1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,243 @@
1.4 +/*
1.5 + * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
1.29 +#define SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
1.30 +
1.31 +#include "gc_implementation/g1/concurrentMark.inline.hpp"
1.32 +#include "gc_implementation/g1/dirtyCardQueue.hpp"
1.33 +#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
1.34 +#include "gc_implementation/g1/g1_globals.hpp"
1.35 +#include "gc_implementation/g1/g1OopClosures.inline.hpp"
1.36 +#include "gc_implementation/g1/heapRegion.hpp"
1.37 +#include "gc_implementation/g1/heapRegionRemSet.hpp"
1.38 +#include "utilities/workgroup.hpp"
1.39 +
1.40 +// Closures and tasks associated with any self-forwarding pointers
1.41 +// installed as a result of an evacuation failure.
1.42 +
1.43 +class UpdateRSetDeferred : public OopsInHeapRegionClosure {
1.44 +private:
1.45 + G1CollectedHeap* _g1;
1.46 + DirtyCardQueue *_dcq;
1.47 + G1SATBCardTableModRefBS* _ct_bs;
1.48 +
1.49 +public:
1.50 + UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
1.51 + _g1(g1), _ct_bs(_g1->g1_barrier_set()), _dcq(dcq) {}
1.52 +
1.53 + virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1.54 + virtual void do_oop( oop* p) { do_oop_work(p); }
1.55 + template <class T> void do_oop_work(T* p) {
1.56 + assert(_from->is_in_reserved(p), "paranoia");
1.57 + if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
1.58 + !_from->is_survivor()) {
1.59 + size_t card_index = _ct_bs->index_for(p);
1.60 + if (_ct_bs->mark_card_deferred(card_index)) {
1.61 + _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
1.62 + }
1.63 + }
1.64 + }
1.65 +};
1.66 +
1.67 +class RemoveSelfForwardPtrObjClosure: public ObjectClosure {
1.68 +private:
1.69 + G1CollectedHeap* _g1;
1.70 + ConcurrentMark* _cm;
1.71 + HeapRegion* _hr;
1.72 + size_t _marked_bytes;
1.73 + OopsInHeapRegionClosure *_update_rset_cl;
1.74 + bool _during_initial_mark;
1.75 + bool _during_conc_mark;
1.76 + uint _worker_id;
1.77 +
1.78 +public:
1.79 + RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm,
1.80 + HeapRegion* hr,
1.81 + OopsInHeapRegionClosure* update_rset_cl,
1.82 + bool during_initial_mark,
1.83 + bool during_conc_mark,
1.84 + uint worker_id) :
1.85 + _g1(g1), _cm(cm), _hr(hr), _marked_bytes(0),
1.86 + _update_rset_cl(update_rset_cl),
1.87 + _during_initial_mark(during_initial_mark),
1.88 + _during_conc_mark(during_conc_mark),
1.89 + _worker_id(worker_id) { }
1.90 +
1.91 + size_t marked_bytes() { return _marked_bytes; }
1.92 +
1.93 + // <original comment>
1.94 + // The original idea here was to coalesce evacuated and dead objects.
1.95 + // However that caused complications with the block offset table (BOT).
1.96 + // In particular if there were two TLABs, one of them partially refined.
1.97 + // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
1.98 + // The BOT entries of the unrefined part of TLAB_2 point to the start
1.99 + // of TLAB_2. If the last object of the TLAB_1 and the first object
1.100 + // of TLAB_2 are coalesced, then the cards of the unrefined part
1.101 + // would point into middle of the filler object.
1.102 + // The current approach is to not coalesce and leave the BOT contents intact.
1.103 + // </original comment>
1.104 + //
1.105 + // We now reset the BOT when we start the object iteration over the
1.106 + // region and refine its entries for every object we come across. So
1.107 + // the above comment is not really relevant and we should be able
1.108 + // to coalesce dead objects if we want to.
1.109 + void do_object(oop obj) {
1.110 + HeapWord* obj_addr = (HeapWord*) obj;
1.111 + assert(_hr->is_in(obj_addr), "sanity");
1.112 + size_t obj_size = obj->size();
1.113 + _hr->update_bot_for_object(obj_addr, obj_size);
1.114 +
1.115 + if (obj->is_forwarded() && obj->forwardee() == obj) {
1.116 + // The object failed to move.
1.117 +
1.118 + // We consider all objects that we find self-forwarded to be
1.119 + // live. What we'll do is that we'll update the prev marking
1.120 + // info so that they are all under PTAMS and explicitly marked.
1.121 + _cm->markPrev(obj);
1.122 + if (_during_initial_mark) {
1.123 + // For the next marking info we'll only mark the
1.124 + // self-forwarded objects explicitly if we are during
1.125 + // initial-mark (since, normally, we only mark objects pointed
1.126 + // to by roots if we succeed in copying them). By marking all
1.127 + // self-forwarded objects we ensure that we mark any that are
1.128 + // still pointed to be roots. During concurrent marking, and
1.129 + // after initial-mark, we don't need to mark any objects
1.130 + // explicitly and all objects in the CSet are considered
1.131 + // (implicitly) live. So, we won't mark them explicitly and
1.132 + // we'll leave them over NTAMS.
