1 /*
   2  * Copyright (c) 2002, 2010, 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 "gc_implementation/parallelScavenge/cardTableExtension.hpp"
  27 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
  28 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
  29 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
  30 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
  31 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
  32 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
  33 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
  34 #include "gc_implementation/parallelScavenge/psTasks.hpp"
  35 #include "gc_implementation/shared/isGCActiveMark.hpp"
  36 #include "gc_implementation/shared/spaceDecorator.hpp"
  37 #include "gc_interface/gcCause.hpp"
  38 #include "memory/collectorPolicy.hpp"
  39 #include "memory/gcLocker.inline.hpp"
  40 #include "memory/referencePolicy.hpp"
  41 #include "memory/referenceProcessor.hpp"
  42 #include "memory/resourceArea.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/oop.psgc.inline.hpp"
  45 #include "runtime/biasedLocking.hpp"
  46 #include "runtime/fprofiler.hpp"
  47 #include "runtime/handles.inline.hpp"
  48 #include "runtime/threadCritical.hpp"
  49 #include "runtime/vmThread.hpp"
  50 #include "runtime/vm_operations.hpp"
  51 #include "services/memoryService.hpp"
  52 #include "utilities/stack.inline.hpp"
  53 
  54 
  55 HeapWord*                  PSScavenge::_to_space_top_before_gc = NULL;
  56 int                        PSScavenge::_consecutive_skipped_scavenges = 0;
  57 ReferenceProcessor*        PSScavenge::_ref_processor = NULL;
  58 CardTableExtension*        PSScavenge::_card_table = NULL;
  59 bool                       PSScavenge::_survivor_overflow = false;
  60 int                        PSScavenge::_tenuring_threshold = 0;
  61 HeapWord*                  PSScavenge::_young_generation_boundary = NULL;
  62 elapsedTimer               PSScavenge::_accumulated_time;
  63 Stack<markOop>             PSScavenge::_preserved_mark_stack;
  64 Stack<oop>                 PSScavenge::_preserved_oop_stack;
  65 CollectorCounters*         PSScavenge::_counters = NULL;
  66 bool                       PSScavenge::_promotion_failed = false;
  67 
  68 // Define before use
  69 class PSIsAliveClosure: public BoolObjectClosure {
  70 public:
  71   void do_object(oop p) {
  72     assert(false, "Do not call.");
  73   }
  74   bool do_object_b(oop p) {
  75     return (!PSScavenge::is_obj_in_young((HeapWord*) p)) || p->is_forwarded();
  76   }
  77 };
  78 
  79 PSIsAliveClosure PSScavenge::_is_alive_closure;
  80 
  81 class PSKeepAliveClosure: public OopClosure {
  82 protected:
  83   MutableSpace* _to_space;
  84   PSPromotionManager* _promotion_manager;
  85 
  86 public:
  87   PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
  88     ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  89     assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
  90     _to_space = heap->young_gen()->to_space();
  91 
  92     assert(_promotion_manager != NULL, "Sanity");
  93   }
  94 
  95   template <class T> void do_oop_work(T* p) {
  96     assert (!oopDesc::is_null(*p), "expected non-null ref");
  97     assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
  98             "expected an oop while scanning weak refs");
  99 
 100     // Weak refs may be visited more than once.
