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/gcLocker.inline.hpp" 40 #include "gc/shared/gcTimer.hpp" 41 #include "gc/shared/gcTrace.hpp" 42 #include "gc/shared/gcTraceTime.hpp" 43 #include "gc/shared/isGCActiveMark.hpp" 44 #include "gc/shared/referencePolicy.hpp" 45 #include "gc/shared/referenceProcessor.hpp" 46 #include "gc/shared/spaceDecorator.hpp" 47 #include "memory/resourceArea.hpp" 48 #include "oops/oop.inline.hpp" 49 #include "runtime/biasedLocking.hpp" 50 #include "runtime/fprofiler.hpp" 51 #include "runtime/handles.inline.hpp" 52 #include "runtime/threadCritical.hpp" 53 #include "runtime/vmThread.hpp" 54 #include "runtime/vm_operations.hpp" 55 #include "services/memoryService.hpp" 56 #include "utilities/stack.inline.hpp" 57 58 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 59 int PSScavenge::_consecutive_skipped_scavenges = 0; 60 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 61 CardTableExtension* PSScavenge::_card_table = NULL; 62 bool PSScavenge::_survivor_overflow = false; 63 uint PSScavenge::_tenuring_threshold = 0; 64 HeapWord* PSScavenge::_young_generation_boundary = NULL; 65 uintptr_t PSScavenge::_young_generation_boundary_compressed = 0; 66 elapsedTimer PSScavenge::_accumulated_time; 67 STWGCTimer PSScavenge::_gc_timer; 68 ParallelScavengeTracer PSScavenge::_gc_tracer; 69 Stack<markOop, mtGC> PSScavenge::_preserved_mark_stack; 70 Stack<oop, mtGC> PSScavenge::_preserved_oop_stack; 71 CollectorCounters* PSScavenge::_counters = NULL; 72 73 // Define before use 74 class PSIsAliveClosure: public BoolObjectClosure { 75 public: 76 bool do_object_b(oop p) { 77 return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded(); 78 } 79 }; 80 81 PSIsAliveClosure PSScavenge::_is_alive_closure; 82 83 class PSKeepAliveClosure: public OopClosure { 84 protected: 85 MutableSpace* _to_space; 86 PSPromotionManager* _promotion_manager; 87 88 public: 89 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 90 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 91 _to_space = heap->young_gen()->to_space(); 92 93 assert(_promotion_manager != NULL, "Sanity"); 94 } 95 96 template <class T> void do_oop_work(T* p) { 97 assert (!oopDesc::is_null(*p), "expected non-null ref"); 98 assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(), 99 "expected an oop while scanning weak refs"); 100 101 // Weak refs may be visited more than once. 102 if (PSScavenge::should_scavenge(p, _to_space)) { 103 _promotion_manager->copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(p); 104 } 105 } 106 virtual void do_oop(oop* p) { PSKeepAliveClosure::do_oop_work(p); } 107 virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); } 108 }; 109 110 class PSEvacuateFollowersClosure: public VoidClosure { 111 private: 112 PSPromotionManager* _promotion_manager; 113 public: 114 PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {} 115 116 virtual void do_void() { 117 assert(_promotion_manager != NULL, "Sanity"); 118 _promotion_manager->drain_stacks(true); 119 guarantee(_promotion_manager->stacks_empty(), 120 "stacks should be empty at this point"); 121 } 122 }; 123 124 class PSPromotionFailedClosure : public ObjectClosure { 125 virtual void do_object(oop obj) { 126 if (obj->is_forwarded()) { 127 obj->init_mark(); 128 } 129 } 130 }; 131 132 class PSRefProcTaskProxy: public GCTask { 133 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask; 134 ProcessTask & _rp_task; 135 uint _work_id; 136 public: 137 PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id) 138 : _rp_task(rp_task), 139 _work_id(work_id) 140 { } 141 142 private: 143 virtual char* name() { return (char *)"Process referents by policy in parallel"; } 144 virtual void do_it(GCTaskManager* manager, uint which); 145 }; 146 147 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which) 148 { 149 PSPromotionManager* promotion_manager = 150 PSPromotionManager::gc_thread_promotion_manager(which); 151 assert(promotion_manager != NULL, "sanity check"); 152 PSKeepAliveClosure keep_alive(promotion_manager); 153 PSEvacuateFollowersClosure evac_followers(promotion_manager); 154 PSIsAliveClosure is_alive; 155 _rp_task.work(_work_id, is_alive, keep_alive, evac_followers); 156 } 157 158 class PSRefEnqueueTaskProxy: public GCTask { 159 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask; 160 EnqueueTask& _enq_task; 161 uint _work_id; 162 163 public: 164 PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id) 165 : _enq_task(enq_task), 166 _work_id(work_id) 167 { } 168 169 virtual char* name() { return (char *)"Enqueue reference objects in parallel"; } 170 virtual void do_it(GCTaskManager* manager, uint which) 171 { 172 _enq_task.work(_work_id); 173 } 174 }; 175 176 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor { 177 virtual void execute(ProcessTask& task); 178 virtual void execute(EnqueueTask& task); 179 }; 180 181 void PSRefProcTaskExecutor::execute(ProcessTask& task) 182 { 183 GCTaskQueue* q = GCTaskQueue::create(); 184 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 185 for(uint i=0; i < manager->active_workers(); i++) { 186 q->enqueue(new PSRefProcTaskProxy(task, i)); 187 } 188 ParallelTaskTerminator terminator(manager->active_workers(), 189 (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth()); 190 if (task.marks_oops_alive() && manager->active_workers() > 1) { 191 for (uint j = 0; j < manager->active_workers(); j++) { 192 q->enqueue(new StealTask(&terminator)); 193 } 194 } 195 manager->execute_and_wait(q); 196 } 197 198 199 void PSRefProcTaskExecutor::execute(EnqueueTask& task) 200 { 201 GCTaskQueue* q = GCTaskQueue::create(); 202 GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager(); 203 for(uint i=0; i < manager->active_workers(); i++) { 204 q->enqueue(new PSRefEnqueueTaskProxy(task, i)); 205 } 206 manager->execute_and_wait(q); 207 } 208 209 // This method contains all heap specific policy for invoking scavenge. 210 // PSScavenge::invoke_no_policy() will do nothing but attempt to 211 // scavenge. It will not clean up after failed promotions, bail out if 212 // we've exceeded policy time limits, or any other special behavior. 213 // All such policy should be placed here. 214 // 215 // Note that this method should only be called from the vm_thread while 216 // at a safepoint! 217 bool PSScavenge::invoke() { 218 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 219 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 220 assert(!ParallelScavengeHeap::heap()->is_gc_active(), "not reentrant"); 221 222 ParallelScavengeHeap* const heap = ParallelScavengeHeap::heap(); 223 PSAdaptiveSizePolicy* policy = heap->size_policy(); 224 IsGCActiveMark mark; 225 226 const bool scavenge_done = PSScavenge::invoke_no_policy(); 227 const bool need_full_gc = !scavenge_done || 228 policy->should_full_GC(heap->old_gen()->free_in_bytes()); 229 bool full_gc_done = false; 230 231 if (UsePerfData) { 232 PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters(); 233 const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped; 234 counters->update_full_follows_scavenge(ffs_val); 235 } 236 237 if (need_full_gc) { 238 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 239 CollectorPolicy* cp = heap->collector_policy(); 240 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 241 242 if (UseParallelOldGC) { 243 full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs); 244 } else { 245 full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs); 246 } 247 } 248 249 return full_gc_done; 250 } 251 252 // This method contains no policy. You should probably 253 // be calling invoke() instead. 254 bool PSScavenge::invoke_no_policy() { 255 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 256 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 257 258 assert(_preserved_mark_stack.is_empty(), "should be empty"); 259 assert(_preserved_oop_stack.is_empty(), "should be empty"); 260 261 _gc_timer.register_gc_start(); 262 263 TimeStamp scavenge_entry; 264 TimeStamp scavenge_midpoint; 265 TimeStamp scavenge_exit; 266 267 scavenge_entry.update(); 268 269 if (GC_locker::check_active_before_gc()) { 270 return false; 271 } 272 273 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 274 GCCause::Cause gc_cause = heap->gc_cause(); 275 276 // Check for potential problems. 277 if (!should_attempt_scavenge()) { 278 return false; 279 } 280 281 _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start()); 282 283 bool promotion_failure_occurred = false; 284 285 PSYoungGen* young_gen = heap->young_gen(); 286 PSOldGen* old_gen = heap->old_gen(); 287 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 288 289 heap->increment_total_collections(); 290 291 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 292 293 if ((gc_cause != GCCause::_java_lang_system_gc) || 294 UseAdaptiveSizePolicyWithSystemGC) { 295 // Gather the feedback data for eden occupancy. 