1 /* 2 * Copyright (c) 2002, 2012, 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 "gc_implementation/parallelScavenge/cardTableExtension.hpp" 28 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" 29 #include "gc_implementation/parallelScavenge/generationSizer.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/isGCActiveMark.hpp" 37 #include "gc_implementation/shared/spaceDecorator.hpp" 38 #include "gc_interface/gcCause.hpp" 39 #include "memory/collectorPolicy.hpp" 40 #include "memory/gcLocker.inline.hpp" 41 #include "memory/referencePolicy.hpp" 42 #include "memory/referenceProcessor.hpp" 43 #include "memory/resourceArea.hpp" 44 #include "oops/oop.inline.hpp" 45 #include "oops/oop.psgc.inline.hpp" 46 #include "runtime/biasedLocking.hpp" 47 #include "runtime/fprofiler.hpp" 48 #include "runtime/handles.inline.hpp" 49 #include "runtime/threadCritical.hpp" 50 #include "runtime/vmThread.hpp" 51 #include "runtime/vm_operations.hpp" 52 #include "services/memoryService.hpp" 53 #include "utilities/stack.inline.hpp" 54 55 56 HeapWord* PSScavenge::_to_space_top_before_gc = NULL; 57 int PSScavenge::_consecutive_skipped_scavenges = 0; 58 ReferenceProcessor* PSScavenge::_ref_processor = NULL; 59 CardTableExtension* PSScavenge::_card_table = NULL; 60 bool PSScavenge::_survivor_overflow = false; 61 int PSScavenge::_tenuring_threshold = 0; 62 HeapWord* PSScavenge::_young_generation_boundary = NULL; 63 elapsedTimer PSScavenge::_accumulated_time; 64 Stack<markOop> PSScavenge::_preserved_mark_stack; 65 Stack<oop> PSScavenge::_preserved_oop_stack; 66 CollectorCounters* PSScavenge::_counters = NULL; 67 bool PSScavenge::_promotion_failed = false; 68 69 // Define before use 70 class PSIsAliveClosure: public BoolObjectClosure { 71 public: 72 void do_object(oop p) { 73 assert(false, "Do not call."); 74 } 75 bool do_object_b(oop p) { 76 return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded(); 77 } 78 }; 79 80 PSIsAliveClosure PSScavenge::_is_alive_closure; 81 82 class PSKeepAliveClosure: public OopClosure { 83 protected: 84 MutableSpace* _to_space; 85 PSPromotionManager* _promotion_manager; 86 87 public: 88 PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) { 89 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 90 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 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 PSScavenge::copy_and_push_safe_barrier(_promotion_manager, 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 void 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(!Universe::heap()->is_gc_active(), "not reentrant"); 221 222 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 223 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 224 225 PSAdaptiveSizePolicy* policy = heap->size_policy(); 226 IsGCActiveMark mark; 227 228 bool scavenge_was_done = PSScavenge::invoke_no_policy(); 229 230 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 231 if (UsePerfData) 232 counters->update_full_follows_scavenge(0); 233 if (!scavenge_was_done || 234 policy->should_full_GC(heap->old_gen()->free_in_bytes())) { 235 if (UsePerfData) 236 counters->update_full_follows_scavenge(full_follows_scavenge); 237 GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy); 238 CollectorPolicy* cp = heap->collector_policy(); 239 const bool clear_all_softrefs = cp->should_clear_all_soft_refs(); 240 241 if (UseParallelOldGC) { 242 PSParallelCompact::invoke_no_policy(clear_all_softrefs); 243 } else { 244 PSMarkSweep::invoke_no_policy(clear_all_softrefs); 245 } 246 } 247 } 248 249 // This method contains no policy. You should probably 250 // be calling invoke() instead. 251 bool PSScavenge::invoke_no_policy() { 252 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 253 assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); 254 255 assert(_preserved_mark_stack.is_empty(), "should be empty"); 256 assert(_preserved_oop_stack.is_empty(), "should be empty"); 257 258 TimeStamp scavenge_entry; 259 TimeStamp scavenge_midpoint; 260 TimeStamp scavenge_exit; 261 262 scavenge_entry.update(); 263 264 if (GC_locker::check_active_before_gc()) { 265 return false; 266 } 267 268 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 269 GCCause::Cause gc_cause = heap->gc_cause(); 270 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 271 272 // Check for potential problems. 