 101     if (PSScavenge::should_scavenge(p, _to_space)) {
 102       PSScavenge::copy_and_push_safe_barrier(_promotion_manager, p);
 103     }
 104   }
 105   virtual void do_oop(oop* p)       { PSKeepAliveClosure::do_oop_work(p); }
 106   virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
 107 };
 108 
 109 class PSEvacuateFollowersClosure: public VoidClosure {
 110  private:
 111   PSPromotionManager* _promotion_manager;
 112  public:
 113   PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
 114 
 115   virtual void do_void() {
 116     assert(_promotion_manager != NULL, "Sanity");
 117     _promotion_manager->drain_stacks(true);
 118     guarantee(_promotion_manager->stacks_empty(),
 119               "stacks should be empty at this point");
 120   }
 121 };
 122 
 123 class PSPromotionFailedClosure : public ObjectClosure {
 124   virtual void do_object(oop obj) {
 125     if (obj->is_forwarded()) {
 126       obj->init_mark();
 127     }
 128   }
 129 };
 130 
 131 class PSRefProcTaskProxy: public GCTask {
 132   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
 133   ProcessTask & _rp_task;
 134   uint          _work_id;
 135 public:
 136   PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
 137     : _rp_task(rp_task),
 138       _work_id(work_id)
 139   { }
 140 
 141 private:
 142   virtual char* name() { return (char *)"Process referents by policy in parallel"; }
 143   virtual void do_it(GCTaskManager* manager, uint which);
 144 };
 145 
 146 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
 147 {
 148   PSPromotionManager* promotion_manager =
 149     PSPromotionManager::gc_thread_promotion_manager(which);
 150   assert(promotion_manager != NULL, "sanity check");
 151   PSKeepAliveClosure keep_alive(promotion_manager);
 152   PSEvacuateFollowersClosure evac_followers(promotion_manager);
 153   PSIsAliveClosure is_alive;
 154   _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
 155 }
 156 
 157 class PSRefEnqueueTaskProxy: public GCTask {
 158   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
 159   EnqueueTask& _enq_task;
 160   uint         _work_id;
 161 
 162 public:
 163   PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
 164     : _enq_task(enq_task),
 165       _work_id(work_id)
 166   { }
 167 
 168   virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
 169   virtual void do_it(GCTaskManager* manager, uint which)
 170   {
 171     _enq_task.work(_work_id);
 172   }
 173 };
 174 
 175 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
 176   virtual void execute(ProcessTask& task);
 177   virtual void execute(EnqueueTask& task);
 178 };
 179 
 180 void PSRefProcTaskExecutor::execute(ProcessTask& task)
 181 {
 182   GCTaskQueue* q = GCTaskQueue::create();
 183   for(uint i=0; i<ParallelGCThreads; i++) {
 184     q->enqueue(new PSRefProcTaskProxy(task, i));
 185   }
 186   ParallelTaskTerminator terminator(
 187                  ParallelScavengeHeap::gc_task_manager()->workers(),
 188                  (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
 189   if (task.marks_oops_alive() && ParallelGCThreads > 1) {
 190     for (uint j=0; j<ParallelGCThreads; j++) {
 191       q->enqueue(new StealTask(&terminator));
 192     }
 193   }
 194   ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q);
 195 }
 196 
 197 
 198 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
 199 {
 200   GCTaskQueue* q = GCTaskQueue::create();
 201   for(uint i=0; i<ParallelGCThreads; i++) {
 202     q->enqueue(new PSRefEnqueueTaskProxy(task, i));
 203   }
 204   ParallelScavengeHeap::gc_task_manager()->execute_and_wait(q);
 205 }
 206 
 207 // This method contains all heap specific policy for invoking scavenge.
 208 // PSScavenge::invoke_no_policy() will do nothing but attempt to
 209 // scavenge. It will not clean up after failed promotions, bail out if
 210 // we've exceeded policy time limits, or any other special behavior.
 211 // All such policy should be placed here.
 212 //
 213 // Note that this method should only be called from the vm_thread while
 214 // at a safepoint!