296 young_gen->eden_space()->accumulate_statistics(); 297 } 298 299 if (ZapUnusedHeapArea) { 300 // Save information needed to minimize mangling 301 heap->record_gen_tops_before_GC(); 302 } 303 304 heap->print_heap_before_gc(); 305 heap->trace_heap_before_gc(&_gc_tracer); 306 307 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 308 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 309 310 size_t prev_used = heap->used(); 311 312 // Fill in TLABs 313 heap->accumulate_statistics_all_tlabs(); 314 heap->ensure_parsability(true); // retire TLABs 315 316 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 317 HandleMark hm; // Discard invalid handles created during verification 318 Universe::verify(" VerifyBeforeGC:"); 319 } 320 321 { 322 ResourceMark rm; 323 HandleMark hm; 324 325 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 326 GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL, _gc_tracer.gc_id()); 327 TraceCollectorStats tcs(counters()); 328 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 329 330 if (TraceYoungGenTime) accumulated_time()->start(); 331 332 // Let the size policy know we're starting 333 size_policy->minor_collection_begin(); 334 335 // Verify the object start arrays. 336 if (VerifyObjectStartArray && 337 VerifyBeforeGC) { 338 old_gen->verify_object_start_array(); 339 } 340 341 // Verify no unmarked old->young roots 342 if (VerifyRememberedSets) { 343 CardTableExtension::verify_all_young_refs_imprecise(); 344 } 345 346 if (!ScavengeWithObjectsInToSpace) { 347 assert(young_gen->to_space()->is_empty(), 348 "Attempt to scavenge with live objects in to_space"); 349 young_gen->to_space()->clear(SpaceDecorator::Mangle); 350 } else if (ZapUnusedHeapArea) { 351 young_gen->to_space()->mangle_unused_area(); 352 } 353 save_to_space_top_before_gc(); 354 355 COMPILER2_PRESENT(DerivedPointerTable::clear()); 356 357 reference_processor()->enable_discovery(); 358 reference_processor()->setup_policy(false); 359 360 // We track how much was promoted to the next generation for 361 // the AdaptiveSizePolicy. 362 size_t old_gen_used_before = old_gen->used_in_bytes(); 363 364 // For PrintGCDetails 365 size_t young_gen_used_before = young_gen->used_in_bytes(); 366 367 // Reset our survivor overflow. 368 set_survivor_overflow(false); 369 370 // We need to save the old top values before 371 // creating the promotion_manager. We pass the top 372 // values to the card_table, to prevent it from 373 // straying into the promotion labs. 374 HeapWord* old_top = old_gen->object_space()->top(); 375 376 // Release all previously held resources 377 gc_task_manager()->release_all_resources(); 378 379 // Set the number of GC threads to be used in this collection 380 gc_task_manager()->set_active_gang(); 381 gc_task_manager()->task_idle_workers(); 382 // Get the active number of workers here and use that value 383 // throughout the methods. 384 uint active_workers = gc_task_manager()->active_workers(); 385 heap->set_par_threads(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, _gc_tracer.gc_id()); 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, _gc_tracer.gc_id()); 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, _gc_tracer.gc_id()); 446 } else { 447 stats = reference_processor()->process_discovered_references( 448 &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer, _gc_tracer.gc_id()); 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, _gc_tracer.gc_id()); 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 ((gc_cause != GCCause::_java_lang_system_gc) || 564 UseAdaptiveSizePolicyWithSystemGC)) { 565 566 // Calculate optimal free space amounts 567 assert(young_gen->max_size() > 568 young_gen->from_space()->capacity_in_bytes() + 569 young_gen->to_space()->capacity_in_bytes(), 570 "Sizes of space in young gen are out-of-bounds"); 571 572 size_t young_live = young_gen->used_in_bytes(); 573 size_t eden_live = young_gen->eden_space()->used_in_bytes(); 574 size_t cur_eden = young_gen->eden_space()->capacity_in_bytes(); 575 size_t max_old_gen_size = old_gen->max_gen_size(); 576 size_t max_eden_size = max_young_size - 577 young_gen->from_space()->capacity_in_bytes() - 578 young_gen->to_space()->capacity_in_bytes(); 579 580 // Used for diagnostics 581 size_policy->clear_generation_free_space_flags(); 582 583 size_policy->compute_eden_space_size(young_live, 584 eden_live, 585 cur_eden, 586 max_eden_size, 587 false /* not full gc*/); 588 589 size_policy->check_gc_overhead_limit(young_live, 590 eden_live, 591 max_old_gen_size, 592 max_eden_size, 593 false /* not full gc*/, 594 gc_cause, 595 heap->collector_policy()); 596 597 size_policy->decay_supplemental_growth(false /* not full gc*/); 598 } 599 // Resize the young generation at every collection 600 // even if new sizes have not been calculated. This is 601 // to allow resizes that may have been inhibited by the 602 // relative location of the "to" and "from" spaces. 