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src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp

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  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 "memory/allocation.hpp"
  27 #include "memory/universe.hpp"
  28 
  29 #include "gc/shared/gcArguments.hpp"
  30 #include "gc/shared/gcTimer.hpp"
  31 #include "gc/shared/gcTraceTime.inline.hpp"
  32 #include "gc/shared/locationPrinter.inline.hpp"
  33 #include "gc/shared/memAllocator.hpp"
  34 #include "gc/shared/plab.hpp"
  35 #include "gc/shared/tlab_globals.hpp"
  36 
  37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"

  38 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
  39 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  40 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
  41 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
  42 #include "gc/shenandoah/shenandoahControlThread.hpp"

  43 #include "gc/shenandoah/shenandoahFreeSet.hpp"

  44 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
  45 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  46 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  47 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
  48 #include "gc/shenandoah/shenandoahInitLogger.hpp"
  49 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  50 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
  51 #include "gc/shenandoah/shenandoahMetrics.hpp"
  52 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"

  53 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
  54 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
  55 #include "gc/shenandoah/shenandoahPadding.hpp"
  56 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
  57 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
  58 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"

  59 #include "gc/shenandoah/shenandoahStringDedup.hpp"
  60 #include "gc/shenandoah/shenandoahSTWMark.hpp"
  61 #include "gc/shenandoah/shenandoahUtils.hpp"
  62 #include "gc/shenandoah/shenandoahVerifier.hpp"
  63 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
  64 #include "gc/shenandoah/shenandoahVMOperations.hpp"
  65 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
  66 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"


  67 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
  68 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
  69 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"

  70 #if INCLUDE_JFR
  71 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
  72 #endif
  73 


  74 #include "classfile/systemDictionary.hpp"
  75 #include "memory/classLoaderMetaspace.hpp"
  76 #include "memory/metaspaceUtils.hpp"
  77 #include "oops/compressedOops.inline.hpp"
  78 #include "prims/jvmtiTagMap.hpp"
  79 #include "runtime/atomic.hpp"
  80 #include "runtime/globals.hpp"
  81 #include "runtime/interfaceSupport.inline.hpp"
  82 #include "runtime/java.hpp"
  83 #include "runtime/orderAccess.hpp"
  84 #include "runtime/safepointMechanism.hpp"
  85 #include "runtime/vmThread.hpp"
  86 #include "services/mallocTracker.hpp"
  87 #include "services/memTracker.hpp"
  88 #include "utilities/events.hpp"
  89 #include "utilities/powerOfTwo.hpp"
  90 
  91 class ShenandoahPretouchHeapTask : public AbstractGangTask {
  92 private:
  93   ShenandoahRegionIterator _regions;

 140 jint ShenandoahHeap::initialize() {
 141   //
 142   // Figure out heap sizing
 143   //
 144 
 145   size_t init_byte_size = InitialHeapSize;
 146   size_t min_byte_size  = MinHeapSize;
 147   size_t max_byte_size  = MaxHeapSize;
 148   size_t heap_alignment = HeapAlignment;
 149 
 150   size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
 151 
 152   Universe::check_alignment(max_byte_size,  reg_size_bytes, "Shenandoah heap");
 153   Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
 154 
 155   _num_regions = ShenandoahHeapRegion::region_count();
 156   assert(_num_regions == (max_byte_size / reg_size_bytes),
 157          "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
 158          _num_regions, max_byte_size, reg_size_bytes);
 159 
 160   // Now we know the number of regions, initialize the heuristics.
 161   initialize_heuristics();
 162 
 163   size_t num_committed_regions = init_byte_size / reg_size_bytes;
 164   num_committed_regions = MIN2(num_committed_regions, _num_regions);
 165   assert(num_committed_regions <= _num_regions, "sanity");
 166   _initial_size = num_committed_regions * reg_size_bytes;
 167 
 168   size_t num_min_regions = min_byte_size / reg_size_bytes;
 169   num_min_regions = MIN2(num_min_regions, _num_regions);
 170   assert(num_min_regions <= _num_regions, "sanity");
 171   _minimum_size = num_min_regions * reg_size_bytes;
 172 
 173   // Default to max heap size.
 174   _soft_max_size = _num_regions * reg_size_bytes;
 175 
 176   _committed = _initial_size;
 177 




 178   size_t heap_page_size   = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
 179   size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
 180   size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
 181 
 182   //
 183   // Reserve and commit memory for heap
 184   //
 185 
 186   ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
 187   initialize_reserved_region(heap_rs);
 188   _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
 189   _heap_region_special = heap_rs.special();
 190 
 191   assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
 192          "Misaligned heap: " PTR_FORMAT, p2i(base()));
 193 
 194 #if SHENANDOAH_OPTIMIZED_MARKTASK
 195   // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
 196   // Fail if we ever attempt to address more than we can.
 197   if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
 198     FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
 199                           "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
 200                           "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
 201                 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
 202     vm_exit_during_initialization("Fatal Error", buf);
 203   }
 204 #endif
 205 
 206   ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
 207   if (!_heap_region_special) {
 208     os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
 209                               "Cannot commit heap memory");
 210   }
 211 






























 212   //
 213   // Reserve and commit memory for bitmap(s)
 214   //
 215 
 216   _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
 217   _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
 218 
 219   size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
 220 
 221   guarantee(bitmap_bytes_per_region != 0,
 222             "Bitmap bytes per region should not be zero");
 223   guarantee(is_power_of_2(bitmap_bytes_per_region),
 224             "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
 225 
 226   if (bitmap_page_size > bitmap_bytes_per_region) {
 227     _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
 228     _bitmap_bytes_per_slice = bitmap_page_size;
 229   } else {
 230     _bitmap_regions_per_slice = 1;
 231     _bitmap_bytes_per_slice = bitmap_bytes_per_region;

 235             "Should have at least one region per slice: " SIZE_FORMAT,
 236             _bitmap_regions_per_slice);
 237 
 238   guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
 239             "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
 240             _bitmap_bytes_per_slice, bitmap_page_size);
 241 
 242   ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
 243   MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
 244   _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
 245   _bitmap_region_special = bitmap.special();
 246 
 247   size_t bitmap_init_commit = _bitmap_bytes_per_slice *
 248                               align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
 249   bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
 250   if (!_bitmap_region_special) {
 251     os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
 252                               "Cannot commit bitmap memory");
 253   }
 254 
 255   _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions, _max_workers);
 256 
 257   if (ShenandoahVerify) {
 258     ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
 259     if (!verify_bitmap.special()) {
 260       os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
 261                                 "Cannot commit verification bitmap memory");
 262     }
 263     MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
 264     MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
 265     _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
 266     _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
 267   }
 268 
 269   // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
 270   ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
 271   MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
 272   _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
 273   _aux_bitmap_region_special = aux_bitmap.special();
 274   _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
 275 

 381   // There should probably be Shenandoah-specific options for these,
 382   // just as there are G1-specific options.
 383   {
 384     ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
 385     satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
 386     satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
 387   }
 388 
 389   _monitoring_support = new ShenandoahMonitoringSupport(this);
 390   _phase_timings = new ShenandoahPhaseTimings(max_workers());
 391   ShenandoahCodeRoots::initialize();
 392 
 393   if (ShenandoahPacing) {
 394     _pacer = new ShenandoahPacer(this);
 395     _pacer->setup_for_idle();
 396   } else {
 397     _pacer = NULL;
 398   }
 399 
 400   _control_thread = new ShenandoahControlThread();

 401 
 402   ShenandoahInitLogger::print();
 403 
 404   return JNI_OK;
 405 }
 406 
 407 void ShenandoahHeap::initialize_mode() {











 408   if (ShenandoahGCMode != NULL) {
 409     if (strcmp(ShenandoahGCMode, "satb") == 0) {
 410       _gc_mode = new ShenandoahSATBMode();
 411     } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
 412       _gc_mode = new ShenandoahIUMode();
 413     } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
 414       _gc_mode = new ShenandoahPassiveMode();


 415     } else {
 416       vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
 417     }
 418   } else {
 419     ShouldNotReachHere();
 420   }
 421   _gc_mode->initialize_flags();
 422   if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
 423     vm_exit_during_initialization(
 424             err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
 425                     _gc_mode->name()));
 426   }
 427   if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
 428     vm_exit_during_initialization(
 429             err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
 430                     _gc_mode->name()));
 431   }
 432 }
 433 
 434 void ShenandoahHeap::initialize_heuristics() {
 435   assert(_gc_mode != NULL, "Must be initialized");
 436   _heuristics = _gc_mode->initialize_heuristics();
 437 
 438   if (_heuristics->is_diagnostic() && !UnlockDiagnosticVMOptions) {
 439     vm_exit_during_initialization(
 440             err_msg("Heuristics \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
 441                     _heuristics->name()));
 442   }
 443   if (_heuristics->is_experimental() && !UnlockExperimentalVMOptions) {
 444     vm_exit_during_initialization(
 445             err_msg("Heuristics \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
 446                     _heuristics->name()));
 447   }
 448 }
 449 
 450 #ifdef _MSC_VER
 451 #pragma warning( push )
 452 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 453 #endif
 454 
 455 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
 456   CollectedHeap(),



 457   _initial_size(0),
 458   _used(0),
 459   _committed(0),
 460   _bytes_allocated_since_gc_start(0),
 461   _max_workers(MAX2(ConcGCThreads, ParallelGCThreads)),
 462   _workers(NULL),
 463   _safepoint_workers(NULL),
 464   _heap_region_special(false),
 465   _num_regions(0),
 466   _regions(NULL),
 467   _update_refs_iterator(this),




 468   _control_thread(NULL),

 469   _shenandoah_policy(policy),
 470   _gc_mode(NULL),
 471   _heuristics(NULL),
 472   _free_set(NULL),
 473   _pacer(NULL),
 474   _verifier(NULL),
 475   _phase_timings(NULL),
 476   _monitoring_support(NULL),
 477   _memory_pool(NULL),


 478   _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
 479   _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
 480   _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
 481   _soft_ref_policy(),
 482   _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),
 483   _ref_processor(new ShenandoahReferenceProcessor(MAX2(_max_workers, 1U))),
 484   _marking_context(NULL),
 485   _bitmap_size(0),
 486   _bitmap_regions_per_slice(0),
 487   _bitmap_bytes_per_slice(0),
 488   _bitmap_region_special(false),
 489   _aux_bitmap_region_special(false),
 490   _liveness_cache(NULL),
 491   _collection_set(NULL)

 492 {
 493   // Initialize GC mode early, so we can adjust barrier support
 494   initialize_mode();
 495   BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));
 496 
 497   _max_workers = MAX2(_max_workers, 1U);
 498   _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
 499                             /* are_GC_task_threads */ true,
 500                             /* are_ConcurrentGC_threads */ true);
 501   if (_workers == NULL) {
 502     vm_exit_during_initialization("Failed necessary allocation.");
 503   } else {
 504     _workers->initialize_workers();
 505   }
 506 
 507   if (ParallelGCThreads > 1) {
 508     _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
 509                                                 ParallelGCThreads,
 510                       /* are_GC_task_threads */ false,
 511                  /* are_ConcurrentGC_threads */ false);
 512     _safepoint_workers->initialize_workers();
 513   }
 514 }
 515 
 516 #ifdef _MSC_VER
 517 #pragma warning( pop )
 518 #endif
 519 
 520 class ShenandoahResetBitmapTask : public AbstractGangTask {
 521 private:
 522   ShenandoahRegionIterator _regions;
 523 
 524 public:
 525   ShenandoahResetBitmapTask() :
 526     AbstractGangTask("Shenandoah Reset Bitmap") {}
 527 
 528   void work(uint worker_id) {
 529     ShenandoahHeapRegion* region = _regions.next();
 530     ShenandoahHeap* heap = ShenandoahHeap::heap();
 531     ShenandoahMarkingContext* const ctx = heap->marking_context();
 532     while (region != NULL) {
 533       if (heap->is_bitmap_slice_committed(region)) {
 534         ctx->clear_bitmap(region);
 535       }
 536       region = _regions.next();
 537     }
 538   }
 539 };
 540 
 541 void ShenandoahHeap::reset_mark_bitmap() {
 542   assert_gc_workers(_workers->active_workers());
 543   mark_incomplete_marking_context();
 544 
 545   ShenandoahResetBitmapTask task;
 546   _workers->run_task(&task);
 547 }
 548 
 549 void ShenandoahHeap::print_on(outputStream* st) const {
 550   st->print_cr("Shenandoah Heap");
 551   st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
 552                byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
 553                byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
 554                byte_size_in_proper_unit(committed()),    proper_unit_for_byte_size(committed()),
 555                byte_size_in_proper_unit(used()),         proper_unit_for_byte_size(used()));
 556   st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
 557                num_regions(),
 558                byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
 559                proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
 560 
 561   st->print("Status: ");
 562   if (has_forwarded_objects())                 st->print("has forwarded objects, ");
 563   if (is_concurrent_mark_in_progress())        st->print("marking, ");

 564   if (is_evacuation_in_progress())             st->print("evacuating, ");
 565   if (is_update_refs_in_progress())            st->print("updating refs, ");
 566   if (is_degenerated_gc_in_progress())         st->print("degenerated gc, ");
 567   if (is_full_gc_in_progress())                st->print("full gc, ");
 568   if (is_full_gc_move_in_progress())           st->print("full gc move, ");
 569   if (is_concurrent_weak_root_in_progress())   st->print("concurrent weak roots, ");
 570   if (is_concurrent_strong_root_in_progress() &&
 571       !is_concurrent_weak_root_in_progress())  st->print("concurrent strong roots, ");
 572 
 573   if (cancelled_gc()) {
 574     st->print("cancelled");
 575   } else {
 576     st->print("not cancelled");
 577   }
 578   st->cr();
 579 
 580   st->print_cr("Reserved region:");
 581   st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
 582                p2i(reserved_region().start()),
 583                p2i(reserved_region().end()));

 606     assert(thread->is_Worker_thread(), "Only worker thread expected");
 607     ShenandoahThreadLocalData::initialize_gclab(thread);
 608   }
 609 };
 610 
 611 void ShenandoahHeap::post_initialize() {
 612   CollectedHeap::post_initialize();
 613   MutexLocker ml(Threads_lock);
 614 
 615   ShenandoahInitWorkerGCLABClosure init_gclabs;
 616   _workers->threads_do(&init_gclabs);
 617 
 618   // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
 619   // Now, we will let WorkGang to initialize gclab when new worker is created.
 620   _workers->set_initialize_gclab();
 621   if (_safepoint_workers != NULL) {
 622     _safepoint_workers->threads_do(&init_gclabs);
 623     _safepoint_workers->set_initialize_gclab();
 624   }
 625 
 626   _heuristics->initialize();
 627 
 628   JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
 629 }
 630 







































 631 size_t ShenandoahHeap::used() const {
 632   return Atomic::load(&_used);
 633 }
 634 
 635 size_t ShenandoahHeap::committed() const {
 636   return Atomic::load(&_committed);
 637 }
 638 
 639 void ShenandoahHeap::increase_committed(size_t bytes) {
 640   shenandoah_assert_heaplocked_or_safepoint();
 641   _committed += bytes;
 642 }
 643 
 644 void ShenandoahHeap::decrease_committed(size_t bytes) {
 645   shenandoah_assert_heaplocked_or_safepoint();
 646   _committed -= bytes;
 647 }
 648 
 649 void ShenandoahHeap::increase_used(size_t bytes) {
 650   Atomic::add(&_used, bytes, memory_order_relaxed);
 651 }
 652 
 653 void ShenandoahHeap::set_used(size_t bytes) {
 654   Atomic::store(&_used, bytes);
 655 }
 656 
 657 void ShenandoahHeap::decrease_used(size_t bytes) {
 658   assert(used() >= bytes, "never decrease heap size by more than we've left");
 659   Atomic::sub(&_used, bytes, memory_order_relaxed);
 660 }
 661 
 662 void ShenandoahHeap::increase_allocated(size_t bytes) {
 663   Atomic::add(&_bytes_allocated_since_gc_start, bytes, memory_order_relaxed);
 664 }
 665 
 666 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
 667   size_t bytes = words * HeapWordSize;
 668   if (!waste) {
 669     increase_used(bytes);
 670   }
 671   increase_allocated(bytes);
 672   if (ShenandoahPacing) {
 673     control_thread()->pacing_notify_alloc(words);
 674     if (waste) {
 675       pacer()->claim_for_alloc(words, true);
 676     }
 677   }
 678 }
 679 
 680 size_t ShenandoahHeap::capacity() const {
 681   return committed();
 682 }
 683 
 684 size_t ShenandoahHeap::max_capacity() const {
 685   return _num_regions * ShenandoahHeapRegion::region_size_bytes();
 686 }
 687 
 688 size_t ShenandoahHeap::soft_max_capacity() const {
 689   size_t v = Atomic::load(&_soft_max_size);
 690   assert(min_capacity() <= v && v <= max_capacity(),
 691          "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
 692          min_capacity(), v, max_capacity());
 693   return v;
 694 }
 695 
 696 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
 697   assert(min_capacity() <= v && v <= max_capacity(),
 698          "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
 699          min_capacity(), v, max_capacity());
 700   Atomic::store(&_soft_max_size, v);







