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/oopStorageParState.hpp"
42 #include "gc/shared/referenceProcessor.hpp"
43 #include "memory/allocation.inline.hpp"
44 #include "runtime/mutex.hpp"
45 #include "services/management.hpp"
46 #include "utilities/macros.hpp"
47
48 void G1RootProcessor::worker_has_discovered_all_strong_classes() {
49 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
50
51 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes);
52 if (new_value == n_workers()) {
53 // This thread is last. Notify the others.
54 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
55 _lock.notify_all();
56 }
57 }
58
59 void G1RootProcessor::wait_until_all_strong_classes_discovered() {
60 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
61
62 if ((uint)_n_workers_discovered_strong_classes != n_workers()) {
63 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
64 while ((uint)_n_workers_discovered_strong_classes != n_workers()) {
65 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false);
66 }
67 }
68 }
69
70 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
71 _g1h(g1h),
72 _process_strong_tasks(G1RP_PS_NumElements),
73 _srs(n_workers),
74 _par_state_string(StringTable::weak_storage()),
75 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
76 _n_workers_discovered_strong_classes(0) {}
77
78 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_i) {
79 G1GCPhaseTimes* phase_times = _g1h->phase_times();
80
81 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_i);
82
83 G1EvacuationRootClosures* closures = pss->closures();
84 process_java_roots(closures, phase_times, worker_i);
85
86 // This is the point where this worker thread will not find more strong CLDs/nmethods.
87 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
88 if (closures->trace_metadata()) {
89 worker_has_discovered_all_strong_classes();
90 }
91
92 process_vm_roots(closures, phase_times, worker_i);
93
94 {
95 // Now the CM ref_processor roots.
96 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i);
97 if (_process_strong_tasks.try_claim_task(G1RP_PS_refProcessor_oops_do)) {
98 // We need to treat the discovered reference lists of the
99 // concurrent mark ref processor as roots and keep entries
100 // (which are added by the marking threads) on them live
101 // until they can be processed at the end of marking.
102 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
103 }
104 }
105
106 if (closures->trace_metadata()) {
107 {
108 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i);
109 // Barrier to make sure all workers passed
110 // the strong CLD and strong nmethods phases.
111 wait_until_all_strong_classes_discovered();
112 }
113
114 // Now take the complement of the strong CLDs.
115 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i);
116 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata.");
117 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds());
118 } else {
119 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);
120 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);
121 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata.");
122 }
123
124 // During conc marking we have to filter the per-thread SATB buffers
125 // to make sure we remove any oops into the CSet (which will show up
126 // as implicitly live).
127 {
128 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);
129 if (_process_strong_tasks.try_claim_task(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_or_rebuild_in_progress()) {
130 G1BarrierSet::satb_mark_queue_set().filter_thread_buffers();
131 }
132 }
133
134 _process_strong_tasks.all_tasks_completed(n_workers());
135 }
136
137 // Adaptor to pass the closures to the strong roots in the VM.
138 class StrongRootsClosures : public G1RootClosures {
139 OopClosure* _roots;
140 CLDClosure* _clds;
141 CodeBlobClosure* _blobs;
142 public:
143 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
144 _roots(roots), _clds(clds), _blobs(blobs) {}
145
146 OopClosure* weak_oops() { return NULL; }
147 OopClosure* strong_oops() { return _roots; }
148
149 CLDClosure* weak_clds() { return NULL; }
150 CLDClosure* strong_clds() { return _clds; }
151
152 CodeBlobClosure* strong_codeblobs() { return _blobs; }
153 };
154
155 void G1RootProcessor::process_strong_roots(OopClosure* oops,
156 CLDClosure* clds,
157 CodeBlobClosure* blobs) {
158 StrongRootsClosures closures(oops, clds, blobs);
159
160 process_java_roots(&closures, NULL, 0);
161 process_vm_roots(&closures, NULL, 0);
162
163 _process_strong_tasks.all_tasks_completed(n_workers());
164 }
165
166 // Adaptor to pass the closures to all the roots in the VM.