 215 void PSScavenge::invoke() {
 216   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 217   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 218   assert(!Universe::heap()->is_gc_active(), "not reentrant");
 219 
 220   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 221   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 222 
 223   PSAdaptiveSizePolicy* policy = heap->size_policy();
 224   IsGCActiveMark mark;
 225 
 226   bool scavenge_was_done = PSScavenge::invoke_no_policy();
 227 
 228   PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 229   if (UsePerfData)
 230     counters->update_full_follows_scavenge(0);
 231   if (!scavenge_was_done ||
 232       policy->should_full_GC(heap->old_gen()->free_in_bytes())) {
 233     if (UsePerfData)
 234       counters->update_full_follows_scavenge(full_follows_scavenge);
 235     GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
 236     CollectorPolicy* cp = heap->collector_policy();
 237     const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
 238 
 239     if (UseParallelOldGC) {
 240       PSParallelCompact::invoke_no_policy(clear_all_softrefs);
 241     } else {
 242       PSMarkSweep::invoke_no_policy(clear_all_softrefs);
 243     }
 244   }
 245 }
 246 
 247 // This method contains no policy. You should probably
 248 // be calling invoke() instead.
 249 bool PSScavenge::invoke_no_policy() {
 250   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 251   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 252 
 253   assert(_preserved_mark_stack.is_empty(), "should be empty");
 254   assert(_preserved_oop_stack.is_empty(), "should be empty");
 255 
 256   TimeStamp scavenge_entry;
 257   TimeStamp scavenge_midpoint;
 258   TimeStamp scavenge_exit;
 259 
 260   scavenge_entry.update();
 261 
 262   if (GC_locker::check_active_before_gc()) {
 263     return false;
 264   }
 265 
 266   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 267   GCCause::Cause gc_cause = heap->gc_cause();
 268   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 269 
 270   // Check for potential problems.
 271   if (!should_attempt_scavenge()) {
 272     return false;
 273   }
 274 
 275   bool promotion_failure_occurred = false;
 276 
 277   PSYoungGen* young_gen = heap->young_gen();
 278   PSOldGen* old_gen = heap->old_gen();
 279   PSPermGen* perm_gen = heap->perm_gen();
 280   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
 281   heap->increment_total_collections();
 282 
 283   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
 284 
 285   if ((gc_cause != GCCause::_java_lang_system_gc) ||
 286        UseAdaptiveSizePolicyWithSystemGC) {
 287     // Gather the feedback data for eden occupancy.
 288     young_gen->eden_space()->accumulate_statistics();
 289   }
 290 
 291   if (ZapUnusedHeapArea) {
 292     // Save information needed to minimize mangling
 293     heap->record_gen_tops_before_GC();
 294   }
 295 
 296   if (PrintHeapAtGC) {
 297     Universe::print_heap_before_gc();
 298   }
 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 */);
 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     NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
 353     COMPILER2_PRESENT(DerivedPointerTable::clear());
 354 
 355     reference_processor()->enable_discovery();
 356     reference_processor()->setup_policy(false);
 357 
 358     // We track how much was promoted to the next generation for
 359     // the AdaptiveSizePolicy.
 360     size_t old_gen_used_before = old_gen->used_in_bytes();
 361 
 362     // For PrintGCDetails
 363     size_t young_gen_used_before = young_gen->used_in_bytes();
 364 
 365     // Reset our survivor overflow.
 366     set_survivor_overflow(false);
 367 
 368     // We need to save the old/perm top values before
 369     // creating the promotion_manager. We pass the top
 370     // values to the card_table, to prevent it from
 371     // straying into the promotion labs.
 372     HeapWord* old_top = old_gen->object_space()->top();
 373     HeapWord* perm_top = perm_gen->object_space()->top();
 374 
 375     // Release all previously held resources
 376     gc_task_manager()->release_all_resources();
 377 
 378     PSPromotionManager::pre_scavenge();
 379 
 380     // We'll use the promotion manager again later.