 701 }
 702 
 703 size_t ShenandoahHeap::min_capacity() const {
 704   return _minimum_size;
 705 }
 706 
 707 size_t ShenandoahHeap::initial_capacity() const {
 708   return _initial_size;
 709 }
 710 
 711 bool ShenandoahHeap::is_in(const void* p) const {
 712   HeapWord* heap_base = (HeapWord*) base();
 713   HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
 714   return p >= heap_base && p < last_region_end;
 715 }
 716 























 717 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
 718   assert (ShenandoahUncommit, "should be enabled");
 719 
 720   // Application allocates from the beginning of the heap, and GC allocates at
 721   // the end of it. It is more efficient to uncommit from the end, so that applications
 722   // could enjoy the near committed regions. GC allocations are much less frequent,
 723   // and therefore can accept the committing costs.
 724 
 725   size_t count = 0;
 726   for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
 727     ShenandoahHeapRegion* r = get_region(i - 1);
 728     if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
 729       ShenandoahHeapLocker locker(lock());
 730       if (r->is_empty_committed()) {
 731         if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
 732           break;
 733         }
 734 
 735         r->make_uncommitted();
 736         count++;
 737       }
 738     }
 739     SpinPause(); // allow allocators to take the lock
 740   }
 741 
 742   if (count > 0) {
 743     control_thread()->notify_heap_changed();























 744   }
 745 }
 746 




 747 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
 748   // New object should fit the GCLAB size
 749   size_t min_size = MAX2(size, PLAB::min_size());
 750 
 751   // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
 752   size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
 753   new_size = MIN2(new_size, PLAB::max_size());
 754   new_size = MAX2(new_size, PLAB::min_size());
 755 
 756   // Record new heuristic value even if we take any shortcut. This captures
 757   // the case when moderately-sized objects always take a shortcut. At some point,
 758   // heuristics should catch up with them.
 759   ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
 760 
 761   if (new_size < size) {
 762     // New size still does not fit the object. Fall back to shared allocation.
 763     // This avoids retiring perfectly good GCLABs, when we encounter a large object.
 764     return NULL;
 765   }
 766 

 776 
 777   assert (size <= actual_size, "allocation should fit");
 778 
 779   if (ZeroTLAB) {
 780     // ..and clear it.
 781     Copy::zero_to_words(gclab_buf, actual_size);
 782   } else {
 783     // ...and zap just allocated object.
 784 #ifdef ASSERT
 785     // Skip mangling the space corresponding to the object header to
 786     // ensure that the returned space is not considered parsable by
 787     // any concurrent GC thread.
 788     size_t hdr_size = oopDesc::header_size();
 789     Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
 790 #endif // ASSERT
 791   }
 792   gclab->set_buf(gclab_buf, actual_size);
 793   return gclab->allocate(size);
 794 }
 795 









































































































 796 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
 797                                             size_t requested_size,
 798                                             size_t* actual_size) {
 799   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
 800   HeapWord* res = allocate_memory(req);
 801   if (res != NULL) {
 802     *actual_size = req.actual_size();
 803   } else {
 804     *actual_size = 0;
 805   }
 806   return res;
 807 }
 808 
 809 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
 810                                              size_t word_size,
 811                                              size_t* actual_size) {
 812   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
 813   HeapWord* res = allocate_memory(req);
 814   if (res != NULL) {
 815     *actual_size = req.actual_size();
 816   } else {
 817     *actual_size = 0;
 818   }
 819   return res;
 820 }
 821 













 822 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
 823   intptr_t pacer_epoch = 0;
 824   bool in_new_region = false;
 825   HeapWord* result = NULL;
 826 
 827   if (req.is_mutator_alloc()) {
 828     if (ShenandoahPacing) {
 829       pacer()->pace_for_alloc(req.size());
 830       pacer_epoch = pacer()->epoch();
 831     }
 832 
 833     if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
 834       result = allocate_memory_under_lock(req, in_new_region);
 835     }
 836 
 837     // Allocation failed, block until control thread reacted, then retry allocation.
 838     //
 839     // It might happen that one of the threads requesting allocation would unblock
 840     // way later after GC happened, only to fail the second allocation, because
 841     // other threads have already depleted the free storage. In this case, a better

 850       tries++;
 851       control_thread()->handle_alloc_failure(req);
 852       result = allocate_memory_under_lock(req, in_new_region);
 853     }
 854 
 855     while (result == NULL && tries <= ShenandoahFullGCThreshold) {
 856       tries++;
 857       control_thread()->handle_alloc_failure(req);
 858       result = allocate_memory_under_lock(req, in_new_region);
 859     }
 860 
 861   } else {
 862     assert(req.is_gc_alloc(), "Can only accept GC allocs here");
 863     result = allocate_memory_under_lock(req, in_new_region);
 864     // Do not call handle_alloc_failure() here, because we cannot block.
 865     // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
 866   }
 867 
 868   if (in_new_region) {
 869     control_thread()->notify_heap_changed();

 870   }
 871 
 872   if (result != NULL) {

 873     size_t requested = req.size();
 874     size_t actual = req.actual_size();

 875 
 876     assert (req.is_lab_alloc() || (requested == actual),
 877             "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
 878             ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
 879 
 880     if (req.is_mutator_alloc()) {
 881       notify_mutator_alloc_words(actual, false);

 882 
 883       // If we requested more than we were granted, give the rest back to pacer.
 884       // This only matters if we are in the same pacing epoch: do not try to unpace
 885       // over the budget for the other phase.
 886       if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
 887         pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
 888       }
 889     } else {
 890       increase_used(actual*HeapWordSize);
 891     }
 892   }
 893 
 894   return result;
 895 }
 896 
 897 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {




 898   ShenandoahHeapLocker locker(lock());
 899   return _free_set->allocate(req, in_new_region);





















 900 }
 901 
 902 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
 903                                         bool*  gc_overhead_limit_was_exceeded) {
 904   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
 905   return allocate_memory(req);
 906 }
 907 
 908 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
 909                                                              size_t size,
 910                                                              Metaspace::MetadataType mdtype) {
 911   MetaWord* result;
 912 
 913   // Inform metaspace OOM to GC heuristics if class unloading is possible.
 914   if (heuristics()->can_unload_classes()) {
 915     ShenandoahHeuristics* h = heuristics();
 916     h->record_metaspace_oom();
 917   }
 918 
 919   // Expand and retry allocation
 920   result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
 921   if (result != NULL) {
 922     return result;
 923   }
 924 
 925   // Start full GC
 926   collect(GCCause::_metadata_GC_clear_soft_refs);
 927 
 928   // Retry allocation
 929   result = loader_data->metaspace_non_null()->allocate(size, mdtype);
 930   if (result != NULL) {
 931     return result;
 932   }
 933 
 934   // Expand and retry allocation
 935   result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);

 974 
 975   void work(uint worker_id) {
 976     if (_concurrent) {
 977       ShenandoahConcurrentWorkerSession worker_session(worker_id);
 978       ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
 979       ShenandoahEvacOOMScope oom_evac_scope;
 980       do_work();
 981     } else {
 982       ShenandoahParallelWorkerSession worker_session(worker_id);
 983       ShenandoahEvacOOMScope oom_evac_scope;
 984       do_work();
 985     }
 986   }
 987 
 988 private:
 989   void do_work() {
 990     ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
 991     ShenandoahHeapRegion* r;
 992     while ((r =_cs->claim_next()) != NULL) {
 993       assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());

 994       _sh->marked_object_iterate(r, &cl);
 995 
 996       if (ShenandoahPacing) {
 997         _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
 998       }




























































 999 
1000       if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1001         break;
1002       }
1003     }
1004   }
1005 };
1006 
1007 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1008   ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1009   workers()->run_task(&task);






1010 }
1011 
1012 void ShenandoahHeap::trash_cset_regions() {
1013   ShenandoahHeapLocker locker(lock());
1014 
1015   ShenandoahCollectionSet* set = collection_set();
1016   ShenandoahHeapRegion* r;
1017   set->clear_current_index();
1018   while ((r = set->next()) != NULL) {
1019     r->make_trash();
1020   }
1021   collection_set()->clear();
1022 }
1023 
1024 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1025   st->print_cr("Heap Regions:");
1026   st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1027   st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1028   st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1029   st->print_cr("SN=alloc sequence number");
1030 
1031   for (size_t i = 0; i < num_regions(); i++) {
1032     get_region(i)->print_on(st);
1033   }
1034 }
1035 
1036 void ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1037   assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1038 
1039   oop humongous_obj = cast_to_oop(start->bottom());
1040   size_t size = humongous_obj->size();
1041   size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1042   size_t index = start->index() + required_regions - 1;
1043 
1044   assert(!start->has_live(), "liveness must be zero");
1045 
1046   for(size_t i = 0; i < required_regions; i++) {
1047     // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1048     // as it expects that every region belongs to a humongous region starting with a humongous start region.
1049     ShenandoahHeapRegion* region = get_region(index --);
1050 
1051     assert(region->is_humongous(), "expect correct humongous start or continuation");
1052     assert(!region->is_cset(), "Humongous region should not be in collection set");
1053 
1054     region->make_trash_immediate();
1055   }

1056 }
1057 
1058 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1059 public:
1060   ShenandoahCheckCleanGCLABClosure() {}
1061   void do_thread(Thread* thread) {
1062     PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1063     assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1064     assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");




1065   }
1066 };
1067 
1068 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1069 private:
1070   bool const _resize;
1071 public:
1072   ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1073   void do_thread(Thread* thread) {
1074     PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1075     assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1076     gclab->retire();
1077     if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1078       ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1079     }












1080   }
1081 };
1082 
1083 void ShenandoahHeap::labs_make_parsable() {
1084   assert(UseTLAB, "Only call with UseTLAB");
1085 
1086   ShenandoahRetireGCLABClosure cl(false);
1087 
1088   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1089     ThreadLocalAllocBuffer& tlab = t->tlab();
1090     tlab.make_parsable();
1091     cl.do_thread(t);
1092   }
1093 
1094   workers()->threads_do(&cl);
1095 }
1096 
1097 void ShenandoahHeap::tlabs_retire(bool resize) {
1098   assert(UseTLAB, "Only call with UseTLAB");
1099   assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");

1117   }
1118   workers()->threads_do(&cl);
1119 #endif
1120 }
1121 
1122 void ShenandoahHeap::gclabs_retire(bool resize) {
1123   assert(UseTLAB, "Only call with UseTLAB");
1124   assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1125 
1126   ShenandoahRetireGCLABClosure cl(resize);
1127   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1128     cl.do_thread(t);
1129   }
1130   workers()->threads_do(&cl);
1131 
1132   if (safepoint_workers() != NULL) {
1133     safepoint_workers()->threads_do(&cl);
1134   }
1135 }
1136 































1137 // Returns size in bytes
1138 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1139   if (ShenandoahElasticTLAB) {
1140     // With Elastic TLABs, return the max allowed size, and let the allocation path
1141     // figure out the safe size for current allocation.
1142     return ShenandoahHeapRegion::max_tlab_size_bytes();
1143   } else {
1144     return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1145   }
1146 }
1147 
1148 size_t ShenandoahHeap::max_tlab_size() const {
1149   // Returns size in words
1150   return ShenandoahHeapRegion::max_tlab_size_words();
1151 }
1152 
1153 void ShenandoahHeap::collect(GCCause::Cause cause) {
1154   control_thread()->request_gc(cause);
1155 }
1156 

1512       if (start >= max) break;
1513 
1514       for (size_t i = cur; i < end; i++) {
1515         ShenandoahHeapRegion* current = _heap->get_region(i);
1516         _blk->heap_region_do(current);
1517       }
1518     }
1519   }
1520 };
1521 
1522 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1523   assert(blk->is_thread_safe(), "Only thread-safe closures here");
1524   if (num_regions() > ShenandoahParallelRegionStride) {
1525     ShenandoahParallelHeapRegionTask task(blk);
1526     workers()->run_task(&task);
1527   } else {
1528     heap_region_iterate(blk);
1529   }
1530 }
1531 
1532 class ShenandoahInitMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1533 private:
1534   ShenandoahMarkingContext* const _ctx;
1535 public:
1536   ShenandoahInitMarkUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1537 
1538   void heap_region_do(ShenandoahHeapRegion* r) {
1539     assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1540     if (r->is_active()) {
1541       // Check if region needs updating its TAMS. We have updated it already during concurrent
1542       // reset, so it is very likely we don't need to do another write here.
1543       if (_ctx->top_at_mark_start(r) != r->top()) {
1544         _ctx->capture_top_at_mark_start(r);
1545       }
1546     } else {
1547       assert(_ctx->top_at_mark_start(r) == r->top(),
1548              "Region " SIZE_FORMAT " should already have correct TAMS", r->index());
1549     }
1550   }
1551 
1552   bool is_thread_safe() { return true; }
1553 };
1554 
1555 class ShenandoahRendezvousClosure : public HandshakeClosure {
1556 public:
1557   inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1558   inline void do_thread(Thread* thread) {}
1559 };
1560 
1561 void ShenandoahHeap::rendezvous_threads() {
1562   ShenandoahRendezvousClosure cl;
1563   Handshake::execute(&cl);
1564 }
1565 
1566 void ShenandoahHeap::recycle_trash() {
1567   free_set()->recycle_trash();
1568 }
1569 
1570 class ShenandoahResetUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1571 private:
1572   ShenandoahMarkingContext* const _ctx;
1573 public:
1574   ShenandoahResetUpdateRegionStateClosure() : _ctx(ShenandoahHeap::heap()->marking_context()) {}
1575 
1576   void heap_region_do(ShenandoahHeapRegion* r) {
1577     if (r->is_active()) {
1578       // Reset live data and set TAMS optimistically. We would recheck these under the pause
1579       // anyway to capture any updates that happened since now.
1580       r->clear_live_data();
1581       _ctx->capture_top_at_mark_start(r);
1582     }
1583   }
1584 
1585   bool is_thread_safe() { return true; }
1586 };
1587 
1588 void ShenandoahHeap::prepare_gc() {
1589   reset_mark_bitmap();
1590 
1591   ShenandoahResetUpdateRegionStateClosure cl;
1592   parallel_heap_region_iterate(&cl);
1593 }
1594 
1595 class ShenandoahFinalMarkUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
1596 private:
1597   ShenandoahMarkingContext* const _ctx;
1598   ShenandoahHeapLock* const _lock;
1599 
1600 public:
1601   ShenandoahFinalMarkUpdateRegionStateClosure() :
1602     _ctx(ShenandoahHeap::heap()->complete_marking_context()), _lock(ShenandoahHeap::heap()->lock()) {}
1603 
1604   void heap_region_do(ShenandoahHeapRegion* r) {
1605     if (r->is_active()) {
1606       // All allocations past TAMS are implicitly live, adjust the region data.
1607       // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
1608       HeapWord *tams = _ctx->top_at_mark_start(r);
1609       HeapWord *top = r->top();
1610       if (top > tams) {
1611         r->increase_live_data_alloc_words(pointer_delta(top, tams));
1612       }
1613 
1614       // We are about to select the collection set, make sure it knows about
1615       // current pinning status. Also, this allows trashing more regions that
1616       // now have their pinning status dropped.
1617       if (r->is_pinned()) {
1618         if (r->pin_count() == 0) {
1619           ShenandoahHeapLocker locker(_lock);
1620           r->make_unpinned();
1621         }
1622       } else {
1623         if (r->pin_count() > 0) {
1624           ShenandoahHeapLocker locker(_lock);
1625           r->make_pinned();
1626         }
1627       }
1628 
1629       // Remember limit for updating refs. It's guaranteed that we get no
1630       // from-space-refs written from here on.
1631       r->set_update_watermark_at_safepoint(r->top());
1632     } else {
1633       assert(!r->has_live(), "Region " SIZE_FORMAT " should have no live data", r->index());
1634       assert(_ctx->top_at_mark_start(r) == r->top(),
1635              "Region " SIZE_FORMAT " should have correct TAMS", r->index());
1636     }
1637   }
1638 
1639   bool is_thread_safe() { return true; }
1640 };
1641 
1642 void ShenandoahHeap::prepare_regions_and_collection_set(bool concurrent) {
1643   assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
1644   {
1645     ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_update_region_states :
1646                                          ShenandoahPhaseTimings::degen_gc_final_update_region_states);
1647     ShenandoahFinalMarkUpdateRegionStateClosure cl;
1648     parallel_heap_region_iterate(&cl);
1649 
1650     assert_pinned_region_status();
1651   }
1652 
1653   {
1654     ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::choose_cset :
1655                                          ShenandoahPhaseTimings::degen_gc_choose_cset);
1656     ShenandoahHeapLocker locker(lock());
1657     _collection_set->clear();
1658     heuristics()->choose_collection_set(_collection_set);
1659   }
1660 
1661   {
1662     ShenandoahGCPhase phase(concurrent ? ShenandoahPhaseTimings::final_rebuild_freeset :
1663                                          ShenandoahPhaseTimings::degen_gc_final_rebuild_freeset);
1664     ShenandoahHeapLocker locker(lock());
1665     _free_set->rebuild();
1666   }
1667 }
1668 
1669 void ShenandoahHeap::do_class_unloading() {
1670   _unloader.unload();
1671 }
1672 
1673 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1674   // Weak refs processing
1675   ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1676                                                 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1677   ShenandoahTimingsTracker t(phase);
1678   ShenandoahGCWorkerPhase worker_phase(phase);
1679   ref_processor()->process_references(phase, workers(), false /* concurrent */);
1680 }
1681 
1682 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1683   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1684 
1685   // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1686   // make them parsable for update code to work correctly. Plus, we can compute new sizes
1687   // for future GCLABs here.
1688   if (UseTLAB) {
1689     ShenandoahGCPhase phase(concurrent ?
1690                             ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1691                             ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1692     gclabs_retire(ResizeTLAB);
1693   }
1694 
1695   _update_refs_iterator.reset();
1696 }
1697 
1698 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1699   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1700     ShenandoahThreadLocalData::set_gc_state(t, state);
1701   }
1702 }
1703 
1704 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1705   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1706   _gc_state.set_cond(mask, value);
1707   set_gc_state_all_threads(_gc_state.raw_value());
1708 }
1709 
1710 void ShenandoahHeap::set_concurrent_mark_in_progress(bool in_progress) {
1711   assert(!has_forwarded_objects(), "Not expected before/after mark phase");
1712   set_gc_state_mask(MARKING, in_progress);
1713   ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(in_progress, !in_progress);












































