1 /*
2 * Copyright (c) 2017, 2018, 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.hpp"
29 #include "gc/g1/g1FullGCCompactionPoint.hpp"
30 #include "gc/g1/g1FullGCMarker.hpp"
31 #include "gc/g1/g1FullGCOopClosures.inline.hpp"
32 #include "gc/g1/g1FullGCPrepareTask.hpp"
33 #include "gc/g1/g1HotCardCache.hpp"
34 #include "gc/g1/heapRegion.inline.hpp"
35 #include "gc/shared/gcTraceTime.inline.hpp"
36 #include "gc/shared/referenceProcessor.hpp"
37 #include "logging/log.hpp"
38 #include "memory/iterator.inline.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "utilities/ticks.hpp"
41
42 bool G1FullGCPrepareTask::G1CalculatePointersClosure::do_heap_region(HeapRegion* hr) {
43 if (hr->is_humongous()) {
44 oop obj = oop(hr->humongous_start_region()->bottom());
45 if (_bitmap->is_marked(obj)) {
46 if (hr->is_starts_humongous()) {
47 obj->forward_to(obj);
48 }
49 } else {
50 free_humongous_region(hr);
51 }
52 } else if (!hr->is_pinned()) {
53 prepare_for_compaction(hr);
54 }
55
56 // Reset data structures not valid after Full GC.
57 reset_region_metadata(hr);
58
59 return false;
60 }
61
62 G1FullGCPrepareTask::G1FullGCPrepareTask(G1FullCollector* collector) :
63 G1FullGCTask("G1 Prepare Compact Task", collector),
64 _hrclaimer(collector->workers()),
65 _freed_regions(false) {
66 }
67
68 void G1FullGCPrepareTask::set_freed_regions() {
69 if (!_freed_regions) {
70 _freed_regions = true;
71 }
72 }
73
74 bool G1FullGCPrepareTask::has_freed_regions() {
75 return _freed_regions;
76 }
77
78 void G1FullGCPrepareTask::work(uint worker_id) {
79 Ticks start = Ticks::now();
80 G1FullGCCompactionPoint* compaction_point = collector()->compaction_point(worker_id);
81 G1CalculatePointersClosure closure(collector()->mark_bitmap(), compaction_point);
82 G1CollectedHeap::heap()->heap_region_par_iterate_from_start(&closure, &_hrclaimer);
83
84 // Update humongous region sets
85 closure.update_sets();
86 compaction_point->update();
87
88 // Check if any regions was freed by this worker and store in task.
89 if (closure.freed_regions()) {
90 set_freed_regions();
91 }
92 log_task("Prepare compaction task", worker_id, start);
93 }
94
95 G1FullGCPrepareTask::G1CalculatePointersClosure::G1CalculatePointersClosure(G1CMBitMap* bitmap,
96 G1FullGCCompactionPoint* cp) :
97 _g1h(G1CollectedHeap::heap()),
98 _bitmap(bitmap),
99 _cp(cp),
100 _humongous_regions_removed(0) { }
101
102 void G1FullGCPrepareTask::G1CalculatePointersClosure::free_humongous_region(HeapRegion* hr) {
103 FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
104
105 hr->set_containing_set(NULL);
106 _humongous_regions_removed++;
107
108 _g1h->free_humongous_region(hr, &dummy_free_list);
109 prepare_for_compaction(hr);
110 dummy_free_list.remove_all();
111 }
112
113 void G1FullGCPrepareTask::G1CalculatePointersClosure::reset_region_metadata(HeapRegion* hr) {
114 hr->rem_set()->clear();
115 hr->clear_cardtable();
116
117 if (_g1h->g1_hot_card_cache()->use_cache()) {
118 _g1h->g1_hot_card_cache()->reset_card_counts(hr);
119 }
120 }
121
122 G1FullGCPrepareTask::G1PrepareCompactLiveClosure::G1PrepareCompactLiveClosure(G1FullGCCompactionPoint* cp) :
123 _cp(cp) { }
124
125 size_t G1FullGCPrepareTask::G1PrepareCompactLiveClosure::apply(oop object) {
126 size_t size = object->size();
127 _cp->forward(object, size);
128 return size;
129 }
130
131 size_t G1FullGCPrepareTask::G1RePrepareClosure::apply(oop obj) {
132 // We only re-prepare objects forwarded within the current region, so
133 // skip objects that are already forwarded to another region.