273 if (!should_attempt_scavenge()) { 274 return false; 275 } 276 277 bool promotion_failure_occurred = false; 278 279 PSYoungGen* young_gen = heap->young_gen(); 280 PSOldGen* old_gen = heap->old_gen(); 281 PSPermGen* perm_gen = heap->perm_gen(); 282 PSAdaptiveSizePolicy* size_policy = heap->size_policy(); 283 heap->increment_total_collections(); 284 285 AdaptiveSizePolicyOutput(size_policy, heap->total_collections()); 286 287 if ((gc_cause != GCCause::_java_lang_system_gc) || 288 UseAdaptiveSizePolicyWithSystemGC) { 289 // Gather the feedback data for eden occupancy. 290 young_gen->eden_space()->accumulate_statistics(); 291 } 292 293 if (ZapUnusedHeapArea) { 294 // Save information needed to minimize mangling 295 heap->record_gen_tops_before_GC(); 296 } 297 298 heap->print_heap_before_gc(); 299 300 assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity"); 301 assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity"); 302 303 size_t prev_used = heap->used(); 304 assert(promotion_failed() == false, "Sanity"); 305 306 // Fill in TLABs 307 heap->accumulate_statistics_all_tlabs(); 308 heap->ensure_parsability(true); // retire TLABs 309 310 if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) { 311 HandleMark hm; // Discard invalid handles created during verification 312 gclog_or_tty->print(" VerifyBeforeGC:"); 313 Universe::verify(true); 314 } 315 316 { 317 ResourceMark rm; 318 HandleMark hm; 319 320 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps); 321 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 322 TraceTime t1("GC", PrintGC, !PrintGCDetails, gclog_or_tty); 323 TraceCollectorStats tcs(counters()); 324 TraceMemoryManagerStats tms(false /* not full GC */,gc_cause); 325 326 if (TraceGen0Time) accumulated_time()->start(); 327 328 // Let the size policy know we're starting 329 size_policy->minor_collection_begin(); 330 331 // Verify the object start arrays. 332 if (VerifyObjectStartArray && 333 VerifyBeforeGC) { 334 old_gen->verify_object_start_array(); 335 perm_gen->verify_object_start_array(); 336 } 337 338 // Verify no unmarked old->young roots 339 if (VerifyRememberedSets) { 340 CardTableExtension::verify_all_young_refs_imprecise(); 341 } 342 343 if (!ScavengeWithObjectsInToSpace) { 344 assert(young_gen->to_space()->is_empty(), 345 "Attempt to scavenge with live objects in to_space"); 346 young_gen->to_space()->clear(SpaceDecorator::Mangle); 347 } else if (ZapUnusedHeapArea) { 348 young_gen->to_space()->mangle_unused_area(); 349 } 350 save_to_space_top_before_gc(); 351 352 COMPILER2_PRESENT(DerivedPointerTable::clear()); 353 354 reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/); 355 reference_processor()->setup_policy(false); 356 357 // We track how much was promoted to the next generation for 358 // the AdaptiveSizePolicy. 359 size_t old_gen_used_before = old_gen->used_in_bytes(); 360 361 // For PrintGCDetails 362 size_t young_gen_used_before = young_gen->used_in_bytes(); 363 364 // Reset our survivor overflow. 365 set_survivor_overflow(false); 366 367 // We need to save the old/perm top values before 368 // creating the promotion_manager. We pass the top 369 // values to the card_table, to prevent it from 370 // straying into the promotion labs. 371 HeapWord* old_top = old_gen->object_space()->top(); 372 HeapWord* perm_top = perm_gen->object_space()->top(); 373 374 // Release all previously held resources 375 gc_task_manager()->release_all_resources(); 376 377 // Set the number of GC threads to be used in this collection 378 gc_task_manager()->set_active_gang(); 379 gc_task_manager()->task_idle_workers(); 380 // Get the active number of workers here and use that value 381 // throughout the methods. 