229 lines
9.1 KiB
C++
229 lines
9.1 KiB
C++
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/*
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* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
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#define SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
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#include "gc_implementation/g1/concurrentMark.inline.hpp"
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#include "gc_implementation/g1/dirtyCardQueue.hpp"
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#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
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#include "gc_implementation/g1/g1_globals.hpp"
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#include "gc_implementation/g1/g1OopClosures.inline.hpp"
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#include "gc_implementation/g1/heapRegion.hpp"
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#include "gc_implementation/g1/heapRegionRemSet.hpp"
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#include "utilities/workgroup.hpp"
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// Closures and tasks associated with any self-forwarding pointers
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// installed as a result of an evacuation failure.
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class UpdateRSetDeferred : public OopsInHeapRegionClosure {
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private:
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G1CollectedHeap* _g1;
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DirtyCardQueue *_dcq;
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CardTableModRefBS* _ct_bs;
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public:
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UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
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_g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
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virtual void do_oop(narrowOop* p) { do_oop_work(p); }
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virtual void do_oop( oop* p) { do_oop_work(p); }
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template <class T> void do_oop_work(T* p) {
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assert(_from->is_in_reserved(p), "paranoia");
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if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
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!_from->is_survivor()) {
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size_t card_index = _ct_bs->index_for(p);
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if (_ct_bs->mark_card_deferred(card_index)) {
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_dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
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}
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}
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}
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};
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class RemoveSelfForwardPtrObjClosure: public ObjectClosure {
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private:
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G1CollectedHeap* _g1;
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ConcurrentMark* _cm;
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HeapRegion* _hr;
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size_t _prev_marked_bytes;
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size_t _next_marked_bytes;
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OopsInHeapRegionClosure *_update_rset_cl;
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public:
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RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm,
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HeapRegion* hr,
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OopsInHeapRegionClosure* update_rset_cl) :
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_g1(g1), _cm(cm), _hr(hr),
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_update_rset_cl(update_rset_cl),
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_prev_marked_bytes(0), _next_marked_bytes(0) {}
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size_t prev_marked_bytes() { return _prev_marked_bytes; }
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size_t next_marked_bytes() { return _next_marked_bytes; }
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// <original comment>
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// The original idea here was to coalesce evacuated and dead objects.
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// However that caused complications with the block offset table (BOT).
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// In particular if there were two TLABs, one of them partially refined.
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// |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
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// The BOT entries of the unrefined part of TLAB_2 point to the start
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// of TLAB_2. If the last object of the TLAB_1 and the first object
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// of TLAB_2 are coalesced, then the cards of the unrefined part
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// would point into middle of the filler object.
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// The current approach is to not coalesce and leave the BOT contents intact.
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// </original comment>
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//
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// We now reset the BOT when we start the object iteration over the
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// region and refine its entries for every object we come across. So
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// the above comment is not really relevant and we should be able
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// to coalesce dead objects if we want to.
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void do_object(oop obj) {
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HeapWord* obj_addr = (HeapWord*) obj;
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assert(_hr->is_in(obj_addr), "sanity");
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size_t obj_size = obj->size();
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_hr->update_bot_for_object(obj_addr, obj_size);
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if (obj->is_forwarded() && obj->forwardee() == obj) {
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// The object failed to move.
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assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
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_cm->markPrev(obj);
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assert(_cm->isPrevMarked(obj), "Should be marked!");
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_prev_marked_bytes += (obj_size * HeapWordSize);
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if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
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_cm->markAndGrayObjectIfNecessary(obj);
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}
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obj->set_mark(markOopDesc::prototype());
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// While we were processing RSet buffers during the collection,
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// we actually didn't scan any cards on the collection set,
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// since we didn't want to update remembered sets with entries
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// that point into the collection set, given that live objects
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// from the collection set are about to move and such entries
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// will be stale very soon.
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// This change also dealt with a reliability issue which
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// involved scanning a card in the collection set and coming
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// across an array that was being chunked and looking malformed.
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// The problem is that, if evacuation fails, we might have
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// remembered set entries missing given that we skipped cards on
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// the collection set. So, we'll recreate such entries now.
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obj->oop_iterate(_update_rset_cl);
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assert(_cm->isPrevMarked(obj), "Should be marked!");
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} else {
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// The object has been either evacuated or is dead. Fill it with a
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// dummy object.
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MemRegion mr((HeapWord*)obj, obj_size);
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CollectedHeap::fill_with_object(mr);
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_cm->clearRangeBothMaps(mr);
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}
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}
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};
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class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
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G1CollectedHeap* _g1h;
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ConcurrentMark* _cm;
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OopsInHeapRegionClosure *_update_rset_cl;
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public:
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RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,
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OopsInHeapRegionClosure* update_rset_cl) :
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_g1h(g1h), _update_rset_cl(update_rset_cl),
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_cm(_g1h->concurrent_mark()) { }
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bool doHeapRegion(HeapRegion *hr) {
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assert(!hr->isHumongous(), "sanity");
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assert(hr->in_collection_set(), "bad CS");
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if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) {
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if (hr->evacuation_failed()) {
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RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl);
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// In the common case (i.e. when there is no evacuation
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// failure) we make sure that the following is done when
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// the region is freed so that it is "ready-to-go" when it's
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// re-allocated. However, when evacuation failure happens, a
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// region will remain in the heap and might ultimately be added
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// to a CSet in the future. So we have to be careful here and
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// make sure the region's RSet is ready for parallel iteration
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// whenever this might be required in the future.
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hr->rem_set()->reset_for_par_iteration();
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hr->reset_bot();
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_update_rset_cl->set_region(hr);
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hr->object_iterate(&rspc);
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// A number of manipulations to make the TAMS for this region
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// be the current top, and the marked bytes be the ones observed
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// in the iteration.
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if (_cm->at_least_one_mark_complete()) {
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// The comments below are the postconditions achieved by the
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// calls. Note especially the last such condition, which says that
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// the count of marked bytes has been properly restored.
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hr->note_start_of_marking(false);
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// _next_top_at_mark_start == top, _next_marked_bytes == 0
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hr->add_to_marked_bytes(rspc.prev_marked_bytes());
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// _next_marked_bytes == prev_marked_bytes.
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hr->note_end_of_marking();
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// _prev_top_at_mark_start == top(),
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// _prev_marked_bytes == prev_marked_bytes
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}
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// If there is no mark in progress, we modified the _next variables
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// above needlessly, but harmlessly.
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if (_g1h->mark_in_progress()) {
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hr->note_start_of_marking(false);
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// _next_top_at_mark_start == top, _next_marked_bytes == 0
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// _next_marked_bytes == next_marked_bytes.
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}
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}
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}
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return false;
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}
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};
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class G1ParRemoveSelfForwardPtrsTask: public AbstractGangTask {
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protected:
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G1CollectedHeap* _g1h;
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public:
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G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) :
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AbstractGangTask("G1 Remove Self-forwarding Pointers"),
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_g1h(g1h) { }
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void work(uint worker_id) {
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UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
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DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
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UpdateRSetDeferred deferred_update(_g1h, &dcq);
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OopsInHeapRegionClosure *update_rset_cl = &deferred_update;
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if (!G1DeferredRSUpdate) {
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update_rset_cl = &immediate_update;
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}
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RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl);
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HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);
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_g1h->collection_set_iterate_from(hr, &rsfp_cl);
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}
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};
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#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
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