< prev index next >

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

Print this page

  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 
  27 #include "compiler/oopMap.hpp"
  28 #include "gc/shared/continuationGCSupport.hpp"
  29 #include "gc/shared/gcTraceTime.inline.hpp"
  30 #include "gc/shared/preservedMarks.inline.hpp"

  31 #include "gc/shared/tlab_globals.hpp"
  32 #include "gc/shared/workerThread.hpp"
  33 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
  34 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
  35 #include "gc/shenandoah/shenandoahConcurrentGC.hpp"
  36 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  37 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  38 #include "gc/shenandoah/shenandoahFullGC.hpp"
  39 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
  40 #include "gc/shenandoah/shenandoahMark.inline.hpp"
  41 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
  42 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
  43 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  44 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  45 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  46 #include "gc/shenandoah/shenandoahMetrics.hpp"
  47 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
  48 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
  49 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
  50 #include "gc/shenandoah/shenandoahSTWMark.hpp"

 211   // Coming out of Full GC, we would not have any forwarded objects.
 212   // This also prevents resolves with fwdptr from kicking in while adjusting pointers in phase3.
 213   heap->set_has_forwarded_objects(false);
 214 
 215   heap->set_full_gc_move_in_progress(true);
 216 
 217   // Setup workers for the rest
 218   OrderAccess::fence();
 219 
 220   // Initialize worker slices
 221   ShenandoahHeapRegionSet** worker_slices = NEW_C_HEAP_ARRAY(ShenandoahHeapRegionSet*, heap->max_workers(), mtGC);
 222   for (uint i = 0; i < heap->max_workers(); i++) {
 223     worker_slices[i] = new ShenandoahHeapRegionSet();
 224   }
 225 
 226   {
 227     // The rest of code performs region moves, where region status is undefined
 228     // until all phases run together.
 229     ShenandoahHeapLocker lock(heap->lock());
 230 


 231     phase2_calculate_target_addresses(worker_slices);
 232 
 233     OrderAccess::fence();
 234 
 235     phase3_update_references();
 236 
 237     phase4_compact_objects(worker_slices);
 238 
 239     phase5_epilog();


 240   }
 241 
 242   // Resize metaspace
 243   MetaspaceGC::compute_new_size();
 244 
 245   // Free worker slices
 246   for (uint i = 0; i < heap->max_workers(); i++) {
 247     delete worker_slices[i];
 248   }
 249   FREE_C_HEAP_ARRAY(ShenandoahHeapRegionSet*, worker_slices);
 250 
 251   heap->set_full_gc_move_in_progress(false);
 252   heap->set_full_gc_in_progress(false);
 253 
 254   if (ShenandoahVerify) {
 255     heap->verifier()->verify_after_fullgc();
 256   }
 257 
 258   if (VerifyAfterGC) {
 259     Universe::verify();

 352       ShenandoahHeapRegion* new_to_region;
 353       if (_empty_regions_pos < _empty_regions.length()) {
 354         new_to_region = _empty_regions.at(_empty_regions_pos);
 355         _empty_regions_pos++;
 356       } else {
 357         // Out of empty region? Compact within the same region.
 358         new_to_region = _from_region;
 359       }
 360 
 361       assert(new_to_region != _to_region, "must not reuse same to-region");
 362       assert(new_to_region != nullptr, "must not be null");
 363       _to_region = new_to_region;
 364       _compact_point = _to_region->bottom();
 365     }
 366 
 367     // Object fits into current region, record new location, if object does not move:
 368     assert(_compact_point + obj_size <= _to_region->end(), "must fit");
 369     shenandoah_assert_not_forwarded(nullptr, p);
 370     if (_compact_point != cast_from_oop<HeapWord*>(p)) {
 371       _preserved_marks->push_if_necessary(p, p->mark());
 372       p->forward_to(cast_to_oop(_compact_point));
 373     }
 374     _compact_point += obj_size;
 375   }
 376 };
 377 
 378 class ShenandoahPrepareForCompactionTask : public WorkerTask {
 379 private:
 380   PreservedMarksSet*        const _preserved_marks;
 381   ShenandoahHeap*           const _heap;
 382   ShenandoahHeapRegionSet** const _worker_slices;
 383 
 384 public:
 385   ShenandoahPrepareForCompactionTask(PreservedMarksSet *preserved_marks, ShenandoahHeapRegionSet **worker_slices) :
 386     WorkerTask("Shenandoah Prepare For Compaction"),
 387     _preserved_marks(preserved_marks),
 388     _heap(ShenandoahHeap::heap()), _worker_slices(worker_slices) {
 389   }
 390 
 391   static bool is_candidate_region(ShenandoahHeapRegion* r) {
 392     // Empty region: get it into the slice to defragment the slice itself.