382 uint active_workers = gc_task_manager()->active_workers(); 383 heap->set_par_threads(active_workers); 384 385 PSPromotionManager::pre_scavenge(); 386 387 // We'll use the promotion manager again later. 388 PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager(); 389 { 390 // TraceTime("Roots"); 391 ParallelScavengeHeap::ParStrongRootsScope psrs; 392 393 GCTaskQueue* q = GCTaskQueue::create(); 394 395 uint stripe_total = active_workers; 396 for(uint i=0; i < stripe_total; i++) { 397 q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total)); 398 } 399 400 q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top)); 401 402 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe)); 403 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles)); 404 // We scan the thread roots in parallel 405 Threads::create_thread_roots_tasks(q); 406 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer)); 407 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler)); 408 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management)); 409 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary)); 410 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti)); 411 q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache)); 412 413 ParallelTaskTerminator terminator( 414 active_workers, 415 (TaskQueueSetSuper*) promotion_manager->stack_array_depth()); 416 if (active_workers > 1) { 417 for (uint j = 0; j < active_workers; j++) { 418 q->enqueue(new StealTask(&terminator)); 419 } 420 } 421 422 gc_task_manager()->execute_and_wait(q); 423 } 424 425 scavenge_midpoint.update(); 426 427 // Process reference objects discovered during scavenge 428 { 429 reference_processor()->setup_policy(false); // not always_clear 430 reference_processor()->set_active_mt_degree(active_workers); 431 PSKeepAliveClosure keep_alive(promotion_manager); 432 PSEvacuateFollowersClosure evac_followers(promotion_manager); 433 if (reference_processor()->processing_is_mt()) { 434 PSRefProcTaskExecutor task_executor; 435 reference_processor()->process_discovered_references( 436 &_is_alive_closure, &keep_alive, &evac_followers, &task_executor); 437 } else { 438 reference_processor()->process_discovered_references( 439 &_is_alive_closure, &keep_alive, &evac_followers, NULL); 440 } 441 } 442 443 // Enqueue reference objects discovered during scavenge. 444 if (reference_processor()->processing_is_mt()) { 445 PSRefProcTaskExecutor task_executor; 446 reference_processor()->enqueue_discovered_references(&task_executor); 447 } else { 448 reference_processor()->enqueue_discovered_references(NULL); 449 } 450 451 if (!JavaObjectsInPerm) { 452 // Unlink any dead interned Strings 453 StringTable::unlink(&_is_alive_closure); 454 // Process the remaining live ones 455 PSScavengeRootsClosure root_closure(promotion_manager); 456 StringTable::oops_do(&root_closure); 457 } 458 459 // Finally, flush the promotion_manager's labs, and deallocate its stacks. 460 PSPromotionManager::post_scavenge(); 461 462 promotion_failure_occurred = promotion_failed(); 463 if (promotion_failure_occurred) { 464 clean_up_failed_promotion(); 465 if (PrintGC) { 466 gclog_or_tty->print("--"); 467 } 468 } 469 470 // Let the size policy know we're done. Note that we count promotion 471 // failure cleanup time as part of the collection (otherwise, we're 472 // implicitly saying it's mutator time). 473 size_policy->minor_collection_end(gc_cause); 474 475 if (!promotion_failure_occurred) { 476 // Swap the survivor spaces. 