1 /*
2 * Copyright (c) 2015, 2020, 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/g1GCParPhaseTimesTracker.hpp"
36 #include "gc/g1/g1GCPhaseTimes.hpp"
37 #include "gc/g1/g1ParScanThreadState.inline.hpp"
38 #include "gc/g1/g1Policy.hpp"
39 #include "gc/g1/g1RootClosures.hpp"
40 #include "gc/g1/g1RootProcessor.hpp"
41 #include "gc/g1/heapRegion.inline.hpp"
42 #include "gc/shared/referenceProcessor.hpp"
43 #include "memory/allocation.inline.hpp"
44 #include "memory/universe.hpp"
45 #include "runtime/mutex.hpp"
46 #include "services/management.hpp"
47 #include "utilities/macros.hpp"
48
49 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
50 _g1h(g1h),
51 _process_strong_tasks(G1RP_PS_NumElements),
52 _srs(n_workers) {}
53
54 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_id) {
55 G1GCPhaseTimes* phase_times = _g1h->phase_times();
56
57 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_id);
58
59 G1EvacuationRootClosures* closures = pss->closures();
60 process_java_roots(closures, phase_times, worker_id);
61
62 process_vm_roots(closures, phase_times, worker_id);
63
64 {
65 // Now the CM ref_processor roots.
66 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_id);
67 if (_process_strong_tasks.try_claim_task(G1RP_PS_refProcessor_oops_do)) {
68 // We need to treat the discovered reference lists of the
69 // concurrent mark ref processor as roots and keep entries
70 // (which are added by the marking threads) on them live
71 // until they can be processed at the end of marking.
72 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
73 }
74 }
75
76 _process_strong_tasks.all_tasks_completed(n_workers());
77 }
78
79 // Adaptor to pass the closures to the strong roots in the VM.
80 class StrongRootsClosures : public G1RootClosures {
81 OopClosure* _roots;
82 CLDClosure* _clds;
83 CodeBlobClosure* _blobs;
84 public:
85 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
86 _roots(roots), _clds(clds), _blobs(blobs) {}
87
88 OopClosure* weak_oops() { return NULL; }
89 OopClosure* strong_oops() { return _roots; }
90
91 CLDClosure* weak_clds() { return NULL; }
92 CLDClosure* strong_clds() { return _clds; }
93
94 CodeBlobClosure* strong_codeblobs() { return _blobs; }
95 };
96
97 void G1RootProcessor::process_strong_roots(OopClosure* oops,
98 CLDClosure* clds,
99 CodeBlobClosure* blobs) {
100 StrongRootsClosures closures(oops, clds, blobs);
101
102 process_java_roots(&closures, NULL, 0);
103 process_vm_roots(&closures, NULL, 0);
104
105 _process_strong_tasks.all_tasks_completed(n_workers());
106 }
107
108 // Adaptor to pass the closures to all the roots in the VM.
109 class AllRootsClosures : public G1RootClosures {
110 OopClosure* _roots;
111 CLDClosure* _clds;
112 public:
113 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
114 _roots(roots), _clds(clds) {}
115
116 OopClosure* weak_oops() { return _roots; }
117 OopClosure* strong_oops() { return _roots; }
118
119 // By returning the same CLDClosure for both weak and strong CLDs we ensure
120 // that a single walk of the CLDG will invoke the closure on all CLDs i the
121 // system.
122 CLDClosure* weak_clds() { return _clds; }
123 CLDClosure* strong_clds() { return _clds; }
124
125 // We don't want to visit code blobs more than once, so we return NULL for the
126 // strong case and walk the entire code cache as a separate step.
127 CodeBlobClosure* strong_codeblobs() { return NULL; }
128 };
129
130 void G1RootProcessor::process_all_roots(OopClosure* oops,
131 CLDClosure* clds,
132 CodeBlobClosure* blobs) {
133 AllRootsClosures closures(oops, clds);
134
135 process_java_roots(&closures, NULL, 0);
136 process_vm_roots(&closures, NULL, 0);
137
138 process_code_cache_roots(blobs, NULL, 0);
139
140 _process_strong_tasks.all_tasks_completed(n_workers());
141 }
142
143 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
144 G1GCPhaseTimes* phase_times,
145 uint worker_id) {
146 // We need to make make sure that the "strong" nmethods are processed first
147 // using the strong closure. Only after that we process the weakly reachable
148 // nmethods.
149 // We need to strictly separate the strong and weak nmethod processing because
150 // any processing claims that nmethod, i.e. will not be iterated again.
151 // Which means if an nmethod is processed first and claimed, the strong processing
152 // will not happen, and the oops reachable by that nmethod will not be marked
153 // properly.
154 //
155 // That is why we process strong nmethods first, synchronize all threads via a
156 // barrier, and only then allow weak processing. To minimize the wait time at
157 // that barrier we do the strong nmethod processing first, and immediately after-
158 // wards indicate that that thread is done. Hopefully other root processing after
159 // nmethod processing is enough so there is no need to wait.
160 //
161 // This is only required in the concurrent start pause with class unloading enabled.
162 {
163 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_id);
164 bool is_par = n_workers() > 1;
165 Threads::possibly_parallel_oops_do(is_par,
166 closures->strong_oops(),
167 closures->strong_codeblobs());
168 }
169
170 {
171 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_id);
172 if (_process_strong_tasks.try_claim_task(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
173 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
174 }
175 }
176 }
177
178 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
179 G1GCPhaseTimes* phase_times,
180 uint worker_id) {
181 OopClosure* strong_roots = closures->strong_oops();
182
183 {
184 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_id);
185 if (_process_strong_tasks.try_claim_task(G1RP_PS_Universe_oops_do)) {
186 Universe::oops_do(strong_roots);
187 }
188 }
189
190 {
191 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_id);
192 if (_process_strong_tasks.try_claim_task(G1RP_PS_JNIHandles_oops_do)) {
193 JNIHandles::oops_do(strong_roots);
194 }
195 }
196
197 {
198 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_id);
199 if (_process_strong_tasks.try_claim_task(G1RP_PS_ObjectSynchronizer_oops_do)) {
200 ObjectSynchronizer::oops_do(strong_roots);
201 }
202 }
203
204 {
205 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_id);
206 if (_process_strong_tasks.try_claim_task(G1RP_PS_Management_oops_do)) {
207 Management::oops_do(strong_roots);
208 }
209 }
210
211 {
212 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_id);
213 if (_process_strong_tasks.try_claim_task(G1RP_PS_jvmti_oops_do)) {
214 JvmtiExport::oops_do(strong_roots);
215 }
216 }
217
218 #if INCLUDE_AOT
219 if (UseAOT) {
220 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_id);
221 if (_process_strong_tasks.try_claim_task(G1RP_PS_aot_oops_do)) {
222 AOTLoader::oops_do(strong_roots);
223 }
224 }
225 #endif
226
227 {
228 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_id);
229 if (_process_strong_tasks.try_claim_task(G1RP_PS_SystemDictionary_oops_do)) {
230 SystemDictionary::oops_do(strong_roots);
231 }
232 }
233 }
234
235 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
236 G1GCPhaseTimes* phase_times,
237 uint worker_id) {
238 if (_process_strong_tasks.try_claim_task(G1RP_PS_CodeCache_oops_do)) {
239 CodeCache::blobs_do(code_closure);
240 }
241 }
242
243 uint G1RootProcessor::n_workers() const {
244 return _srs.n_threads();
245 }