1 /*
2 * Copyright (c) 2015, 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
27 #include "aot/aotLoader.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "code/codeCache.hpp"
31 #include "gc/g1/g1CodeBlobClosure.hpp"
32 #include "gc/g1/g1CollectedHeap.inline.hpp"
33 #include "gc/g1/g1CollectorState.hpp"
34 #include "gc/g1/g1GCPhaseTimes.hpp"
35 #include "gc/g1/g1ParScanThreadState.inline.hpp"
36 #include "gc/g1/g1Policy.hpp"
37 #include "gc/g1/g1RootClosures.hpp"
38 #include "gc/g1/g1RootProcessor.hpp"
39 #include "gc/g1/heapRegion.inline.hpp"
40 #include "gc/shared/weakProcessor.hpp"
41 #include "memory/allocation.inline.hpp"
42 #include "runtime/mutex.hpp"
43 #include "services/management.hpp"
44 #include "utilities/macros.hpp"
45
46 void G1RootProcessor::worker_has_discovered_all_strong_classes() {
47 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
48
49 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes);
50 if (new_value == n_workers()) {
51 // This thread is last. Notify the others.
52 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
53 _lock.notify_all();
54 }
55 }
56
57 void G1RootProcessor::wait_until_all_strong_classes_discovered() {
58 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
59
60 if ((uint)_n_workers_discovered_strong_classes != n_workers()) {
61 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
62 while ((uint)_n_workers_discovered_strong_classes != n_workers()) {
63 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false);
64 }
65 }
66 }
67
68 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
69 _g1h(g1h),
70 _process_strong_tasks(G1RP_PS_NumElements),
71 _srs(n_workers),
72 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
73 _n_workers_discovered_strong_classes(0) {}
74
75 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_i) {
76 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
77
78 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_i);
79
80 G1EvacuationRootClosures* closures = pss->closures();
81 process_java_roots(closures, phase_times, worker_i);
82
83 // This is the point where this worker thread will not find more strong CLDs/nmethods.
84 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
85 if (closures->trace_metadata()) {
86 worker_has_discovered_all_strong_classes();
87 }
88
89 process_vm_roots(closures, phase_times, worker_i);
90 process_string_table_roots(closures, phase_times, worker_i);
91
92 {
93 // Now the CM ref_processor roots.
94 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i);
95 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
96 // We need to treat the discovered reference lists of the
97 // concurrent mark ref processor as roots and keep entries
98 // (which are added by the marking threads) on them live
99 // until they can be processed at the end of marking.
100 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
101 }
102 }
103
104 if (closures->trace_metadata()) {
105 {
106 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i);
107 // Barrier to make sure all workers passed
108 // the strong CLD and strong nmethods phases.
109 wait_until_all_strong_classes_discovered();
110 }
111
112 // Now take the complement of the strong CLDs.
113 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i);
114 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata.");
115 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds());
116 } else {
117 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);
118 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);
119 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata.");
120 }
121
122 // During conc marking we have to filter the per-thread SATB buffers
123 // to make sure we remove any oops into the CSet (which will show up
124 // as implicitly live).
125 {
126 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);
127 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_or_rebuild_in_progress()) {
128 JavaThread::satb_mark_queue_set().filter_thread_buffers();
129 }
130 }
131
132 _process_strong_tasks.all_tasks_completed(n_workers());
133 }
134
135 // Adaptor to pass the closures to the strong roots in the VM.
136 class StrongRootsClosures : public G1RootClosures {
137 OopClosure* _roots;
138 CLDClosure* _clds;
139 CodeBlobClosure* _blobs;
140 public:
141 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
142 _roots(roots), _clds(clds), _blobs(blobs) {}
143
144 OopClosure* weak_oops() { return NULL; }
145 OopClosure* strong_oops() { return _roots; }
146
147 CLDClosure* weak_clds() { return NULL; }
148 CLDClosure* strong_clds() { return _clds; }
149
150 CodeBlobClosure* strong_codeblobs() { return _blobs; }
151 };
152
153 void G1RootProcessor::process_strong_roots(OopClosure* oops,
154 CLDClosure* clds,
155 CodeBlobClosure* blobs) {
156 StrongRootsClosures closures(oops, clds, blobs);
157
158 process_java_roots(&closures, NULL, 0);
159 process_vm_roots(&closures, NULL, 0);
160
161 _process_strong_tasks.all_tasks_completed(n_workers());
162 }
163
164 // Adaptor to pass the closures to all the roots in the VM.