1714 }
1715 
1716 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1717   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1718   set_gc_state_mask(EVACUATION, in_progress);
1719 }
1720 
1721 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1722   if (in_progress) {
1723     _concurrent_strong_root_in_progress.set();
1724   } else {
1725     _concurrent_strong_root_in_progress.unset();
1726   }
1727 }
1728 
1729 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
1730   set_gc_state_mask(WEAK_ROOTS, cond);
1731 }
1732 
1733 GCTracer* ShenandoahHeap::tracer() {

1738   return _free_set->used();
1739 }
1740 
1741 bool ShenandoahHeap::try_cancel_gc() {
1742   while (true) {
1743     jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
1744     if (prev == CANCELLABLE) return true;
1745     else if (prev == CANCELLED) return false;
1746     assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
1747     assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
1748     Thread* thread = Thread::current();
1749     if (thread->is_Java_thread()) {
1750       // We need to provide a safepoint here, otherwise we might
1751       // spin forever if a SP is pending.
1752       ThreadBlockInVM sp(JavaThread::cast(thread));
1753       SpinPause();
1754     }
1755   }
1756 }
1757 








1758 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
1759   if (try_cancel_gc()) {
1760     FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
1761     log_info(gc)("%s", msg.buffer());
1762     Events::log(Thread::current(), "%s", msg.buffer());

1763   }
1764 }
1765 
1766 uint ShenandoahHeap::max_workers() {
1767   return _max_workers;
1768 }
1769 
1770 void ShenandoahHeap::stop() {
1771   // The shutdown sequence should be able to terminate when GC is running.
1772 



1773   // Step 0. Notify policy to disable event recording.
1774   _shenandoah_policy->record_shutdown();
1775 
1776   // Step 1. Notify control thread that we are in shutdown.
1777   // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
1778   // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
1779   control_thread()->prepare_for_graceful_shutdown();
1780 
1781   // Step 2. Notify GC workers that we are cancelling GC.
1782   cancel_gc(GCCause::_shenandoah_stop_vm);
1783 
1784   // Step 3. Wait until GC worker exits normally.
1785   control_thread()->stop();
1786 }
1787 
1788 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
1789   if (!unload_classes()) return;
1790   // Unload classes and purge SystemDictionary.
1791   {
1792     ShenandoahPhaseTimings::Phase phase = full_gc ?

1857 }
1858 
1859 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
1860   set_gc_state_mask(HAS_FORWARDED, cond);
1861 }
1862 
1863 void ShenandoahHeap::set_unload_classes(bool uc) {
1864   _unload_classes.set_cond(uc);
1865 }
1866 
1867 bool ShenandoahHeap::unload_classes() const {
1868   return _unload_classes.is_set();
1869 }
1870 
1871 address ShenandoahHeap::in_cset_fast_test_addr() {
1872   ShenandoahHeap* heap = ShenandoahHeap::heap();
1873   assert(heap->collection_set() != NULL, "Sanity");
1874   return (address) heap->collection_set()->biased_map_address();
1875 }
1876 
1877 address ShenandoahHeap::cancelled_gc_addr() {
1878   return (address) ShenandoahHeap::heap()->_cancelled_gc.addr_of();
1879 }
1880 
1881 address ShenandoahHeap::gc_state_addr() {
1882   return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
1883 }
1884 
1885 size_t ShenandoahHeap::bytes_allocated_since_gc_start() {
1886   return Atomic::load(&_bytes_allocated_since_gc_start);
1887 }
1888 
1889 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
1890   Atomic::store(&_bytes_allocated_since_gc_start, (size_t)0);





1891 }
1892 
1893 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
1894   _degenerated_gc_in_progress.set_cond(in_progress);
1895 }
1896 
1897 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
1898   _full_gc_in_progress.set_cond(in_progress);
1899 }
1900 
1901 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
1902   assert (is_full_gc_in_progress(), "should be");
1903   _full_gc_move_in_progress.set_cond(in_progress);
1904 }
1905 
1906 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
1907   set_gc_state_mask(UPDATEREFS, in_progress);
1908 }
1909 
1910 void ShenandoahHeap::register_nmethod(nmethod* nm) {

1939     if (r->is_active()) {
1940       if (r->is_pinned()) {
1941         if (r->pin_count() == 0) {
1942           r->make_unpinned();
1943         }
1944       } else {
1945         if (r->pin_count() > 0) {
1946           r->make_pinned();
1947         }
1948       }
1949     }
1950   }
1951 
1952   assert_pinned_region_status();
1953 }
1954 
1955 #ifdef ASSERT
1956 void ShenandoahHeap::assert_pinned_region_status() {
1957   for (size_t i = 0; i < num_regions(); i++) {
1958     ShenandoahHeapRegion* r = get_region(i);
1959     assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
1960            "Region " SIZE_FORMAT " pinning status is inconsistent", i);


1961   }
1962 }
1963 #endif
1964 
1965 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
1966   return _gc_timer;
1967 }
1968 
1969 void ShenandoahHeap::prepare_concurrent_roots() {
1970   assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
1971   assert(!is_stw_gc_in_progress(), "Only concurrent GC");
1972   set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
1973   set_concurrent_weak_root_in_progress(true);
1974   if (unload_classes()) {
1975     _unloader.prepare();
1976   }
1977 }
1978 
1979 void ShenandoahHeap::finish_concurrent_roots() {
1980   assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");

2000       assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2001     } else {
2002       // Use ConcGCThreads outside safepoints
2003       assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2004     }
2005   }
2006 }
2007 #endif
2008 
2009 ShenandoahVerifier* ShenandoahHeap::verifier() {
2010   guarantee(ShenandoahVerify, "Should be enabled");
2011   assert (_verifier != NULL, "sanity");
2012   return _verifier;
2013 }
2014 
2015 template<bool CONCURRENT>
2016 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2017 private:
2018   ShenandoahHeap* _heap;
2019   ShenandoahRegionIterator* _regions;


2020 public:
2021   ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions) :
2022     AbstractGangTask("Shenandoah Update References"),
2023     _heap(ShenandoahHeap::heap()),
2024     _regions(regions) {


2025   }
2026 
2027   void work(uint worker_id) {
2028     if (CONCURRENT) {
2029       ShenandoahConcurrentWorkerSession worker_session(worker_id);
2030       ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2031       do_work<ShenandoahConcUpdateRefsClosure>();
2032     } else {
2033       ShenandoahParallelWorkerSession worker_session(worker_id);
2034       do_work<ShenandoahSTWUpdateRefsClosure>();
2035     }
2036   }
2037 
2038 private:
2039   template<class T>
2040   void do_work() {
2041     T cl;
2042     ShenandoahHeapRegion* r = _regions->next();
2043     ShenandoahMarkingContext* const ctx = _heap->complete_marking_context();




2044     while (r != NULL) {
2045       HeapWord* update_watermark = r->get_update_watermark();
2046       assert (update_watermark >= r->bottom(), "sanity");


2047       if (r->is_active() && !r->is_cset()) {
2048         _heap->marked_object_oop_iterate(r, &cl, update_watermark);


































































2049       }
2050       if (ShenandoahPacing) {
2051         _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2052       }
2053       if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2054         return;
2055       }
2056       r = _regions->next();
2057     }
2058   }
2059 };
2060 
2061 void ShenandoahHeap::update_heap_references(bool concurrent) {
2062   assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2063 
2064   if (concurrent) {
2065     ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator);
2066     workers()->run_task(&task);
2067   } else {
2068     ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator);
2069     workers()->run_task(&task);
2070   }
2071 }
2072 
2073 
2074 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2075 private:
2076   ShenandoahHeapLock* const _lock;
2077 
2078 public:
2079   ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2080 
2081   void heap_region_do(ShenandoahHeapRegion* r) {
2082     // Drop unnecessary "pinned" state from regions that does not have CP marks
2083     // anymore, as this would allow trashing them.
2084 
2085     if (r->is_active()) {
2086       if (r->is_pinned()) {
2087         if (r->pin_count() == 0) {
2088           ShenandoahHeapLocker locker(_lock);

2225   EventMark em("%s", msg);
2226 
2227   op_uncommit(shrink_before, shrink_until);
2228 }
2229 
2230 void ShenandoahHeap::try_inject_alloc_failure() {
2231   if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2232     _inject_alloc_failure.set();
2233     os::naked_short_sleep(1);
2234     if (cancelled_gc()) {
2235       log_info(gc)("Allocation failure was successfully injected");
2236     }
2237   }
2238 }
2239 
2240 bool ShenandoahHeap::should_inject_alloc_failure() {
2241   return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2242 }
2243 
2244 void ShenandoahHeap::initialize_serviceability() {
2245   _memory_pool = new ShenandoahMemoryPool(this);
2246   _cycle_memory_manager.add_pool(_memory_pool);
2247   _stw_memory_manager.add_pool(_memory_pool);









2248 }
2249 
2250 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2251   GrowableArray<GCMemoryManager*> memory_managers(2);
2252   memory_managers.append(&_cycle_memory_manager);
2253   memory_managers.append(&_stw_memory_manager);
2254   return memory_managers;
2255 }
2256 
2257 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2258   GrowableArray<MemoryPool*> memory_pools(1);
2259   memory_pools.append(_memory_pool);





2260   return memory_pools;
2261 }
2262 
2263 MemoryUsage ShenandoahHeap::memory_usage() {
2264   return _memory_pool->get_memory_usage();
2265 }
2266 
2267 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2268   _heap(ShenandoahHeap::heap()),
2269   _index(0) {}
2270 
2271 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2272   _heap(heap),
2273   _index(0) {}
2274 
2275 void ShenandoahRegionIterator::reset() {
2276   _index = 0;
2277 }
2278 
2279 bool ShenandoahRegionIterator::has_next() const {
2280   return _index < _heap->num_regions();
2281 }
2282 
2283 char ShenandoahHeap::gc_state() const {
2284   return _gc_state.raw_value();
2285 }
2286 
2287 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2288 #ifdef ASSERT
2289   assert(_liveness_cache != NULL, "sanity");
2290   assert(worker_id < _max_workers, "sanity");
2291   for (uint i = 0; i < num_regions(); i++) {
2292     assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2293   }
2294 #endif
2295   return _liveness_cache[worker_id];
2296 }
2297 
2298 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2299   assert(worker_id < _max_workers, "sanity");
2300   assert(_liveness_cache != NULL, "sanity");
2301   ShenandoahLiveData* ld = _liveness_cache[worker_id];

2302   for (uint i = 0; i < num_regions(); i++) {
2303     ShenandoahLiveData live = ld[i];
2304     if (live > 0) {
2305       ShenandoahHeapRegion* r = get_region(i);
2306       r->increase_live_data_gc_words(live);
2307       ld[i] = 0;
2308     }
2309   }
2310 }















































































































































































































  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 "memory/allocation.hpp"
  27 #include "memory/universe.hpp"
  28 
  29 #include "gc/shared/gcArguments.hpp"
  30 #include "gc/shared/gcTimer.hpp"
  31 #include "gc/shared/gcTraceTime.inline.hpp"
  32 #include "gc/shared/locationPrinter.inline.hpp"
  33 #include "gc/shared/memAllocator.hpp"
  34 #include "gc/shared/plab.hpp"
  35 #include "gc/shared/tlab_globals.hpp"
  36 
  37 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
  38 #include "gc/shenandoah/shenandoahCardTable.hpp"
  39 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
  40 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  41 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
  42 #include "gc/shenandoah/shenandoahConcurrentMark.hpp"
  43 #include "gc/shenandoah/shenandoahControlThread.hpp"
  44 #include "gc/shenandoah/shenandoahRegulatorThread.hpp"
  45 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  46 #include "gc/shenandoah/shenandoahGlobalGeneration.hpp"
  47 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
  48 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  49 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  50 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
  51 #include "gc/shenandoah/shenandoahInitLogger.hpp"
  52 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  53 #include "gc/shenandoah/shenandoahMemoryPool.hpp"
  54 #include "gc/shenandoah/shenandoahMetrics.hpp"
  55 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
  56 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
  57 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
  58 #include "gc/shenandoah/shenandoahPacer.inline.hpp"
  59 #include "gc/shenandoah/shenandoahPadding.hpp"
  60 #include "gc/shenandoah/shenandoahParallelCleaning.inline.hpp"
  61 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
  62 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
  63 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
  64 #include "gc/shenandoah/shenandoahStringDedup.hpp"
  65 #include "gc/shenandoah/shenandoahSTWMark.hpp"
  66 #include "gc/shenandoah/shenandoahUtils.hpp"
  67 #include "gc/shenandoah/shenandoahVerifier.hpp"
  68 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
  69 #include "gc/shenandoah/shenandoahVMOperations.hpp"
  70 #include "gc/shenandoah/shenandoahWorkGroup.hpp"
  71 #include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
  72 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
  73 #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
  74 #include "gc/shenandoah/mode/shenandoahIUMode.hpp"
  75 #include "gc/shenandoah/mode/shenandoahPassiveMode.hpp"
  76 #include "gc/shenandoah/mode/shenandoahSATBMode.hpp"
  77 
  78 #if INCLUDE_JFR
  79 #include "gc/shenandoah/shenandoahJfrSupport.hpp"
  80 #endif
  81 
  82 #include "gc/shenandoah/heuristics/shenandoahOldHeuristics.hpp"
  83 
  84 #include "classfile/systemDictionary.hpp"
  85 #include "memory/classLoaderMetaspace.hpp"
  86 #include "memory/metaspaceUtils.hpp"
  87 #include "oops/compressedOops.inline.hpp"
  88 #include "prims/jvmtiTagMap.hpp"
  89 #include "runtime/atomic.hpp"
  90 #include "runtime/globals.hpp"
  91 #include "runtime/interfaceSupport.inline.hpp"
  92 #include "runtime/java.hpp"
  93 #include "runtime/orderAccess.hpp"
  94 #include "runtime/safepointMechanism.hpp"
  95 #include "runtime/vmThread.hpp"
  96 #include "services/mallocTracker.hpp"
  97 #include "services/memTracker.hpp"
  98 #include "utilities/events.hpp"
  99 #include "utilities/powerOfTwo.hpp"
 100 
 101 class ShenandoahPretouchHeapTask : public AbstractGangTask {
 102 private:
 103   ShenandoahRegionIterator _regions;

 150 jint ShenandoahHeap::initialize() {
 151   //
 152   // Figure out heap sizing
 153   //
 154 
 155   size_t init_byte_size = InitialHeapSize;
 156   size_t min_byte_size  = MinHeapSize;
 157   size_t max_byte_size  = MaxHeapSize;
 158   size_t heap_alignment = HeapAlignment;
 159 
 160   size_t reg_size_bytes = ShenandoahHeapRegion::region_size_bytes();
 161 
 162   Universe::check_alignment(max_byte_size,  reg_size_bytes, "Shenandoah heap");
 163   Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
 164 
 165   _num_regions = ShenandoahHeapRegion::region_count();
 166   assert(_num_regions == (max_byte_size / reg_size_bytes),
 167          "Regions should cover entire heap exactly: " SIZE_FORMAT " != " SIZE_FORMAT "/" SIZE_FORMAT,
 168          _num_regions, max_byte_size, reg_size_bytes);
 169 