477 478 479 young_gen->eden_space()->clear(SpaceDecorator::Mangle); 480 young_gen->from_space()->clear(SpaceDecorator::Mangle); 481 young_gen->swap_spaces(); 482 483 size_t survived = young_gen->from_space()->used_in_bytes(); 484 size_t promoted = old_gen->used_in_bytes() - old_gen_used_before; 485 size_policy->update_averages(_survivor_overflow, survived, promoted); 486 487 // A successful scavenge should restart the GC time limit count which is 488 // for full GC's. 489 size_policy->reset_gc_overhead_limit_count(); 490 if (UseAdaptiveSizePolicy) { 491 // Calculate the new survivor size and tenuring threshold 492 493 if (PrintAdaptiveSizePolicy) { 494 gclog_or_tty->print("AdaptiveSizeStart: "); 495 gclog_or_tty->stamp(); 496 gclog_or_tty->print_cr(" collection: %d ", 497 heap->total_collections()); 498 499 if (Verbose) { 500 gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d" 501 " perm_gen_capacity: %d ", 502 old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(), 503 perm_gen->capacity_in_bytes()); 504 } 505 } 506 507 508 if (UsePerfData) { 509 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 510 counters->update_old_eden_size( 511 size_policy->calculated_eden_size_in_bytes()); 512 counters->update_old_promo_size( 513 size_policy->calculated_promo_size_in_bytes()); 514 counters->update_old_capacity(old_gen->capacity_in_bytes()); 515 counters->update_young_capacity(young_gen->capacity_in_bytes()); 516 counters->update_survived(survived); 517 counters->update_promoted(promoted); 518 counters->update_survivor_overflowed(_survivor_overflow); 519 } 520 521 size_t survivor_limit = 522 size_policy->max_survivor_size(young_gen->max_size()); 523 _tenuring_threshold = 524 size_policy->compute_survivor_space_size_and_threshold( 525 _survivor_overflow, 526 _tenuring_threshold, 527 survivor_limit); 528 529 if (PrintTenuringDistribution) { 530 gclog_or_tty->cr(); 531 gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)", 532 size_policy->calculated_survivor_size_in_bytes(), 533 _tenuring_threshold, MaxTenuringThreshold); 534 } 535 536 if (UsePerfData) { 537 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 538 counters->update_tenuring_threshold(_tenuring_threshold); 539 counters->update_survivor_size_counters(); 540 } 541 542 // Do call at minor collections? 543 // Don't check if the size_policy is ready at this 544 // level. Let the size_policy check that internally. 545 if (UseAdaptiveSizePolicy && 546 UseAdaptiveGenerationSizePolicyAtMinorCollection && 547 ((gc_cause != GCCause::_java_lang_system_gc) || 548 UseAdaptiveSizePolicyWithSystemGC)) { 549 550 // Calculate optimial free space amounts 551 assert(young_gen->max_size() > 552 young_gen->from_space()->capacity_in_bytes() + 553 young_gen->to_space()->capacity_in_bytes(), 554 "Sizes of space in young gen are out-of-bounds"); 555 size_t max_eden_size = young_gen->max_size() - 556 young_gen->from_space()->capacity_in_bytes() - 557 young_gen->to_space()->capacity_in_bytes(); 558 size_policy->compute_generation_free_space(young_gen->used_in_bytes(), 559 young_gen->eden_space()->used_in_bytes(), 560 old_gen->used_in_bytes(), 561 perm_gen->used_in_bytes(), 562 young_gen->eden_space()->capacity_in_bytes(), 563 old_gen->max_gen_size(), 564 max_eden_size, 565 false /* full gc*/, 566 gc_cause, 567 heap->collector_policy()); 568 569 } 570 // Resize the young generation at every collection 571 // even if new sizes have not been calculated. This is 572 // to allow resizes that may have been inhibited by the 573 // relative location of the "to" and "from" spaces. 574 575 // Resizing the old gen at minor collects can cause increases 576 // that don't feed back to the generation sizing policy until 577 // a major collection. Don't resize the old gen here. 578 579 heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(), 580 size_policy->calculated_survivor_size_in_bytes()); 581 582 if (PrintAdaptiveSizePolicy) { 583 gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ", 584 heap->total_collections()); 585 } 586 } 587 588 // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can 589 // cause the change of the heap layout. Make sure eden is reshaped if that's the case. 590 // Also update() will case adaptive NUMA chunk resizing. 