165 class AllRootsClosures : public G1RootClosures {
166 OopClosure* _roots;
167 CLDClosure* _clds;
168 public:
169 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
170 _roots(roots), _clds(clds) {}
171
172 OopClosure* weak_oops() { return _roots; }
173 OopClosure* strong_oops() { return _roots; }
174
175 // By returning the same CLDClosure for both weak and strong CLDs we ensure
176 // that a single walk of the CLDG will invoke the closure on all CLDs i the
177 // system.
178 CLDClosure* weak_clds() { return _clds; }
179 CLDClosure* strong_clds() { return _clds; }
180
181 // We don't want to visit code blobs more than once, so we return NULL for the
182 // strong case and walk the entire code cache as a separate step.
183 CodeBlobClosure* strong_codeblobs() { return NULL; }
184 };
185
186 void G1RootProcessor::process_all_roots(OopClosure* oops,
187 CLDClosure* clds,
188 CodeBlobClosure* blobs,
189 bool process_string_table) {
190 AllRootsClosures closures(oops, clds);
191
192 process_java_roots(&closures, NULL, 0);
193 process_vm_roots(&closures, NULL, 0);
194
195 if (process_string_table) {
196 process_string_table_roots(&closures, NULL, 0);
197 }
198 process_code_cache_roots(blobs, NULL, 0);
199
200 _process_strong_tasks.all_tasks_completed(n_workers());
201 }
202
203 void G1RootProcessor::process_all_roots(OopClosure* oops,
204 CLDClosure* clds,
205 CodeBlobClosure* blobs) {
206 process_all_roots(oops, clds, blobs, true);
207 }
208
209 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops,
210 CLDClosure* clds,
211 CodeBlobClosure* blobs) {
212 assert(!ClassUnloading, "Should only be used when class unloading is disabled");
213 process_all_roots(oops, clds, blobs, false);
214 }
215
216 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
217 G1GCPhaseTimes* phase_times,
218 uint worker_i) {
219 // Iterating over the CLDG and the Threads are done early to allow us to
220 // first process the strong CLDs and nmethods and then, after a barrier,
221 // let the thread process the weak CLDs and nmethods.
222 {
223 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
224 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
225 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
226 }
227 }
228
229 {
230 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
231 bool is_par = n_workers() > 1;
232 Threads::possibly_parallel_oops_do(is_par,
233 closures->strong_oops(),
234 closures->strong_codeblobs());
235 }
236 }
237
238 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
239 G1GCPhaseTimes* phase_times,
240 uint worker_i) {
241 OopClosure* strong_roots = closures->strong_oops();
242 OopClosure* weak_roots = closures->weak_oops();
243
244 {
245 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i);
246 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) {
247 Universe::oops_do(strong_roots);
248 }
249 }
250
251 {
252 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i);
253 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {
254 JNIHandles::oops_do(strong_roots);
255 }
256 }
257
258 {
259 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i);
260 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {
261 ObjectSynchronizer::oops_do(strong_roots);
262 }
263 }
264
265 {
266 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i);
267 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) {
268 Management::oops_do(strong_roots);
269 }
270 }
271
272 {
273 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i);
274 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) {
275 JvmtiExport::oops_do(strong_roots);
276 }
277 }
278
279 #if INCLUDE_AOT
280 if (UseAOT) {
281 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i);
282 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) {
283 AOTLoader::oops_do(strong_roots);
284 }
285 }
286 #endif
287
288 {
289 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i);
290 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {
291 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
292 }
293 }
294 }
295
296 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures,
297 G1GCPhaseTimes* phase_times,
298 uint worker_i) {
299 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed");
300 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i);
301 // All threads execute the following. A specific chunk of buckets
302 // from the StringTable are the individual tasks.
303 StringTable::possibly_parallel_oops_do(closures->weak_oops());
304 }
305
306 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
307 G1GCPhaseTimes* phase_times,
308 uint worker_i) {
309 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) {
310 CodeCache::blobs_do(code_closure);
311 }
312 }
313
314 void G1RootProcessor::process_full_gc_weak_roots(OopClosure* oops) {
315 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
316 _g1h->ref_processor_stw()->weak_oops_do(oops);
317 }
318
319 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_weakProcessor_oops_do)) {
320 WeakProcessor::oops_do(oops);
321 }
322 }
323
324 uint G1RootProcessor::n_workers() const {
325 return _srs.n_threads();
326 }