rev 6446 : [mq]: ref-write-new-fix

   1 
   2 /*
   3  * Copyright (c) 2002, 2014, Oracle and/or its affiliates. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #include "precompiled.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "gc_implementation/parallelScavenge/cardTableExtension.hpp"
  30 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
  31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
  32 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
  33 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
  34 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
  35 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
  36 #include "gc_implementation/parallelScavenge/psTasks.hpp"
  37 #include "gc_implementation/shared/gcHeapSummary.hpp"
  38 #include "gc_implementation/shared/gcTimer.hpp"
  39 #include "gc_implementation/shared/gcTrace.hpp"
  40 #include "gc_implementation/shared/gcTraceTime.hpp"
  41 #include "gc_implementation/shared/isGCActiveMark.hpp"
  42 #include "gc_implementation/shared/spaceDecorator.hpp"
  43 #include "gc_interface/gcCause.hpp"
  44 #include "memory/collectorPolicy.hpp"
  45 #include "memory/gcLocker.inline.hpp"
  46 #include "memory/referencePolicy.hpp"
  47 #include "memory/referenceProcessor.hpp"
  48 #include "memory/resourceArea.hpp"
  49 #include "oops/oop.inline.hpp"
  50 #include "oops/oop.psgc.inline.hpp"
  51 #include "runtime/biasedLocking.hpp"
  52 #include "runtime/fprofiler.hpp"
  53 #include "runtime/handles.inline.hpp"
  54 #include "runtime/threadCritical.hpp"
  55 #include "runtime/vmThread.hpp"
  56 #include "runtime/vm_operations.hpp"
  57 #include "services/memoryService.hpp"
  58 #include "utilities/stack.inline.hpp"
  59 
  60 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
  61 
  62 HeapWord*                  PSScavenge::_to_space_top_before_gc = NULL;
  63 int                        PSScavenge::_consecutive_skipped_scavenges = 0;
  64 ReferenceProcessor*        PSScavenge::_ref_processor = NULL;
  65 CardTableExtension*        PSScavenge::_card_table = NULL;
  66 bool                       PSScavenge::_survivor_overflow = false;
  67 uint                       PSScavenge::_tenuring_threshold = 0;
  68 HeapWord*                  PSScavenge::_young_generation_boundary = NULL;
  69 uintptr_t                  PSScavenge::_young_generation_boundary_compressed = 0;
  70 elapsedTimer               PSScavenge::_accumulated_time;
  71 STWGCTimer                 PSScavenge::_gc_timer;
  72 ParallelScavengeTracer     PSScavenge::_gc_tracer;
  73 Stack<markOop, mtGC>       PSScavenge::_preserved_mark_stack;
  74 Stack<oop, mtGC>           PSScavenge::_preserved_oop_stack;
  75 CollectorCounters*         PSScavenge::_counters = NULL;
  76 
  77 // Define before use
  78 class PSIsAliveClosure: public BoolObjectClosure {
  79 public:
  80   bool do_object_b(oop p) {
  81     return (!PSScavenge::is_obj_in_young(p)) || p->is_forwarded();
  82   }
  83 };
  84 
  85 PSIsAliveClosure PSScavenge::_is_alive_closure;
  86 
  87 class PSKeepAliveClosure: public OopClosure {
  88 protected:
  89   MutableSpace* _to_space;
  90   PSPromotionManager* _promotion_manager;
  91 
  92 public:
  93   PSKeepAliveClosure(PSPromotionManager* pm) : _promotion_manager(pm) {
  94     ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  95     assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
  96     _to_space = heap->young_gen()->to_space();
  97 
  98     assert(_promotion_manager != NULL, "Sanity");
  99   }
 100 
 101   template <class T> void do_oop_work(T* p) {
 102     assert (!oopDesc::is_null(*p), "expected non-null ref");
 103     assert ((oopDesc::load_decode_heap_oop_not_null(p))->is_oop(),
 104             "expected an oop while scanning weak refs");
 105 
 106     // Weak refs may be visited more than once.