 170   size_t num_committed_regions = init_byte_size / reg_size_bytes;
 171   num_committed_regions = MIN2(num_committed_regions, _num_regions);
 172   assert(num_committed_regions <= _num_regions, "sanity");
 173   _initial_size = num_committed_regions * reg_size_bytes;
 174 
 175   size_t num_min_regions = min_byte_size / reg_size_bytes;
 176   num_min_regions = MIN2(num_min_regions, _num_regions);
 177   assert(num_min_regions <= _num_regions, "sanity");
 178   _minimum_size = num_min_regions * reg_size_bytes;
 179 
 180   // Default to max heap size.
 181   _soft_max_size = _num_regions * reg_size_bytes;
 182 
 183   _committed = _initial_size;
 184 
 185   // Now we know the number of regions and heap sizes, initialize the heuristics.
 186   initialize_generations();
 187   initialize_heuristics();
 188 
 189   size_t heap_page_size   = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
 190   size_t bitmap_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
 191   size_t region_page_size = UseLargePages ? (size_t)os::large_page_size() : (size_t)os::vm_page_size();
 192 
 193   //
 194   // Reserve and commit memory for heap
 195   //
 196 
 197   ReservedHeapSpace heap_rs = Universe::reserve_heap(max_byte_size, heap_alignment);
 198   initialize_reserved_region(heap_rs);
 199   _heap_region = MemRegion((HeapWord*)heap_rs.base(), heap_rs.size() / HeapWordSize);
 200   _heap_region_special = heap_rs.special();
 201 
 202   assert((((size_t) base()) & ShenandoahHeapRegion::region_size_bytes_mask()) == 0,
 203          "Misaligned heap: " PTR_FORMAT, p2i(base()));
 204 
 205 #if SHENANDOAH_OPTIMIZED_MARKTASK
 206   // The optimized ShenandoahMarkTask takes some bits away from the full object bits.
 207   // Fail if we ever attempt to address more than we can.
 208   if ((uintptr_t)heap_rs.end() >= ShenandoahMarkTask::max_addressable()) {
 209     FormatBuffer<512> buf("Shenandoah reserved [" PTR_FORMAT ", " PTR_FORMAT") for the heap, \n"
 210                           "but max object address is " PTR_FORMAT ". Try to reduce heap size, or try other \n"
 211                           "VM options that allocate heap at lower addresses (HeapBaseMinAddress, AllocateHeapAt, etc).",
 212                 p2i(heap_rs.base()), p2i(heap_rs.end()), ShenandoahMarkTask::max_addressable());
 213     vm_exit_during_initialization("Fatal Error", buf);
 214   }
 215 #endif
 216 
 217   ReservedSpace sh_rs = heap_rs.first_part(max_byte_size);
 218   if (!_heap_region_special) {
 219     os::commit_memory_or_exit(sh_rs.base(), _initial_size, heap_alignment, false,
 220                               "Cannot commit heap memory");
 221   }
 222 
 223   BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this, _heap_region));
 224 
 225   //
 226   // After reserving the Java heap, create the card table, barriers, and workers, in dependency order
 227   //
 228   if (mode()->is_generational()) {
 229     ShenandoahDirectCardMarkRememberedSet *rs;
 230     ShenandoahCardTable* card_table = ShenandoahBarrierSet::barrier_set()->card_table();
 231     size_t card_count = card_table->cards_required(heap_rs.size() / HeapWordSize) - 1;
 232     rs = new ShenandoahDirectCardMarkRememberedSet(ShenandoahBarrierSet::barrier_set()->card_table(), card_count);
 233     _card_scan = new ShenandoahScanRemembered<ShenandoahDirectCardMarkRememberedSet>(rs);
 234   }
 235 
 236   _workers = new ShenandoahWorkGang("Shenandoah GC Threads", _max_workers,
 237                             /* are_GC_task_threads */ true,
 238                             /* are_ConcurrentGC_threads */ true);
 239   if (_workers == NULL) {
 240     vm_exit_during_initialization("Failed necessary allocation.");
 241   } else {
 242     _workers->initialize_workers();
 243   }
 244 
 245   if (ParallelGCThreads > 1) {
 246     _safepoint_workers = new ShenandoahWorkGang("Safepoint Cleanup Thread",
 247                                                 ParallelGCThreads,
 248                       /* are_GC_task_threads */ false,
 249                  /* are_ConcurrentGC_threads */ false);
 250     _safepoint_workers->initialize_workers();
 251   }
 252 
 253   //
 254   // Reserve and commit memory for bitmap(s)
 255   //
 256 
 257   _bitmap_size = ShenandoahMarkBitMap::compute_size(heap_rs.size());
 258   _bitmap_size = align_up(_bitmap_size, bitmap_page_size);
 259 
 260   size_t bitmap_bytes_per_region = reg_size_bytes / ShenandoahMarkBitMap::heap_map_factor();
 261 
 262   guarantee(bitmap_bytes_per_region != 0,
 263             "Bitmap bytes per region should not be zero");
 264   guarantee(is_power_of_2(bitmap_bytes_per_region),
 265             "Bitmap bytes per region should be power of two: " SIZE_FORMAT, bitmap_bytes_per_region);
 266 
 267   if (bitmap_page_size > bitmap_bytes_per_region) {
 268     _bitmap_regions_per_slice = bitmap_page_size / bitmap_bytes_per_region;
 269     _bitmap_bytes_per_slice = bitmap_page_size;
 270   } else {
 271     _bitmap_regions_per_slice = 1;
 272     _bitmap_bytes_per_slice = bitmap_bytes_per_region;

 276             "Should have at least one region per slice: " SIZE_FORMAT,
 277             _bitmap_regions_per_slice);
 278 
 279   guarantee(((_bitmap_bytes_per_slice) % bitmap_page_size) == 0,
 280             "Bitmap slices should be page-granular: bps = " SIZE_FORMAT ", page size = " SIZE_FORMAT,
 281             _bitmap_bytes_per_slice, bitmap_page_size);
 282 
 283   ReservedSpace bitmap(_bitmap_size, bitmap_page_size);
 284   MemTracker::record_virtual_memory_type(bitmap.base(), mtGC);
 285   _bitmap_region = MemRegion((HeapWord*) bitmap.base(), bitmap.size() / HeapWordSize);
 286   _bitmap_region_special = bitmap.special();
 287 
 288   size_t bitmap_init_commit = _bitmap_bytes_per_slice *
 289                               align_up(num_committed_regions, _bitmap_regions_per_slice) / _bitmap_regions_per_slice;
 290   bitmap_init_commit = MIN2(_bitmap_size, bitmap_init_commit);
 291   if (!_bitmap_region_special) {
 292     os::commit_memory_or_exit((char *) _bitmap_region.start(), bitmap_init_commit, bitmap_page_size, false,
 293                               "Cannot commit bitmap memory");
 294   }
 295 
 296   _marking_context = new ShenandoahMarkingContext(_heap_region, _bitmap_region, _num_regions);
 297 
 298   if (ShenandoahVerify) {
 299     ReservedSpace verify_bitmap(_bitmap_size, bitmap_page_size);
 300     if (!verify_bitmap.special()) {
 301       os::commit_memory_or_exit(verify_bitmap.base(), verify_bitmap.size(), bitmap_page_size, false,
 302                                 "Cannot commit verification bitmap memory");
 303     }
 304     MemTracker::record_virtual_memory_type(verify_bitmap.base(), mtGC);
 305     MemRegion verify_bitmap_region = MemRegion((HeapWord *) verify_bitmap.base(), verify_bitmap.size() / HeapWordSize);
 306     _verification_bit_map.initialize(_heap_region, verify_bitmap_region);
 307     _verifier = new ShenandoahVerifier(this, &_verification_bit_map);
 308   }
 309 
 310   // Reserve aux bitmap for use in object_iterate(). We don't commit it here.
 311   ReservedSpace aux_bitmap(_bitmap_size, bitmap_page_size);
 312   MemTracker::record_virtual_memory_type(aux_bitmap.base(), mtGC);
 313   _aux_bitmap_region = MemRegion((HeapWord*) aux_bitmap.base(), aux_bitmap.size() / HeapWordSize);
 314   _aux_bitmap_region_special = aux_bitmap.special();
 315   _aux_bit_map.initialize(_heap_region, _aux_bitmap_region);
 316 

 422   // There should probably be Shenandoah-specific options for these,
 423   // just as there are G1-specific options.
 424   {
 425     ShenandoahSATBMarkQueueSet& satbqs = ShenandoahBarrierSet::satb_mark_queue_set();
 426     satbqs.set_process_completed_buffers_threshold(20); // G1SATBProcessCompletedThreshold
 427     satbqs.set_buffer_enqueue_threshold_percentage(60); // G1SATBBufferEnqueueingThresholdPercent
 428   }
 429 
 430   _monitoring_support = new ShenandoahMonitoringSupport(this);
 431   _phase_timings = new ShenandoahPhaseTimings(max_workers());
 432   ShenandoahCodeRoots::initialize();
 433 
 434   if (ShenandoahPacing) {
 435     _pacer = new ShenandoahPacer(this);
 436     _pacer->setup_for_idle();
 437   } else {
 438     _pacer = NULL;
 439   }
 440 
 441   _control_thread = new ShenandoahControlThread();
 442   _regulator_thread = new ShenandoahRegulatorThread(_control_thread);
 443 
 444   ShenandoahInitLogger::print();
 445 
 446   return JNI_OK;
 447 }
 448 
 449 void ShenandoahHeap::initialize_generations() {
 450   size_t max_capacity_new      = young_generation_capacity(max_capacity());
 451   size_t soft_max_capacity_new = young_generation_capacity(soft_max_capacity());
 452   size_t max_capacity_old      = max_capacity() - max_capacity_new;
 453   size_t soft_max_capacity_old = soft_max_capacity() - soft_max_capacity_new;
 454 
 455   _young_generation = new ShenandoahYoungGeneration(_max_workers, max_capacity_new, soft_max_capacity_new);
 456   _old_generation = new ShenandoahOldGeneration(_max_workers, max_capacity_old, soft_max_capacity_old);
 457   _global_generation = new ShenandoahGlobalGeneration(_max_workers);
 458 }
 459 
 460 void ShenandoahHeap::initialize_heuristics() {
 461   if (ShenandoahGCMode != NULL) {
 462     if (strcmp(ShenandoahGCMode, "satb") == 0) {
 463       _gc_mode = new ShenandoahSATBMode();
 464     } else if (strcmp(ShenandoahGCMode, "iu") == 0) {
 465       _gc_mode = new ShenandoahIUMode();
 466     } else if (strcmp(ShenandoahGCMode, "passive") == 0) {
 467       _gc_mode = new ShenandoahPassiveMode();
 468     } else if (strcmp(ShenandoahGCMode, "generational") == 0) {
 469       _gc_mode = new ShenandoahGenerationalMode();
 470     } else {
 471       vm_exit_during_initialization("Unknown -XX:ShenandoahGCMode option");
 472     }
 473   } else {
 474     ShouldNotReachHere();
 475   }
 476   _gc_mode->initialize_flags();
 477   if (_gc_mode->is_diagnostic() && !UnlockDiagnosticVMOptions) {
 478     vm_exit_during_initialization(
 479             err_msg("GC mode \"%s\" is diagnostic, and must be enabled via -XX:+UnlockDiagnosticVMOptions.",
 480                     _gc_mode->name()));
 481   }
 482   if (_gc_mode->is_experimental() && !UnlockExperimentalVMOptions) {
 483     vm_exit_during_initialization(
 484             err_msg("GC mode \"%s\" is experimental, and must be enabled via -XX:+UnlockExperimentalVMOptions.",
 485                     _gc_mode->name()));
 486   }

 487 
 488   _global_generation->initialize_heuristics(_gc_mode);
 489   if (mode()->is_generational()) {
 490     _young_generation->initialize_heuristics(_gc_mode);
 491     _old_generation->initialize_heuristics(_gc_mode);









 492   }
 493 }
 494 
 495 #ifdef _MSC_VER
 496 #pragma warning( push )
 497 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 498 #endif
 499 
 500 ShenandoahHeap::ShenandoahHeap(ShenandoahCollectorPolicy* policy) :
 501   CollectedHeap(),
 502   _gc_generation(NULL),
 503   _mixed_evac(false),
 504   _prep_for_mixed_evac_in_progress(false),
 505   _initial_size(0),
 506   _used(0),
 507   _committed(0),
 508   _max_workers(MAX3(ConcGCThreads, ParallelGCThreads, 1U)),

 509   _workers(NULL),
 510   _safepoint_workers(NULL),
 511   _heap_region_special(false),
 512   _num_regions(0),
 513   _regions(NULL),
 514   _update_refs_iterator(this),
 515   _cancel_requested_time(0),
 516   _young_generation(NULL),
 517   _global_generation(NULL),
 518   _old_generation(NULL),
 519   _control_thread(NULL),
 520   _regulator_thread(NULL),
 521   _shenandoah_policy(policy),


 522   _free_set(NULL),
 523   _pacer(NULL),
 524   _verifier(NULL),
 525   _phase_timings(NULL),
 526   _monitoring_support(NULL),
 527   _memory_pool(NULL),
 528   _young_gen_memory_pool(NULL),
 529   _old_gen_memory_pool(NULL),
 530   _stw_memory_manager("Shenandoah Pauses", "end of GC pause"),
 531   _cycle_memory_manager("Shenandoah Cycles", "end of GC cycle"),
 532   _gc_timer(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
 533   _soft_ref_policy(),
 534   _log_min_obj_alignment_in_bytes(LogMinObjAlignmentInBytes),

 535   _marking_context(NULL),
 536   _bitmap_size(0),
 537   _bitmap_regions_per_slice(0),
 538   _bitmap_bytes_per_slice(0),
 539   _bitmap_region_special(false),
 540   _aux_bitmap_region_special(false),
 541   _liveness_cache(NULL),
 542   _collection_set(NULL),
 543   _card_scan(NULL)
 544 {





















 545 }
 546 
 547 #ifdef _MSC_VER
 548 #pragma warning( pop )
 549 #endif
 550 





























 551 void ShenandoahHeap::print_on(outputStream* st) const {
 552   st->print_cr("Shenandoah Heap");
 553   st->print_cr(" " SIZE_FORMAT "%s max, " SIZE_FORMAT "%s soft max, " SIZE_FORMAT "%s committed, " SIZE_FORMAT "%s used",
 554                byte_size_in_proper_unit(max_capacity()), proper_unit_for_byte_size(max_capacity()),
 555                byte_size_in_proper_unit(soft_max_capacity()), proper_unit_for_byte_size(soft_max_capacity()),
 556                byte_size_in_proper_unit(committed()),    proper_unit_for_byte_size(committed()),
 557                byte_size_in_proper_unit(used()),         proper_unit_for_byte_size(used()));
 558   st->print_cr(" " SIZE_FORMAT " x " SIZE_FORMAT"%s regions",
 559                num_regions(),
 560                byte_size_in_proper_unit(ShenandoahHeapRegion::region_size_bytes()),
 561                proper_unit_for_byte_size(ShenandoahHeapRegion::region_size_bytes()));
 562 
 563   st->print("Status: ");
 564   if (has_forwarded_objects())                 st->print("has forwarded objects, ");
 565   if (is_concurrent_old_mark_in_progress())    st->print("old marking, ");
 566   if (is_concurrent_young_mark_in_progress())  st->print("young marking, ");
 567   if (is_evacuation_in_progress())             st->print("evacuating, ");
 568   if (is_update_refs_in_progress())            st->print("updating refs, ");
 569   if (is_degenerated_gc_in_progress())         st->print("degenerated gc, ");
 570   if (is_full_gc_in_progress())                st->print("full gc, ");
 571   if (is_full_gc_move_in_progress())           st->print("full gc move, ");
 572   if (is_concurrent_weak_root_in_progress())   st->print("concurrent weak roots, ");
 573   if (is_concurrent_strong_root_in_progress() &&
 574       !is_concurrent_weak_root_in_progress())  st->print("concurrent strong roots, ");
 575 
 576   if (cancelled_gc()) {
 577     st->print("cancelled");
 578   } else {
 579     st->print("not cancelled");
 580   }
 581   st->cr();
 582 
 583   st->print_cr("Reserved region:");
 584   st->print_cr(" - [" PTR_FORMAT ", " PTR_FORMAT ") ",
 585                p2i(reserved_region().start()),
 586                p2i(reserved_region().end()));