 381     PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
 382     {
 383       // TraceTime("Roots");
 384       ParallelScavengeHeap::ParStrongRootsScope psrs;
 385 
 386       GCTaskQueue* q = GCTaskQueue::create();
 387 
 388       for(uint i=0; i<ParallelGCThreads; i++) {
 389         q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i));
 390       }
 391 
 392       q->enqueue(new SerialOldToYoungRootsTask(perm_gen, perm_top));
 393 
 394       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
 395       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
 396       // We scan the thread roots in parallel
 397       Threads::create_thread_roots_tasks(q);
 398       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
 399       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
 400       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
 401       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
 402       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
 403       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
 404 
 405       ParallelTaskTerminator terminator(
 406                   gc_task_manager()->workers(),
 407                   (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
 408       if (ParallelGCThreads>1) {
 409         for (uint j=0; j<ParallelGCThreads; j++) {
 410           q->enqueue(new StealTask(&terminator));
 411         }
 412       }
 413 
 414       gc_task_manager()->execute_and_wait(q);
 415     }
 416 
 417     scavenge_midpoint.update();
 418 
 419     // Process reference objects discovered during scavenge
 420     {
 421       reference_processor()->setup_policy(false); // not always_clear
 422       PSKeepAliveClosure keep_alive(promotion_manager);
 423       PSEvacuateFollowersClosure evac_followers(promotion_manager);
 424       if (reference_processor()->processing_is_mt()) {
 425         PSRefProcTaskExecutor task_executor;
 426         reference_processor()->process_discovered_references(
 427           &_is_alive_closure, &keep_alive, &evac_followers, &task_executor);
 428       } else {
 429         reference_processor()->process_discovered_references(
 430           &_is_alive_closure, &keep_alive, &evac_followers, NULL);
 431       }
 432     }
 433 
 434     // Enqueue reference objects discovered during scavenge.
 435     if (reference_processor()->processing_is_mt()) {
 436       PSRefProcTaskExecutor task_executor;
 437       reference_processor()->enqueue_discovered_references(&task_executor);
 438     } else {
 439       reference_processor()->enqueue_discovered_references(NULL);
 440     }
 441 
 442     // Finally, flush the promotion_manager's labs, and deallocate its stacks.
 443     PSPromotionManager::post_scavenge();
 444 
 445     promotion_failure_occurred = promotion_failed();
 446     if (promotion_failure_occurred) {
 447       clean_up_failed_promotion();
 448       if (PrintGC) {
 449         gclog_or_tty->print("--");
 450       }
 451     }
 452 
 453     // Let the size policy know we're done.  Note that we count promotion
 454     // failure cleanup time as part of the collection (otherwise, we're
 455     // implicitly saying it's mutator time).
 456     size_policy->minor_collection_end(gc_cause);
 457 
 458     if (!promotion_failure_occurred) {
 459       // Swap the survivor spaces.
 460 
 461 
 462       young_gen->eden_space()->clear(SpaceDecorator::Mangle);
 463       young_gen->from_space()->clear(SpaceDecorator::Mangle);
 464       young_gen->swap_spaces();
 465 
 466       size_t survived = young_gen->from_space()->used_in_bytes();
 467       size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
 468       size_policy->update_averages(_survivor_overflow, survived, promoted);
 469 
 470       // A successful scavenge should restart the GC time limit count which is
 471       // for full GC's.