 107     if (PSScavenge::should_scavenge(p, _to_space)) {
 108       PSScavenge::copy_and_push_safe_barrier<T, /*promote_immediately=*/false>(_promotion_manager, p);
 109     }
 110   }
 111   virtual void do_oop(oop* p)       { PSKeepAliveClosure::do_oop_work(p); }
 112   virtual void do_oop(narrowOop* p) { PSKeepAliveClosure::do_oop_work(p); }
 113 };
 114 
 115 class PSEvacuateFollowersClosure: public VoidClosure {
 116  private:
 117   PSPromotionManager* _promotion_manager;
 118  public:
 119   PSEvacuateFollowersClosure(PSPromotionManager* pm) : _promotion_manager(pm) {}
 120 
 121   virtual void do_void() {
 122     assert(_promotion_manager != NULL, "Sanity");
 123     _promotion_manager->drain_stacks(true);
 124     guarantee(_promotion_manager->stacks_empty(),
 125               "stacks should be empty at this point");
 126   }
 127 };
 128 
 129 class PSPromotionFailedClosure : public ObjectClosure {
 130   virtual void do_object(oop obj) {
 131     if (obj->is_forwarded()) {
 132       obj->init_mark();
 133     }
 134   }
 135 };
 136 
 137 class PSRefProcTaskProxy: public GCTask {
 138   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
 139   ProcessTask & _rp_task;
 140   uint          _work_id;
 141 public:
 142   PSRefProcTaskProxy(ProcessTask & rp_task, uint work_id)
 143     : _rp_task(rp_task),
 144       _work_id(work_id)
 145   { }
 146 
 147 private:
 148   virtual char* name() { return (char *)"Process referents by policy in parallel"; }
 149   virtual void do_it(GCTaskManager* manager, uint which);
 150 };
 151 
 152 void PSRefProcTaskProxy::do_it(GCTaskManager* manager, uint which)
 153 {
 154   PSPromotionManager* promotion_manager =
 155     PSPromotionManager::gc_thread_promotion_manager(which);
 156   assert(promotion_manager != NULL, "sanity check");
 157   PSKeepAliveClosure keep_alive(promotion_manager);
 158   PSEvacuateFollowersClosure evac_followers(promotion_manager);
 159   PSIsAliveClosure is_alive;
 160   _rp_task.work(_work_id, is_alive, keep_alive, evac_followers);
 161 }
 162 
 163 class PSRefEnqueueTaskProxy: public GCTask {
 164   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
 165   EnqueueTask& _enq_task;
 166   uint         _work_id;
 167 
 168 public:
 169   PSRefEnqueueTaskProxy(EnqueueTask& enq_task, uint work_id)
 170     : _enq_task(enq_task),
 171       _work_id(work_id)
 172   { }
 173 
 174   virtual char* name() { return (char *)"Enqueue reference objects in parallel"; }
 175   virtual void do_it(GCTaskManager* manager, uint which)
 176   {
 177     _enq_task.work(_work_id);
 178   }
 179 };
 180 
 181 class PSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
 182   virtual void execute(ProcessTask& task);
 183   virtual void execute(EnqueueTask& task);
 184 };
 185 
 186 void PSRefProcTaskExecutor::execute(ProcessTask& task)
 187 {
 188   GCTaskQueue* q = GCTaskQueue::create();
 189   GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
 190   for(uint i=0; i < manager->active_workers(); i++) {
 191     q->enqueue(new PSRefProcTaskProxy(task, i));
 192   }
 193   ParallelTaskTerminator terminator(manager->active_workers(),
 194                  (TaskQueueSetSuper*) PSPromotionManager::stack_array_depth());
 195   if (task.marks_oops_alive() && manager->active_workers() > 1) {
 196     for (uint j = 0; j < manager->active_workers(); j++) {
 197       q->enqueue(new StealTask(&terminator));
 198     }
 199   }
 200   manager->execute_and_wait(q);
 201 }
 202 
 203 
 204 void PSRefProcTaskExecutor::execute(EnqueueTask& task)
 205 {
 206   GCTaskQueue* q = GCTaskQueue::create();
 207   GCTaskManager* manager = ParallelScavengeHeap::gc_task_manager();
 208   for(uint i=0; i < manager->active_workers(); i++) {
 209     q->enqueue(new PSRefEnqueueTaskProxy(task, i));
 210   }
 211   manager->execute_and_wait(q);
 212 }
 213 
 214 // This method contains all heap specific policy for invoking scavenge.
 215 // PSScavenge::invoke_no_policy() will do nothing but attempt to
 216 // scavenge. It will not clean up after failed promotions, bail out if
 217 // we've exceeded policy time limits, or any other special behavior.
 218 // All such policy should be placed here.
 219 //
 220 // Note that this method should only be called from the vm_thread while
 221 // at a safepoint!