 475 
 476   for (size_t c = heap->num_regions(); c > 0; c--) {
 477     ShenandoahHeapRegion *r = heap->get_region(c - 1);
 478     if (r->is_humongous_continuation() || (r->new_top() == r->bottom())) {
 479       // To-region candidate: record this, and continue scan
 480       to_begin = r->index();
 481       continue;
 482     }
 483 
 484     if (r->is_humongous_start() && r->is_stw_move_allowed()) {
 485       // From-region candidate: movable humongous region
 486       oop old_obj = cast_to_oop(r->bottom());
 487       size_t words_size = old_obj->size();
 488       size_t num_regions = ShenandoahHeapRegion::required_regions(words_size * HeapWordSize);
 489 
 490       size_t start = to_end - num_regions;
 491 
 492       if (start >= to_begin && start != r->index()) {
 493         // Fits into current window, and the move is non-trivial. Record the move then, and continue scan.
 494         _preserved_marks->get(0)->push_if_necessary(old_obj, old_obj->mark());
 495         old_obj->forward_to(cast_to_oop(heap->get_region(start)->bottom()));
 496         to_end = start;
 497         continue;
 498       }
 499     }
 500 
 501     // Failed to fit. Scan starting from current region.
 502     to_begin = r->index();
 503     to_end = r->index();
 504   }
 505 }
 506 
 507 class ShenandoahEnsureHeapActiveClosure: public ShenandoahHeapRegionClosure {
 508 private:
 509   ShenandoahHeap* const _heap;
 510 
 511 public:
 512   ShenandoahEnsureHeapActiveClosure() : _heap(ShenandoahHeap::heap()) {}
 513   void heap_region_do(ShenandoahHeapRegion* r) {
 514     if (r->is_trash()) {
 515       r->recycle();

 735   }
 736 
 737   // Compute the new addresses for humongous objects
 738   {
 739     ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_calculate_addresses_humong);
 740     calculate_target_humongous_objects();
 741   }
 742 }
 743 
 744 class ShenandoahAdjustPointersClosure : public MetadataVisitingOopIterateClosure {
 745 private:
 746   ShenandoahHeap* const _heap;
 747   ShenandoahMarkingContext* const _ctx;
 748 
 749   template <class T>
 750   inline void do_oop_work(T* p) {
 751     T o = RawAccess<>::oop_load(p);
 752     if (!CompressedOops::is_null(o)) {
 753       oop obj = CompressedOops::decode_not_null(o);
 754       assert(_ctx->is_marked(obj), "must be marked");
 755       if (obj->is_forwarded()) {
 756         oop forw = obj->forwardee();
 757         RawAccess<IS_NOT_NULL>::oop_store(p, forw);
 758       }
 759     }
 760   }
 761 
 762 public:
 763   ShenandoahAdjustPointersClosure() :
 764     _heap(ShenandoahHeap::heap()),
 765     _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
 766 
 767   void do_oop(oop* p)       { do_oop_work(p); }
 768   void do_oop(narrowOop* p) { do_oop_work(p); }
 769   void do_method(Method* m) {}
 770   void do_nmethod(nmethod* nm) {}
 771 };
 772 
 773 class ShenandoahAdjustPointersObjectClosure : public ObjectClosure {
 774 private:
 775   ShenandoahHeap* const _heap;
 776   ShenandoahAdjustPointersClosure _cl;