 609     assert(thread->is_Worker_thread(), "Only worker thread expected");
 610     ShenandoahThreadLocalData::initialize_gclab(thread);
 611   }
 612 };
 613 
 614 void ShenandoahHeap::post_initialize() {
 615   CollectedHeap::post_initialize();
 616   MutexLocker ml(Threads_lock);
 617 
 618   ShenandoahInitWorkerGCLABClosure init_gclabs;
 619   _workers->threads_do(&init_gclabs);
 620 
 621   // gclab can not be initialized early during VM startup, as it can not determinate its max_size.
 622   // Now, we will let WorkGang to initialize gclab when new worker is created.
 623   _workers->set_initialize_gclab();
 624   if (_safepoint_workers != NULL) {
 625     _safepoint_workers->threads_do(&init_gclabs);
 626     _safepoint_workers->set_initialize_gclab();
 627   }
 628 


 629   JFR_ONLY(ShenandoahJFRSupport::register_jfr_type_serializers());
 630 }
 631 
 632 
 633 ShenandoahOldHeuristics* ShenandoahHeap::old_heuristics() {
 634   return (ShenandoahOldHeuristics*) _old_generation->heuristics();
 635 }
 636 
 637 bool ShenandoahHeap::doing_mixed_evacuations() {
 638   return old_heuristics()->unprocessed_old_collection_candidates() > 0;
 639 }
 640 
 641 bool ShenandoahHeap::is_gc_generation_young() const {
 642   return _gc_generation != NULL && _gc_generation->generation_mode() == YOUNG;
 643 }
 644 
 645 // There are three JVM parameters for setting young gen capacity:
 646 //    NewSize, MaxNewSize, NewRatio.
 647 //
 648 // If only NewSize is set, it assigns a fixed size and the other two parameters are ignored.
 649 // Otherwise NewRatio applies.
 650 //
 651 // If NewSize is set in any combination, it provides a lower bound.
 652 //
 653 // If MaxNewSize is set it provides an upper bound.
 654 // If this bound is smaller than NewSize, it supersedes,
 655 // resulting in a fixed size given by MaxNewSize.
 656 size_t ShenandoahHeap::young_generation_capacity(size_t capacity) {
 657   if (FLAG_IS_CMDLINE(NewSize) && !FLAG_IS_CMDLINE(MaxNewSize) && !FLAG_IS_CMDLINE(NewRatio)) {
 658     capacity = MIN2(NewSize, capacity);
 659   } else {
 660     capacity /= NewRatio + 1;
 661     if (FLAG_IS_CMDLINE(NewSize)) {
 662       capacity = MAX2(NewSize, capacity);
 663     }
 664     if (FLAG_IS_CMDLINE(MaxNewSize)) {
 665       capacity = MIN2(MaxNewSize, capacity);
 666     }
 667   }
 668   return capacity;
 669 }
 670 
 671 size_t ShenandoahHeap::used() const {
 672   return Atomic::load(&_used);
 673 }
 674 
 675 size_t ShenandoahHeap::committed() const {
 676   return Atomic::load(&_committed);
 677 }
 678 
 679 void ShenandoahHeap::increase_committed(size_t bytes) {
 680   shenandoah_assert_heaplocked_or_safepoint();
 681   _committed += bytes;
 682 }
 683 
 684 void ShenandoahHeap::decrease_committed(size_t bytes) {
 685   shenandoah_assert_heaplocked_or_safepoint();
 686   _committed -= bytes;
 687 }
 688 
 689 void ShenandoahHeap::increase_used(size_t bytes) {
 690   Atomic::add(&_used, bytes, memory_order_relaxed);
 691 }
 692 
 693 void ShenandoahHeap::set_used(size_t bytes) {
 694   Atomic::store(&_used, bytes);
 695 }
 696 
 697 void ShenandoahHeap::decrease_used(size_t bytes) {
 698   assert(used() >= bytes, "never decrease heap size by more than we've left");
 699   Atomic::sub(&_used, bytes, memory_order_relaxed);
 700 }
 701 




 702 void ShenandoahHeap::notify_mutator_alloc_words(size_t words, bool waste) {
 703   size_t bytes = words * HeapWordSize;
 704   if (!waste) {
 705     increase_used(bytes);
 706   }
 707 
 708   if (ShenandoahPacing) {
 709     control_thread()->pacing_notify_alloc(words);
 710     if (waste) {
 711       pacer()->claim_for_alloc(words, true);
 712     }
 713   }
 714 }
 715 
 716 size_t ShenandoahHeap::capacity() const {
 717   return committed();
 718 }
 719 
 720 size_t ShenandoahHeap::max_capacity() const {
 721   return _num_regions * ShenandoahHeapRegion::region_size_bytes();
 722 }
 723 
 724 size_t ShenandoahHeap::soft_max_capacity() const {
 725   size_t v = Atomic::load(&_soft_max_size);
 726   assert(min_capacity() <= v && v <= max_capacity(),
 727          "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
 728          min_capacity(), v, max_capacity());
 729   return v;
 730 }
 731 
 732 void ShenandoahHeap::set_soft_max_capacity(size_t v) {
 733   assert(min_capacity() <= v && v <= max_capacity(),
 734          "Should be in bounds: " SIZE_FORMAT " <= " SIZE_FORMAT " <= " SIZE_FORMAT,
 735          min_capacity(), v, max_capacity());
 736   Atomic::store(&_soft_max_size, v);
 737 
 738   if (mode()->is_generational()) {
 739     size_t soft_max_capacity_young = young_generation_capacity(_soft_max_size);
 740     size_t soft_max_capacity_old = _soft_max_size - soft_max_capacity_young;
 741     _young_generation->set_soft_max_capacity(soft_max_capacity_young);
 742     _old_generation->set_soft_max_capacity(soft_max_capacity_old);
 743   }
 744 }
 745 
 746 size_t ShenandoahHeap::min_capacity() const {
 747   return _minimum_size;
 748 }
 749 
 750 size_t ShenandoahHeap::initial_capacity() const {
 751   return _initial_size;
 752 }
 753 
 754 bool ShenandoahHeap::is_in(const void* p) const {
 755   HeapWord* heap_base = (HeapWord*) base();
 756   HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
 757   return p >= heap_base && p < last_region_end;
 758 }
 759 
 760 bool ShenandoahHeap::is_in_young(const void* p) const {
 761   return is_in(p) && heap_region_containing(p)->affiliation() == ShenandoahRegionAffiliation::YOUNG_GENERATION;
 762 }
 763 
 764 bool ShenandoahHeap::is_in_old(const void* p) const {
 765   return is_in(p) && heap_region_containing(p)->affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION;
 766 }
 767 
 768 bool ShenandoahHeap::is_in_active_generation(oop obj) const {
 769   if (!mode()->is_generational()) {
 770     // everything is the same single generation
 771     return true;
 772   }
 773 
 774   if (active_generation() == NULL) {
 775     // no collection is happening, only expect this to be called
 776     // when concurrent processing is active, but that could change
 777     return false;
 778   }
 779 
 780   return active_generation()->contains(obj);
 781 }
 782 
 783 void ShenandoahHeap::op_uncommit(double shrink_before, size_t shrink_until) {
 784   assert (ShenandoahUncommit, "should be enabled");
 785 
 786   // Application allocates from the beginning of the heap, and GC allocates at
 787   // the end of it. It is more efficient to uncommit from the end, so that applications
 788   // could enjoy the near committed regions. GC allocations are much less frequent,
 789   // and therefore can accept the committing costs.
 790 
 791   size_t count = 0;
 792   for (size_t i = num_regions(); i > 0; i--) { // care about size_t underflow
 793     ShenandoahHeapRegion* r = get_region(i - 1);
 794     if (r->is_empty_committed() && (r->empty_time() < shrink_before)) {
 795       ShenandoahHeapLocker locker(lock());
 796       if (r->is_empty_committed()) {
 797         if (committed() < shrink_until + ShenandoahHeapRegion::region_size_bytes()) {
 798           break;
 799         }
 800 
 801         r->make_uncommitted();
 802         count++;
 803       }
 804     }
 805     SpinPause(); // allow allocators to take the lock
 806   }
 807 
 808   if (count > 0) {
 809     control_thread()->notify_heap_changed();
 810     regulator_thread()->notify_heap_changed();
 811   }
 812 }
 813 
 814 void ShenandoahHeap::handle_old_evacuation(HeapWord* obj, size_t words, bool promotion) {
 815   // Only register the copy of the object that won the evacuation race.
 816   card_scan()->register_object_wo_lock(obj);
 817 
 818   // Mark the entire range of the evacuated object as dirty.  At next remembered set scan,
 819   // we will clear dirty bits that do not hold interesting pointers.  It's more efficient to
 820   // do this in batch, in a background GC thread than to try to carefully dirty only cards
 821   // that hold interesting pointers right now.
 822   card_scan()->mark_range_as_dirty(obj, words);
 823 
 824   if (promotion) {
 825     // This evacuation was a promotion, track this as allocation against old gen
 826     old_generation()->increase_allocated(words * HeapWordSize);
 827   }
 828 }
 829 
 830 void ShenandoahHeap::handle_old_evacuation_failure() {
 831   if (_old_gen_oom_evac.try_set()) {
 832     log_info(gc)("Old gen evac failure.");
 833   }
 834 }
 835 
 836 void ShenandoahHeap::handle_promotion_failure() {
 837   old_heuristics()->handle_promotion_failure();
 838 }
 839 
 840 HeapWord* ShenandoahHeap::allocate_from_gclab_slow(Thread* thread, size_t size) {
 841   // New object should fit the GCLAB size
 842   size_t min_size = MAX2(size, PLAB::min_size());
 843 
 844   // Figure out size of new GCLAB, looking back at heuristics. Expand aggressively.
 845   size_t new_size = ShenandoahThreadLocalData::gclab_size(thread) * 2;
 846   new_size = MIN2(new_size, PLAB::max_size());
 847   new_size = MAX2(new_size, PLAB::min_size());
 848 
 849   // Record new heuristic value even if we take any shortcut. This captures
 850   // the case when moderately-sized objects always take a shortcut. At some point,
 851   // heuristics should catch up with them.
 852   ShenandoahThreadLocalData::set_gclab_size(thread, new_size);
 853 
 854   if (new_size < size) {
 855     // New size still does not fit the object. Fall back to shared allocation.
 856     // This avoids retiring perfectly good GCLABs, when we encounter a large object.
 857     return NULL;
 858   }
 859 

 869 
 870   assert (size <= actual_size, "allocation should fit");
 871 
 872   if (ZeroTLAB) {
 873     // ..and clear it.
 874     Copy::zero_to_words(gclab_buf, actual_size);
 875   } else {
 876     // ...and zap just allocated object.
 877 #ifdef ASSERT
 878     // Skip mangling the space corresponding to the object header to
 879     // ensure that the returned space is not considered parsable by
 880     // any concurrent GC thread.
 881     size_t hdr_size = oopDesc::header_size();
 882     Copy::fill_to_words(gclab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
 883 #endif // ASSERT
 884   }
 885   gclab->set_buf(gclab_buf, actual_size);
 886   return gclab->allocate(size);
 887 }
 888 
 889 // Establish a new PLAB and allocate size HeapWords within it.
 890 HeapWord* ShenandoahHeap::allocate_from_plab_slow(Thread* thread, size_t size) {
 891   // New object should fit the PLAB size
 892   size_t min_size = MAX2(size, PLAB::min_size());
 893 
 894   // Figure out size of new PLAB, looking back at heuristics. Expand aggressively.
 895   size_t new_size = ShenandoahThreadLocalData::plab_size(thread) * 2;
 896   new_size = MIN2(new_size, PLAB::max_size());
 897   new_size = MAX2(new_size, PLAB::min_size());
 898 
 899   size_t unalignment = new_size % CardTable::card_size_in_words;
 900   if (unalignment != 0) {
 901     new_size = new_size - unalignment + CardTable::card_size_in_words;
 902   }
 903 
 904   // Record new heuristic value even if we take any shortcut. This captures
 905   // the case when moderately-sized objects always take a shortcut. At some point,
 906   // heuristics should catch up with them.  Note that the requested new_size may
 907   // not be honored, but we remember that this is the preferred size.
 908   ShenandoahThreadLocalData::set_plab_size(thread, new_size);
 909 
 910   if (new_size < size) {
 911     // New size still does not fit the object. Fall back to shared allocation.
 912     // This avoids retiring perfectly good PLABs, when we encounter a large object.
 913     return NULL;
 914   }
 915 
 916   // Retire current PLAB, and allocate a new one.
 917   PLAB* plab = ShenandoahThreadLocalData::plab(thread);
 918   // CAUTION: retire_plab may register the remnant filler object with the remembered set scanner without a lock.  This
 919   // is safe iff it is assured that each PLAB is a whole-number multiple of card-mark memory size and each PLAB is
 920   // aligned with the start of a card's memory range.
 921   retire_plab(plab);
 922 
 923   size_t actual_size = 0;
 924   HeapWord* plab_buf = allocate_new_plab(min_size, new_size, &actual_size);
 925   if (plab_buf == NULL) {
 926     return NULL;
 927   }
 928 
 929   assert (size <= actual_size, "allocation should fit");
 930 
 931   if (ZeroTLAB) {
 932     // ..and clear it.
 933     Copy::zero_to_words(plab_buf, actual_size);
 934   } else {
 935     // ...and zap just allocated object.
 936 #ifdef ASSERT
 937     // Skip mangling the space corresponding to the object header to
 938     // ensure that the returned space is not considered parsable by
 939     // any concurrent GC thread.
 940     size_t hdr_size = oopDesc::header_size();
 941     Copy::fill_to_words(plab_buf + hdr_size, actual_size - hdr_size, badHeapWordVal);
 942 #endif // ASSERT
 943   }
 944   plab->set_buf(plab_buf, actual_size);
 945   return plab->allocate(size);
 946 }
 947 
 948 void ShenandoahHeap::retire_plab(PLAB* plab) {
 949   if (!mode()->is_generational()) {
 950     plab->retire();
 951   } else {
 952     size_t waste = plab->waste();
 953     HeapWord* top = plab->top();
 954     plab->retire();
 955     if (top != NULL && plab->waste() > waste && is_in_old(top)) {
 956       // If retiring the plab created a filler object, then we
 957       // need to register it with our card scanner so it can
 958       // safely walk the region backing the plab.
 959       log_debug(gc)("retire_plab() is registering remnant of size " SIZE_FORMAT " at " PTR_FORMAT,
 960                     plab->waste() - waste, p2i(top));
 961       card_scan()->register_object_wo_lock(top);
 962     }
 963   }
 964 }
 965 
 966 void ShenandoahHeap::cancel_mixed_collections() {
 967   assert(_old_generation != NULL, "Should only have mixed collections in generation mode.");
 968   old_heuristics()->abandon_collection_candidates();
 969 }
 970 
 971 void ShenandoahHeap::coalesce_and_fill_old_regions() {
 972   class ShenandoahGlobalCoalesceAndFill : public ShenandoahHeapRegionClosure {
 973    public:
 974     virtual void heap_region_do(ShenandoahHeapRegion* region) override {
 975       // old region is not in the collection set and was not immediately trashed
 976       if (region->is_old() && region->is_active() && !region->is_humongous()) {
 977         // Reset the coalesce and fill boundary because this is a global collect
 978         // and cannot be preempted by young collects. We want to be sure the entire
 979         // region is coalesced here and does not resume from a previously interrupted
 980         // or completed coalescing.
 981         region->begin_preemptible_coalesce_and_fill();
 982         region->oop_fill_and_coalesce();
 983       }
 984     }
 985 
 986     virtual bool is_thread_safe() override {
 987       return true;
 988     }
 989   };
 990   ShenandoahGlobalCoalesceAndFill coalesce;
 991   parallel_heap_region_iterate(&coalesce);
 992 }
 993 
 994 HeapWord* ShenandoahHeap::allocate_new_tlab(size_t min_size,
 995                                             size_t requested_size,
 996                                             size_t* actual_size) {
 997   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_tlab(min_size, requested_size);
 998   HeapWord* res = allocate_memory(req);
 999   if (res != NULL) {
1000     *actual_size = req.actual_size();
1001   } else {
1002     *actual_size = 0;
1003   }
1004   return res;
1005 }
1006 
1007 HeapWord* ShenandoahHeap::allocate_new_gclab(size_t min_size,
1008                                              size_t word_size,
1009                                              size_t* actual_size) {
1010   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_gclab(min_size, word_size);
1011   HeapWord* res = allocate_memory(req);
1012   if (res != NULL) {
1013     *actual_size = req.actual_size();
1014   } else {
1015     *actual_size = 0;
1016   }
1017   return res;
1018 }
1019 
1020 HeapWord* ShenandoahHeap::allocate_new_plab(size_t min_size,
1021                                             size_t word_size,
1022                                             size_t* actual_size) {
1023   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_plab(min_size, word_size);
1024   HeapWord* res = allocate_memory(req);
1025   if (res != NULL) {
1026     *actual_size = req.actual_size();
1027   } else {
1028     *actual_size = 0;
1029   }
1030   return res;
1031 }
1032 
1033 HeapWord* ShenandoahHeap::allocate_memory(ShenandoahAllocRequest& req) {
1034   intptr_t pacer_epoch = 0;
1035   bool in_new_region = false;
1036   HeapWord* result = NULL;
1037 
1038   if (req.is_mutator_alloc()) {
1039     if (ShenandoahPacing) {
1040       pacer()->pace_for_alloc(req.size());
1041       pacer_epoch = pacer()->epoch();
1042     }
1043 
1044     if (!ShenandoahAllocFailureALot || !should_inject_alloc_failure()) {
1045       result = allocate_memory_under_lock(req, in_new_region);
1046     }
1047 
1048     // Allocation failed, block until control thread reacted, then retry allocation.
1049     //
1050     // It might happen that one of the threads requesting allocation would unblock
1051     // way later after GC happened, only to fail the second allocation, because
1052     // other threads have already depleted the free storage. In this case, a better

