rev 11552 : imported patch 8159978-collection-set-as-array
rev 11553 : imported patch 8159978-erikh-review
1 /*
2 * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 #include "gc/g1/dirtyCardQueue.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1CollectorState.hpp"
29 #include "gc/g1/g1ConcurrentMark.inline.hpp"
30 #include "gc/g1/g1EvacFailure.hpp"
31 #include "gc/g1/g1HeapVerifier.hpp"
32 #include "gc/g1/g1OopClosures.inline.hpp"
33 #include "gc/g1/g1_globals.hpp"
34 #include "gc/g1/heapRegion.hpp"
35 #include "gc/g1/heapRegionRemSet.hpp"
36 #include "gc/shared/preservedMarks.inline.hpp"
37
38 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
39 private:
40 G1CollectedHeap* _g1;
41 DirtyCardQueue *_dcq;
42 G1SATBCardTableModRefBS* _ct_bs;
43
44 public:
45 UpdateRSetDeferred(DirtyCardQueue* dcq) :
46 _g1(G1CollectedHeap::heap()), _ct_bs(_g1->g1_barrier_set()), _dcq(dcq) {}
47
48 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
49 virtual void do_oop( oop* p) { do_oop_work(p); }
50 template <class T> void do_oop_work(T* p) {
51 assert(_from->is_in_reserved(p), "paranoia");
52 assert(!_from->is_survivor(), "Unexpected evac failure in survivor region");
53
54 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p))) {
55 size_t card_index = _ct_bs->index_for(p);
56 if (_ct_bs->mark_card_deferred(card_index)) {
57 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
58 }
59 }
60 }
61 };
62
63 class RemoveSelfForwardPtrObjClosure: public ObjectClosure {
64 private:
65 G1CollectedHeap* _g1;
66 G1ConcurrentMark* _cm;
67 HeapRegion* _hr;
68 size_t _marked_bytes;
69 OopsInHeapRegionClosure *_update_rset_cl;
70 bool _during_initial_mark;
71 uint _worker_id;
72 HeapWord* _last_forwarded_object_end;
73
74 public:
75 RemoveSelfForwardPtrObjClosure(HeapRegion* hr,
76 OopsInHeapRegionClosure* update_rset_cl,
77 bool during_initial_mark,
78 uint worker_id) :
79 _g1(G1CollectedHeap::heap()),
80 _cm(_g1->concurrent_mark()),
81 _hr(hr),
82 _marked_bytes(0),
83 _update_rset_cl(update_rset_cl),
84 _during_initial_mark(during_initial_mark),
85 _worker_id(worker_id),
86 _last_forwarded_object_end(hr->bottom()) { }
87
88 size_t marked_bytes() { return _marked_bytes; }
89
90 // Iterate over the live objects in the region to find self-forwarded objects
91 // that need to be kept live. We need to update the remembered sets of these
92 // objects. Further update the BOT and marks.
93 // We can coalesce and overwrite the remaining heap contents with dummy objects
94 // as they have either been dead or evacuated (which are unreferenced now, i.e.
95 // dead too) already.
96 void do_object(oop obj) {
97 HeapWord* obj_addr = (HeapWord*) obj;
98 assert(_hr->is_in(obj_addr), "sanity");
99
100 if (obj->is_forwarded() && obj->forwardee() == obj) {
101 // The object failed to move.
102
103 zap_dead_objects(_last_forwarded_object_end, obj_addr);
104 // We consider all objects that we find self-forwarded to be
105 // live. What we'll do is that we'll update the prev marking
106 // info so that they are all under PTAMS and explicitly marked.
107 if (!_cm->isPrevMarked(obj)) {
108 _cm->markPrev(obj);
109 }
110 if (_during_initial_mark) {
111 // For the next marking info we'll only mark the
112 // self-forwarded objects explicitly if we are during
113 // initial-mark (since, normally, we only mark objects pointed
114 // to by roots if we succeed in copying them). By marking all
115 // self-forwarded objects we ensure that we mark any that are
116 // still pointed to be roots. During concurrent marking, and
117 // after initial-mark, we don't need to mark any objects
118 // explicitly and all objects in the CSet are considered
119 // (implicitly) live. So, we won't mark them explicitly and
120 // we'll leave them over NTAMS.
121 _cm->grayRoot(obj, _hr);
122 }
123 size_t obj_size = obj->size();
124
125 _marked_bytes += (obj_size * HeapWordSize);
126 PreservedMarks::init_forwarded_mark(obj);
127
128 // While we were processing RSet buffers during the collection,
129 // we actually didn't scan any cards on the collection set,
130 // since we didn't want to update remembered sets with entries
131 // that point into the collection set, given that live objects
132 // from the collection set are about to move and such entries
133 // will be stale very soon.
134 // This change also dealt with a reliability issue which
135 // involved scanning a card in the collection set and coming
136 // across an array that was being chunked and looking malformed.
