1 /*
2 * Copyright (c) 2017, 2022, 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/g1CollectedHeap.hpp"
27 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
28 #include "gc/g1/g1FullCollector.inline.hpp"
29 #include "gc/g1/g1FullGCCompactionPoint.hpp"
30 #include "gc/g1/g1FullGCCompactTask.hpp"
31 #include "gc/g1/heapRegion.inline.hpp"
32 #include "gc/shared/gcTraceTime.inline.hpp"
33 #include "logging/log.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "utilities/ticks.hpp"
36
37 // Do work for all skip-compacting regions.
38 class G1ResetSkipCompactingClosure : public HeapRegionClosure {
39 G1FullCollector* _collector;
40
41 public:
42 G1ResetSkipCompactingClosure(G1FullCollector* collector) : _collector(collector) { }
43
44 bool do_heap_region(HeapRegion* r) {
45 uint region_index = r->hrm_index();
46 // Only for skip-compaction regions; early return otherwise.
47 if (!_collector->is_skip_compacting(region_index)) {
48 return false;
49 }
50 #ifdef ASSERT
51 if (r->is_humongous()) {
52 oop obj = cast_to_oop(r->humongous_start_region()->bottom());
53 assert(_collector->mark_bitmap()->is_marked(obj), "must be live");
54 } else if (r->is_open_archive()) {
55 bool is_empty = (_collector->live_words(r->hrm_index()) == 0);
56 assert(!is_empty, "should contain at least one live obj");
57 } else if (r->is_closed_archive()) {
58 // should early-return above
59 ShouldNotReachHere();
60 } else {
61 assert(_collector->live_words(region_index) > _collector->scope()->region_compaction_threshold(),
62 "should be quite full");
63 }
64 #endif
65 assert(_collector->compaction_top(r) == nullptr,
66 "region %u compaction_top " PTR_FORMAT " must not be different from bottom " PTR_FORMAT,
67 r->hrm_index(), p2i(_collector->compaction_top(r)), p2i(r->bottom()));
68
69 r->reset_skip_compacting_after_full_gc();
70 return false;
71 }
72 };
73
74 void G1FullGCCompactTask::G1CompactRegionClosure::clear_in_bitmap(oop obj) {
75 assert(_bitmap->is_marked(obj), "Should only compact marked objects");
76 _bitmap->clear(obj);
77 }
78
79 size_t G1FullGCCompactTask::G1CompactRegionClosure::apply(oop obj) {
80 size_t size = obj->size();
81 if (obj->is_forwarded()) {
82 HeapWord* destination = cast_from_oop<HeapWord*>(obj->forwardee());
83
84 // copy object and reinit its mark
85 HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
86 assert(obj_addr != destination, "everything in this pass should be moving");
87 Copy::aligned_conjoint_words(obj_addr, destination, size);
88
89 // There is no need to transform stack chunks - marking already did that.
90 cast_to_oop(destination)->init_mark();
91 assert(cast_to_oop(destination)->klass() != NULL, "should have a class");
92 }
93
94 // Clear the mark for the compacted object to allow reuse of the
95 // bitmap without an additional clearing step.
96 clear_in_bitmap(obj);
97 return size;
98 }
99
100 void G1FullGCCompactTask::compact_region(HeapRegion* hr) {
101 assert(!hr->is_pinned(), "Should be no pinned region in compaction queue");
102 assert(!hr->is_humongous(), "Should be no humongous regions in compaction queue");
103
104 if (!collector()->is_free(hr->hrm_index())) {
105 // The compaction closure not only copies the object to the new
106 // location, but also clears the bitmap for it. This is needed
107 // for bitmap verification and to be able to use the bitmap
108 // for evacuation failures in the next young collection. Testing
109 // showed that it was better overall to clear bit by bit, compared
110 // to clearing the whole region at the end. This difference was
111 // clearly seen for regions with few marks.
112 G1CompactRegionClosure compact(collector()->mark_bitmap());
113 hr->apply_to_marked_objects(collector()->mark_bitmap(), &compact);
114 }
115
116 hr->reset_compacted_after_full_gc(_collector->compaction_top(hr));
117 }
118
119 void G1FullGCCompactTask::work(uint worker_id) {
120 Ticks start = Ticks::now();
121 GrowableArray<HeapRegion*>* compaction_queue = collector()->compaction_point(worker_id)->regions();
122 for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
123 it != compaction_queue->end();
124 ++it) {
125 compact_region(*it);
126 }
127
128 G1ResetSkipCompactingClosure hc(collector());
129 G1CollectedHeap::heap()->heap_region_par_iterate_from_worker_offset(&hc, &_claimer, worker_id);
130 log_task("Compaction task", worker_id, start);
131 }
132
133 void G1FullGCCompactTask::serial_compaction() {
134 GCTraceTime(Debug, gc, phases) tm("Phase 4: Serial Compaction", collector()->scope()->timer());
135 GrowableArray<HeapRegion*>* compaction_queue = collector()->serial_compaction_point()->regions();
136 for (GrowableArrayIterator<HeapRegion*> it = compaction_queue->begin();
137 it != compaction_queue->end();
138 ++it) {
139 compact_region(*it);
140 }
141 }