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/oopStorageParState.hpp"
42 #include "gc/shared/referenceProcessor.hpp"
43 #include "gc/shared/weakProcessor.hpp"
44 #include "memory/allocation.inline.hpp"
45 #include "runtime/mutex.hpp"
46 #include "services/management.hpp"
47 #include "utilities/macros.hpp"
48
49 void G1RootProcessor::worker_has_discovered_all_strong_classes() {
50 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
51
52 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes);
53 if (new_value == n_workers()) {
54 // This thread is last. Notify the others.
55 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
56 _lock.notify_all();
57 }
58 }
59
60 void G1RootProcessor::wait_until_all_strong_classes_discovered() {
61 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
62
63 if ((uint)_n_workers_discovered_strong_classes != n_workers()) {
64 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
65 while ((uint)_n_workers_discovered_strong_classes != n_workers()) {
66 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false);
67 }
68 }
69 }
70
71 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
72 _g1h(g1h),
73 _process_strong_tasks(G1RP_PS_NumElements),
74 _srs(n_workers),
75 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
76 _par_state_string(StringTable::weak_storage()),
77 _n_workers_discovered_strong_classes(0) {}
78
79 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_i) {
80 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
81
82 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_i);
83
84 G1EvacuationRootClosures* closures = pss->closures();
85 process_java_roots(closures, phase_times, worker_i);
86
87 // This is the point where this worker thread will not find more strong CLDs/nmethods.
88 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
89 if (closures->trace_metadata()) {
90 worker_has_discovered_all_strong_classes();
91 }
92
93 process_vm_roots(closures, phase_times, worker_i);
94 process_string_table_roots(closures, phase_times, worker_i);
95
96 {
97 // Now the CM ref_processor roots.
98 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i);
99 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
100 // We need to treat the discovered reference lists of the
101 // concurrent mark ref processor as roots and keep entries
102 // (which are added by the marking threads) on them live
103 // until they can be processed at the end of marking.
104 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
105 }
106 }
107
108 if (closures->trace_metadata()) {
109 {
110 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i);
111 // Barrier to make sure all workers passed
112 // the strong CLD and strong nmethods phases.
113 wait_until_all_strong_classes_discovered();
114 }
115
116 // Now take the complement of the strong CLDs.
117 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i);
118 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata.");
119 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds());
120 } else {
121 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);
122 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);
123 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata.");
124 }
125
126 // During conc marking we have to filter the per-thread SATB buffers
127 // to make sure we remove any oops into the CSet (which will show up
128 // as implicitly live).
129 {
130 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);
131 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_or_rebuild_in_progress()) {
132 G1BarrierSet::satb_mark_queue_set().filter_thread_buffers();
133 }
134 }
135
136 _process_strong_tasks.all_tasks_completed(n_workers());
137 }
138
139 // Adaptor to pass the closures to the strong roots in the VM.
140 class StrongRootsClosures : public G1RootClosures {
141 OopClosure* _roots;
142 CLDClosure* _clds;
143 CodeBlobClosure* _blobs;
144 public:
145 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
146 _roots(roots), _clds(clds), _blobs(blobs) {}
147
148 OopClosure* weak_oops() { return NULL; }
149 OopClosure* strong_oops() { return _roots; }
150
151 CLDClosure* weak_clds() { return NULL; }
152 CLDClosure* strong_clds() { return _clds; }
153
154 CodeBlobClosure* strong_codeblobs() { return _blobs; }
155 };
156
157 void G1RootProcessor::process_strong_roots(OopClosure* oops,
158 CLDClosure* clds,
159 CodeBlobClosure* blobs) {
160 StrongRootsClosures closures(oops, clds, blobs);
161
162 process_java_roots(&closures, NULL, 0);
163 process_vm_roots(&closures, NULL, 0);
164
165 _process_strong_tasks.all_tasks_completed(n_workers());
166 }
167
168 // Adaptor to pass the closures to all the roots in the VM.
169 class AllRootsClosures : public G1RootClosures {
170 OopClosure* _roots;
171 CLDClosure* _clds;
172 public:
173 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
174 _roots(roots), _clds(clds) {}
175
176 OopClosure* weak_oops() { return _roots; }
177 OopClosure* strong_oops() { return _roots; }
178
179 // By returning the same CLDClosure for both weak and strong CLDs we ensure
180 // that a single walk of the CLDG will invoke the closure on all CLDs i the
181 // system.