 846     DerivedPointerTable::update_pointers();
 847 #endif
 848   }
 849 
 850   ShenandoahAdjustPointersTask adjust_pointers_task;
 851   workers->run_task(&adjust_pointers_task);
 852 }
 853 
 854 class ShenandoahCompactObjectsClosure : public ObjectClosure {
 855 private:
 856   ShenandoahHeap* const _heap;
 857   uint            const _worker_id;
 858 
 859 public:
 860   ShenandoahCompactObjectsClosure(uint worker_id) :
 861     _heap(ShenandoahHeap::heap()), _worker_id(worker_id) {}
 862 
 863   void do_object(oop p) {
 864     assert(_heap->complete_marking_context()->is_marked(p), "must be marked");
 865     size_t size = p->size();
 866     if (p->is_forwarded()) {
 867       HeapWord* compact_from = cast_from_oop<HeapWord*>(p);
 868       HeapWord* compact_to = cast_from_oop<HeapWord*>(p->forwardee());
 869       assert(compact_from != compact_to, "Forwarded object should move");
 870       Copy::aligned_conjoint_words(compact_from, compact_to, size);
 871       oop new_obj = cast_to_oop(compact_to);
 872 
 873       ContinuationGCSupport::relativize_stack_chunk(new_obj);
 874       new_obj->init_mark();
 875     }
 876   }
 877 };
 878 
 879 class ShenandoahCompactObjectsTask : public WorkerTask {
 880 private:
 881   ShenandoahHeap* const _heap;
 882   ShenandoahHeapRegionSet** const _worker_slices;
 883 
 884 public:
 885   ShenandoahCompactObjectsTask(ShenandoahHeapRegionSet** worker_slices) :
 886     WorkerTask("Shenandoah Compact Objects"),
 887     _heap(ShenandoahHeap::heap()),
 888     _worker_slices(worker_slices) {

 953   }
 954 
 955   size_t get_live() {
 956     return _live;
 957   }
 958 };
 959 
 960 void ShenandoahFullGC::compact_humongous_objects() {
 961   // Compact humongous regions, based on their fwdptr objects.
 962   //
 963   // This code is serial, because doing the in-slice parallel sliding is tricky. In most cases,
 964   // humongous regions are already compacted, and do not require further moves, which alleviates
 965   // sliding costs. We may consider doing this in parallel in the future.
 966 
 967   ShenandoahHeap* heap = ShenandoahHeap::heap();
 968 
 969   for (size_t c = heap->num_regions(); c > 0; c--) {
 970     ShenandoahHeapRegion* r = heap->get_region(c - 1);
 971     if (r->is_humongous_start()) {
 972       oop old_obj = cast_to_oop(r->bottom());
 973       if (!old_obj->is_forwarded()) {
 974         // No need to move the object, it stays at the same slot
 975         continue;
 976       }
 977       size_t words_size = old_obj->size();
 978       size_t num_regions = ShenandoahHeapRegion::required_regions(words_size * HeapWordSize);
 979 
 980       size_t old_start = r->index();
 981       size_t old_end   = old_start + num_regions - 1;
 982       size_t new_start = heap->heap_region_index_containing(old_obj->forwardee());
 983       size_t new_end   = new_start + num_regions - 1;
 984       assert(old_start != new_start, "must be real move");
 985       assert(r->is_stw_move_allowed(), "Region " SIZE_FORMAT " should be movable", r->index());
 986 
 987       Copy::aligned_conjoint_words(r->bottom(), heap->get_region(new_start)->bottom(), words_size);
 988       ContinuationGCSupport::relativize_stack_chunk(cast_to_oop<HeapWord*>(r->bottom()));
 989 
 990       oop new_obj = cast_to_oop(heap->get_region(new_start)->bottom());
 991       new_obj->init_mark();
 992 
 993       {
 994         for (size_t c = old_start; c <= old_end; c++) {
 995           ShenandoahHeapRegion* r = heap->get_region(c);
 996           r->make_regular_bypass();
 997           r->set_top(r->bottom());
 998         }
 999 
1000         for (size_t c = new_start; c <= new_end; c++) {
1001           ShenandoahHeapRegion* r = heap->get_region(c);
1002           if (c == new_start) {