591 assert(young_gen->eden_space()->is_empty(), "eden space should be empty now"); 592 young_gen->eden_space()->update(); 593 594 heap->gc_policy_counters()->update_counters(); 595 596 heap->resize_all_tlabs(); 597 598 assert(young_gen->to_space()->is_empty(), "to space should be empty now"); 599 } 600 601 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 602 603 NOT_PRODUCT(reference_processor()->verify_no_references_recorded()); 604 605 // Re-verify object start arrays 606 if (VerifyObjectStartArray && 607 VerifyAfterGC) { 608 old_gen->verify_object_start_array(); 609 perm_gen->verify_object_start_array(); 610 } 611 612 // Verify all old -> young cards are now precise 613 if (VerifyRememberedSets) { 614 // Precise verification will give false positives. Until this is fixed, 615 // use imprecise verification. 616 // CardTableExtension::verify_all_young_refs_precise(); 617 CardTableExtension::verify_all_young_refs_imprecise(); 618 } 619 620 if (TraceGen0Time) accumulated_time()->stop(); 621 622 if (PrintGC) { 623 if (PrintGCDetails) { 624 // Don't print a GC timestamp here. This is after the GC so 625 // would be confusing. 626 young_gen->print_used_change(young_gen_used_before); 627 } 628 heap->print_heap_change(prev_used); 629 } 630 631 // Track memory usage and detect low memory 632 MemoryService::track_memory_usage(); 633 heap->update_counters(); 634 635 gc_task_manager()->release_idle_workers(); 636 } 637 638 if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) { 639 HandleMark hm; // Discard invalid handles created during verification 640 gclog_or_tty->print(" VerifyAfterGC:"); 641 Universe::verify(false); 642 } 643 644 heap->print_heap_after_gc(); 645 646 if (ZapUnusedHeapArea) { 647 young_gen->eden_space()->check_mangled_unused_area_complete(); 648 young_gen->from_space()->check_mangled_unused_area_complete(); 649 young_gen->to_space()->check_mangled_unused_area_complete(); 650 } 651 652 scavenge_exit.update(); 653 654 if (PrintGCTaskTimeStamps) { 655 tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT, 656 scavenge_entry.ticks(), scavenge_midpoint.ticks(), 657 scavenge_exit.ticks()); 658 gc_task_manager()->print_task_time_stamps(); 659 } 660 661 #ifdef TRACESPINNING 662 ParallelTaskTerminator::print_termination_counts(); 663 #endif 664 665 return !promotion_failure_occurred; 666 } 667 668 // This method iterates over all objects in the young generation, 669 // unforwarding markOops. It then restores any preserved mark oops, 670 // and clears the _preserved_mark_stack. 671 void PSScavenge::clean_up_failed_promotion() { 672 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 673 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 674 assert(promotion_failed(), "Sanity"); 675 676 PSYoungGen* young_gen = heap->young_gen(); 677 678 { 679 ResourceMark rm; 680 681 // Unforward all pointers in the young gen. 682 PSPromotionFailedClosure unforward_closure; 683 young_gen->object_iterate(&unforward_closure); 684 685 if (PrintGC && Verbose) { 686 gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size()); 687 } 688 689 // Restore any saved marks. 690 while (!_preserved_oop_stack.is_empty()) { 691 oop obj = _preserved_oop_stack.pop(); 692 markOop mark = _preserved_mark_stack.pop(); 693 obj->set_mark(mark); 694 } 695 696 // Clear the preserved mark and oop stack caches. 697 _preserved_mark_stack.clear(true); 698 _preserved_oop_stack.clear(true); 699 _promotion_failed = false; 700 } 701 702 // Reset the PromotionFailureALot counters. 703 NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();) 704 } 705 706 // This method is called whenever an attempt to promote an object 707 // fails. Some markOops will need preservation, some will not. Note 708 // that the entire eden is traversed after a failed promotion, with 709 // all forwarded headers replaced by the default markOop. This means 710 // it is not neccessary to preserve most markOops. 711 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) { 712 _promotion_failed = true; 713 if (obj_mark->must_be_preserved_for_promotion_failure(obj)) { 714 // Should use per-worker private stakcs hetre rather than 715 // locking a common pair of stacks. 