182 CLDClosure* weak_clds() { return _clds; }
183 CLDClosure* strong_clds() { return _clds; }
184
185 // We don't want to visit code blobs more than once, so we return NULL for the
186 // strong case and walk the entire code cache as a separate step.
187 CodeBlobClosure* strong_codeblobs() { return NULL; }
188 };
189
190 void G1RootProcessor::process_all_roots(OopClosure* oops,
191 CLDClosure* clds,
192 CodeBlobClosure* blobs,
193 bool process_string_table) {
194 AllRootsClosures closures(oops, clds);
195
196 process_java_roots(&closures, NULL, 0);
197 process_vm_roots(&closures, NULL, 0);
198
199 if (process_string_table) {
200 process_string_table_roots(&closures, NULL, 0);
201 }
202 process_code_cache_roots(blobs, NULL, 0);
203
204 _process_strong_tasks.all_tasks_completed(n_workers());
205 }
206
207 void G1RootProcessor::process_all_roots(OopClosure* oops,
208 CLDClosure* clds,
209 CodeBlobClosure* blobs) {
210 process_all_roots(oops, clds, blobs, true);
211 }
212
213 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops,
214 CLDClosure* clds,
215 CodeBlobClosure* blobs) {
216 assert(!ClassUnloading, "Should only be used when class unloading is disabled");
217 process_all_roots(oops, clds, blobs, false);
218 }
219
220 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
221 G1GCPhaseTimes* phase_times,
222 uint worker_i) {
223 // Iterating over the CLDG and the Threads are done early to allow us to
224 // first process the strong CLDs and nmethods and then, after a barrier,
225 // let the thread process the weak CLDs and nmethods.
226 {
227 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
228 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
229 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
230 }
231 }
232
233 {
234 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
235 bool is_par = n_workers() > 1;
236 Threads::possibly_parallel_oops_do(is_par,
237 closures->strong_oops(),
238 closures->strong_codeblobs());
239 }
240 }
241
242 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
243 G1GCPhaseTimes* phase_times,
244 uint worker_i) {
245 OopClosure* strong_roots = closures->strong_oops();
246 OopClosure* weak_roots = closures->weak_oops();
247
248 {
249 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i);
250 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) {
251 Universe::oops_do(strong_roots);
252 }
253 }
254
255 {
256 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i);
257 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {
258 JNIHandles::oops_do(strong_roots);
259 }
260 }
261
262 {
263 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i);
264 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {
265 ObjectSynchronizer::oops_do(strong_roots);
266 }
267 }
268
269 {
270 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i);
271 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) {
272 Management::oops_do(strong_roots);
273 }
274 }
275
276 {
277 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i);
278 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) {
279 JvmtiExport::oops_do(strong_roots);
280 }
281 }
282
283 #if INCLUDE_AOT
284 if (UseAOT) {
285 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i);
286 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) {
287 AOTLoader::oops_do(strong_roots);
288 }
289 }
290 #endif
291
292 {
293 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i);
294 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {
295 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
296 }
297 }
298 }
299
300 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures,
301 G1GCPhaseTimes* phase_times,
302 uint worker_i) {
303 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed");
304 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i);
305 // All threads execute the following. A specific chunk of buckets
306 // from the StringTable are the individual tasks.
307 StringTable::possibly_parallel_oops_do(&_par_state_string, closures->weak_oops());
308 }
309
310 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
311 G1GCPhaseTimes* phase_times,
312 uint worker_i) {
313 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) {
314 CodeCache::blobs_do(code_closure);
315 }
316 }
317
318 void G1RootProcessor::process_full_gc_weak_roots(OopClosure* oops) {
319 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
320 _g1h->ref_processor_stw()->weak_oops_do(oops);
321 }
322
323 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_weakProcessor_oops_do)) {
324 WeakProcessor::oops_do(oops);
325 }
326 }
327
328 uint G1RootProcessor::n_workers() const {
329 return _srs.n_threads();
330 }