 222 bool PSScavenge::invoke() {
 223   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 224   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 225   assert(!Universe::heap()->is_gc_active(), "not reentrant");
 226 
 227   ParallelScavengeHeap* const heap = (ParallelScavengeHeap*)Universe::heap();
 228   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 229 
 230   PSAdaptiveSizePolicy* policy = heap->size_policy();
 231   IsGCActiveMark mark;
 232 
 233   const bool scavenge_done = PSScavenge::invoke_no_policy();
 234   const bool need_full_gc = !scavenge_done ||
 235     policy->should_full_GC(heap->old_gen()->free_in_bytes());
 236   bool full_gc_done = false;
 237 
 238   if (UsePerfData) {
 239     PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
 240     const int ffs_val = need_full_gc ? full_follows_scavenge : not_skipped;
 241     counters->update_full_follows_scavenge(ffs_val);
 242   }
 243 
 244   if (need_full_gc) {
 245     GCCauseSetter gccs(heap, GCCause::_adaptive_size_policy);
 246     CollectorPolicy* cp = heap->collector_policy();
 247     const bool clear_all_softrefs = cp->should_clear_all_soft_refs();
 248 
 249     if (UseParallelOldGC) {
 250       full_gc_done = PSParallelCompact::invoke_no_policy(clear_all_softrefs);
 251     } else {
 252       full_gc_done = PSMarkSweep::invoke_no_policy(clear_all_softrefs);
 253     }
 254   }
 255 
 256   return full_gc_done;
 257 }
 258 
 259 // This method contains no policy. You should probably
 260 // be calling invoke() instead.
 261 bool PSScavenge::invoke_no_policy() {
 262   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 263   assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
 264 
 265   assert(_preserved_mark_stack.is_empty(), "should be empty");
 266   assert(_preserved_oop_stack.is_empty(), "should be empty");
 267 
 268   _gc_timer.register_gc_start();
 269 
 270   TimeStamp scavenge_entry;
 271   TimeStamp scavenge_midpoint;
 272   TimeStamp scavenge_exit;
 273 
 274   scavenge_entry.update();
 275 
 276   if (GC_locker::check_active_before_gc()) {
 277     return false;
 278   }
 279 
 280   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 281   GCCause::Cause gc_cause = heap->gc_cause();
 282   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 283 
 284   // Check for potential problems.
 285   if (!should_attempt_scavenge()) {
 286     return false;
 287   }
 288 
 289   _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
 290 
 291   bool promotion_failure_occurred = false;
 292 
 293   PSYoungGen* young_gen = heap->young_gen();
 294   PSOldGen* old_gen = heap->old_gen();
 295   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
 296 
 297   heap->increment_total_collections();
 298 
 299   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
 300 
 301   if ((gc_cause != GCCause::_java_lang_system_gc) ||
 302        UseAdaptiveSizePolicyWithSystemGC) {
 303     // Gather the feedback data for eden occupancy.
 304     young_gen->eden_space()->accumulate_statistics();
 305   }
 306 
 307   if (ZapUnusedHeapArea) {
 308     // Save information needed to minimize mangling
 309     heap->record_gen_tops_before_GC();
 310   }
 311 
 312   heap->print_heap_before_gc();
 313   heap->trace_heap_before_gc(&_gc_tracer);
 314 
 315   assert(!NeverTenure || _tenuring_threshold == markOopDesc::max_age + 1, "Sanity");
 316   assert(!AlwaysTenure || _tenuring_threshold == 0, "Sanity");
 317 
 318   size_t prev_used = heap->used();
 319 
 320   // Fill in TLABs
 321   heap->accumulate_statistics_all_tlabs();
 322   heap->ensure_parsability(true);  // retire TLABs
 323 
 324   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 325     HandleMark hm;  // Discard invalid handles created during verification
 326     Universe::verify(" VerifyBeforeGC:");
 327   }
 328 
 329   {
 330     ResourceMark rm;
 331     HandleMark hm;
 332 
 333     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 334     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 335     GCTraceTime t1(GCCauseString("GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
 336     TraceCollectorStats tcs(counters());
 337     TraceMemoryManagerStats tms(false /* not full GC */,gc_cause);
 338 
 339     if (TraceGen0Time) accumulated_time()->start();
 340 
 341     // Let the size policy know we're starting
 342     size_policy->minor_collection_begin();
 343 
 344     // Verify the object start arrays.