167 class AllRootsClosures : public G1RootClosures {
168 OopClosure* _roots;
169 CLDClosure* _clds;
170 public:
171 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
172 _roots(roots), _clds(clds) {}
173
174 OopClosure* weak_oops() { return _roots; }
175 OopClosure* strong_oops() { return _roots; }
176
177 // By returning the same CLDClosure for both weak and strong CLDs we ensure
178 // that a single walk of the CLDG will invoke the closure on all CLDs i the
179 // system.
180 CLDClosure* weak_clds() { return _clds; }
181 CLDClosure* strong_clds() { return _clds; }
182
183 // We don't want to visit code blobs more than once, so we return NULL for the
184 // strong case and walk the entire code cache as a separate step.
185 CodeBlobClosure* strong_codeblobs() { return NULL; }
186 };
187
188 void G1RootProcessor::process_all_roots(OopClosure* oops,
189 CLDClosure* clds,
190 CodeBlobClosure* blobs) {
191 AllRootsClosures closures(oops, clds);
192
193 process_java_roots(&closures, NULL, 0);
194 process_vm_roots(&closures, NULL, 0);
195
196 process_code_cache_roots(blobs, NULL, 0);
197
198 _process_strong_tasks.all_tasks_completed(n_workers());
199 }
200
201 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
202 G1GCPhaseTimes* phase_times,
203 uint worker_i) {
204 // Iterating over the CLDG and the Threads are done early to allow us to
205 // first process the strong CLDs and nmethods and then, after a barrier,
206 // let the thread process the weak CLDs and nmethods.
207 {
208 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
209 if (_process_strong_tasks.try_claim_task(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
210 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
211 }
212 }
213
214 {
215 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
216 bool is_par = n_workers() > 1;
217 Threads::possibly_parallel_oops_do(is_par,
218 closures->strong_oops(),
219 closures->strong_codeblobs());
220 }
221 }
222
223 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
224 G1GCPhaseTimes* phase_times,
225 uint worker_i) {
226 OopClosure* strong_roots = closures->strong_oops();
227
228 {
229 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i);
230 if (_process_strong_tasks.try_claim_task(G1RP_PS_Universe_oops_do)) {
231 Universe::oops_do(strong_roots);
232 }
233 }
234
235 {
236 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i);
237 if (_process_strong_tasks.try_claim_task(G1RP_PS_JNIHandles_oops_do)) {
238 JNIHandles::oops_do(strong_roots);
239 }
240 }
241
242 {
243 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i);
244 if (_process_strong_tasks.try_claim_task(G1RP_PS_ObjectSynchronizer_oops_do)) {
245 ObjectSynchronizer::oops_do(strong_roots);
246 }
247 }
248
249 {
250 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i);
251 if (_process_strong_tasks.try_claim_task(G1RP_PS_Management_oops_do)) {
252 Management::oops_do(strong_roots);
253 }
254 }
255
256 {
257 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i);
258 if (_process_strong_tasks.try_claim_task(G1RP_PS_jvmti_oops_do)) {
259 JvmtiExport::oops_do(strong_roots);
260 }
261 }
262
263 #if INCLUDE_AOT
264 if (UseAOT) {
265 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i);
266 if (_process_strong_tasks.try_claim_task(G1RP_PS_aot_oops_do)) {
267 AOTLoader::oops_do(strong_roots);
268 }
269 }
270 #endif
271
272 {
273 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i);
274 if (_process_strong_tasks.try_claim_task(G1RP_PS_SystemDictionary_oops_do)) {
275 SystemDictionary::oops_do(strong_roots);
276 }
277 }
278 }
279
280 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
281 G1GCPhaseTimes* phase_times,
282 uint worker_i) {
283 if (_process_strong_tasks.try_claim_task(G1RP_PS_CodeCache_oops_do)) {
284 CodeCache::blobs_do(code_closure);
285 }
286 }
287
288 uint G1RootProcessor::n_workers() const {
289 return _srs.n_threads();
290 }