 472       size_policy->reset_gc_overhead_limit_count();
 473       if (UseAdaptiveSizePolicy) {
 474         // Calculate the new survivor size and tenuring threshold
 475 
 476         if (PrintAdaptiveSizePolicy) {
 477           gclog_or_tty->print("AdaptiveSizeStart: ");
 478           gclog_or_tty->stamp();
 479           gclog_or_tty->print_cr(" collection: %d ",
 480                          heap->total_collections());
 481 
 482           if (Verbose) {
 483             gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
 484               " perm_gen_capacity: %d ",
 485               old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
 486               perm_gen->capacity_in_bytes());
 487           }
 488         }
 489 
 490 
 491         if (UsePerfData) {
 492           PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 493           counters->update_old_eden_size(
 494             size_policy->calculated_eden_size_in_bytes());
 495           counters->update_old_promo_size(
 496             size_policy->calculated_promo_size_in_bytes());
 497           counters->update_old_capacity(old_gen->capacity_in_bytes());
 498           counters->update_young_capacity(young_gen->capacity_in_bytes());
 499           counters->update_survived(survived);
 500           counters->update_promoted(promoted);
 501           counters->update_survivor_overflowed(_survivor_overflow);
 502         }
 503 
 504         size_t survivor_limit =
 505           size_policy->max_survivor_size(young_gen->max_size());
 506         _tenuring_threshold =
 507           size_policy->compute_survivor_space_size_and_threshold(
 508                                                            _survivor_overflow,
 509                                                            _tenuring_threshold,
 510                                                            survivor_limit);
 511 
 512        if (PrintTenuringDistribution) {
 513          gclog_or_tty->cr();
 514          gclog_or_tty->print_cr("Desired survivor size %ld bytes, new threshold %d (max %d)",
 515                                 size_policy->calculated_survivor_size_in_bytes(),
 516                                 _tenuring_threshold, MaxTenuringThreshold);
 517        }
 518 
 519         if (UsePerfData) {
 520           PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 521           counters->update_tenuring_threshold(_tenuring_threshold);
 522           counters->update_survivor_size_counters();
 523         }
 524 
 525         // Do call at minor collections?
 526         // Don't check if the size_policy is ready at this
 527         // level.  Let the size_policy check that internally.
 528         if (UseAdaptiveSizePolicy &&
 529             UseAdaptiveGenerationSizePolicyAtMinorCollection &&
 530             ((gc_cause != GCCause::_java_lang_system_gc) ||
 531               UseAdaptiveSizePolicyWithSystemGC)) {
 532 
 533           // Calculate optimial free space amounts
 534           assert(young_gen->max_size() >
 535             young_gen->from_space()->capacity_in_bytes() +
 536             young_gen->to_space()->capacity_in_bytes(),
 537             "Sizes of space in young gen are out-of-bounds");
 538           size_t max_eden_size = young_gen->max_size() -
 539             young_gen->from_space()->capacity_in_bytes() -
 540             young_gen->to_space()->capacity_in_bytes();
 541           size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
 542                                    young_gen->eden_space()->used_in_bytes(),
 543                                    old_gen->used_in_bytes(),
 544                                    perm_gen->used_in_bytes(),
 545                                    young_gen->eden_space()->capacity_in_bytes(),
 546                                    old_gen->max_gen_size(),
 547                                    max_eden_size,
 548                                    false  /* full gc*/,
 549                                    gc_cause,
 550                                    heap->collector_policy());
 551 
 552         }
 553         // Resize the young generation at every collection
 554         // even if new sizes have not been calculated.  This is
 555         // to allow resizes that may have been inhibited by the
 556         // relative location of the "to" and "from" spaces.
 557 
 558         // Resizing the old gen at minor collects can cause increases
 559         // that don't feed back to the generation sizing policy until
 560         // a major collection.  Don't resize the old gen here.
 561 
 562         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
 563                         size_policy->calculated_survivor_size_in_bytes());
 564 
 565         if (PrintAdaptiveSizePolicy) {
 566           gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
 567                          heap->total_collections());
 568         }
 569       }
 570 
 571       // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
 572       // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
 573       // Also update() will case adaptive NUMA chunk resizing.
 574       assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
 575       young_gen->eden_space()->update();
 576 
 577       heap->gc_policy_counters()->update_counters();
 578 
 579       heap->resize_all_tlabs();
 580 
 581       assert(young_gen->to_space()->is_empty(), "to space should be empty now");
 582     }
 583 
 584     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 585 
 586     NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
 587 
 588     // Re-verify object start arrays
 589     if (VerifyObjectStartArray &&
 590         VerifyAfterGC) {
 591       old_gen->verify_object_start_array();
 592       perm_gen->verify_object_start_array();
 593     }
 594 
 595     // Verify all old -> young cards are now precise
 596     if (VerifyRememberedSets) {
 597       // Precise verification will give false positives. Until this is fixed,
 598       // use imprecise verification.