1061       tries++;
1062       control_thread()->handle_alloc_failure(req);
1063       result = allocate_memory_under_lock(req, in_new_region);
1064     }
1065 
1066     while (result == NULL && tries <= ShenandoahFullGCThreshold) {
1067       tries++;
1068       control_thread()->handle_alloc_failure(req);
1069       result = allocate_memory_under_lock(req, in_new_region);
1070     }
1071 
1072   } else {
1073     assert(req.is_gc_alloc(), "Can only accept GC allocs here");
1074     result = allocate_memory_under_lock(req, in_new_region);
1075     // Do not call handle_alloc_failure() here, because we cannot block.
1076     // The allocation failure would be handled by the LRB slowpath with handle_alloc_failure_evac().
1077   }
1078 
1079   if (in_new_region) {
1080     control_thread()->notify_heap_changed();
1081     regulator_thread()->notify_heap_changed();
1082   }
1083 
1084   if (result != NULL) {
1085     ShenandoahGeneration* alloc_generation = generation_for(req.affiliation());
1086     size_t requested = req.size();
1087     size_t actual = req.actual_size();
1088     size_t actual_bytes = actual * HeapWordSize;
1089 
1090     assert (req.is_lab_alloc() || (requested == actual),
1091             "Only LAB allocations are elastic: %s, requested = " SIZE_FORMAT ", actual = " SIZE_FORMAT,
1092             ShenandoahAllocRequest::alloc_type_to_string(req.type()), requested, actual);
1093 
1094     if (req.is_mutator_alloc()) {
1095       notify_mutator_alloc_words(actual, false);
1096       alloc_generation->increase_allocated(actual_bytes);
1097 
1098       // If we requested more than we were granted, give the rest back to pacer.
1099       // This only matters if we are in the same pacing epoch: do not try to unpace
1100       // over the budget for the other phase.
1101       if (ShenandoahPacing && (pacer_epoch > 0) && (requested > actual)) {
1102         pacer()->unpace_for_alloc(pacer_epoch, requested - actual);
1103       }
1104     } else {
1105       increase_used(actual_bytes);
1106     }
1107   }
1108 
1109   return result;
1110 }
1111 
1112 HeapWord* ShenandoahHeap::allocate_memory_under_lock(ShenandoahAllocRequest& req, bool& in_new_region) {
1113   if (mode()->is_generational() && req.affiliation() == YOUNG_GENERATION && young_generation()->used() + req.size() >= young_generation()->max_capacity()) {
1114     return nullptr;
1115   }
1116 
1117   ShenandoahHeapLocker locker(lock());
1118   HeapWord* result = _free_set->allocate(req, in_new_region);
1119   if (result != NULL && req.affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION) {
1120     // Register the newly allocated object while we're holding the global lock since there's no synchronization
1121     // built in to the implementation of register_object().  There are potential races when multiple independent
1122     // threads are allocating objects, some of which might span the same card region.  For example, consider
1123     // a card table's memory region within which three objects are being allocated by three different threads:
1124     //
1125     // objects being "concurrently" allocated:
1126     //    [-----a------][-----b-----][--------------c------------------]
1127     //            [---- card table memory range --------------]
1128     //
1129     // Before any objects are allocated, this card's memory range holds no objects.  Note that:
1130     //   allocation of object a wants to set the has-object, first-start, and last-start attributes of the preceding card region.
1131     //   allocation of object b wants to set the has-object, first-start, and last-start attributes of this card region.
1132     //   allocation of object c also wants to set the has-object, first-start, and last-start attributes of this card region.
1133     //
1134     // The thread allocating b and the thread allocating c can "race" in various ways, resulting in confusion, such as last-start
1135     // representing object b while first-start represents object c.  This is why we need to require all register_object()
1136     // invocations to be "mutually exclusive" with respect to each card's memory range.
1137     ShenandoahHeap::heap()->card_scan()->register_object(result);
1138   }
1139   return result;
1140 }
1141 
1142 HeapWord* ShenandoahHeap::mem_allocate(size_t size,
1143                                         bool*  gc_overhead_limit_was_exceeded) {
1144   ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared(size);
1145   return allocate_memory(req);
1146 }
1147 
1148 MetaWord* ShenandoahHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
1149                                                              size_t size,
1150                                                              Metaspace::MetadataType mdtype) {
1151   MetaWord* result;
1152 
1153   // Inform metaspace OOM to GC heuristics if class unloading is possible.
1154   ShenandoahHeuristics* h = global_generation()->heuristics();
1155   if (h->can_unload_classes()) {
1156     h->record_metaspace_oom();
1157   }
1158 
1159   // Expand and retry allocation
1160   result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);
1161   if (result != NULL) {
1162     return result;
1163   }
1164 
1165   // Start full GC
1166   collect(GCCause::_metadata_GC_clear_soft_refs);
1167 
1168   // Retry allocation
1169   result = loader_data->metaspace_non_null()->allocate(size, mdtype);
1170   if (result != NULL) {
1171     return result;
1172   }
1173 
1174   // Expand and retry allocation
1175   result = loader_data->metaspace_non_null()->expand_and_allocate(size, mdtype);

1214 
1215   void work(uint worker_id) {
1216     if (_concurrent) {
1217       ShenandoahConcurrentWorkerSession worker_session(worker_id);
1218       ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
1219       ShenandoahEvacOOMScope oom_evac_scope;
1220       do_work();
1221     } else {
1222       ShenandoahParallelWorkerSession worker_session(worker_id);
1223       ShenandoahEvacOOMScope oom_evac_scope;
1224       do_work();
1225     }
1226   }
1227 
1228 private:
1229   void do_work() {
1230     ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1231     ShenandoahHeapRegion* r;
1232     while ((r =_cs->claim_next()) != NULL) {
1233       assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1234 
1235       _sh->marked_object_iterate(r, &cl);
1236 
1237       if (ShenandoahPacing) {
1238         _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1239       }
1240       if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1241         break;
1242       }
1243     }
1244   }
1245 };
1246 
1247 // Unlike ShenandoahEvacuationTask, this iterates over all regions rather than just the collection set.
1248 // This is needed in order to promote humongous start regions if age() >= tenure threshold.
1249 class ShenandoahGenerationalEvacuationTask : public AbstractGangTask {
1250 private:
1251   ShenandoahHeap* const _sh;
1252   ShenandoahRegionIterator *_regions;
1253   bool _concurrent;
1254 public:
1255   ShenandoahGenerationalEvacuationTask(ShenandoahHeap* sh,
1256                                        ShenandoahRegionIterator* iterator,
1257                                        bool concurrent) :
1258     AbstractGangTask("Shenandoah Evacuation"),
1259     _sh(sh),
1260     _regions(iterator),
1261     _concurrent(concurrent)
1262   {}
1263 
1264   void work(uint worker_id) {
1265     if (_concurrent) {
1266       ShenandoahConcurrentWorkerSession worker_session(worker_id);
1267       ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
1268       ShenandoahEvacOOMScope oom_evac_scope;
1269       do_work();
1270     } else {
1271       ShenandoahParallelWorkerSession worker_session(worker_id);
1272       ShenandoahEvacOOMScope oom_evac_scope;
1273       do_work();
1274     }
1275   }
1276 
1277 private:
1278   void do_work() {
1279     ShenandoahConcurrentEvacuateRegionObjectClosure cl(_sh);
1280     ShenandoahHeapRegion* r;
1281     while ((r = _regions->next()) != nullptr) {
1282       log_debug(gc)("GenerationalEvacuationTask do_work(), looking at %s region " SIZE_FORMAT ", (age: %d) [%s, %s]",
1283                     r->is_old()? "old": r->is_young()? "young": "free", r->index(), r->age(),
1284                     r->is_active()? "active": "inactive",
1285                     r->is_humongous()? (r->is_humongous_start()? "humongous_start": "humongous_continuation"): "regular");
1286       if (r->is_cset()) {
1287         assert(r->has_live(), "Region " SIZE_FORMAT " should have been reclaimed early", r->index());
1288         _sh->marked_object_iterate(r, &cl);
1289         if (ShenandoahPacing) {
1290           _sh->pacer()->report_evac(r->used() >> LogHeapWordSize);
1291         }
1292       } else if (r->is_young() && r->is_active() && r->is_humongous_start() && (r->age() > InitialTenuringThreshold)) {
1293         // We promote humongous_start regions along with their affiliated continuations during evacuation rather than
1294         // doing this work during a safepoint.  We cannot put humongous regions into the collection set because that
1295         // triggers the load-reference barrier (LRB) to copy on reference fetch.
1296         r->promote_humongous();
1297       }
1298       // else, region is free, or OLD, or not in collection set, or humongous_continuation,
1299       // or is young humongous_start that is too young to be promoted
1300 
1301       if (_sh->check_cancelled_gc_and_yield(_concurrent)) {
1302         break;
1303       }
1304     }
1305   }
1306 };
1307 
1308 void ShenandoahHeap::evacuate_collection_set(bool concurrent) {
1309   if (ShenandoahHeap::heap()->mode()->is_generational()) {
1310     ShenandoahRegionIterator regions;
1311     ShenandoahGenerationalEvacuationTask task(this, &regions, concurrent);
1312     workers()->run_task(&task);
1313   } else {
1314     ShenandoahEvacuationTask task(this, _collection_set, concurrent);
1315     workers()->run_task(&task);
1316   }
1317 }
1318 
1319 void ShenandoahHeap::trash_cset_regions() {
1320   ShenandoahHeapLocker locker(lock());
1321 
1322   ShenandoahCollectionSet* set = collection_set();
1323   ShenandoahHeapRegion* r;
1324   set->clear_current_index();
1325   while ((r = set->next()) != NULL) {
1326     r->make_trash();
1327   }
1328   collection_set()->clear();
1329 }
1330 
1331 void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
1332   st->print_cr("Heap Regions:");
1333   st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
1334   st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
1335   st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
1336   st->print_cr("SN=alloc sequence number");
1337 
1338   for (size_t i = 0; i < num_regions(); i++) {
1339     get_region(i)->print_on(st);
1340   }
1341 }
1342 
1343 size_t ShenandoahHeap::trash_humongous_region_at(ShenandoahHeapRegion* start) {
1344   assert(start->is_humongous_start(), "reclaim regions starting with the first one");
1345 
1346   oop humongous_obj = cast_to_oop(start->bottom());
1347   size_t size = humongous_obj->size();
1348   size_t required_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
1349   size_t index = start->index() + required_regions - 1;
1350 
1351   assert(!start->has_live(), "liveness must be zero");
1352 
1353   for(size_t i = 0; i < required_regions; i++) {
1354     // Reclaim from tail. Otherwise, assertion fails when printing region to trace log,
1355     // as it expects that every region belongs to a humongous region starting with a humongous start region.
1356     ShenandoahHeapRegion* region = get_region(index --);
1357 
1358     assert(region->is_humongous(), "expect correct humongous start or continuation");
1359     assert(!region->is_cset(), "Humongous region should not be in collection set");
1360 
1361     region->make_trash_immediate();
1362   }
1363   return required_regions;
1364 }
1365 
1366 class ShenandoahCheckCleanGCLABClosure : public ThreadClosure {
1367 public:
1368   ShenandoahCheckCleanGCLABClosure() {}
1369   void do_thread(Thread* thread) {
1370     PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1371     assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1372     assert(gclab->words_remaining() == 0, "GCLAB should not need retirement");
1373 
1374     PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1375     assert(plab != NULL, "PLAB should be initialized for %s", thread->name());
1376     assert(plab->words_remaining() == 0, "PLAB should not need retirement");
1377   }
1378 };
1379 
1380 class ShenandoahRetireGCLABClosure : public ThreadClosure {
1381 private:
1382   bool const _resize;
1383 public:
1384   ShenandoahRetireGCLABClosure(bool resize) : _resize(resize) {}
1385   void do_thread(Thread* thread) {
1386     PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1387     assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1388     ShenandoahHeap::heap()->retire_plab(gclab);
1389     if (_resize && ShenandoahThreadLocalData::gclab_size(thread) > 0) {
1390       ShenandoahThreadLocalData::set_gclab_size(thread, 0);
1391     }
1392 
1393     PLAB* plab = ShenandoahThreadLocalData::plab(thread);
1394     assert(plab != NULL, "PLAB should be initialized for %s", thread->name());
1395     // TODO; Retiring a PLAB disables it so it cannot support future allocations.  This is overkill.  For old-gen
1396     // regions, the important thing is to make the memory parsable by the remembered-set scanning code that drives
1397     // the update-refs processing that follows.  After the updating of old-gen references is done, it is ok to carve
1398     // this remnant object into smaller pieces during the subsequent evacuation pass, as long as the PLAB is made parsable
1399     // again before the next update-refs phase.
1400     ShenandoahHeap::heap()->retire_plab(plab);
1401     if (_resize && ShenandoahThreadLocalData::plab_size(thread) > 0) {
1402       ShenandoahThreadLocalData::set_plab_size(thread, 0);
1403     }
1404   }
1405 };
1406 
1407 void ShenandoahHeap::labs_make_parsable() {
1408   assert(UseTLAB, "Only call with UseTLAB");
1409 
1410   ShenandoahRetireGCLABClosure cl(false);
1411 
1412   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1413     ThreadLocalAllocBuffer& tlab = t->tlab();
1414     tlab.make_parsable();
1415     cl.do_thread(t);
1416   }
1417 
1418   workers()->threads_do(&cl);
1419 }
1420 
1421 void ShenandoahHeap::tlabs_retire(bool resize) {
1422   assert(UseTLAB, "Only call with UseTLAB");
1423   assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");

1441   }
1442   workers()->threads_do(&cl);
1443 #endif
1444 }
1445 
1446 void ShenandoahHeap::gclabs_retire(bool resize) {
1447   assert(UseTLAB, "Only call with UseTLAB");
1448   assert(!resize || ResizeTLAB, "Only call for resize when ResizeTLAB is enabled");
1449 
1450   ShenandoahRetireGCLABClosure cl(resize);
1451   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1452     cl.do_thread(t);
1453   }
1454   workers()->threads_do(&cl);
1455 
1456   if (safepoint_workers() != NULL) {
1457     safepoint_workers()->threads_do(&cl);
1458   }
1459 }
1460 
1461 class ShenandoahTagGCLABClosure : public ThreadClosure {
1462 public:
1463   void do_thread(Thread* thread) {
1464     PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
1465     assert(gclab != NULL, "GCLAB should be initialized for %s", thread->name());
1466     if (gclab->words_remaining() > 0) {
1467       ShenandoahHeapRegion* r = ShenandoahHeap::heap()->heap_region_containing(gclab->allocate(0));
1468       r->set_young_lab_flag();
1469     }
1470   }
1471 };
1472 
1473 void ShenandoahHeap::set_young_lab_region_flags() {
1474   if (!UseTLAB) {
1475     return;
1476   }
1477   for (size_t i = 0; i < _num_regions; i++) {
1478     _regions[i]->clear_young_lab_flags();
1479   }
1480   ShenandoahTagGCLABClosure cl;
1481   workers()->threads_do(&cl);
1482   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1483     cl.do_thread(t);
1484     ThreadLocalAllocBuffer& tlab = t->tlab();
1485     if (tlab.end() != NULL) {
1486       ShenandoahHeapRegion* r = heap_region_containing(tlab.start());
1487       r->set_young_lab_flag();
1488     }
1489   }
1490 }
1491 
1492 // Returns size in bytes
1493 size_t ShenandoahHeap::unsafe_max_tlab_alloc(Thread *thread) const {
1494   if (ShenandoahElasticTLAB) {
1495     // With Elastic TLABs, return the max allowed size, and let the allocation path
1496     // figure out the safe size for current allocation.
1497     return ShenandoahHeapRegion::max_tlab_size_bytes();
1498   } else {
1499     return MIN2(_free_set->unsafe_peek_free(), ShenandoahHeapRegion::max_tlab_size_bytes());
1500   }
1501 }
1502 
1503 size_t ShenandoahHeap::max_tlab_size() const {
1504   // Returns size in words
1505   return ShenandoahHeapRegion::max_tlab_size_words();
1506 }
1507 
1508 void ShenandoahHeap::collect(GCCause::Cause cause) {
1509   control_thread()->request_gc(cause);
1510 }
1511 

