy) { 504 // Calculate the new survivor size and tenuring threshold 505 506 if (PrintAdaptiveSizePolicy) { 507 gclog_or_tty->print("AdaptiveSizeStart: "); 508 gclog_or_tty->stamp(); 509 gclog_or_tty->print_cr(" collection: %d ", 510 heap->total_collections()); 511 512 if (Verbose) { 513 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d", 514 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes()); 515 } 516 } 517 518 519 if (UsePerfData) { 520 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 521 counters->update_old_eden_size( 522 size_policy->calculated_eden_size_in_bytes()); 523 counters->update_old_promo_size( 524 size_policy->calculated_promo_size_in_bytes()); 525 counters->update_old_capacity(old_gen->capacity_in_bytes()); 526 counters->update_young_capacity(young_gen->capacity_in_bytes()); 527 counters->update_survived(survived); 528 counters->update_promoted(promoted); 529 counters->update_survivor_overflowed(_survivor_overflow); 530 } 531 532 size_t max_young_size = young_gen->max_size(); 533 534 // Deciding a free ratio in the young generation is tricky, so if 535 // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating 536 // that the old generation size may have been limited because of them) we 537 // should then limit our young generation size using NewRatio to have it 538 // follow the old generation size. 539 if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) { 540 max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size()); 541 } 542 543 size_t survivor_limit = 544 size_policy->max_survivor_size(max_young_size); 545 _tenuring_threshold = 546 size_policy->compute_survivor_space_size_and_threshold( 547 _survivor_overflow, 548 _tenuring_threshold, 549 survivor_limit); 550 551 if (PrintTenuringDistribution) { 552 gclog_or_tty->cr(); 553 gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold %u (max %u)", 554 size_policy->calculated_survivor_size_in_bytes(), 555 _tenuring_threshold, MaxTenuringThreshold); 556 } 557 558 if (UsePerfData) { 559 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 560 counters->update_tenuring_threshold(_tenuring_threshold); 561 counters->update_survivor_size_counters(); 562 } 563 564 // Do call at minor collections? 565 // Don't check if the size_policy is ready at this 566 // level. Let the size_policy check that internally. 567 if (UseAdaptiveGenerationSizePolicyAtMinorCollection && 568 ((gc_cause != GCCause::_java_lang_system_gc) || 569 UseAdaptiveSizePolicyWithSystemGC)) { 570 571 // Calculate optimial free space amounts 572 assert(young_gen->max_size() > 573 young_gen->from_space()->capacity_in_bytes() + 574 young_gen->to_space()->capacity_in_bytes(), 575 "Sizes of space in young gen are out-of-bounds"); 576 577 size_t young_live = young_gen->used_in_bytes(); 578 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 579 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 580 size_t max_old_gen_size = old_gen->max_gen_size(); 581 size_t max_eden_size = max_young_size - 582 young_gen->from_space()->capacity_in_bytes() - 583 young_gen->to_space()->capacity_in_bytes(); 584 585 // Used for diagnostics 586 size_policy->clear_generation_free_space_flags(); 587 588 size_policy->compute_eden_space_size(young_live, 589 eden_live, 590 cur_eden, 591 max_eden_size, 592 false /* not full gc*/); 593 594 size_policy->check_gc_overhead_limit(young_live, 595 eden_live, 596 max_old_gen_size, 597 max_eden_size, 598 false /* not full gc*/, 599 gc_cause, 600 heap->collector_policy()); 601 602 size_policy->decay_supplemental_growth(false /* not full gc*/); 603 } 604 // Resize the young generation at every collection 605 // even if new sizes have not been calculated. This is 606 // to allow resizes that may have been inhibited by the 607 // relative location of the "to" and "from" spaces. 608 609 // Resizing the old gen at minor collects can cause increases 610 // that don't feed back to the generation sizing policy until 611 // a major collection. Don't resize the old gen here. 612 613 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 614 size_policy->calculated_survivor_size_in_bytes()); 615 616 if (PrintAdaptiveSizePolicy) { 617 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 618 heap->total_collections()); 619 } 620 } 621 622 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 623 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 624 // Also update() will case adaptive NUMA chunk resizing. 