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/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 "gc/shared/weakProcessor.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 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
75 _n_workers_discovered_strong_classes(0) {}
76
77 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_i) {
78 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
79
80 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_i);
81
82 G1EvacuationRootClosures* closures = pss->closures();
83 process_java_roots(closures, phase_times, worker_i);
84
85 // This is the point where this worker thread will not find more strong CLDs/nmethods.
86 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
87 if (closures->trace_metadata()) {
88 worker_has_discovered_all_strong_classes();
89 }
90
91 process_vm_roots(closures, phase_times, worker_i);
92 process_string_table_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.is_task_claimed(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.is_task_claimed(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 bool process_string_table) {
192 AllRootsClosures closures(oops, clds);
193
194 process_java_roots(&closures, NULL, 0);
195 process_vm_roots(&closures, NULL, 0);
196
197 if (process_string_table) {
198 process_string_table_roots(&closures, NULL, 0);
199 }
200 process_code_cache_roots(blobs, NULL, 0);
201
202 _process_strong_tasks.all_tasks_completed(n_workers());
203 }
204
205 void G1RootProcessor::process_all_roots(OopClosure* oops,
206 CLDClosure* clds,
207 CodeBlobClosure* blobs) {
208 process_all_roots(oops, clds, blobs, true);
209 }
210
211 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops,
212 CLDClosure* clds,
213 CodeBlobClosure* blobs) {
214 assert(!ClassUnloading, "Should only be used when class unloading is disabled");
215 process_all_roots(oops, clds, blobs, false);
216 }
217
218 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
219 G1GCPhaseTimes* phase_times,
220 uint worker_i) {
221 // Iterating over the CLDG and the Threads are done early to allow us to
222 // first process the strong CLDs and nmethods and then, after a barrier,
223 // let the thread process the weak CLDs and nmethods.
224 {
225 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
226 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
227 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
228 }
229 }
230
231 {
232 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
233 bool is_par = n_workers() > 1;
234 Threads::possibly_parallel_oops_do(is_par,
235 closures->strong_oops(),
236 closures->strong_codeblobs());
237 }
238 }
239
240 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
241 G1GCPhaseTimes* phase_times,
242 uint worker_i) {
243 OopClosure* strong_roots = closures->strong_oops();
244 OopClosure* weak_roots = closures->weak_oops();
245
246 {
247 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i);
248 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) {
249 Universe::oops_do(strong_roots);
250 }
251 }
252
253 {
254 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i);
255 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {
256 JNIHandles::oops_do(strong_roots);
257 }
258 }
259
260 {
261 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i);
262 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {
263 ObjectSynchronizer::oops_do(strong_roots);
264 }
265 }
266
267 {
268 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i);
269 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) {
270 Management::oops_do(strong_roots);
271 }
272 }
273
274 {
275 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i);
276 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) {
277 JvmtiExport::oops_do(strong_roots);
278 }
279 }
280
281 #if INCLUDE_AOT
282 if (UseAOT) {
283 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i);
284 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) {
285 AOTLoader::oops_do(strong_roots);
286 }
287 }
288 #endif
289
290 {
291 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i);
292 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {
293 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
294 }
295 }
296 }
297
298 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures,
299 G1GCPhaseTimes* phase_times,
300 uint worker_i) {
301 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed");
302 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i);
303 // All threads execute the following. A specific chunk of buckets
304 // from the StringTable are the individual tasks.
305 StringTable::possibly_parallel_oops_do(closures->weak_oops());
306 }
307
308 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
309 G1GCPhaseTimes* phase_times,
310 uint worker_i) {
311 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) {
312 CodeCache::blobs_do(code_closure);
313 }
314 }
315
316 void G1RootProcessor::process_full_gc_weak_roots(OopClosure* oops) {
317 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
318 _g1h->ref_processor_stw()->weak_oops_do(oops);
319 }
320
321 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_weakProcessor_oops_do)) {
322 WeakProcessor::oops_do(oops);
323 }
324 }
325
326 uint G1RootProcessor::n_workers() const {
327 return _srs.n_threads();
328 }