  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 
  27 #include "compiler/oopMap.hpp"
  28 #include "gc/shared/continuationGCSupport.hpp"
  29 #include "gc/shared/gcTraceTime.inline.hpp"
  30 #include "gc/shared/preservedMarks.inline.hpp"
  31 #include "gc/shared/slidingForwarding.inline.hpp"
  32 #include "gc/shared/tlab_globals.hpp"
  33 #include "gc/shared/workerThread.hpp"
  34 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
  35 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
  36 #include "gc/shenandoah/shenandoahConcurrentGC.hpp"
  37 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  38 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  39 #include "gc/shenandoah/shenandoahFullGC.hpp"
  40 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
  41 #include "gc/shenandoah/shenandoahMark.inline.hpp"
  42 #include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
  43 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
  44 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  45 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  46 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
  47 #include "gc/shenandoah/shenandoahMetrics.hpp"
  48 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
  49 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
  50 #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp"
  51 #include "gc/shenandoah/shenandoahSTWMark.hpp"

 212   // Coming out of Full GC, we would not have any forwarded objects.
 213   // This also prevents resolves with fwdptr from kicking in while adjusting pointers in phase3.
 214   heap->set_has_forwarded_objects(false);
 215 
 216   heap->set_full_gc_move_in_progress(true);
 217 
 218   // Setup workers for the rest
 219   OrderAccess::fence();
 220 
 221   // Initialize worker slices
 222   ShenandoahHeapRegionSet** worker_slices = NEW_C_HEAP_ARRAY(ShenandoahHeapRegionSet*, heap->max_workers(), mtGC);
 223   for (uint i = 0; i < heap->max_workers(); i++) {
 224     worker_slices[i] = new ShenandoahHeapRegionSet();
 225   }
 226 
 227   {
 228     // The rest of code performs region moves, where region status is undefined
 229     // until all phases run together.
 230     ShenandoahHeapLocker lock(heap->lock());
 231 
 232     SlidingForwarding::begin();
 233 
 234     phase2_calculate_target_addresses(worker_slices);
 235 
 236     OrderAccess::fence();
 237 
 238     phase3_update_references();
 239 
 240     phase4_compact_objects(worker_slices);
 241 
 242     phase5_epilog();
 243 
 244     SlidingForwarding::end();
 245   }
 246 
 247   // Resize metaspace
 248   MetaspaceGC::compute_new_size();
 249 
 250   // Free worker slices
 251   for (uint i = 0; i < heap->max_workers(); i++) {
 252     delete worker_slices[i];
 253   }
 254   FREE_C_HEAP_ARRAY(ShenandoahHeapRegionSet*, worker_slices);
 255 
 256   heap->set_full_gc_move_in_progress(false);
 257   heap->set_full_gc_in_progress(false);
 258 
 259   if (ShenandoahVerify) {
 260     heap->verifier()->verify_after_fullgc();
 261   }
 262 
 263   if (VerifyAfterGC) {
 264     Universe::verify();

 357       ShenandoahHeapRegion* new_to_region;
 358       if (_empty_regions_pos < _empty_regions.length()) {
 359         new_to_region = _empty_regions.at(_empty_regions_pos);
 360         _empty_regions_pos++;
 361       } else {
 362         // Out of empty region? Compact within the same region.
 363         new_to_region = _from_region;
 364       }
 365 
 366       assert(new_to_region != _to_region, "must not reuse same to-region");
 367       assert(new_to_region != nullptr, "must not be null");
 368       _to_region = new_to_region;
 369       _compact_point = _to_region->bottom();
 370     }
 371 
 372     // Object fits into current region, record new location, if object does not move:
 373     assert(_compact_point + obj_size <= _to_region->end(), "must fit");
 374     shenandoah_assert_not_forwarded(nullptr, p);
 375     if (_compact_point != cast_from_oop<HeapWord*>(p)) {
 376       _preserved_marks->push_if_necessary(p, p->mark());
 377       SlidingForwarding::forward_to(p, cast_to_oop(_compact_point));
 378     }
 379     _compact_point += obj_size;
 380   }
 381 };
 382 
 383 class ShenandoahPrepareForCompactionTask : public WorkerTask {
 384 private:
 385   PreservedMarksSet*        const _preserved_marks;
 386   ShenandoahHeap*           const _heap;
 387   ShenandoahHeapRegionSet** const _worker_slices;
 388 
 389 public:
 390   ShenandoahPrepareForCompactionTask(PreservedMarksSet *preserved_marks, ShenandoahHeapRegionSet **worker_slices) :
 391     WorkerTask("Shenandoah Prepare For Compaction"),
 392     _preserved_marks(preserved_marks),
 393     _heap(ShenandoahHeap::heap()), _worker_slices(worker_slices) {
 394   }
 395 
 396   static bool is_candidate_region(ShenandoahHeapRegion* r) {
 397     // Empty region: get it into the slice to defragment the slice itself.