625 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 626 young_gen->eden_space()->update(); 627 628 heap->gc_policy_counters()->update_counters(); 629 630 heap->resize_all_tlabs(); 631 632 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 633 } 634 635 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 636 637 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 638 639 { 640 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer); 641 642 CodeCache::prune_scavenge_root_nmethods(); 643 } 644 645 // Re-verify object start arrays 646 if (VerifyObjectStartArray && 647 VerifyAfterGC) { 648 old_gen->verify_object_start_array(); 649 } 650 651 // Verify all old -> young cards are now precise 652 if (VerifyRememberedSets) { 653 // Precise verification will give false positives. Until this is fixed, 654 // use imprecise verification. 655 // CardTableExtension::verify_all_young_refs_precise(); 656 CardTableExtension::verify_all_young_refs_imprecise(); 657 } 658 659 if (TraceGen0Time) accumulated_time()->stop(); 660 661 if (PrintGC) { 662 if (PrintGCDetails) { 663 // Don't print a GC timestamp here. This is after the GC so 664 // would be confusing. 665 young_gen->print_used_change(young_gen_used_before); 666 } 667 heap->print_heap_change(prev_used); 668 } 669 670 // Track memory usage and detect low memory 671 MemoryService::track_memory_usage(); 672 heap->update_counters(); 673 674 gc_task_manager()->release_idle_workers(); 675 } 676 677 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 678 HandleMark hm; // Discard invalid handles created during verification 679 Universe::verify(" VerifyAfterGC:"); 680 } 681 682 heap->print_heap_after_gc(); 683 heap->trace_heap_after_gc(&_gc_tracer); 684 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 685 686 if (ZapUnusedHeapArea) { 687 young_gen->eden_space()->check_mangled_unused_area_complete(); 688 young_gen->from_space()->check_mangled_unused_area_complete(); 689 young_gen->to_space()->check_mangled_unused_area_complete(); 690 } 691 692 scavenge_exit.update(); 693 694 if (PrintGCTaskTimeStamps) { 695 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, 696 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 697 scavenge_exit.ticks()); 698 gc_task_manager()->print_task_time_stamps(); 699 } 700 701 #ifdef TRACESPINNING 702 ParallelTaskTerminator::print_termination_counts(); 703 #endif 704 705 706 _gc_timer.register_gc_end(); 707 708 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 709 710 return !promotion_failure_occurred; 711 } 712 713 // This method iterates over all objects in the young generation, 714 // unforwarding markOops. It then restores any preserved mark oops, 715 // and clears the _preserved_mark_stack. 716 void PSScavenge::clean_up_failed_promotion() { 717 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 718 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 719 720 PSYoungGen* young_gen = heap->young_gen(); 721 722 { 723 ResourceMark rm; 724 725 // Unforward all pointers in the young gen. 726 PSPromotionFailedClosure unforward_closure; 727 young_gen->object_iterate(&unforward_closure); 728 729 if (PrintGC && Verbose) { 730 gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size()); 731 } 732 733 // Restore any saved marks. 734 while (!_preserved_oop_stack.is_empty()) { 735 oop obj = _preserved_oop_stack.pop(); 736 markOop mark = _preserved_mark_stack.pop(); 737 obj->set_mark(mark); 738 } 739 740 // Clear the preserved mark and oop stack caches. 741 _preserved_mark_stack.clear(true); 742 _preserved_oop_stack.clear(true); 743 } 744 745 // Reset the PromotionFailureALot counters. 746 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 747 } 748 749 // This method is called whenever an attempt to promote an object 750 // fails. Some markOops will need preservation, some will not. Note 751 // that the entire eden is traversed after a failed promotion, with 752 // all forwarded headers replaced by the default markOop. This means 753 // it is not necessary to preserve most markOops. 