1 /*
2 * Copyright (c) 2015, 2019, 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 "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeCache.hpp"
31 #include "gc/g1/g1BarrierSet.hpp"
32 #include "gc/g1/g1CodeBlobClosure.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectorState.hpp"
35 #include "gc/g1/g1GCPhaseTimes.hpp"
36 #include "gc/g1/g1ParScanThreadState.inline.hpp"
37 #include "gc/g1/g1Policy.hpp"
38 #include "gc/g1/g1RootClosures.hpp"
39 #include "gc/g1/g1RootProcessor.hpp"
40 #include "gc/g1/heapRegion.inline.hpp"
41 #include "gc/shared/referenceProcessor.hpp"
42 #include "memory/allocation.inline.hpp"
43 #include "memory/universe.hpp"
44 #include "runtime/mutex.hpp"
45 #include "services/management.hpp"
46 #include "utilities/macros.hpp"
47
48 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
49 _g1h(g1h),
50 _process_strong_tasks(G1RP_PS_NumElements),
51 _srs(n_workers) {}
52
53 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_id) {
54 G1GCPhaseTimes* phase_times = _g1h->phase_times();
55
56 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_id);
57
58 G1EvacuationRootClosures* closures = pss->closures();
59 process_java_roots(closures, phase_times, worker_id);
60
61 process_vm_roots(closures, phase_times, worker_id);
62
63 {
64 // Now the CM ref_processor roots.
65 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_id);
66 if (_process_strong_tasks.try_claim_task(G1RP_PS_refProcessor_oops_do)) {
67 // We need to treat the discovered reference lists of the
68 // concurrent mark ref processor as roots and keep entries
69 // (which are added by the marking threads) on them live
70 // until they can be processed at the end of marking.
71 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
72 }
73 }
74
75 _process_strong_tasks.all_tasks_completed(n_workers());
76 }
77
78 // Adaptor to pass the closures to the strong roots in the VM.
79 class StrongRootsClosures : public G1RootClosures {
80 OopClosure* _roots;
81 CLDClosure* _clds;
82 CodeBlobClosure* _blobs;
83 public:
84 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
85 _roots(roots), _clds(clds), _blobs(blobs) {}
86
87 OopClosure* weak_oops() { return NULL; }
88 OopClosure* strong_oops() { return _roots; }
89
90 CLDClosure* weak_clds() { return NULL; }
91 CLDClosure* strong_clds() { return _clds; }
92
93 CodeBlobClosure* strong_codeblobs() { return _blobs; }
94 };
95
96 void G1RootProcessor::process_strong_roots(OopClosure* oops,
97 CLDClosure* clds,
98 CodeBlobClosure* blobs) {
99 StrongRootsClosures closures(oops, clds, blobs);
100
101 process_java_roots(&closures, NULL, 0);
102 process_vm_roots(&closures, NULL, 0);
103
104 _process_strong_tasks.all_tasks_completed(n_workers());
105 }
106
107 // Adaptor to pass the closures to all the roots in the VM.
108 class AllRootsClosures : public G1RootClosures {
109 OopClosure* _roots;
110 CLDClosure* _clds;
111 public:
112 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
113 _roots(roots), _clds(clds) {}
114
115 OopClosure* weak_oops() { return _roots; }
116 OopClosure* strong_oops() { return _roots; }
117
118 // By returning the same CLDClosure for both weak and strong CLDs we ensure
119 // that a single walk of the CLDG will invoke the closure on all CLDs i the
120 // system.
121 CLDClosure* weak_clds() { return _clds; }
122 CLDClosure* strong_clds() { return _clds; }
123
124 // We don't want to visit code blobs more than once, so we return NULL for the
125 // strong case and walk the entire code cache as a separate step.
126 CodeBlobClosure* strong_codeblobs() { return NULL; }
127 };
128
129 void G1RootProcessor::process_all_roots(OopClosure* oops,
130 CLDClosure* clds,
131 CodeBlobClosure* blobs) {
132 AllRootsClosures closures(oops, clds);
133
134 process_java_roots(&closures, NULL, 0);
135 process_vm_roots(&closures, NULL, 0);
136
137 process_code_cache_roots(blobs, NULL, 0);
138
139 _process_strong_tasks.all_tasks_completed(n_workers());
140 }
141
142 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
143 G1GCPhaseTimes* phase_times,
144 uint worker_id) {
145 // We need to make make sure that the "strong" nmethods are processed first
146 // using the strong closure. Only after that we process the weakly reachable
147 // nmethods.
148 // We need to strictly separate the strong and weak nmethod processing because
149 // any processing claims that nmethod, i.e. will not be iterated again.
150 // Which means if an nmethod is processed first and claimed, the strong processing
151 // will not happen, and the oops reachable by that nmethod will not be marked
152 // properly.
153 //
154 // That is why we process strong nmethods first, synchronize all threads via a
155 // barrier, and only then allow weak processing. To minimize the wait time at
156 // that barrier we do the strong nmethod processing first, and immediately after-
157 // wards indicate that that thread is done. Hopefully other root processing after
158 // nmethod processing is enough so there is no need to wait.
159 //
160 // This is only required in the concurrent start pause with class unloading enabled.
161 {
162 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_id);
163 bool is_par = n_workers() > 1;
164 Threads::possibly_parallel_oops_do(is_par,
165 closures->strong_oops(),
166 closures->strong_codeblobs());
167 }
168
169 {
170 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_id);
171 if (_process_strong_tasks.try_claim_task(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
172 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
173 }
174 }
175 }
176
177 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
178 G1GCPhaseTimes* phase_times,
179 uint worker_id) {
180 OopClosure* strong_roots = closures->strong_oops();
181
182 {
183 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_id);
184 if (_process_strong_tasks.try_claim_task(G1RP_PS_Universe_oops_do)) {
185 Universe::oops_do(strong_roots);
186 }
187 }
188
189 {
190 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_id);
191 if (_process_strong_tasks.try_claim_task(G1RP_PS_JNIHandles_oops_do)) {
192 JNIHandles::oops_do(strong_roots);
193 }
194 }
195
196 {
197 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_id);
198 if (_process_strong_tasks.try_claim_task(G1RP_PS_ObjectSynchronizer_oops_do)) {
199 ObjectSynchronizer::oops_do(strong_roots);
200 }
201 }
202
203 {
204 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_id);
205 if (_process_strong_tasks.try_claim_task(G1RP_PS_Management_oops_do)) {
206 Management::oops_do(strong_roots);
207 }
208 }
209
210 {
211 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_id);
212 if (_process_strong_tasks.try_claim_task(G1RP_PS_jvmti_oops_do)) {
213 JvmtiExport::oops_do(strong_roots);
214 }
215 }
216
217 #if INCLUDE_AOT
218 if (UseAOT) {
219 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_id);
220 if (_process_strong_tasks.try_claim_task(G1RP_PS_aot_oops_do)) {
221 AOTLoader::oops_do(strong_roots);
222 }
223 }
224 #endif
225
226 {
227 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_id);
228 if (_process_strong_tasks.try_claim_task(G1RP_PS_SystemDictionary_oops_do)) {
229 SystemDictionary::oops_do(strong_roots);
230 }
231 }
232 }
233
234 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
235 G1GCPhaseTimes* phase_times,
236 uint worker_id) {
237 if (_process_strong_tasks.try_claim_task(G1RP_PS_CodeCache_oops_do)) {
238 CodeCache::blobs_do(code_closure);
239 }
240 }
241
242 uint G1RootProcessor::n_workers() const {
243 return _srs.n_threads();
244 }