 345     if (VerifyObjectStartArray &&
 346         VerifyBeforeGC) {
 347       old_gen->verify_object_start_array();
 348     }
 349 
 350     // Verify no unmarked old->young roots
 351     if (VerifyRememberedSets) {
 352       CardTableExtension::verify_all_young_refs_imprecise();
 353     }
 354 
 355     if (!ScavengeWithObjectsInToSpace) {
 356       assert(young_gen->to_space()->is_empty(),
 357              "Attempt to scavenge with live objects in to_space");
 358       young_gen->to_space()->clear(SpaceDecorator::Mangle);
 359     } else if (ZapUnusedHeapArea) {
 360       young_gen->to_space()->mangle_unused_area();
 361     }
 362     save_to_space_top_before_gc();
 363 
 364     COMPILER2_PRESENT(DerivedPointerTable::clear());
 365 
 366     reference_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
 367     reference_processor()->setup_policy(false);
 368 
 369     // We track how much was promoted to the next generation for
 370     // the AdaptiveSizePolicy.
 371     size_t old_gen_used_before = old_gen->used_in_bytes();
 372 
 373     // For PrintGCDetails
 374     size_t young_gen_used_before = young_gen->used_in_bytes();
 375 
 376     // Reset our survivor overflow.
 377     set_survivor_overflow(false);
 378 
 379     // We need to save the old top values before
 380     // creating the promotion_manager. We pass the top
 381     // values to the card_table, to prevent it from
 382     // straying into the promotion labs.
 383     HeapWord* old_top = old_gen->object_space()->top();
 384 
 385     // Release all previously held resources
 386     gc_task_manager()->release_all_resources();
 387 
 388     // Set the number of GC threads to be used in this collection
 389     gc_task_manager()->set_active_gang();
 390     gc_task_manager()->task_idle_workers();
 391     // Get the active number of workers here and use that value
 392     // throughout the methods.
 393     uint active_workers = gc_task_manager()->active_workers();
 394     heap->set_par_threads(active_workers);
 395 
 396     PSPromotionManager::pre_scavenge();
 397 
 398     // We'll use the promotion manager again later.
 399     PSPromotionManager* promotion_manager = PSPromotionManager::vm_thread_promotion_manager();
 400     {
 401       GCTraceTime tm("Scavenge", false, false, &_gc_timer);
 402       ParallelScavengeHeap::ParStrongRootsScope psrs;
 403 
 404       GCTaskQueue* q = GCTaskQueue::create();
 405 
 406       if (!old_gen->object_space()->is_empty()) {
 407         // There are only old-to-young pointers if there are objects
 408         // in the old gen.
 409         uint stripe_total = active_workers;
 410         for(uint i=0; i < stripe_total; i++) {
 411           q->enqueue(new OldToYoungRootsTask(old_gen, old_top, i, stripe_total));
 412         }
 413       }
 414 
 415       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::universe));
 416       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jni_handles));
 417       // We scan the thread roots in parallel
 418       Threads::create_thread_roots_tasks(q);
 419       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::object_synchronizer));
 420       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::flat_profiler));
 421       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::management));
 422       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::system_dictionary));
 423       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::class_loader_data));
 424       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::jvmti));
 425       q->enqueue(new ScavengeRootsTask(ScavengeRootsTask::code_cache));
 426 
 427       ParallelTaskTerminator terminator(
 428         active_workers,
 429                   (TaskQueueSetSuper*) promotion_manager->stack_array_depth());
 430       if (active_workers > 1) {
 431         for (uint j = 0; j < active_workers; j++) {
 432           q->enqueue(new StealTask(&terminator));
 433         }
 434       }
 435 
 436       gc_task_manager()->execute_and_wait(q);
 437     }
 438 
 439     scavenge_midpoint.update();
 440 
 441     // Process reference objects discovered during scavenge
 442     {
 443       GCTraceTime tm("References", false, false, &_gc_timer);
 444 
 445       reference_processor()->setup_policy(false); // not always_clear
 446       reference_processor()->set_active_mt_degree(active_workers);
 447       PSKeepAliveClosure keep_alive(promotion_manager);
 448       PSEvacuateFollowersClosure evac_followers(promotion_manager);
 449       ReferenceProcessorStats stats;
 450       if (reference_processor()->processing_is_mt()) {
 451         PSRefProcTaskExecutor task_executor;
 452         stats = reference_processor()->process_discovered_references(
 453           &_is_alive_closure, &keep_alive, &evac_followers, &task_executor,
 454           &_gc_timer);
 455       } else {
 456         stats = reference_processor()->process_discovered_references(
 457           &_is_alive_closure, &keep_alive, &evac_followers, NULL, &_gc_timer);
 458       }
 459 
 460       _gc_tracer.report_gc_reference_stats(stats);
 461 
 462       // Enqueue reference objects discovered during scavenge.