137 // The problem is that, if evacuation fails, we might have
138 // remembered set entries missing given that we skipped cards on
139 // the collection set. So, we'll recreate such entries now.
140 obj->oop_iterate(_update_rset_cl);
141
142 HeapWord* obj_end = obj_addr + obj_size;
143 _last_forwarded_object_end = obj_end;
144 _hr->cross_threshold(obj_addr, obj_end);
145 }
146 }
147
148 // Fill the memory area from start to end with filler objects, and update the BOT
149 // and the mark bitmap accordingly.
150 void zap_dead_objects(HeapWord* start, HeapWord* end) {
151 if (start == end) {
152 return;
153 }
154
155 size_t gap_size = pointer_delta(end, start);
156 MemRegion mr(start, gap_size);
157 if (gap_size >= CollectedHeap::min_fill_size()) {
158 CollectedHeap::fill_with_objects(start, gap_size);
159
160 HeapWord* end_first_obj = start + ((oop)start)->size();
161 _hr->cross_threshold(start, end_first_obj);
162 // Fill_with_objects() may have created multiple (i.e. two)
163 // objects, as the max_fill_size() is half a region.
164 // After updating the BOT for the first object, also update the
165 // BOT for the second object to make the BOT complete.
166 if (end_first_obj != end) {
167 _hr->cross_threshold(end_first_obj, end);
168 #ifdef ASSERT
169 size_t size_second_obj = ((oop)end_first_obj)->size();
170 HeapWord* end_of_second_obj = end_first_obj + size_second_obj;
171 assert(end == end_of_second_obj,
172 "More than two objects were used to fill the area from " PTR_FORMAT " to " PTR_FORMAT ", "
173 "second objects size " SIZE_FORMAT " ends at " PTR_FORMAT,
174 p2i(start), p2i(end), size_second_obj, p2i(end_of_second_obj));
175 #endif
176 }
177 }
178 _cm->clearRangePrevBitmap(mr);
179 }
180
181 void zap_remainder() {
182 zap_dead_objects(_last_forwarded_object_end, _hr->top());
183 }
184 };
185
186 class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
187 G1CollectedHeap* _g1h;
188 uint _worker_id;
189 HeapRegionClaimer* _hrclaimer;
190
191 DirtyCardQueue _dcq;
192 UpdateRSetDeferred _update_rset_cl;
193
194 public:
195 RemoveSelfForwardPtrHRClosure(uint worker_id,
196 HeapRegionClaimer* hrclaimer) :
197 _g1h(G1CollectedHeap::heap()),
198 _dcq(&_g1h->dirty_card_queue_set()),
199 _update_rset_cl(&_dcq),
200 _worker_id(worker_id),
201 _hrclaimer(hrclaimer) {
202 }
203
204 size_t remove_self_forward_ptr_by_walking_hr(HeapRegion* hr,
205 bool during_initial_mark) {
206 RemoveSelfForwardPtrObjClosure rspc(hr,
207 &_update_rset_cl,
208 during_initial_mark,
209 _worker_id);
210 _update_rset_cl.set_region(hr);
211 hr->object_iterate(&rspc);
212 // Need to zap the remainder area of the processed region.
213 rspc.zap_remainder();
214
215 return rspc.marked_bytes();
216 }
217
218 bool doHeapRegion(HeapRegion *hr) {
219 bool during_initial_mark = _g1h->collector_state()->during_initial_mark_pause();
220 bool during_conc_mark = _g1h->collector_state()->mark_in_progress();
221
222 assert(!hr->is_pinned(), "Unexpected pinned region at index %u", hr->hrm_index());
223 assert(hr->in_collection_set(), "bad CS");
224
225 if (_hrclaimer->claim_region(hr->hrm_index())) {
226 if (hr->evacuation_failed()) {
227 hr->note_self_forwarding_removal_start(during_initial_mark,
228 during_conc_mark);
229 _g1h->verifier()->check_bitmaps("Self-Forwarding Ptr Removal", hr);
230
231 hr->reset_bot();
232
233 size_t live_bytes = remove_self_forward_ptr_by_walking_hr(hr, during_initial_mark);
234
235 hr->rem_set()->clean_strong_code_roots(hr);
236
237 hr->note_self_forwarding_removal_end(during_initial_mark,
238 during_conc_mark,
239 live_bytes);
240 }
241 }
242 return false;
243 }
244 };
245
246 G1ParRemoveSelfForwardPtrsTask::G1ParRemoveSelfForwardPtrsTask() :
247 AbstractGangTask("G1 Remove Self-forwarding Pointers"),
248 _g1h(G1CollectedHeap::heap()),
249 _hrclaimer(_g1h->workers()->active_workers()) { }
250
251 void G1ParRemoveSelfForwardPtrsTask::work(uint worker_id) {
252 RemoveSelfForwardPtrHRClosure rsfp_cl(worker_id, &_hrclaimer);
253
254 _g1h->collection_set_iterate_from(&rsfp_cl, worker_id);
255 }
--- EOF ---