< prev index next >

src/share/vm/gc/g1/g1EvacFailure.cpp

Print this page
rev 8628 : 8129558: Coalesce dead objects during removal of self-forwarded pointers
Summary: To improve performance of self-forwarding fixup during evacuation failure, coalesce the work done for dead objects.
Reviewed-by:
rev 8629 : imported patch mikael-review
rev 8630 : imported patch tom-fixes
rev 8631 : imported patch tony-fixes
rev 8632 : [mq]: tbenson-more-comments

*** 38,49 **** 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"); --- 38,49 ---- G1CollectedHeap* _g1; DirtyCardQueue *_dcq; G1SATBCardTableModRefBS* _ct_bs; public: ! UpdateRSetDeferred(DirtyCardQueue* dcq) : ! _g1(G1CollectedHeap::heap()), _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");
*** 63,126 **** 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); --- 63,107 ---- ConcurrentMark* _cm; HeapRegion* _hr; size_t _marked_bytes; OopsInHeapRegionClosure *_update_rset_cl; bool _during_initial_mark; uint _worker_id; ! HeapWord* _last_forwarded_object_end; public: ! RemoveSelfForwardPtrObjClosure(HeapRegion* hr, OopsInHeapRegionClosure* update_rset_cl, bool during_initial_mark, uint worker_id) : ! _g1(G1CollectedHeap::heap()), ! _cm(_g1->concurrent_mark()), ! _hr(hr), ! _marked_bytes(0), _update_rset_cl(update_rset_cl), _during_initial_mark(during_initial_mark), _worker_id(worker_id), ! _last_forwarded_object_end(hr->bottom()) { } size_t marked_bytes() { return _marked_bytes; } ! // Iterate over the live objects in the region to find self-forwarded objects ! // that need to be kept live. We need to update the remembered sets of these ! // objects. Further update the BOT and marks. ! // We can coalesce and overwrite the remaining heap contents with dummy objects ! // as they have either been dead or evacuated (which are unreferenced now, i.e. ! // dead too) already. 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 (obj->is_forwarded() && obj->forwardee() == obj) { // The object failed to move. + zap_dead_objects(_last_forwarded_object_end, obj_addr); // 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);
*** 152,191 **** // 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; HeapRegionClaimer* _hrclaimer; DirtyCardQueue _dcq; UpdateRSetDeferred _update_rset_cl; public: ! RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h, ! uint worker_id, HeapRegionClaimer* hrclaimer) : ! _g1h(g1h), _dcq(&g1h->dirty_card_queue_set()), _update_rset_cl(g1h, &_dcq), ! _worker_id(worker_id), _cm(_g1h->concurrent_mark()), _hrclaimer(hrclaimer) { } bool doHeapRegion(HeapRegion *hr) { bool during_initial_mark = _g1h->collector_state()->during_initial_mark_pause(); bool during_conc_mark = _g1h->collector_state()->mark_in_progress(); --- 133,216 ---- // 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); ! _last_forwarded_object_end = obj_end; ! _hr->cross_threshold(obj_addr, obj_end); ! } ! } ! // Fill the memory area from start to end with filler objects, and update the BOT ! // and the mark bitmap accordingly. ! void zap_dead_objects(HeapWord* start, HeapWord* end) { ! if (start == end) { ! return; ! } ! ! size_t gap_size = pointer_delta(end, start); ! MemRegion mr(start, gap_size); ! if (gap_size >= CollectedHeap::min_fill_size()) { ! CollectedHeap::fill_with_objects(start, gap_size); ! ! HeapWord* end_first_obj = start + ((oop)start)->size(); ! _hr->cross_threshold(start, end_first_obj); ! // Fill_with_objects() may have created multiple (i.e. two) ! // objects, as the max_fill_size() is half a region. ! // After updating the BOT for the first object, also update the ! // BOT for the second object to make the BOT complete. ! if (end_first_obj != end) { ! _hr->cross_threshold(end_first_obj, end); ! #ifdef ASSERT ! size_t size_second_obj = ((oop)end_first_obj)->size(); ! HeapWord* end_of_second_obj = end_first_obj + size_second_obj; ! assert(end == end_of_second_obj, ! err_msg("More than two objects were used to fill the area from " PTR_FORMAT " to " PTR_FORMAT ", " ! "second objects size " SIZE_FORMAT " ends at " PTR_FORMAT, ! p2i(start), p2i(end), size_second_obj, p2i(end_of_second_obj))); ! #endif ! } ! } ! _cm->clearRangePrevBitmap(mr); } ! ! void zap_remainder() { ! zap_dead_objects(_last_forwarded_object_end, _hr->top()); } }; class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure { G1CollectedHeap* _g1h; uint _worker_id; HeapRegionClaimer* _hrclaimer; DirtyCardQueue _dcq; UpdateRSetDeferred _update_rset_cl; public: ! RemoveSelfForwardPtrHRClosure(uint worker_id, HeapRegionClaimer* hrclaimer) : ! _g1h(G1CollectedHeap::heap()), ! _dcq(&_g1h->dirty_card_queue_set()), ! _update_rset_cl(&_dcq), ! _worker_id(worker_id), ! _hrclaimer(hrclaimer) { ! } ! ! size_t remove_self_forward_ptr_by_walking_hr(HeapRegion* hr, ! bool during_initial_mark) { ! RemoveSelfForwardPtrObjClosure rspc(hr, ! &_update_rset_cl, ! during_initial_mark, ! _worker_id); ! _update_rset_cl.set_region(hr); ! hr->object_iterate(&rspc); ! // Need to zap the remainder area of the processed region. ! rspc.zap_remainder(); ! ! return rspc.marked_bytes(); } bool doHeapRegion(HeapRegion *hr) { bool during_initial_mark = _g1h->collector_state()->during_initial_mark_pause(); bool during_conc_mark = _g1h->collector_state()->mark_in_progress();
*** 193,207 **** assert(!hr->is_pinned(), err_msg("Unexpected pinned region at index %u", hr->hrm_index())); assert(hr->in_collection_set(), "bad CS"); if (_hrclaimer->claim_region(hr->hrm_index())) { 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 --- 218,227 ----
*** 212,240 **** // 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; } }; ! G1ParRemoveSelfForwardPtrsTask::G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) : ! AbstractGangTask("G1 Remove Self-forwarding Pointers"), _g1h(g1h), ! _hrclaimer(g1h->workers()->active_workers()) {} void G1ParRemoveSelfForwardPtrsTask::work(uint worker_id) { ! RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, worker_id, &_hrclaimer); HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id); _g1h->collection_set_iterate_from(hr, &rsfp_cl); } --- 232,261 ---- // 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(); ! ! size_t live_bytes = remove_self_forward_ptr_by_walking_hr(hr, during_initial_mark); hr->rem_set()->clean_strong_code_roots(hr); hr->note_self_forwarding_removal_end(during_initial_mark, during_conc_mark, ! live_bytes); } } return false; } }; ! G1ParRemoveSelfForwardPtrsTask::G1ParRemoveSelfForwardPtrsTask() : ! AbstractGangTask("G1 Remove Self-forwarding Pointers"), ! _g1h(G1CollectedHeap::heap()), ! _hrclaimer(_g1h->workers()->active_workers()) { } void G1ParRemoveSelfForwardPtrsTask::work(uint worker_id) { ! RemoveSelfForwardPtrHRClosure rsfp_cl(worker_id, &_hrclaimer); HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id); _g1h->collection_set_iterate_from(hr, &rsfp_cl); }
< prev index next >