 463       if (reference_processor()->processing_is_mt()) {
 464         PSRefProcTaskExecutor task_executor;
 465         reference_processor()->enqueue_discovered_references(&task_executor);
 466       } else {
 467         reference_processor()->enqueue_discovered_references(NULL);
 468       }
 469     }
 470 
 471     {
 472       GCTraceTime tm("StringTable", false, false, &_gc_timer);
 473       // Unlink any dead interned Strings and process the remaining live ones.
 474       PSScavengeRootsClosure root_closure(promotion_manager);
 475       StringTable::unlink_or_oops_do(&_is_alive_closure, &root_closure);
 476     }
 477 
 478     // Finally, flush the promotion_manager's labs, and deallocate its stacks.
 479     promotion_failure_occurred = PSPromotionManager::post_scavenge(_gc_tracer);
 480     if (promotion_failure_occurred) {
 481       clean_up_failed_promotion();
 482       if (PrintGC) {
 483         gclog_or_tty->print("--");
 484       }
 485     }
 486 
 487     // Let the size policy know we're done.  Note that we count promotion
 488     // failure cleanup time as part of the collection (otherwise, we're
 489     // implicitly saying it's mutator time).
 490     size_policy->minor_collection_end(gc_cause);
 491 
 492     if (!promotion_failure_occurred) {
 493       // Swap the survivor spaces.
 494       young_gen->eden_space()->clear(SpaceDecorator::Mangle);
 495       young_gen->from_space()->clear(SpaceDecorator::Mangle);
 496       young_gen->swap_spaces();
 497 
 498       size_t survived = young_gen->from_space()->used_in_bytes();
 499       size_t promoted = old_gen->used_in_bytes() - old_gen_used_before;
 500       size_policy->update_averages(_survivor_overflow, survived, promoted);
 501 
 502       // A successful scavenge should restart the GC time limit count which is
 503       // for full GC's.
 504       size_policy->reset_gc_overhead_limit_count();
 505       if (UseAdaptiveSizePolicy) {
 506         // Calculate the new survivor size and tenuring threshold
 507 
 508         if (PrintAdaptiveSizePolicy) {
 509           gclog_or_tty->print("AdaptiveSizeStart: ");
 510           gclog_or_tty->stamp();
 511           gclog_or_tty->print_cr(" collection: %d ",
 512                          heap->total_collections());
 513 
 514           if (Verbose) {
 515             gclog_or_tty->print("old_gen_capacity: " SIZE_FORMAT
 516               " young_gen_capacity: " SIZE_FORMAT,
 517               old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
 518           }
 519         }
 520 
 521 
 522         if (UsePerfData) {
 523           PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 524           counters->update_old_eden_size(
 525             size_policy->calculated_eden_size_in_bytes());
 526           counters->update_old_promo_size(
 527             size_policy->calculated_promo_size_in_bytes());
 528           counters->update_old_capacity(old_gen->capacity_in_bytes());
 529           counters->update_young_capacity(young_gen->capacity_in_bytes());
 530           counters->update_survived(survived);
 531           counters->update_promoted(promoted);
 532           counters->update_survivor_overflowed(_survivor_overflow);
 533         }
 534 
 535         size_t max_young_size = young_gen->max_size();
 536 
 537         // Deciding a free ratio in the young generation is tricky, so if
 538         // MinHeapFreeRatio or MaxHeapFreeRatio are in use (implicating
 539         // that the old generation size may have been limited because of them) we
 540         // should then limit our young generation size using NewRatio to have it
 541         // follow the old generation size.
 542         if (MinHeapFreeRatio != 0 || MaxHeapFreeRatio != 100) {
 543           max_young_size = MIN2(old_gen->capacity_in_bytes() / NewRatio, young_gen->max_size());
 544         }
 545 
 546         size_t survivor_limit =
 547           size_policy->max_survivor_size(max_young_size);
 548         _tenuring_threshold =
 549           size_policy->compute_survivor_space_size_and_threshold(
 550                                                            _survivor_overflow,
 551                                                            _tenuring_threshold,
 552                                                            survivor_limit);
 553 
 554        if (PrintTenuringDistribution) {
 555          gclog_or_tty->cr();
 556          gclog_or_tty->print_cr("Desired survivor size " SIZE_FORMAT " bytes, new threshold "
 557                                 UINTX_FORMAT " (max threshold " UINTX_FORMAT ")",
 558                                 size_policy->calculated_survivor_size_in_bytes(),
 559                                 _tenuring_threshold, MaxTenuringThreshold);
 560        }
 561 
 562         if (UsePerfData) {
 563           PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 564           counters->update_tenuring_threshold(_tenuring_threshold);
 565           counters->update_survivor_size_counters();
 566         }
 567 
 568         // Do call at minor collections?
 569         // Don't check if the size_policy is ready at this
 570         // level.  Let the size_policy check that internally.
 571         if (UseAdaptiveGenerationSizePolicyAtMinorCollection &&
 572             ((gc_cause != GCCause::_java_lang_system_gc) ||
 573               UseAdaptiveSizePolicyWithSystemGC)) {
 574 
 575           // Calculate optimal free space amounts
 576           assert(young_gen->max_size() >
 577             young_gen->from_space()->capacity_in_bytes() +
 578             young_gen->to_space()->capacity_in_bytes(),
 579             "Sizes of space in young gen are out-of-bounds");
 580 
 581           size_t young_live = young_gen->used_in_bytes();
 582           size_t eden_live = young_gen->eden_space()->used_in_bytes();
 583           size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
 584           size_t max_old_gen_size = old_gen->max_gen_size();
 585           size_t max_eden_size = max_young_size -
 586             young_gen->from_space()->capacity_in_bytes() -
 587             young_gen->to_space()->capacity_in_bytes();
 588 
 589           // Used for diagnostics
 590           size_policy->clear_generation_free_space_flags();
 591 
 592           size_policy->compute_eden_space_size(young_live,
 593                                                eden_live,
 594                                                cur_eden,
 595                                                max_eden_size,
 596                                                false /* not full gc*/);
 597 
 598           size_policy->check_gc_overhead_limit(young_live,
 599                                                eden_live,
 600                                                max_old_gen_size,
 601                                                max_eden_size,
 602                                                false /* not full gc*/,
 603                                                gc_cause,
 604                                                heap->collector_policy());
 605 
 606           size_policy->decay_supplemental_growth(false /* not full gc*/);
 607         }
 608         // Resize the young generation at every collection
 609         // even if new sizes have not been calculated.  This is
 610         // to allow resizes that may have been inhibited by the
 611         // relative location of the "to" and "from" spaces.
 612 
 613         // Resizing the old gen at minor collects can cause increases
 614         // that don't feed back to the generation sizing policy until
 615         // a major collection.  Don't resize the old gen here.
 616 
 617         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
 618                         size_policy->calculated_survivor_size_in_bytes());
 619 
 620         if (PrintAdaptiveSizePolicy) {
 621           gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
 622                          heap->total_collections());
 623         }
 624       }
 625 
 626       // Update the structure of the eden. With NUMA-eden CPU hotplugging or offlining can
 627       // cause the change of the heap layout. Make sure eden is reshaped if that's the case.
 628       // Also update() will case adaptive NUMA chunk resizing.
 629       assert(young_gen->eden_space()->is_empty(), "eden space should be empty now");
 630       young_gen->eden_space()->update();
 631 
 632       heap->gc_policy_counters()->update_counters();
 633 
 634       heap->resize_all_tlabs();
 635 
 636       assert(young_gen->to_space()->is_empty(), "to space should be empty now");
 637     }
 638 
 639     COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 640 
 641     NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
 642 
 643     {
 644       GCTraceTime tm("Prune Scavenge Root Methods", false, false, &_gc_timer);
 645 
 646       CodeCache::prune_scavenge_root_nmethods();
 647     }
 648 
 649     // Re-verify object start arrays
 650     if (VerifyObjectStartArray &&
 651         VerifyAfterGC) {
 652       old_gen->verify_object_start_array();
 653     }
 654 
 655     // Verify all old -> young cards are now precise
 656     if (VerifyRememberedSets) {
 657       // Precise verification will give false positives. Until this is fixed,
 658       // use imprecise verification.