754 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 755 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 756 // Should use per-worker private stacks here rather than 757 // locking a common pair of stacks. 758 ThreadCritical tc; 759 _preserved_oop_stack.push(obj); 760 _preserved_mark_stack.push(obj_mark); 761 } 762 } 763 764 bool PSScavenge::should_attempt_scavenge() { 765 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 766 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 767 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 768 769 if (UsePerfData) { 770 counters->update_scavenge_skipped(not_skipped); 771 } 772 773 PSYoungGen* young_gen = heap->young_gen(); 774 PSOldGen* old_gen = heap->old_gen(); 775 776 if (!ScavengeWithObjectsInToSpace) { 777 // Do not attempt to promote unless to_space is empty 778 if (!young_gen->to_space()->is_empty()) { 779 _consecutive_skipped_scavenges++; 780 if (UsePerfData) { 781 counters->update_scavenge_skipped(to_space_not_empty); 782 } 783 return false; 784 } 785 } 786 787 // Test to see if the scavenge will likely fail. 788 PSAdaptiveSizePolicy* policy = heap->size_policy(); 789 790 // A similar test is done in the policy's should_full_GC(). If this is 791 // changed, decide if that test should also be changed. 792 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 793 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 794 bool result = promotion_estimate < old_gen->free_in_bytes(); 795 796 if (PrintGCDetails && Verbose) { 797 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 798 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 799 " padded_average_promoted " SIZE_FORMAT 800 " free in old gen " SIZE_FORMAT, 801 (size_t) policy->average_promoted_in_bytes(), 802 (size_t) policy->padded_average_promoted_in_bytes(), 803 old_gen->free_in_bytes()); 804 if (young_gen->used_in_bytes() < 805 (size_t) policy->padded_average_promoted_in_bytes()) { 806 gclog_or_tty->print_cr(" padded_promoted_average is greater" 807 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 808 } 809 } 810 811 if (result) { 812 _consecutive_skipped_scavenges = 0; 813 } else { 814 _consecutive_skipped_scavenges++; 815 if (UsePerfData) { 816 counters->update_scavenge_skipped(promoted_too_large); 817 } 818 } 819 return result; 820 } 821 822 // Used to add tasks 823 GCTaskManager* const PSScavenge::gc_task_manager() { 824 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 825 "shouldn't return NULL"); 826 return ParallelScavengeHeap::gc_task_manager(); 827 } 828 829 void PSScavenge::initialize() { 830 // Arguments must have been parsed 831 832 if (AlwaysTenure) { 833 _tenuring_threshold = 0; 834 } else if (NeverTenure) { 835 _tenuring_threshold = markOopDesc::max_age + 1; 836 } else { 837 // We want to smooth out our startup times for the AdaptiveSizePolicy 838 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 839 MaxTenuringThreshold; 840 } 841 842 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 843 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 844 845 PSYoungGen* young_gen = heap->young_gen(); 846 PSOldGen* old_gen = heap->old_gen(); 847 848 // Set boundary between young_gen and old_gen 849 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 850 "old above young"); 851 set_young_generation_boundary(young_gen->eden_space()->bottom()); 852 853 // Initialize ref handling object for scavenging. 854 MemRegion mr = young_gen->reserved(); 855 856 _ref_processor = 857 new ReferenceProcessor(mr, // span 858 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 859 (int) ParallelGCThreads, // mt processing degree 860 true, // mt discovery 861 (int) ParallelGCThreads, // mt discovery degree 862 true, // atomic_discovery 863 NULL, // header provides liveness info 864 false); // next field updates do not need write barrier 865 866 // Cache the cardtable 867 BarrierSet* bs = Universe::heap()->barrier_set(); 868 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); 869 _card_table = (CardTableExtension*)bs; 870 871 _counters = new CollectorCounters("PSScavenge", 0); 872 }