 480 
 481   for (size_t c = heap->num_regions(); c > 0; c--) {
 482     ShenandoahHeapRegion *r = heap->get_region(c - 1);
 483     if (r->is_humongous_continuation() || (r->new_top() == r->bottom())) {
 484       // To-region candidate: record this, and continue scan
 485       to_begin = r->index();
 486       continue;
 487     }
 488 
 489     if (r->is_humongous_start() && r->is_stw_move_allowed()) {
 490       // From-region candidate: movable humongous region
 491       oop old_obj = cast_to_oop(r->bottom());
 492       size_t words_size = old_obj->size();
 493       size_t num_regions = ShenandoahHeapRegion::required_regions(words_size * HeapWordSize);
 494 
 495       size_t start = to_end - num_regions;
 496 
 497       if (start >= to_begin && start != r->index()) {
 498         // Fits into current window, and the move is non-trivial. Record the move then, and continue scan.
 499         _preserved_marks->get(0)->push_if_necessary(old_obj, old_obj->mark());
 500         SlidingForwarding::forward_to(old_obj, cast_to_oop(heap->get_region(start)->bottom()));
 501         to_end = start;
 502         continue;
 503       }
 504     }
 505 
 506     // Failed to fit. Scan starting from current region.
 507     to_begin = r->index();
 508     to_end = r->index();
 509   }
 510 }
 511 
 512 class ShenandoahEnsureHeapActiveClosure: public ShenandoahHeapRegionClosure {
 513 private:
 514   ShenandoahHeap* const _heap;
 515 
 516 public:
 517   ShenandoahEnsureHeapActiveClosure() : _heap(ShenandoahHeap::heap()) {}
 518   void heap_region_do(ShenandoahHeapRegion* r) {
 519     if (r->is_trash()) {
 520       r->recycle();

 740   }
 741 
 742   // Compute the new addresses for humongous objects
 743   {
 744     ShenandoahGCPhase phase(ShenandoahPhaseTimings::full_gc_calculate_addresses_humong);
 745     calculate_target_humongous_objects();
 746   }
 747 }
 748 
 749 class ShenandoahAdjustPointersClosure : public MetadataVisitingOopIterateClosure {
 750 private:
 751   ShenandoahHeap* const _heap;
 752   ShenandoahMarkingContext* const _ctx;
 753 
 754   template <class T>
 755   inline void do_oop_work(T* p) {
 756     T o = RawAccess<>::oop_load(p);
 757     if (!CompressedOops::is_null(o)) {
 758       oop obj = CompressedOops::decode_not_null(o);
 759       assert(_ctx->is_marked(obj), "must be marked");
 760       if (SlidingForwarding::is_forwarded(obj)) {
 761         oop forw = SlidingForwarding::forwardee(obj);
 762         RawAccess<IS_NOT_NULL>::oop_store(p, forw);
 763       }
 764     }
 765   }
 766 
 767 public:
 768   ShenandoahAdjustPointersClosure() :
 769     _heap(ShenandoahHeap::heap()),
 770     _ctx(ShenandoahHeap::heap()->complete_marking_context()) {}
 771 
 772   void do_oop(oop* p)       { do_oop_work(p); }
 773   void do_oop(narrowOop* p) { do_oop_work(p); }
 774   void do_method(Method* m) {}
 775   void do_nmethod(nmethod* nm) {}
 776 };
 777 
 778 class ShenandoahAdjustPointersObjectClosure : public ObjectClosure {
 779 private:
 780   ShenandoahHeap* const _heap;
 781   ShenandoahAdjustPointersClosure _cl;