 659       // CardTableExtension::verify_all_young_refs_precise();
 660       CardTableExtension::verify_all_young_refs_imprecise();
 661     }
 662 
 663     if (TraceGen0Time) accumulated_time()->stop();
 664 
 665     if (PrintGC) {
 666       if (PrintGCDetails) {
 667         // Don't print a GC timestamp here.  This is after the GC so
 668         // would be confusing.
 669         young_gen->print_used_change(young_gen_used_before);
 670       }
 671       heap->print_heap_change(prev_used);
 672     }
 673 
 674     // Track memory usage and detect low memory
 675     MemoryService::track_memory_usage();
 676     heap->update_counters();
 677 
 678     gc_task_manager()->release_idle_workers();
 679   }
 680 
 681   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
 682     HandleMark hm;  // Discard invalid handles created during verification
 683     Universe::verify(" VerifyAfterGC:");
 684   }
 685 
 686   heap->print_heap_after_gc();
 687   heap->trace_heap_after_gc(&_gc_tracer);
 688   _gc_tracer.report_tenuring_threshold(tenuring_threshold());
 689 
 690   if (ZapUnusedHeapArea) {
 691     young_gen->eden_space()->check_mangled_unused_area_complete();
 692     young_gen->from_space()->check_mangled_unused_area_complete();
 693     young_gen->to_space()->check_mangled_unused_area_complete();
 694   }
 695 
 696   scavenge_exit.update();
 697 
 698   if (PrintGCTaskTimeStamps) {
 699     tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " " INT64_FORMAT,
 700                   scavenge_entry.ticks(), scavenge_midpoint.ticks(),
 701                   scavenge_exit.ticks());
 702     gc_task_manager()->print_task_time_stamps();
 703   }
 704 
 705 #ifdef TRACESPINNING
 706   ParallelTaskTerminator::print_termination_counts();
 707 #endif
 708 
 709 
 710   _gc_timer.register_gc_end();
 711 
 712   _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
 713 
 714   return !promotion_failure_occurred;
 715 }
 716 
 717 // This method iterates over all objects in the young generation,
 718 // unforwarding markOops. It then restores any preserved mark oops,
 719 // and clears the _preserved_mark_stack.
 720 void PSScavenge::clean_up_failed_promotion() {
 721   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 722   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 723 
 724   PSYoungGen* young_gen = heap->young_gen();
 725 
 726   {
 727     ResourceMark rm;
 728 
 729     // Unforward all pointers in the young gen.
 730     PSPromotionFailedClosure unforward_closure;
 731     young_gen->object_iterate(&unforward_closure);
 732 
 733     if (PrintGC && Verbose) {
 734       gclog_or_tty->print_cr("Restoring " SIZE_FORMAT " marks", _preserved_oop_stack.size());
 735     }
 736 
 737     // Restore any saved marks.
 738     while (!_preserved_oop_stack.is_empty()) {
 739       oop obj      = _preserved_oop_stack.pop();
 740       markOop mark = _preserved_mark_stack.pop();
 741       obj->set_mark(mark);
 742     }
 743 
 744     // Clear the preserved mark and oop stack caches.
 745     _preserved_mark_stack.clear(true);
 746     _preserved_oop_stack.clear(true);
 747   }
 748 
 749   // Reset the PromotionFailureALot counters.
 750   NOT_PRODUCT(Universe::heap()->reset_promotion_should_fail();)
 751 }
 752 
 753 // This method is called whenever an attempt to promote an object
 754 // fails. Some markOops will need preservation, some will not. Note
 755 // that the entire eden is traversed after a failed promotion, with
 756 // all forwarded headers replaced by the default markOop. This means
 757 // it is not necessary to preserve most markOops.
 758 void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {
 759   if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
 760     // Should use per-worker private stacks here rather than
 761     // locking a common pair of stacks.
 762     ThreadCritical tc;
 763     _preserved_oop_stack.push(obj);
 764     _preserved_mark_stack.push(obj_mark);
 765   }
 766 }
 767 
 768 bool PSScavenge::should_attempt_scavenge() {
 769   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 770   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 771   PSGCAdaptivePolicyCounters* counters = heap->gc_policy_counters();
 772 
 773   if (UsePerfData) {
 774     counters->update_scavenge_skipped(not_skipped);
 775   }
 776 
 777   PSYoungGen* young_gen = heap->young_gen();
 778   PSOldGen* old_gen = heap->old_gen();
 779 
 780   if (!ScavengeWithObjectsInToSpace) {
 781     // Do not attempt to promote unless to_space is empty
 782     if (!young_gen->to_space()->is_empty()) {
 783       _consecutive_skipped_scavenges++;
 784       if (UsePerfData) {
 785         counters->update_scavenge_skipped(to_space_not_empty);
 786       }
 787       return false;
 788     }
 789   }
 790 
 791   // Test to see if the scavenge will likely fail.