 599       // CardTableExtension::verify_all_young_refs_precise();
 600       CardTableExtension::verify_all_young_refs_imprecise();
 601     }
 602 
 603     if (TraceGen0Time) accumulated_time()->stop();
 604 
 605     if (PrintGC) {
 606       if (PrintGCDetails) {
 607         // Don't print a GC timestamp here.  This is after the GC so
 608         // would be confusing.
 609         young_gen->print_used_change(young_gen_used_before);
 610       }
 611       heap->print_heap_change(prev_used);
 612     }
 613 
 614     // Track memory usage and detect low memory
 615     MemoryService::track_memory_usage();
 616     heap->update_counters();
 617   }
 618 
 619   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
 620     HandleMark hm;  // Discard invalid handles created during verification
 621     gclog_or_tty->print(" VerifyAfterGC:");
 622     Universe::verify(false);
 623   }
 624 
 625   if (PrintHeapAtGC) {
 626     Universe::print_heap_after_gc();
 627   }
 628 
 629   if (ZapUnusedHeapArea) {
 630     young_gen->eden_space()->check_mangled_unused_area_complete();
 631     young_gen->from_space()->check_mangled_unused_area_complete();
 632     young_gen->to_space()->check_mangled_unused_area_complete();
 633   }
 634 
 635   scavenge_exit.update();
 636 
 637   if (PrintGCTaskTimeStamps) {
 638     tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
 639                   scavenge_entry.ticks(), scavenge_midpoint.ticks(),
 640                   scavenge_exit.ticks());
 641     gc_task_manager()->print_task_time_stamps();
 642   }
 643 
 644 #ifdef TRACESPINNING
 645   ParallelTaskTerminator::print_termination_counts();
 646 #endif
 647 
 648   return !promotion_failure_occurred;
 649 }
 650 
 651 // This method iterates over all objects in the young generation,
 652 // unforwarding markOops. It then restores any preserved mark oops,
 653 // and clears the _preserved_mark_stack.
 654 void PSScavenge::clean_up_failed_promotion() {
 655   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 656   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 657   assert(promotion_failed(), "Sanity");
 658 
 659   PSYoungGen* young_gen = heap->young_gen();
 660 
 661   {
 662     ResourceMark rm;
 663 
 664     // Unforward all pointers in the young gen.
 665     PSPromotionFailedClosure unforward_closure;
 666     young_gen->object_iterate(&unforward_closure);
 667 
 668     if (PrintGC && Verbose) {
 669       gclog_or_tty->print_cr("Restoring %d marks", _preserved_oop_stack.size());
 670     }
 671 
 672     // Restore any saved marks.
 673     while (!_preserved_oop_stack.is_empty()) {
 674       oop obj      = _preserved_oop_stack.pop();
 675       markOop mark = _preserved_mark_stack.pop();
 676       obj->set_mark(mark);
 677     }
 678 
 679     // Clear the preserved mark and oop stack caches.
 680     _preserved_mark_stack.clear(true);
 681     _preserved_oop_stack.clear(true);
 682     _promotion_failed = false;
 683   }
 684 
 685   // Reset the PromotionFailureALot counters.
 686   NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
 687 }
 688 
 689 // This method is called whenever an attempt to promote an object
 690 // fails. Some markOops will need preservation, some will not. Note
 691 // that the entire eden is traversed after a failed promotion, with
 692 // all forwarded headers replaced by the default markOop. This means
 693 // it is not neccessary to preserve most markOops.
 694 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
 695   _promotion_failed = true;
 696   if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
 697     // Should use per-worker private stakcs hetre rather than
 698     // locking a common pair of stacks.