716 ThreadCritical tc; 717 _preserved_oop_stack.push(obj); 718 _preserved_mark_stack.push(obj_mark); 719 } 720 } 721 722 bool PSScavenge::should_attempt_scavenge() { 723 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 724 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 725 PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters(); 726 727 if (UsePerfData) { 728 counters->update_scavenge_skipped(not_skipped); 729 } 730 731 PSYoungGen* young_gen = heap->young_gen(); 732 PSOldGen* old_gen = heap->old_gen(); 733 734 if (!ScavengeWithObjectsInToSpace) { 735 // Do not attempt to promote unless to_space is empty 736 if (!young_gen->to_space()->is_empty()) { 737 _consecutive_skipped_scavenges++; 738 if (UsePerfData) { 739 counters->update_scavenge_skipped(to_space_not_empty); 740 } 741 return false; 742 } 743 } 744 745 // Test to see if the scavenge will likely fail. 746 PSAdaptiveSizePolicy* policy = heap->size_policy(); 747 748 // A similar test is done in the policy's should_full_GC(). If this is 749 // changed, decide if that test should also be changed. 750 size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes(); 751 size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes()); 752 bool result = promotion_estimate < old_gen->free_in_bytes(); 753 754 if (PrintGCDetails && Verbose) { 755 gclog_or_tty->print(result ? " do scavenge: " : " skip scavenge: "); 756 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT 757 " padded_average_promoted " SIZE_FORMAT 758 " free in old gen " SIZE_FORMAT, 759 (size_t) policy->average_promoted_in_bytes(), 760 (size_t) policy->padded_average_promoted_in_bytes(), 761 old_gen->free_in_bytes()); 762 if (young_gen->used_in_bytes() < 763 (size_t) policy->padded_average_promoted_in_bytes()) { 764 gclog_or_tty->print_cr(" padded_promoted_average is greater" 765 " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes()); 766 } 767 } 768 769 if (result) { 770 _consecutive_skipped_scavenges = 0; 771 } else { 772 _consecutive_skipped_scavenges++; 773 if (UsePerfData) { 774 counters->update_scavenge_skipped(promoted_too_large); 775 } 776 } 777 return result; 778 } 779 780 // Used to add tasks 781 GCTaskManager* const PSScavenge::gc_task_manager() { 782 assert(ParallelScavengeHeap::gc_task_manager() != NULL, 783 "shouldn't return NULL"); 784 return ParallelScavengeHeap::gc_task_manager(); 785 } 786 787 void PSScavenge::initialize() { 788 // Arguments must have been parsed 789 790 if (AlwaysTenure) { 791 _tenuring_threshold = 0; 792 } else if (NeverTenure) { 793 _tenuring_threshold = markOopDesc::max_age + 1; 794 } else { 795 // We want to smooth out our startup times for the AdaptiveSizePolicy 796 _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold : 797 MaxTenuringThreshold; 798 } 799 800 ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap(); 801 assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); 802 803 PSYoungGen* young_gen = heap->young_gen(); 804 PSOldGen* old_gen = heap->old_gen(); 805 PSPermGen* perm_gen = heap->perm_gen(); 806 807 // Set boundary between young_gen and old_gen 808 assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(), 809 "perm above old"); 810 assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(), 811 "old above young"); 812 _young_generation_boundary = young_gen->eden_space()->bottom(); 813 814 // Initialize ref handling object for scavenging. 815 MemRegion mr = young_gen->reserved(); 816 817 _ref_processor = 818 new ReferenceProcessor(mr, // span 819 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing 820 (int) ParallelGCThreads, // mt processing degree 821 true, // mt discovery 822 (int) ParallelGCThreads, // mt discovery degree 823 true, // atomic_discovery 824 NULL, // header provides liveness info 825 false); // next field updates do not need write barrier 826 827 // Cache the cardtable 828 BarrierSet* bs = Universe::heap()->barrier_set(); 829 assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind"); 830 _card_table = (CardTableExtension*)bs; 831 832 _counters = new CollectorCounters("PSScavenge", 0); 833 }