1867       if (start >= max) break;
1868 
1869       for (size_t i = cur; i < end; i++) {
1870         ShenandoahHeapRegion* current = _heap->get_region(i);
1871         _blk->heap_region_do(current);
1872       }
1873     }
1874   }
1875 };
1876 
1877 void ShenandoahHeap::parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const {
1878   assert(blk->is_thread_safe(), "Only thread-safe closures here");
1879   if (num_regions() > ShenandoahParallelRegionStride) {
1880     ShenandoahParallelHeapRegionTask task(blk);
1881     workers()->run_task(&task);
1882   } else {
1883     heap_region_iterate(blk);
1884   }
1885 }
1886 























1887 class ShenandoahRendezvousClosure : public HandshakeClosure {
1888 public:
1889   inline ShenandoahRendezvousClosure() : HandshakeClosure("ShenandoahRendezvous") {}
1890   inline void do_thread(Thread* thread) {}
1891 };
1892 
1893 void ShenandoahHeap::rendezvous_threads() {
1894   ShenandoahRendezvousClosure cl;
1895   Handshake::execute(&cl);
1896 }
1897 
1898 void ShenandoahHeap::recycle_trash() {
1899   free_set()->recycle_trash();
1900 }
1901 



































































































1902 void ShenandoahHeap::do_class_unloading() {
1903   _unloader.unload();
1904 }
1905 
1906 void ShenandoahHeap::stw_weak_refs(bool full_gc) {
1907   // Weak refs processing
1908   ShenandoahPhaseTimings::Phase phase = full_gc ? ShenandoahPhaseTimings::full_gc_weakrefs
1909                                                 : ShenandoahPhaseTimings::degen_gc_weakrefs;
1910   ShenandoahTimingsTracker t(phase);
1911   ShenandoahGCWorkerPhase worker_phase(phase);
1912   active_generation()->ref_processor()->process_references(phase, workers(), false /* concurrent */);
1913 }
1914 
1915 void ShenandoahHeap::prepare_update_heap_references(bool concurrent) {
1916   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "must be at safepoint");
1917 
1918   // Evacuation is over, no GCLABs are needed anymore. GCLABs are under URWM, so we need to
1919   // make them parsable for update code to work correctly. Plus, we can compute new sizes
1920   // for future GCLABs here.
1921   if (UseTLAB) {
1922     ShenandoahGCPhase phase(concurrent ?
1923                             ShenandoahPhaseTimings::init_update_refs_manage_gclabs :
1924                             ShenandoahPhaseTimings::degen_gc_init_update_refs_manage_gclabs);
1925     gclabs_retire(ResizeTLAB);
1926   }
1927 
1928   _update_refs_iterator.reset();
1929 }
1930 
1931 void ShenandoahHeap::set_gc_state_all_threads(char state) {
1932   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
1933     ShenandoahThreadLocalData::set_gc_state(t, state);
1934   }
1935 }
1936 
1937 void ShenandoahHeap::set_gc_state_mask(uint mask, bool value) {
1938   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Should really be Shenandoah safepoint");
1939   _gc_state.set_cond(mask, value);
1940   set_gc_state_all_threads(_gc_state.raw_value());
1941 }
1942 
1943 void ShenandoahHeap::set_concurrent_young_mark_in_progress(bool in_progress) {
1944   if (has_forwarded_objects()) {
1945     set_gc_state_mask(YOUNG_MARKING | UPDATEREFS, in_progress);
1946   } else {
1947     set_gc_state_mask(YOUNG_MARKING, in_progress);
1948   }
1949 
1950   manage_satb_barrier(in_progress);
1951 }
1952 
1953 void ShenandoahHeap::set_concurrent_old_mark_in_progress(bool in_progress) {
1954   if (has_forwarded_objects()) {
1955     set_gc_state_mask(OLD_MARKING | UPDATEREFS, in_progress);
1956   } else {
1957     set_gc_state_mask(OLD_MARKING, in_progress);
1958   }
1959 
1960   manage_satb_barrier(in_progress);
1961 }
1962 
1963 void ShenandoahHeap::set_concurrent_prep_for_mixed_evacuation_in_progress(bool in_progress) {
1964   // Unlike other set-gc-state functions, this may happen outside safepoint.
1965   // Is only set and queried by control thread, so no coherence issues.
1966   _prep_for_mixed_evac_in_progress = in_progress;
1967 }
1968 
1969 bool ShenandoahHeap::is_concurrent_prep_for_mixed_evacuation_in_progress() {
1970   return _prep_for_mixed_evac_in_progress;
1971 }
1972 
1973 void ShenandoahHeap::set_aging_cycle(bool in_progress) {
1974   _is_aging_cycle.set_cond(in_progress);
1975 }
1976 
1977 void ShenandoahHeap::manage_satb_barrier(bool active) {
1978   if (is_concurrent_mark_in_progress()) {
1979     // Ignore request to deactivate barrier while concurrent mark is in progress.
1980     // Do not attempt to re-activate the barrier if it is already active.
1981     if (active && !ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
1982       ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
1983     }
1984   } else {
1985     // No concurrent marking is in progress so honor request to deactivate,
1986     // but only if the barrier is already active.
1987     if (!active && ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
1988       ShenandoahBarrierSet::satb_mark_queue_set().set_active_all_threads(active, !active);
1989     }
1990   }
1991 }
1992 
1993 void ShenandoahHeap::set_evacuation_in_progress(bool in_progress) {
1994   assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Only call this at safepoint");
1995   set_gc_state_mask(EVACUATION, in_progress);
1996 }
1997 
1998 void ShenandoahHeap::set_concurrent_strong_root_in_progress(bool in_progress) {
1999   if (in_progress) {
2000     _concurrent_strong_root_in_progress.set();
2001   } else {
2002     _concurrent_strong_root_in_progress.unset();
2003   }
2004 }
2005 
2006 void ShenandoahHeap::set_concurrent_weak_root_in_progress(bool cond) {
2007   set_gc_state_mask(WEAK_ROOTS, cond);
2008 }
2009 
2010 GCTracer* ShenandoahHeap::tracer() {

2015   return _free_set->used();
2016 }
2017 
2018 bool ShenandoahHeap::try_cancel_gc() {
2019   while (true) {
2020     jbyte prev = _cancelled_gc.cmpxchg(CANCELLED, CANCELLABLE);
2021     if (prev == CANCELLABLE) return true;
2022     else if (prev == CANCELLED) return false;
2023     assert(ShenandoahSuspendibleWorkers, "should not get here when not using suspendible workers");
2024     assert(prev == NOT_CANCELLED, "must be NOT_CANCELLED");
2025     Thread* thread = Thread::current();
2026     if (thread->is_Java_thread()) {
2027       // We need to provide a safepoint here, otherwise we might
2028       // spin forever if a SP is pending.
2029       ThreadBlockInVM sp(JavaThread::cast(thread));
2030       SpinPause();
2031     }
2032   }
2033 }
2034 
2035 void ShenandoahHeap::cancel_concurrent_mark() {
2036   _young_generation->cancel_marking();
2037   _old_generation->cancel_marking();
2038   _global_generation->cancel_marking();
2039 
2040   ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking();
2041 }
2042 
2043 void ShenandoahHeap::cancel_gc(GCCause::Cause cause) {
2044   if (try_cancel_gc()) {
2045     FormatBuffer<> msg("Cancelling GC: %s", GCCause::to_string(cause));
2046     log_info(gc)("%s", msg.buffer());
2047     Events::log(Thread::current(), "%s", msg.buffer());
2048     _cancel_requested_time = os::elapsedTime();
2049   }
2050 }
2051 
2052 uint ShenandoahHeap::max_workers() {
2053   return _max_workers;
2054 }
2055 
2056 void ShenandoahHeap::stop() {
2057   // The shutdown sequence should be able to terminate when GC is running.
2058 
2059   // Step 0a. Stop requesting collections.
2060   regulator_thread()->stop();
2061 
2062   // Step 0. Notify policy to disable event recording.
2063   _shenandoah_policy->record_shutdown();
2064 
2065   // Step 1. Notify control thread that we are in shutdown.
2066   // Note that we cannot do that with stop(), because stop() is blocking and waits for the actual shutdown.
2067   // Doing stop() here would wait for the normal GC cycle to complete, never falling through to cancel below.
2068   control_thread()->prepare_for_graceful_shutdown();
2069 
2070   // Step 2. Notify GC workers that we are cancelling GC.
2071   cancel_gc(GCCause::_shenandoah_stop_vm);
2072 
2073   // Step 3. Wait until GC worker exits normally.
2074   control_thread()->stop();
2075 }
2076 
2077 void ShenandoahHeap::stw_unload_classes(bool full_gc) {
2078   if (!unload_classes()) return;
2079   // Unload classes and purge SystemDictionary.
2080   {
2081     ShenandoahPhaseTimings::Phase phase = full_gc ?

2146 }
2147 
2148 void ShenandoahHeap::set_has_forwarded_objects(bool cond) {
2149   set_gc_state_mask(HAS_FORWARDED, cond);
2150 }
2151 
2152 void ShenandoahHeap::set_unload_classes(bool uc) {
2153   _unload_classes.set_cond(uc);
2154 }
2155 
2156 bool ShenandoahHeap::unload_classes() const {
2157   return _unload_classes.is_set();
2158 }
2159 
2160 address ShenandoahHeap::in_cset_fast_test_addr() {
2161   ShenandoahHeap* heap = ShenandoahHeap::heap();
2162   assert(heap->collection_set() != NULL, "Sanity");
2163   return (address) heap->collection_set()->biased_map_address();
2164 }
2165 




2166 address ShenandoahHeap::gc_state_addr() {
2167   return (address) ShenandoahHeap::heap()->_gc_state.addr_of();
2168 }
2169 




2170 void ShenandoahHeap::reset_bytes_allocated_since_gc_start() {
2171   if (mode()->is_generational()) {
2172     young_generation()->reset_bytes_allocated_since_gc_start();
2173     old_generation()->reset_bytes_allocated_since_gc_start();
2174   }
2175 
2176   global_generation()->reset_bytes_allocated_since_gc_start();
2177 }
2178 
2179 void ShenandoahHeap::set_degenerated_gc_in_progress(bool in_progress) {
2180   _degenerated_gc_in_progress.set_cond(in_progress);
2181 }
2182 
2183 void ShenandoahHeap::set_full_gc_in_progress(bool in_progress) {
2184   _full_gc_in_progress.set_cond(in_progress);
2185 }
2186 
2187 void ShenandoahHeap::set_full_gc_move_in_progress(bool in_progress) {
2188   assert (is_full_gc_in_progress(), "should be");
2189   _full_gc_move_in_progress.set_cond(in_progress);
2190 }
2191 
2192 void ShenandoahHeap::set_update_refs_in_progress(bool in_progress) {
2193   set_gc_state_mask(UPDATEREFS, in_progress);
2194 }
2195 
2196 void ShenandoahHeap::register_nmethod(nmethod* nm) {

2225     if (r->is_active()) {
2226       if (r->is_pinned()) {
2227         if (r->pin_count() == 0) {
2228           r->make_unpinned();
2229         }
2230       } else {
2231         if (r->pin_count() > 0) {
2232           r->make_pinned();
2233         }
2234       }
2235     }
2236   }
2237 
2238   assert_pinned_region_status();
2239 }
2240 
2241 #ifdef ASSERT
2242 void ShenandoahHeap::assert_pinned_region_status() {
2243   for (size_t i = 0; i < num_regions(); i++) {
2244     ShenandoahHeapRegion* r = get_region(i);
2245     if (active_generation()->contains(r)) {
2246       assert((r->is_pinned() && r->pin_count() > 0) || (!r->is_pinned() && r->pin_count() == 0),
2247              "Region " SIZE_FORMAT " pinning status is inconsistent", i);
2248     }
2249   }
2250 }
2251 #endif
2252 
2253 ConcurrentGCTimer* ShenandoahHeap::gc_timer() const {
2254   return _gc_timer;
2255 }
2256 
2257 void ShenandoahHeap::prepare_concurrent_roots() {
2258   assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
2259   assert(!is_stw_gc_in_progress(), "Only concurrent GC");
2260   set_concurrent_strong_root_in_progress(!collection_set()->is_empty());
2261   set_concurrent_weak_root_in_progress(true);
2262   if (unload_classes()) {
2263     _unloader.prepare();
2264   }
2265 }
2266 
2267 void ShenandoahHeap::finish_concurrent_roots() {
2268   assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");

2288       assert(nworkers <= ConcGCThreads, "Cannot use more than it has");
2289     } else {
2290       // Use ConcGCThreads outside safepoints
2291       assert(nworkers == ConcGCThreads, "Use ConcGCThreads outside safepoints");
2292     }
2293   }
2294 }
2295 #endif
2296 
2297 ShenandoahVerifier* ShenandoahHeap::verifier() {
2298   guarantee(ShenandoahVerify, "Should be enabled");
2299   assert (_verifier != NULL, "sanity");
2300   return _verifier;
2301 }
2302 
2303 template<bool CONCURRENT>
2304 class ShenandoahUpdateHeapRefsTask : public AbstractGangTask {
2305 private:
2306   ShenandoahHeap* _heap;
2307   ShenandoahRegionIterator* _regions;
2308   bool _mixed_evac;             // true iff most recent evacuation includes old-gen HeapRegions
2309 
2310 public:
2311   ShenandoahUpdateHeapRefsTask(ShenandoahRegionIterator* regions, bool mixed_evac) :
2312     AbstractGangTask("Shenandoah Update References"),
2313     _heap(ShenandoahHeap::heap()),
2314     _regions(regions),
2315     _mixed_evac(mixed_evac)
2316   {
2317   }
2318 
2319   void work(uint worker_id) {
2320     if (CONCURRENT) {
2321       ShenandoahConcurrentWorkerSession worker_session(worker_id);
2322       ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
2323       do_work<ShenandoahConcUpdateRefsClosure>(worker_id);
2324     } else {
2325       ShenandoahParallelWorkerSession worker_session(worker_id);
2326       do_work<ShenandoahSTWUpdateRefsClosure>(worker_id);
2327     }
2328   }
2329 
2330 private:
2331   template<class T>
2332   void do_work(uint worker_id) {
2333     T cl;
2334     ShenandoahHeapRegion* r = _regions->next();
2335 
2336     // We update references for global, old, and young collections.
2337     assert(_heap->active_generation()->is_mark_complete(), "Expected complete marking");
2338     ShenandoahMarkingContext* const ctx = _heap->marking_context();
2339     bool is_mixed = _heap->collection_set()->has_old_regions();
2340     while (r != NULL) {
2341       HeapWord* update_watermark = r->get_update_watermark();
2342       assert (update_watermark >= r->bottom(), "sanity");
2343 
2344       log_debug(gc)("ShenandoahUpdateHeapRefsTask::do_work(%u) looking at region " SIZE_FORMAT, worker_id, r->index());
2345       if (r->is_active() && !r->is_cset()) {
2346         if (!_heap->mode()->is_generational() || (r->affiliation() == ShenandoahRegionAffiliation::YOUNG_GENERATION)) {
2347           _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2348         } else if (r->affiliation() == ShenandoahRegionAffiliation::OLD_GENERATION) {
2349           if (_heap->active_generation()->generation_mode() == GLOBAL) {
2350             _heap->marked_object_oop_iterate(r, &cl, update_watermark);
2351           } else {
2352             // Old region in a young cycle or mixed cycle.
2353             if (!_mixed_evac) {
2354               // This is a young evac..
2355               _heap->card_scan()->process_region(r, &cl, true);
2356             } else {
2357               // This is a _mixed_evac.
2358               //
2359               // TODO: For _mixed_evac, consider building an old-gen remembered set that allows restricted updating
2360               // within old-gen HeapRegions.  This remembered set can be constructed by old-gen concurrent marking
2361               // and augmented by card marking.  For example, old-gen concurrent marking can remember for each old-gen
2362               // card which other old-gen regions it refers to: none, one-other specifically, multiple-other non-specific.
2363               // Update-references when _mixed_evac processess each old-gen memory range that has a traditional DIRTY
2364               // card or if the "old-gen remembered set" indicates that this card holds pointers specifically to an
2365               // old-gen region in the most recent collection set, or if this card holds pointers to other non-specific
2366               // old-gen heap regions.
2367               if (r->is_humongous()) {
2368                 r->oop_iterate_humongous(&cl);
2369               } else {
2370                 // This is a mixed evacuation.  Old regions that are candidates for collection have not been coalesced
2371                 // and filled.  Use mark bits to find objects that need to be updated.
2372                 //
2373                 // Future TODO: establish a second remembered set to identify which old-gen regions point to other old-gen
2374                 // regions which are in the collection set for a particular mixed evacuation.
2375                 HeapWord *p = r->bottom();
2376                 ShenandoahObjectToOopBoundedClosure<T> objs(&cl, p, update_watermark);
2377 
2378                 // Anything beyond update_watermark was allocated during evacuation.  Thus, it is known to not hold
2379                 // references to collection set objects.
2380                 while (p < update_watermark) {
2381                   oop obj = cast_to_oop(p);
2382                   if (ctx->is_marked(obj)) {
2383                     objs.do_object(obj);
2384                     p += obj->size();
2385                   } else {
2386                     // This object is not marked so we don't scan it.
2387                     HeapWord* tams = ctx->top_at_mark_start(r);
2388                     if (p >= tams) {
2389                       p += obj->size();
2390                     } else {
2391                       p = ctx->get_next_marked_addr(p, tams);
2392                     }
2393                   }
2394                 }
2395               }
2396             }
2397           }
2398         } else {
2399           // Because updating of references runs concurrently, it is possible that a FREE inactive region transitions
2400           // to a non-free active region while this loop is executing.  Whenever this happens, the changing of a region's
2401           // active status may propagate at a different speed than the changing of the region's affiliation.
2402 
2403           // When we reach this control point, it is because a race has allowed a region's is_active() status to be seen
2404           // by this thread before the region's affiliation() is seen by this thread.
2405 
2406           // It's ok for this race to occur because the newly transformed region does not have any references to be
2407           // updated.
2408 
2409           assert(r->get_update_watermark() == r->bottom(),
2410                  "%s Region " SIZE_FORMAT " is_active but not recognized as YOUNG or OLD so must be newly transitioned from FREE",
2411                  affiliation_name(r->affiliation()), r->index());
2412         }
2413       }
2414       if (ShenandoahPacing) {
2415         _heap->pacer()->report_updaterefs(pointer_delta(update_watermark, r->bottom()));
2416       }
2417       if (_heap->check_cancelled_gc_and_yield(CONCURRENT)) {
2418         return;
2419       }
2420       r = _regions->next();
2421     }
2422   }
2423 };
2424 
2425 void ShenandoahHeap::update_heap_references(bool concurrent) {
2426   assert(!is_full_gc_in_progress(), "Only for concurrent and degenerated GC");
2427 
2428   if (concurrent) {
2429     ShenandoahUpdateHeapRefsTask<true> task(&_update_refs_iterator, _mixed_evac);
2430     workers()->run_task(&task);
2431   } else {
2432     ShenandoahUpdateHeapRefsTask<false> task(&_update_refs_iterator, _mixed_evac);
2433     workers()->run_task(&task);
2434   }
2435 }
2436 
2437 
2438 class ShenandoahFinalUpdateRefsUpdateRegionStateClosure : public ShenandoahHeapRegionClosure {
2439 private:
2440   ShenandoahHeapLock* const _lock;
2441 
2442 public:
2443   ShenandoahFinalUpdateRefsUpdateRegionStateClosure() : _lock(ShenandoahHeap::heap()->lock()) {}
2444 
2445   void heap_region_do(ShenandoahHeapRegion* r) {
2446     // Drop unnecessary "pinned" state from regions that does not have CP marks
2447     // anymore, as this would allow trashing them.
2448 
2449     if (r->is_active()) {
2450       if (r->is_pinned()) {
2451         if (r->pin_count() == 0) {
2452           ShenandoahHeapLocker locker(_lock);