134 oop forwarded_to = obj->forwardee();
135 if (forwarded_to != NULL && !_current->is_in(forwarded_to)) {
136 return obj->size();
137 }
138
139 // Get size and forward.
140 size_t size = obj->size();
141 _cp->forward(obj, size);
142
143 return size;
144 }
145
146 void G1FullGCPrepareTask::G1CalculatePointersClosure::prepare_for_compaction_work(G1FullGCCompactionPoint* cp,
147 HeapRegion* hr) {
148 G1PrepareCompactLiveClosure prepare_compact(cp);
149 hr->set_compaction_top(hr->bottom());
150 hr->apply_to_marked_objects(_bitmap, &prepare_compact);
151 }
152
153 void G1FullGCPrepareTask::G1CalculatePointersClosure::prepare_for_compaction(HeapRegion* hr) {
154 if (!_cp->is_initialized()) {
155 hr->set_compaction_top(hr->bottom());
156 _cp->initialize(hr, true);
157 }
158 // Add region to the compaction queue and prepare it.
159 _cp->add(hr);
160 prepare_for_compaction_work(_cp, hr);
161 }
162
163 void G1FullGCPrepareTask::prepare_serial_compaction() {
164 GCTraceTime(Debug, gc, phases) debug("Phase 2: Prepare Serial Compaction", collector()->scope()->timer());
165 // At this point we know that no regions were completely freed by
166 // the parallel compaction. That means that the last region of
167 // all compaction queues still have data in them. We try to compact
168 // these regions in serial to avoid a premature OOM.
169 for (uint i = 0; i < collector()->workers(); i++) {
170 G1FullGCCompactionPoint* cp = collector()->compaction_point(i);
171 if (cp->has_regions()) {
172 collector()->serial_compaction_point()->add(cp->remove_last());
173 }
174 }
175
176 // Update the forwarding information for the regions in the serial
177 // compaction point.
178 G1FullGCCompactionPoint* cp = collector()->serial_compaction_point();
179 for (GrowableArrayIterator<HeapRegion*> it = cp->regions()->begin(); it != cp->regions()->end(); ++it) {
180 HeapRegion* current = *it;
181 if (!cp->is_initialized()) {
182 // Initialize the compaction point. Nothing more is needed for the first heap region
183 // since it is already prepared for compaction.
184 cp->initialize(current, false);
185 } else {
186 assert(!current->is_humongous(), "Should be no humongous regions in compaction queue");
187 G1RePrepareClosure re_prepare(cp, current);
188 current->set_compaction_top(current->bottom());
189 current->apply_to_marked_objects(collector()->mark_bitmap(), &re_prepare);
190 }
191 }
192 cp->update();
193 }
194
195 void G1FullGCPrepareTask::G1CalculatePointersClosure::update_sets() {
196 // We'll recalculate total used bytes and recreate the free list
197 // at the end of the GC, so no point in updating those values here.
198 _g1h->remove_from_old_sets(0, _humongous_regions_removed);
199 }
200
201 bool G1FullGCPrepareTask::G1CalculatePointersClosure::freed_regions() {
202 if (_humongous_regions_removed > 0) {
203 // Free regions from dead humongous regions.
204 return true;
205 }
206
207 if (!_cp->has_regions()) {
208 // No regions in queue, so no free ones either.
209 return false;
210 }
211
212 if (_cp->current_region() != _cp->regions()->last()) {
213 // The current region used for compaction is not the last in the
214 // queue. That means there is at least one free region in the queue.
215 return true;
216 }
217
218 // No free regions in the queue.
219 return false;
220 }