| /* |
| * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP |
| #define SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP |
| |
| #include "gc_implementation/g1/concurrentMark.inline.hpp" |
| #include "gc_implementation/g1/dirtyCardQueue.hpp" |
| #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" |
| #include "gc_implementation/g1/g1_globals.hpp" |
| #include "gc_implementation/g1/g1OopClosures.inline.hpp" |
| #include "gc_implementation/g1/heapRegion.hpp" |
| #include "gc_implementation/g1/heapRegionRemSet.hpp" |
| #include "utilities/workgroup.hpp" |
| |
| // Closures and tasks associated with any self-forwarding pointers |
| // installed as a result of an evacuation failure. |
| |
| class UpdateRSetDeferred : public OopsInHeapRegionClosure { |
| private: |
| G1CollectedHeap* _g1; |
| DirtyCardQueue *_dcq; |
| G1SATBCardTableModRefBS* _ct_bs; |
| |
| public: |
| UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) : |
| _g1(g1), _ct_bs(_g1->g1_barrier_set()), _dcq(dcq) {} |
| |
| virtual void do_oop(narrowOop* p) { do_oop_work(p); } |
| virtual void do_oop( oop* p) { do_oop_work(p); } |
| template <class T> void do_oop_work(T* p) { |
| assert(_from->is_in_reserved(p), "paranoia"); |
| if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && |
| !_from->is_survivor()) { |
| size_t card_index = _ct_bs->index_for(p); |
| if (_ct_bs->mark_card_deferred(card_index)) { |
| _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index)); |
| } |
| } |
| } |
| }; |
| |
| class RemoveSelfForwardPtrObjClosure: public ObjectClosure { |
| private: |
| G1CollectedHeap* _g1; |
| ConcurrentMark* _cm; |
| HeapRegion* _hr; |
| size_t _marked_bytes; |
| OopsInHeapRegionClosure *_update_rset_cl; |
| bool _during_initial_mark; |
| bool _during_conc_mark; |
| uint _worker_id; |
| HeapWord* _end_of_last_gap; |
| HeapWord* _last_gap_threshold; |
| HeapWord* _last_obj_threshold; |
| |
| public: |
| RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm, |
| HeapRegion* hr, |
| OopsInHeapRegionClosure* update_rset_cl, |
| bool during_initial_mark, |
| bool during_conc_mark, |
| uint worker_id) : |
| _g1(g1), _cm(cm), _hr(hr), _marked_bytes(0), |
| _update_rset_cl(update_rset_cl), |
| _during_initial_mark(during_initial_mark), |
| _during_conc_mark(during_conc_mark), |
| _worker_id(worker_id), |
| _end_of_last_gap(hr->bottom()), |
| _last_gap_threshold(hr->bottom()), |
| _last_obj_threshold(hr->bottom()) { } |
| |
| size_t marked_bytes() { return _marked_bytes; } |
| |
| // <original comment> |
| // The original idea here was to coalesce evacuated and dead objects. |
| // However that caused complications with the block offset table (BOT). |
| // In particular if there were two TLABs, one of them partially refined. |
| // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~| |
| // The BOT entries of the unrefined part of TLAB_2 point to the start |
| // of TLAB_2. If the last object of the TLAB_1 and the first object |
| // of TLAB_2 are coalesced, then the cards of the unrefined part |
| // would point into middle of the filler object. |
| // The current approach is to not coalesce and leave the BOT contents intact. |
| // </original comment> |
| // |
| // We now reset the BOT when we start the object iteration over the |
| // region and refine its entries for every object we come across. So |
| // the above comment is not really relevant and we should be able |
| // to coalesce dead objects if we want to. |
| void do_object(oop obj) { |
| HeapWord* obj_addr = (HeapWord*) obj; |
| assert(_hr->is_in(obj_addr), "sanity"); |
| size_t obj_size = obj->size(); |
| HeapWord* obj_end = obj_addr + obj_size; |
| |
| if (_end_of_last_gap != obj_addr) { |
| // there was a gap before obj_addr |
| _last_gap_threshold = _hr->cross_threshold(_end_of_last_gap, obj_addr); |
| } |
| |
| if (obj->is_forwarded() && obj->forwardee() == obj) { |
| // The object failed to move. |
| |
| // We consider all objects that we find self-forwarded to be |
| // live. What we'll do is that we'll update the prev marking |
| // info so that they are all under PTAMS and explicitly marked. |
| if (!_cm->isPrevMarked(obj)) { |
| _cm->markPrev(obj); |
| } |
| if (_during_initial_mark) { |
| // For the next marking info we'll only mark the |
| // self-forwarded objects explicitly if we are during |
| // initial-mark (since, normally, we only mark objects pointed |