 792   PSAdaptiveSizePolicy* policy = heap->size_policy();
 793 
 794   // A similar test is done in the policy's should_full_GC().  If this is
 795   // changed, decide if that test should also be changed.
 796   size_t avg_promoted = (size_t) policy->padded_average_promoted_in_bytes();
 797   size_t promotion_estimate = MIN2(avg_promoted, young_gen->used_in_bytes());
 798   bool result = promotion_estimate < old_gen->free_in_bytes();
 799 
 800   if (PrintGCDetails && Verbose) {
 801     gclog_or_tty->print(result ? "  do scavenge: " : "  skip scavenge: ");
 802     gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
 803       " padded_average_promoted " SIZE_FORMAT
 804       " free in old gen " SIZE_FORMAT,
 805       (size_t) policy->average_promoted_in_bytes(),
 806       (size_t) policy->padded_average_promoted_in_bytes(),
 807       old_gen->free_in_bytes());
 808     if (young_gen->used_in_bytes() <
 809         (size_t) policy->padded_average_promoted_in_bytes()) {
 810       gclog_or_tty->print_cr(" padded_promoted_average is greater"
 811         " than maximum promotion = " SIZE_FORMAT, young_gen->used_in_bytes());
 812     }
 813   }
 814 
 815   if (result) {
 816     _consecutive_skipped_scavenges = 0;
 817   } else {
 818     _consecutive_skipped_scavenges++;
 819     if (UsePerfData) {
 820       counters->update_scavenge_skipped(promoted_too_large);
 821     }
 822   }
 823   return result;
 824 }
 825 
 826   // Used to add tasks
 827 GCTaskManager* const PSScavenge::gc_task_manager() {
 828   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
 829    "shouldn't return NULL");
 830   return ParallelScavengeHeap::gc_task_manager();
 831 }
 832 
 833 void PSScavenge::initialize() {
 834   // Arguments must have been parsed
 835 
 836   if (AlwaysTenure || NeverTenure) {
 837     assert(MaxTenuringThreshold == 0 || MaxTenuringThreshold == markOopDesc::max_age + 1,
 838         err_msg("MaxTenuringThreshold should be 0 or markOopDesc::max_age + 1, but is %d", (int) MaxTenuringThreshold));
 839     _tenuring_threshold = MaxTenuringThreshold;
 840   } else {
 841     // We want to smooth out our startup times for the AdaptiveSizePolicy
 842     _tenuring_threshold = (UseAdaptiveSizePolicy) ? InitialTenuringThreshold :
 843                                                     MaxTenuringThreshold;
 844   }
 845 
 846   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
 847   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 848 
 849   PSYoungGen* young_gen = heap->young_gen();
 850   PSOldGen* old_gen = heap->old_gen();
 851 
 852   // Set boundary between young_gen and old_gen
 853   assert(old_gen->reserved().end() <= young_gen->eden_space()->bottom(),
 854          "old above young");
 855   set_young_generation_boundary(young_gen->eden_space()->bottom());
 856 
 857   // Initialize ref handling object for scavenging.
 858   MemRegion mr = young_gen->reserved();
 859 
 860   _ref_processor =
 861     new ReferenceProcessor(mr,                         // span
 862                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
 863                            (int) ParallelGCThreads,    // mt processing degree
 864                            true,                       // mt discovery
 865                            (int) ParallelGCThreads,    // mt discovery degree
 866                            true,                       // atomic_discovery
 867                            NULL,                       // header provides liveness info
 868                            false);                     // next field updates do not need write barrier
 869 
 870   // Cache the cardtable
 871   BarrierSet* bs = Universe::heap()->barrier_set();
 872   assert(bs->kind() == BarrierSet::CardTableModRef, "Wrong barrier set kind");
 873   _card_table = (CardTableExtension*)bs;
 874 
 875   _counters = new CollectorCounters("PSScavenge", 0);
 876 }
--- EOF ---