603 604 // Resizing the old gen at minor collects can cause increases 605 // that don't feed back to the generation sizing policy until 606 // a major collection. Don't resize the old gen here. 607 608 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 609 size_policy->calculated_survivor_size_in_bytes()); 610 611 if (PrintAdaptiveSizePolicy) { 612 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 613 heap->total_collections()); 614 } 615 } 616 617 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 618 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 619 // Also update() will case adaptive NUMA chunk resizing. 620 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 621 young_gen->eden_space()->update(); 622 623 heap->gc_policy_counters()->update_counters(); 624 625 heap->resize_all_tlabs(); 626 627 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 628 } 629 630 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 631 632 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 633 634 { 635 GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer, _gc_tracer.gc_id()); 636 637 CodeCache::prune_scavenge_root_nmethods(); 638 } 639 640 // Re-verify object start arrays 641 if (VerifyObjectStartArray && 642 VerifyAfterGC) { 643 old_gen->verify_object_start_array(); 644 } 645 646 // Verify all old -> young cards are now precise 647 if (VerifyRememberedSets) { 648 // Precise verification will give false positives. Until this is fixed, 649 // use imprecise verification. 650 // CardTableExtension::verify_all_young_refs_precise(); 651 CardTableExtension::verify_all_young_refs_imprecise(); 652 } 653 654 if (TraceYoungGenTime) accumulated_time()->stop(); 655 656 if (PrintGC) { 657 if (PrintGCDetails) { 658 // Don't print a GC timestamp here. This is after the GC so 659 // would be confusing. 660 young_gen->print_used_change(young_gen_used_before); 661 } 662 heap->print_heap_change(prev_used); 663 } 664 665 // Track memory usage and detect low memory 666 MemoryService::track_memory_usage(); 667 heap->update_counters(); 668 669 gc_task_manager()->release_idle_workers(); 670 } 671 672 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 673 HandleMark hm; // Discard invalid handles created during verification 674 Universe::verify(" VerifyAfterGC:"); 675 } 676 677 heap->print_heap_after_gc(); 678 heap->trace_heap_after_gc(&_gc_tracer); 679 _gc_tracer.report_tenuring_threshold(tenuring_threshold()); 680 681 if (ZapUnusedHeapArea) { 682 young_gen->eden_space()->check_mangled_unused_area_complete(); 683 young_gen->from_space()->check_mangled_unused_area_complete(); 684 young_gen->to_space()->check_mangled_unused_area_complete(); 685 } 686 687 scavenge_exit.update(); 688 689 if (PrintGCTaskTimeStamps) { 690 tty->print_cr("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT, 691 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 692 scavenge_exit.ticks()); 693 gc_task_manager()->print_task_time_stamps(); 694 } 695 696 #ifdef TRACESPINNING 697 ParallelTaskTerminator::print_termination_counts(); 698 #endif 699 700 701 _gc_timer.register_gc_end(); 702 703 _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions()); 704 705 return !promotion_failure_occurred; 706 } 707 708 // This method iterates over all objects in the young generation, 709 // unforwarding markOops. It then restores any preserved mark oops, 710 // and clears the _preserved_mark_stack. 711 void PSScavenge::clean_up_failed_promotion() { 712 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 713 PSYoungGen* young_gen = heap->young_gen(); 714 715 { 716 ResourceMark rm; 717 718 // Unforward all pointers in the young gen. 719 PSPromotionFailedClosure unforward_closure; 720 young_gen->object_iterate(&unforward_closure); 721 722 if (PrintGC && Verbose) { 723 gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size()); 724 } 725 726 // Restore any saved marks. 727 while (!_preserved_oop_stack.is_empty()) { 728 oop obj = _preserved_oop_stack.pop(); 729 markOop mark = _preserved_mark_stack.pop(); 730 obj->set_mark(mark); 731 } 732 733 // Clear the preserved mark and oop stack caches. 