 851     DerivedPointerTable::update_pointers();
 852 #endif
 853   }
 854 
 855   ShenandoahAdjustPointersTask adjust_pointers_task;
 856   workers->run_task(&adjust_pointers_task);
 857 }
 858 
 859 class ShenandoahCompactObjectsClosure : public ObjectClosure {
 860 private:
 861   ShenandoahHeap* const _heap;
 862   uint            const _worker_id;
 863 
 864 public:
 865   ShenandoahCompactObjectsClosure(uint worker_id) :
 866     _heap(ShenandoahHeap::heap()), _worker_id(worker_id) {}
 867 
 868   void do_object(oop p) {
 869     assert(_heap->complete_marking_context()->is_marked(p), "must be marked");
 870     size_t size = p->size();
 871     if (SlidingForwarding::is_forwarded(p)) {
 872       HeapWord* compact_from = cast_from_oop<HeapWord*>(p);
 873       HeapWord* compact_to = cast_from_oop<HeapWord*>(SlidingForwarding::forwardee(p));
 874       assert(compact_from != compact_to, "Forwarded object should move");
 875       Copy::aligned_conjoint_words(compact_from, compact_to, size);
 876       oop new_obj = cast_to_oop(compact_to);
 877 
 878       ContinuationGCSupport::relativize_stack_chunk(new_obj);
 879       new_obj->init_mark();
 880     }
 881   }
 882 };
 883 
 884 class ShenandoahCompactObjectsTask : public WorkerTask {
 885 private:
 886   ShenandoahHeap* const _heap;
 887   ShenandoahHeapRegionSet** const _worker_slices;
 888 
 889 public:
 890   ShenandoahCompactObjectsTask(ShenandoahHeapRegionSet** worker_slices) :
 891     WorkerTask("Shenandoah Compact Objects"),
 892     _heap(ShenandoahHeap::heap()),
 893     _worker_slices(worker_slices) {

 958   }
 959 
 960   size_t get_live() {
 961     return _live;
 962   }
 963 };
 964 
 965 void ShenandoahFullGC::compact_humongous_objects() {
 966   // Compact humongous regions, based on their fwdptr objects.
 967   //
 968   // This code is serial, because doing the in-slice parallel sliding is tricky. In most cases,
 969   // humongous regions are already compacted, and do not require further moves, which alleviates
 970   // sliding costs. We may consider doing this in parallel in the future.
 971 
 972   ShenandoahHeap* heap = ShenandoahHeap::heap();
 973 
 974   for (size_t c = heap->num_regions(); c > 0; c--) {
 975     ShenandoahHeapRegion* r = heap->get_region(c - 1);
 976     if (r->is_humongous_start()) {
 977       oop old_obj = cast_to_oop(r->bottom());
 978       if (SlidingForwarding::is_not_forwarded(old_obj)) {
 979         // No need to move the object, it stays at the same slot
 980         continue;
 981       }
 982       size_t words_size = old_obj->size();
 983       size_t num_regions = ShenandoahHeapRegion::required_regions(words_size * HeapWordSize);
 984 
 985       size_t old_start = r->index();
 986       size_t old_end   = old_start + num_regions - 1;
 987       size_t new_start = heap->heap_region_index_containing(SlidingForwarding::forwardee(old_obj));
 988       size_t new_end   = new_start + num_regions - 1;
 989       assert(old_start != new_start, "must be real move");
 990       assert(r->is_stw_move_allowed(), "Region " SIZE_FORMAT " should be movable", r->index());
 991 
 992       Copy::aligned_conjoint_words(r->bottom(), heap->get_region(new_start)->bottom(), words_size);
 993       ContinuationGCSupport::relativize_stack_chunk(cast_to_oop<HeapWord*>(r->bottom()));
 994 
 995       oop new_obj = cast_to_oop(heap->get_region(new_start)->bottom());
 996       new_obj->init_mark();
 997 
 998       {
 999         for (size_t c = old_start; c <= old_end; c++) {
1000           ShenandoahHeapRegion* r = heap->get_region(c);
1001           r->make_regular_bypass();
1002           r->set_top(r->bottom());
1003         }
1004 
1005         for (size_t c = new_start; c <= new_end; c++) {
1006           ShenandoahHeapRegion* r = heap->get_region(c);
1007           if (c == new_start) {
< prev index next >