 699     ThreadCritical tc;
 700     _preserved_oop_stack.push(obj);
 701     _preserved_mark_stack.push(obj_mark);
 702   }
 703 }
 704 
 705 bool PSScavenge::should_attempt_scavenge() {
 706   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 707   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 708   PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 709 
 710   if (UsePerfData) {
 711     counters->update_scavenge_skipped(not_skipped);
 712   }
 713 
 714   PSYoungGen* young_gen = heap->young_gen();
 715   PSOldGen* old_gen = heap->old_gen();
 716 
 717   if (!ScavengeWithObjectsInToSpace) {
 718     // Do not attempt to promote unless to_space is empty
 719     if (!young_gen->to_space()->is_empty()) {
 720       _consecutive_skipped_scavenges++;
 721       if (UsePerfData) {
 722         counters->update_scavenge_skipped(to_space_not_empty);
 723       }
 724       return false;
 725     }
 726   }
 727 
 728   // Test to see if the scavenge will likely fail.
 729   PSAdaptiveSizePolicy* policy = heap->size_policy();
 730 
 731   // A similar test is done in the policy's should_full_GC().  If this is
 732   // changed, decide if that test should also be changed.
 733   size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
 734   size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
 735   bool result = promotion_estimate < old_gen->free_in_bytes();
 736 
 737   if (PrintGCDetails && Verbose) {
 738     gclog_or_tty->print(result ? "  do scavenge: " : "  skip scavenge: ");
 739     gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
 740       " padded_average_promoted " SIZE_FORMAT
 741       " free in old gen " SIZE_FORMAT,
 742       (size_t) policy->average_promoted_in_bytes(),
 743       (size_t) policy->padded_average_promoted_in_bytes(),
 744       old_gen->free_in_bytes());
 745     if (young_gen->used_in_bytes() <
 746         (size_t) policy->padded_average_promoted_in_bytes()) {
 747       gclog_or_tty->print_cr(" padded_promoted_average is greater"
 748         " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
 749     }
 750   }
 751 
 752   if (result) {
 753     _consecutive_skipped_scavenges = 0;
 754   } else {
 755     _consecutive_skipped_scavenges++;
 756     if (UsePerfData) {
 757       counters->update_scavenge_skipped(promoted_too_large);
 758     }
 759   }
 760   return result;
 761 }
 762 
 763   // Used to add tasks
 764 GCTaskManager* const PSScavenge::gc_task_manager() {
 765   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
 766    "shouldn't return NULL");
 767   return ParallelScavengeHeap::gc_task_manager();
 768 }
 769 
 770 void PSScavenge::initialize() {
 771   // Arguments must have been parsed
 772 
 773   if (AlwaysTenure) {
 774     _tenuring_threshold = 0;
 775   } else if (NeverTenure) {
 776     _tenuring_threshold = markOopDesc::max_age + 1;
 777   } else {
 778     // We want to smooth out our startup times for the AdaptiveSizePolicy
 779     _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
 780                                                     MaxTenuringThreshold;
 781   }
 782 
 783   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 784   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 785 
 786   PSYoungGen* young_gen = heap->young_gen();
 787   PSOldGen* old_gen = heap->old_gen();
 788   PSPermGen* perm_gen = heap->perm_gen();
 789 
 790   // Set boundary between young_gen and old_gen
 791   assert(perm_gen->reserved().end() <= old_gen->object_space()->bottom(),
 792          "perm above old");
 793   assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
 794          "old above young");
 795   _young_generation_boundary = young_gen->eden_space()->bottom();
 796 
 797   // Initialize ref handling object for scavenging.
 798   MemRegion mr = young_gen->reserved();
 799   _ref_processor = ReferenceProcessor::create_ref_processor(
 800     mr,                         // span
 801     true,                       // atomic_discovery
 802     true,                       // mt_discovery
 803     NULL,                       // is_alive_non_header
 804     ParallelGCThreads,
 805     ParallelRefProcEnabled);
 806 
 807   // Cache the cardtable
 808   BarrierSet* bs = Universe::heap()->barrier_set();
 809   assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
 810   _card_table = (CardTableExtension*)bs;
 811 
 812   _counters = new CollectorCounters("PSScavenge", 0);
 813 }