| // to by roots if we succeed in copying them). By marking all |
| // self-forwarded objects we ensure that we mark any that are |
| // still pointed to be roots. During concurrent marking, and |
| // after initial-mark, we don't need to mark any objects |
| // explicitly and all objects in the CSet are considered |
| // (implicitly) live. So, we won't mark them explicitly and |
| // we'll leave them over NTAMS. |
| _cm->grayRoot(obj, obj_size, _worker_id, _hr); |
| } |
| _marked_bytes += (obj_size * HeapWordSize); |
| obj->set_mark(markOopDesc::prototype()); |
| |
| // While we were processing RSet buffers during the collection, |
| // we actually didn't scan any cards on the collection set, |
| // since we didn't want to update remembered sets with entries |
| // that point into the collection set, given that live objects |
| // from the collection set are about to move and such entries |
| // will be stale very soon. |
| // This change also dealt with a reliability issue which |
| // involved scanning a card in the collection set and coming |
| // across an array that was being chunked and looking malformed. |
| // The problem is that, if evacuation fails, we might have |
| // remembered set entries missing given that we skipped cards on |
| // the collection set. So, we'll recreate such entries now. |
| obj->oop_iterate(_update_rset_cl); |
| } else { |
| |
| // The object has been either evacuated or is dead. Fill it with a |
| // dummy object. |
| MemRegion mr(obj_addr, obj_size); |
| CollectedHeap::fill_with_object(mr); |
| |
| // must nuke all dead objects which we skipped when iterating over the region |
| _cm->clearRangePrevBitmap(MemRegion(_end_of_last_gap, obj_end)); |
| } |
| _end_of_last_gap = obj_end; |
| _last_obj_threshold = _hr->cross_threshold(obj_addr, obj_end); |
| } |
| }; |
| |
| class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure { |
| G1CollectedHeap* _g1h; |
| ConcurrentMark* _cm; |
| uint _worker_id; |
| |
| DirtyCardQueue _dcq; |
| UpdateRSetDeferred _update_rset_cl; |
| |
| public: |
| RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h, |
| uint worker_id) : |
| _g1h(g1h), _dcq(&g1h->dirty_card_queue_set()), _update_rset_cl(g1h, &_dcq), |
| _worker_id(worker_id), _cm(_g1h->concurrent_mark()) { |
| } |
| |
| bool doHeapRegion(HeapRegion *hr) { |
| bool during_initial_mark = _g1h->g1_policy()->during_initial_mark_pause(); |
| bool during_conc_mark = _g1h->mark_in_progress(); |
| |
| assert(!hr->isHumongous(), "sanity"); |
| assert(hr->in_collection_set(), "bad CS"); |
| |
| if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) { |
| if (hr->evacuation_failed()) { |
| RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, &_update_rset_cl, |
| during_initial_mark, |
| during_conc_mark, |
| _worker_id); |
| |
| hr->note_self_forwarding_removal_start(during_initial_mark, |
| during_conc_mark); |
| _g1h->check_bitmaps("Self-Forwarding Ptr Removal", hr); |
| |
| // In the common case (i.e. when there is no evacuation |
| // failure) we make sure that the following is done when |
| // the region is freed so that it is "ready-to-go" when it's |
| // re-allocated. However, when evacuation failure happens, a |
| // region will remain in the heap and might ultimately be added |
| // to a CSet in the future. So we have to be careful here and |
| // make sure the region's RSet is ready for parallel iteration |
| // whenever this might be required in the future. |
| hr->rem_set()->reset_for_par_iteration(); |
| hr->reset_bot(); |
| _update_rset_cl.set_region(hr); |
| hr->object_iterate(&rspc); |
| |
| hr->rem_set()->clean_strong_code_roots(hr); |
| |
| hr->note_self_forwarding_removal_end(during_initial_mark, |
| during_conc_mark, |
| rspc.marked_bytes()); |
| } |
| } |
| return false; |
| } |
| }; |
| |
| class G1ParRemoveSelfForwardPtrsTask: public AbstractGangTask { |
| protected: |
| G1CollectedHeap* _g1h; |
| |
| public: |
| G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) : |
| AbstractGangTask("G1 Remove Self-forwarding Pointers"), |
| _g1h(g1h) { } |
| |
| void work(uint worker_id) { |
| RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, worker_id); |
| |
| HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id); |
| _g1h->collection_set_iterate_from(hr, &rsfp_cl); |
| } |
| }; |
| |
| #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP |