rev 48019 : 8191821: Finer granularity for GC verification
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1 /*
2 * Copyright (c) 2017, 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 "code/codeCache.hpp"
27 #include "gc/g1/g1CollectedHeap.hpp"
28 #include "gc/g1/g1CollectorPolicy.hpp"
29 #include "gc/g1/g1FullCollector.hpp"
30 #include "gc/g1/g1FullGCAdjustTask.hpp"
31 #include "gc/g1/g1FullGCCompactTask.hpp"
32 #include "gc/g1/g1FullGCMarker.inline.hpp"
33 #include "gc/g1/g1FullGCMarkTask.hpp"
34 #include "gc/g1/g1FullGCPrepareTask.hpp"
35 #include "gc/g1/g1FullGCReferenceProcessorExecutor.hpp"
36 #include "gc/g1/g1FullGCScope.hpp"
37 #include "gc/g1/g1OopClosures.hpp"
38 #include "gc/g1/g1Policy.hpp"
39 #include "gc/g1/g1StringDedup.hpp"
40 #include "gc/shared/gcTraceTime.inline.hpp"
41 #include "gc/shared/preservedMarks.hpp"
42 #include "gc/shared/referenceProcessor.hpp"
43 #include "gc/shared/weakProcessor.hpp"
44 #include "logging/log.hpp"
45 #include "runtime/biasedLocking.hpp"
46 #include "utilities/debug.hpp"
47
48 static void clear_and_activate_derived_pointers() {
49 #if COMPILER2_OR_JVMCI
50 DerivedPointerTable::clear();
51 #endif
52 }
53
54 static void deactivate_derived_pointers() {
55 #if COMPILER2_OR_JVMCI
56 DerivedPointerTable::set_active(false);
57 #endif
58 }
59
60 static void update_derived_pointers() {
61 #if COMPILER2_OR_JVMCI
62 DerivedPointerTable::update_pointers();
63 #endif
64 }
65
66 G1CMBitMap* G1FullCollector::mark_bitmap() {
67 return _heap->concurrent_mark()->next_mark_bitmap();
68 }
69
70 ReferenceProcessor* G1FullCollector::reference_processor() {
71 return _heap->ref_processor_stw();
72 }
73
74 G1FullCollector::G1FullCollector(G1CollectedHeap* heap, bool explicit_gc, bool clear_soft_refs) :
75 _heap(heap),
76 _scope(explicit_gc, clear_soft_refs),
77 _num_workers(heap->workers()->active_workers()),
78 _oop_queue_set(_num_workers),
79 _array_queue_set(_num_workers),
80 _preserved_marks_set(true),
81 _serial_compaction_point(),
82 _is_alive(heap->concurrent_mark()->next_mark_bitmap()),
83 _is_alive_mutator(heap->ref_processor_stw(), &_is_alive) {
84 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
85
86 _preserved_marks_set.init(_num_workers);
87 _markers = NEW_C_HEAP_ARRAY(G1FullGCMarker*, _num_workers, mtGC);
88 _compaction_points = NEW_C_HEAP_ARRAY(G1FullGCCompactionPoint*, _num_workers, mtGC);
89 for (uint i = 0; i < _num_workers; i++) {
90 _markers[i] = new G1FullGCMarker(i, _preserved_marks_set.get(i), mark_bitmap());
91 _compaction_points[i] = new G1FullGCCompactionPoint();
92 _oop_queue_set.register_queue(i, marker(i)->oop_stack());
93 _array_queue_set.register_queue(i, marker(i)->objarray_stack());
94 }
95 }
96
97 G1FullCollector::~G1FullCollector() {
98 for (uint i = 0; i < _num_workers; i++) {
99 delete _markers[i];
100 delete _compaction_points[i];
101 }
102 FREE_C_HEAP_ARRAY(G1FullGCMarker*, _markers);
103 FREE_C_HEAP_ARRAY(G1FullGCCompactionPoint*, _compaction_points);
104 }
105
106 void G1FullCollector::prepare_collection() {
107 _heap->g1_policy()->record_full_collection_start();
108
109 _heap->print_heap_before_gc();
110 _heap->print_heap_regions();
111
112 _heap->abort_concurrent_cycle();
113 _heap->verify_before_full_collection(scope()->is_explicit_gc());
114
115 _heap->gc_prologue(true);
116 _heap->prepare_heap_for_full_collection();
117
118 reference_processor()->enable_discovery();
119 reference_processor()->setup_policy(scope()->should_clear_soft_refs());
120
121 // When collecting the permanent generation Method*s may be moving,
122 // so we either have to flush all bcp data or convert it into bci.
123 CodeCache::gc_prologue();
124
125 // We should save the marks of the currently locked biased monitors.
126 // The marking doesn't preserve the marks of biased objects.
127 BiasedLocking::preserve_marks();
128
129 // Clear and activate derived pointer collection.
130 clear_and_activate_derived_pointers();
131 }
132
133 void G1FullCollector::collect() {
134 phase1_mark_live_objects();
135 verify_after_marking();
136
137 // Don't add any more derived pointers during later phases
138 deactivate_derived_pointers();
139
140 phase2_prepare_compaction();
141
142 phase3_adjust_pointers();
143
144 phase4_do_compaction();
145 }
146
147 void G1FullCollector::complete_collection() {
148 // Restore all marks.