2589   EventMark em("%s", msg);
2590 
2591   op_uncommit(shrink_before, shrink_until);
2592 }
2593 
2594 void ShenandoahHeap::try_inject_alloc_failure() {
2595   if (ShenandoahAllocFailureALot && !cancelled_gc() && ((os::random() % 1000) > 950)) {
2596     _inject_alloc_failure.set();
2597     os::naked_short_sleep(1);
2598     if (cancelled_gc()) {
2599       log_info(gc)("Allocation failure was successfully injected");
2600     }
2601   }
2602 }
2603 
2604 bool ShenandoahHeap::should_inject_alloc_failure() {
2605   return _inject_alloc_failure.is_set() && _inject_alloc_failure.try_unset();
2606 }
2607 
2608 void ShenandoahHeap::initialize_serviceability() {
2609   if (mode()->is_generational()) {
2610     _young_gen_memory_pool = new ShenandoahYoungGenMemoryPool(this);
2611     _old_gen_memory_pool = new ShenandoahOldGenMemoryPool(this);
2612     _cycle_memory_manager.add_pool(_young_gen_memory_pool);
2613     _cycle_memory_manager.add_pool(_old_gen_memory_pool);
2614     _stw_memory_manager.add_pool(_young_gen_memory_pool);
2615     _stw_memory_manager.add_pool(_old_gen_memory_pool);
2616   } else {
2617     _memory_pool = new ShenandoahMemoryPool(this);
2618     _cycle_memory_manager.add_pool(_memory_pool);
2619     _stw_memory_manager.add_pool(_memory_pool);
2620   }
2621 }
2622 
2623 GrowableArray<GCMemoryManager*> ShenandoahHeap::memory_managers() {
2624   GrowableArray<GCMemoryManager*> memory_managers(2);
2625   memory_managers.append(&_cycle_memory_manager);
2626   memory_managers.append(&_stw_memory_manager);
2627   return memory_managers;
2628 }
2629 
2630 GrowableArray<MemoryPool*> ShenandoahHeap::memory_pools() {
2631   GrowableArray<MemoryPool*> memory_pools(1);
2632   if (mode()->is_generational()) {
2633     memory_pools.append(_young_gen_memory_pool);
2634     memory_pools.append(_old_gen_memory_pool);
2635   } else {
2636     memory_pools.append(_memory_pool);
2637   }
2638   return memory_pools;
2639 }
2640 
2641 MemoryUsage ShenandoahHeap::memory_usage() {
2642   return MemoryUsage(_initial_size, used(), committed(), max_capacity());
2643 }
2644 
2645 ShenandoahRegionIterator::ShenandoahRegionIterator() :
2646   _heap(ShenandoahHeap::heap()),
2647   _index(0) {}
2648 
2649 ShenandoahRegionIterator::ShenandoahRegionIterator(ShenandoahHeap* heap) :
2650   _heap(heap),
2651   _index(0) {}
2652 
2653 void ShenandoahRegionIterator::reset() {
2654   _index = 0;
2655 }
2656 
2657 bool ShenandoahRegionIterator::has_next() const {
2658   return _index < _heap->num_regions();
2659 }
2660 
2661 char ShenandoahHeap::gc_state() const {
2662   return _gc_state.raw_value();
2663 }
2664 
2665 ShenandoahLiveData* ShenandoahHeap::get_liveness_cache(uint worker_id) {
2666 #ifdef ASSERT
2667   assert(_liveness_cache != NULL, "sanity");
2668   assert(worker_id < _max_workers, "sanity");
2669   for (uint i = 0; i < num_regions(); i++) {
2670     assert(_liveness_cache[worker_id][i] == 0, "liveness cache should be empty");
2671   }
2672 #endif
2673   return _liveness_cache[worker_id];
2674 }
2675 
2676 void ShenandoahHeap::flush_liveness_cache(uint worker_id) {
2677   assert(worker_id < _max_workers, "sanity");
2678   assert(_liveness_cache != NULL, "sanity");
2679   ShenandoahLiveData* ld = _liveness_cache[worker_id];
2680 
2681   for (uint i = 0; i < num_regions(); i++) {
2682     ShenandoahLiveData live = ld[i];
2683     if (live > 0) {
2684       ShenandoahHeapRegion* r = get_region(i);
2685       r->increase_live_data_gc_words(live);
2686       ld[i] = 0;
2687     }
2688   }
2689 }
2690 
2691 void ShenandoahHeap::purge_old_satb_buffers(bool abandon) {
2692   ((ShenandoahOldGeneration*)_old_generation)->purge_satb_buffers(abandon);
2693 }
2694 
2695 template<>
2696 void ShenandoahGenerationRegionClosure<YOUNG>::heap_region_do(ShenandoahHeapRegion* region) {
2697   // Visit young and free regions
2698   if (region->affiliation() != OLD_GENERATION) {
2699     _cl->heap_region_do(region);
2700   }
2701 }
2702 
2703 template<>
2704 void ShenandoahGenerationRegionClosure<OLD>::heap_region_do(ShenandoahHeapRegion* region) {
2705   // Visit old and free regions
2706   if (region->affiliation() != YOUNG_GENERATION) {
2707     _cl->heap_region_do(region);
2708   }
2709 }
2710 
2711 template<>
2712 void ShenandoahGenerationRegionClosure<GLOBAL>::heap_region_do(ShenandoahHeapRegion* region) {
2713   _cl->heap_region_do(region);
2714 }
2715 
2716 // Assure that the remember set has a dirty card everywhere there is an interesting pointer.
2717 // This examines the read_card_table between bottom() and top() since all PLABS are retired
2718 // before the safepoint for init_mark.  Actually, we retire them before update-references and don't
2719 // restore them until the start of evacuation.
2720 void ShenandoahHeap::verify_rem_set_at_mark() {
2721   shenandoah_assert_safepoint();
2722   assert(mode()->is_generational(), "Only verify remembered set for generational operational modes");
2723 
2724   ShenandoahRegionIterator iterator;
2725   RememberedScanner* scanner = card_scan();
2726   ShenandoahVerifyRemSetClosure check_interesting_pointers(true);
2727   ShenandoahMarkingContext* ctx;
2728 
2729   log_debug(gc)("Verifying remembered set at %s mark", doing_mixed_evacuations()? "mixed": "young");
2730 
2731   if (doing_mixed_evacuations() ||
2732       is_concurrent_prep_for_mixed_evacuation_in_progress() || active_generation()->generation_mode() == GLOBAL) {
2733     ctx = complete_marking_context();
2734   } else {
2735     ctx = nullptr;
2736   }
2737 
2738   while (iterator.has_next()) {
2739     ShenandoahHeapRegion* r = iterator.next();
2740     if (r == nullptr)
2741       break;
2742     if (r->is_old() && r->is_active()) {
2743       HeapWord* obj_addr = r->bottom();
2744       if (r->is_humongous_start()) {
2745         oop obj = cast_to_oop(obj_addr);
2746         if (!ctx || ctx->is_marked(obj)) {
2747           // For humongous objects, the typical object is an array, so the following checks may be overkill
2748           // For regular objects (not object arrays), if the card holding the start of the object is dirty,
2749           // we do not need to verify that cards spanning interesting pointers within this object are dirty.
2750           if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
2751             obj->oop_iterate(&check_interesting_pointers);
2752           }
2753           // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
2754         }
2755         // else, this humongous object is not marked so no need to verify its internal pointers
2756         if (!scanner->verify_registration(obj_addr, ctx)) {
2757           ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, NULL,
2758                                           "Verify init-mark remembered set violation", "object not properly registered", __FILE__, __LINE__);
2759         }
2760       } else if (!r->is_humongous()) {
2761         HeapWord* top = r->top();
2762         while (obj_addr < top) {
2763           oop obj = cast_to_oop(obj_addr);
2764           // ctx->is_marked() returns true if mark bit set (TAMS not relevant during init mark)
2765           if (!ctx || ctx->is_marked(obj)) {
2766             // For regular objects (not object arrays), if the card holding the start of the object is dirty,
2767             // we do not need to verify that cards spanning interesting pointers within this object are dirty.
2768             if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
2769               obj->oop_iterate(&check_interesting_pointers);
2770             }
2771             // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
2772             if (!scanner->verify_registration(obj_addr, ctx)) {
2773               ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, NULL,
2774                                             "Verify init-mark remembered set violation", "object not properly registered", __FILE__, __LINE__);
2775             }
2776             obj_addr += obj->size();
2777           } else {
2778             // This object is not live so we don't verify dirty cards contained therein
2779             assert(ctx->top_at_mark_start(r) == top, "Expect tams == top at start of mark.");
2780             obj_addr = ctx->get_next_marked_addr(obj_addr, top);
2781           }
2782         }
2783       } // else, we ignore humongous continuation region
2784     } // else, this is not an OLD region so we ignore it
2785   } // all regions have been processed
2786 }
2787 
2788 void ShenandoahHeap::help_verify_region_rem_set(ShenandoahHeapRegion* r, ShenandoahMarkingContext* ctx, HeapWord* from,
2789                                                 HeapWord* top, HeapWord* registration_watermark, const char* message) {
2790   RememberedScanner* scanner = card_scan();
2791   ShenandoahVerifyRemSetClosure check_interesting_pointers(false);
2792 
2793   HeapWord* obj_addr = from;
2794   if (r->is_humongous_start()) {
2795     oop obj = cast_to_oop(obj_addr);
2796     if (!ctx || ctx->is_marked(obj)) {
2797       size_t card_index = scanner->card_index_for_addr(obj_addr);
2798       // For humongous objects, the typical object is an array, so the following checks may be overkill
2799       // For regular objects (not object arrays), if the card holding the start of the object is dirty,
2800       // we do not need to verify that cards spanning interesting pointers within this object are dirty.
2801       if (!scanner->is_write_card_dirty(card_index) || obj->is_objArray()) {
2802         obj->oop_iterate(&check_interesting_pointers);
2803       }
2804       // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
2805     }
2806     // else, this humongous object is not live so no need to verify its internal pointers
2807 
2808     if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
2809       ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, NULL, message,
2810                                        "object not properly registered", __FILE__, __LINE__);
2811     }
2812   } else if (!r->is_humongous()) {
2813     while (obj_addr < top) {
2814       oop obj = cast_to_oop(obj_addr);
2815       // ctx->is_marked() returns true if mark bit set or if obj above TAMS.
2816       if (!ctx || ctx->is_marked(obj)) {
2817         size_t card_index = scanner->card_index_for_addr(obj_addr);
2818         // For regular objects (not object arrays), if the card holding the start of the object is dirty,
2819         // we do not need to verify that cards spanning interesting pointers within this object are dirty.
2820         if (!scanner->is_write_card_dirty(card_index) || obj->is_objArray()) {
2821           obj->oop_iterate(&check_interesting_pointers);
2822         }
2823         // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
2824 
2825         if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
2826           ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, NULL, message,
2827                                            "object not properly registered", __FILE__, __LINE__);
2828         }
2829         obj_addr += obj->size();
2830       } else {
2831         // This object is not live so we don't verify dirty cards contained therein
2832         HeapWord* tams = ctx->top_at_mark_start(r);
2833         obj_addr = ctx->get_next_marked_addr(obj_addr, tams);
2834       }
2835     }
2836   }
2837 }
2838 
2839 void ShenandoahHeap::verify_rem_set_after_full_gc() {
2840   shenandoah_assert_safepoint();
2841   assert(mode()->is_generational(), "Only verify remembered set for generational operational modes");
2842 
2843   ShenandoahRegionIterator iterator;
2844 
2845   while (iterator.has_next()) {
2846     ShenandoahHeapRegion* r = iterator.next();
2847     if (r == nullptr)
2848       break;
2849     if (r->is_old() && !r->is_cset()) {
2850       help_verify_region_rem_set(r, nullptr, r->bottom(), r->top(), r->top(), "Remembered set violation at end of Full GC");
2851     }
2852   }
2853 }
2854 
2855 // Assure that the remember set has a dirty card everywhere there is an interesting pointer.  Even though
2856 // the update-references scan of remembered set only examines cards up to update_watermark, the remembered
2857 // set should be valid through top.  This examines the write_card_table between bottom() and top() because
2858 // all PLABS are retired immediately before the start of update refs.
2859 void ShenandoahHeap::verify_rem_set_at_update_ref() {
2860   shenandoah_assert_safepoint();
2861   assert(mode()->is_generational(), "Only verify remembered set for generational operational modes");
2862 
2863   ShenandoahRegionIterator iterator;
2864   ShenandoahMarkingContext* ctx;
2865 
2866   if (doing_mixed_evacuations() ||
2867       is_concurrent_prep_for_mixed_evacuation_in_progress() || active_generation()->generation_mode() == GLOBAL) {
2868     ctx = complete_marking_context();
2869   } else {
2870     ctx = nullptr;
2871   }
2872 
2873   while (iterator.has_next()) {
2874     ShenandoahHeapRegion* r = iterator.next();
2875     if (r == nullptr)
2876       break;
2877     if (r->is_old() && !r->is_cset()) {
2878       help_verify_region_rem_set(r, ctx, r->bottom(), r->top(), r->get_update_watermark(),
2879                                  "Remembered set violation at init-update-references");
2880     }
2881   }
2882 }
2883 
2884 ShenandoahGeneration* ShenandoahHeap::generation_for(ShenandoahRegionAffiliation affiliation) const {
2885   if (!mode()->is_generational()) {
2886     return global_generation();
2887   } else if (affiliation == YOUNG_GENERATION) {
2888     return young_generation();
2889   } else if (affiliation == OLD_GENERATION) {
2890     return old_generation();
2891   }
2892 
2893   ShouldNotReachHere();
2894   return nullptr;
2895 }
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