1.133 + _cm->grayRoot(obj, obj_size, _worker_id, _hr);
1.134 + }
1.135 + _marked_bytes += (obj_size * HeapWordSize);
1.136 + obj->set_mark(markOopDesc::prototype());
1.137 +
1.138 + // While we were processing RSet buffers during the collection,
1.139 + // we actually didn't scan any cards on the collection set,
1.140 + // since we didn't want to update remembered sets with entries
1.141 + // that point into the collection set, given that live objects
1.142 + // from the collection set are about to move and such entries
1.143 + // will be stale very soon.
1.144 + // This change also dealt with a reliability issue which
1.145 + // involved scanning a card in the collection set and coming
1.146 + // across an array that was being chunked and looking malformed.
1.147 + // The problem is that, if evacuation fails, we might have
1.148 + // remembered set entries missing given that we skipped cards on
1.149 + // the collection set. So, we'll recreate such entries now.
1.150 + obj->oop_iterate(_update_rset_cl);
1.151 + assert(_cm->isPrevMarked(obj), "Should be marked!");
1.152 + } else {
1.153 + // The object has been either evacuated or is dead. Fill it with a
1.154 + // dummy object.
1.155 + MemRegion mr((HeapWord*) obj, obj_size);
1.156 + CollectedHeap::fill_with_object(mr);
1.157 + }
1.158 + }
1.159 +};
1.160 +
1.161 +class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
1.162 + G1CollectedHeap* _g1h;
1.163 + ConcurrentMark* _cm;
1.164 + OopsInHeapRegionClosure *_update_rset_cl;
1.165 + uint _worker_id;
1.166 +
1.167 +public:
1.168 + RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,
1.169 + OopsInHeapRegionClosure* update_rset_cl,
1.170 + uint worker_id) :
1.171 + _g1h(g1h), _update_rset_cl(update_rset_cl),
1.172 + _worker_id(worker_id), _cm(_g1h->concurrent_mark()) { }
1.173 +
1.174 + bool doHeapRegion(HeapRegion *hr) {
1.175 + bool during_initial_mark = _g1h->g1_policy()->during_initial_mark_pause();
1.176 + bool during_conc_mark = _g1h->mark_in_progress();
1.177 +
1.178 + assert(!hr->isHumongous(), "sanity");
1.179 + assert(hr->in_collection_set(), "bad CS");
1.180 +
1.181 + if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) {
1.182 + if (hr->evacuation_failed()) {
1.183 + RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl,
1.184 + during_initial_mark,
1.185 + during_conc_mark,
1.186 + _worker_id);
1.187 +
1.188 + MemRegion mr(hr->bottom(), hr->end());
1.189 + // We'll recreate the prev marking info so we'll first clear
1.190 + // the prev bitmap range for this region. We never mark any
1.191 + // CSet objects explicitly so the next bitmap range should be
1.192 + // cleared anyway.
1.193 + _cm->clearRangePrevBitmap(mr);
1.194 +
1.195 + hr->note_self_forwarding_removal_start(during_initial_mark,
1.196 + during_conc_mark);
1.197 +
1.198 + // In the common case (i.e. when there is no evacuation
1.199 + // failure) we make sure that the following is done when
1.200 + // the region is freed so that it is "ready-to-go" when it's
1.201 + // re-allocated. However, when evacuation failure happens, a
1.202 + // region will remain in the heap and might ultimately be added
1.203 + // to a CSet in the future. So we have to be careful here and
1.204 + // make sure the region's RSet is ready for parallel iteration
1.205 + // whenever this might be required in the future.
1.206 + hr->rem_set()->reset_for_par_iteration();
1.207 + hr->reset_bot();
1.208 + _update_rset_cl->set_region(hr);
1.209 + hr->object_iterate(&rspc);
1.210 +
1.211 + hr->note_self_forwarding_removal_end(during_initial_mark,
1.212 + during_conc_mark,
1.213 + rspc.marked_bytes());
1.214 + }
1.215 + }
1.216 + return false;
1.217 + }
1.218 +};
1.219 +
1.220 +class G1ParRemoveSelfForwardPtrsTask: public AbstractGangTask {
1.221 +protected:
1.222 + G1CollectedHeap* _g1h;
1.223 +
1.224 +public:
1.225 + G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) :
1.226 + AbstractGangTask("G1 Remove Self-forwarding Pointers"),
1.227 + _g1h(g1h) { }
1.228 +
1.229 + void work(uint worker_id) {
1.230 + UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
1.231 + DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
1.232 + UpdateRSetDeferred deferred_update(_g1h, &dcq);
1.233 +
1.234 + OopsInHeapRegionClosure *update_rset_cl = &deferred_update;
1.235 + if (!G1DeferredRSUpdate) {
1.236 + update_rset_cl = &immediate_update;
1.237 + }
1.238 +
1.239 + RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl, worker_id);
1.240 +
1.241 + HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);
1.242 + _g1h->collection_set_iterate_from(hr, &rsfp_cl);
1.243 + }
1.244 +};
1.245 +
1.246 +#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