734 _preserved_mark_stack.clear(true); 735 _preserved_oop_stack.clear(true); 736 } 737 738 // Reset the PromotionFailureALot counters. 739 NOT_PRODUCT(heap->reset_promotion_should_fail();) 740 } 741 742 // This method is called whenever an attempt to promote an object 743 // fails. Some markOops will need preservation, some will not. Note 744 // that the entire eden is traversed after a failed promotion, with 745 // all forwarded headers replaced by the default markOop. This means 746 // it is not necessary to preserve most markOops. 747 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 748 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 749 // Should use per-worker private stacks here rather than 750 // locking a common pair of stacks. 751 ThreadCritical tc; 752 _preserved_oop_stack.push(obj); 753 _preserved_mark_stack.push(obj_mark); 754 } 755 } 756 757 bool PSScavenge::should_attempt_scavenge() { 758 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 759 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 760 761 if (UsePerfData) { 762 counters->update_scavenge_skipped(not_skipped); 763 } 764 765 PSYoungGen* young_gen = heap->young_gen(); 766 PSOldGen* old_gen = heap->old_gen(); 767 768 if (!ScavengeWithObjectsInToSpace) { 769 // Do not attempt to promote unless to_space is empty 770 if (!young_gen->to_space()->is_empty()) { 771 _consecutive_skipped_scavenges++; 772 if (UsePerfData) { 773 counters->update_scavenge_skipped(to_space_not_empty); 774 } 775 return false; 776 } 777 } 778 779 // Test to see if the scavenge will likely fail. 780 PSAdaptiveSizePolicy* policy = heap->size_policy(); 781 782 // A similar test is done in the policy's should_full_GC(). If this is 783 // changed, decide if that test should also be changed. 784 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 785 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 786 bool result = promotion_estimate < old_gen->free_in_bytes(); 787 788 if (PrintGCDetails && Verbose) { 789 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 790 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 791 " padded_average_promoted " SIZE_FORMAT 792 " free in old gen " SIZE_FORMAT, 793 (size_t) policy->average_promoted_in_bytes(), 794 (size_t) policy->padded_average_promoted_in_bytes(), 795 old_gen->free_in_bytes()); 796 if (young_gen->used_in_bytes() < 797 (size_t) policy->padded_average_promoted_in_bytes()) { 798 gclog_or_tty->print_cr(" padded_promoted_average is greater" 799 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 800 } 801 } 802 803 if (result) { 804 _consecutive_skipped_scavenges = 0; 805 } else { 806 _consecutive_skipped_scavenges++; 807 if (UsePerfData) { 808 counters->update_scavenge_skipped(promoted_too_large); 809 } 810 } 811 return result; 812 } 813 814 // Used to add tasks 815 GCTaskManager* const PSScavenge::gc_task_manager() { 816 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 817 "shouldn't return NULL"); 818 return ParallelScavengeHeap::gc_task_manager(); 819 } 820 821 void PSScavenge::initialize() { 822 // Arguments must have been parsed 823 824 if (AlwaysTenure || NeverTenure) { 825 assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1, 826 err_msg("MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold)); 827 _tenuring_threshold = MaxTenuringThreshold; 828 } else { 829 // We want to smooth out our startup times for the AdaptiveSizePolicy 830 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 831 MaxTenuringThreshold; 832 } 833 834 ParallelScavengeHeap* heap = ParallelScavengeHeap::heap(); 835 PSYoungGen* young_gen = heap->young_gen(); 836 PSOldGen* old_gen = heap->old_gen(); 837 838 // Set boundary between young_gen and old_gen 839 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 840 "old above young"); 841 set_young_generation_boundary(young_gen->eden_space()->bottom()); 842 843 // Initialize ref handling object for scavenging. 844 MemRegion mr = young_gen->reserved(); 845 846 _ref_processor = 847 new ReferenceProcessor(mr, // span 848 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 849 (int) ParallelGCThreads, // mt processing degree 850 true, // mt discovery 851 (int) ParallelGCThreads, // mt discovery degree 852 true, // atomic_discovery 853 NULL); // header provides liveness info 854 855 // Cache the cardtable 856 _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set()); 857 858 _counters = new CollectorCounters("PSScavenge", 0); 859 }