149 restore_marks();
150
151 // When the pointers have been adjusted and moved, we can
152 // update the derived pointer table.
153 update_derived_pointers();
154
155 BiasedLocking::restore_marks();
156 CodeCache::gc_epilogue();
157 JvmtiExport::gc_epilogue();
158
159 _heap->prepare_heap_for_mutators();
160
161 _heap->g1_policy()->record_full_collection_end();
162 _heap->gc_epilogue(true);
163
164 _heap->verify_after_full_collection();
165
166 _heap->print_heap_after_full_collection(scope()->heap_transition());
167 }
168
169 void G1FullCollector::phase1_mark_live_objects() {
170 // Recursively traverse all live objects and mark them.
171 GCTraceTime(Info, gc, phases) info("Phase 1: Mark live objects", scope()->timer());
172
173 // Do the actual marking.
174 G1FullGCMarkTask marking_task(this);
175 run_task(&marking_task);
176
177 // Process references discovered during marking.
178 G1FullGCReferenceProcessingExecutor reference_processing(this);
179 reference_processing.execute(scope()->timer(), scope()->tracer());
180
181 // Weak oops cleanup.
182 {
183 GCTraceTime(Debug, gc, phases) trace("Phase 1: Weak Processing", scope()->timer());
184 WeakProcessor::weak_oops_do(&_is_alive, &do_nothing_cl);
185 }
186
187 // Class unloading and cleanup.
188 if (ClassUnloading) {
189 GCTraceTime(Debug, gc, phases) debug("Phase 1: Class Unloading and Cleanup", scope()->timer());
190 // Unload classes and purge the SystemDictionary.
191 bool purged_class = SystemDictionary::do_unloading(&_is_alive, scope()->timer());
192 _heap->complete_cleaning(&_is_alive, purged_class);
193 } else {
194 GCTraceTime(Debug, gc, phases) debug("Phase 1: String and Symbol Tables Cleanup", scope()->timer());
195 // If no class unloading just clean out strings and symbols.
196 _heap->partial_cleaning(&_is_alive, true, true, G1StringDedup::is_enabled());
197 }
198
199 scope()->tracer()->report_object_count_after_gc(&_is_alive);
200 }
201
202 void G1FullCollector::prepare_compaction_common() {
203 G1FullGCPrepareTask task(this);
204 run_task(&task);
205
206 // To avoid OOM when there is memory left.
207 if (!task.has_freed_regions()) {
208 task.prepare_serial_compaction();
209 }
210 }
211
212 void G1FullCollector::phase2_prepare_compaction() {
213 GCTraceTime(Info, gc, phases) info("Phase 2: Prepare for compaction", scope()->timer());
214 prepare_compaction_ext(); // Will call prepare_compaction_common() above.
215 }
216
217 void G1FullCollector::phase3_adjust_pointers() {
218 // Adjust the pointers to reflect the new locations
219 GCTraceTime(Info, gc, phases) info("Phase 3: Adjust pointers and remembered sets", scope()->timer());
220
221 G1FullGCAdjustTask task(this);
222 run_task(&task);
223 }
224
225 void G1FullCollector::phase4_do_compaction() {
226 // Compact the heap using the compaction queues created in phase 2.
227 GCTraceTime(Info, gc, phases) info("Phase 4: Compact heap", scope()->timer());
228 G1FullGCCompactTask task(this);
229 run_task(&task);
230
231 // Serial compact to avoid OOM when very few free regions.
232 if (serial_compaction_point()->has_regions()) {
233 task.serial_compaction();
234 }
235 }
236
237 void G1FullCollector::restore_marks() {
238 SharedRestorePreservedMarksTaskExecutor task_executor(_heap->workers());
239 _preserved_marks_set.restore(&task_executor);
240 _preserved_marks_set.reclaim();
241 }
242
243 void G1FullCollector::run_task(AbstractGangTask* task) {
244 _heap->workers()->run_task(task, _num_workers);
245 }
246
247 void G1FullCollector::verify_after_marking() {
248 if (!VerifyDuringGC || !_heap->verifier()->should_verify(G1HeapVerifier::G1VerifyFull)) {
249 //Only do verification if VerifyDuringGC and Verify_Full is set.
250 return;
251 }
252
253 HandleMark hm; // handle scope
254 #if COMPILER2_OR_JVMCI
255 DerivedPointerTableDeactivate dpt_deact;
256 #endif
257 _heap->prepare_for_verify();
258 // Note: we can verify only the heap here. When an object is
259 // marked, the previous value of the mark word (including
260 // identity hash values, ages, etc) is preserved, and the mark
261 // word is set to markOop::marked_value - effectively removing
262 // any hash values from the mark word. These hash values are
263 // used when verifying the dictionaries and so removing them
264 // from the mark word can make verification of the dictionaries
265 // fail. At the end of the GC, the original mark word values
266 // (including hash values) are restored to the appropriate
267 // objects.
268 GCTraceTime(Info, gc, verify)("Verifying During GC (full)");
269 _heap->verify(VerifyOption_G1UseFullMarking);
270 }
--- EOF ---