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 StringTable::reset_dead_counter();
79 }
80
81 G1RootProcessor::~G1RootProcessor() {
82 StringTable::finish_dead_counter();
83 }
84
85 void G1RootProcessor::evacuate_roots(G1ParScanThreadState* pss, uint worker_i) {
86 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
87
88 G1EvacPhaseTimesTracker timer(phase_times, pss, G1GCPhaseTimes::ExtRootScan, worker_i);
89
90 G1EvacuationRootClosures* closures = pss->closures();
91 process_java_roots(closures, phase_times, worker_i);
92
93 // This is the point where this worker thread will not find more strong CLDs/nmethods.
94 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
95 if (closures->trace_metadata()) {
96 worker_has_discovered_all_strong_classes();
97 }
98
99 process_vm_roots(closures, phase_times, worker_i);
100 process_string_table_roots(closures, phase_times, worker_i);
101
102 {
103 // Now the CM ref_processor roots.
104 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i);
105 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
106 // We need to treat the discovered reference lists of the
107 // concurrent mark ref processor as roots and keep entries
108 // (which are added by the marking threads) on them live
109 // until they can be processed at the end of marking.
110 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
111 }
112 }
113
114 if (closures->trace_metadata()) {
115 {
116 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i);
117 // Barrier to make sure all workers passed
118 // the strong CLD and strong nmethods phases.
119 wait_until_all_strong_classes_discovered();
120 }
121
122 // Now take the complement of the strong CLDs.
123 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i);
124 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata.");
125 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds());
126 } else {
127 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);
128 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);
129 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata.");
130 }
131
132 // During conc marking we have to filter the per-thread SATB buffers
133 // to make sure we remove any oops into the CSet (which will show up
134 // as implicitly live).
135 {
136 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);
137 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_or_rebuild_in_progress()) {
138 G1BarrierSet::satb_mark_queue_set().filter_thread_buffers();
139 }
140 }
141
142 _process_strong_tasks.all_tasks_completed(n_workers());
143 }
144
145 // Adaptor to pass the closures to the strong roots in the VM.
146 class StrongRootsClosures : public G1RootClosures {
147 OopClosure* _roots;
148 CLDClosure* _clds;
149 CodeBlobClosure* _blobs;
150 public:
151 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
152 _roots(roots), _clds(clds), _blobs(blobs) {}
153
154 OopClosure* weak_oops() { return NULL; }
155 OopClosure* strong_oops() { return _roots; }
156
157 CLDClosure* weak_clds() { return NULL; }
158 CLDClosure* strong_clds() { return _clds; }
159
160 CodeBlobClosure* strong_codeblobs() { return _blobs; }
161 };
162
163 void G1RootProcessor::process_strong_roots(OopClosure* oops,
164 CLDClosure* clds,
165 CodeBlobClosure* blobs) {
166 StrongRootsClosures closures(oops, clds, blobs);
167
168 process_java_roots(&closures, NULL, 0);
169 process_vm_roots(&closures, NULL, 0);
170
171 _process_strong_tasks.all_tasks_completed(n_workers());
172 }
173
174 // Adaptor to pass the closures to all the roots in the VM.
175 class AllRootsClosures : public G1RootClosures {
176 OopClosure* _roots;
177 CLDClosure* _clds;
178 public:
179 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
180 _roots(roots), _clds(clds) {}
181
182 OopClosure* weak_oops() { return _roots; }
183 OopClosure* strong_oops() { return _roots; }
184
185 // By returning the same CLDClosure for both weak and strong CLDs we ensure
186 // that a single walk of the CLDG will invoke the closure on all CLDs i the
187 // system.
188 CLDClosure* weak_clds() { return _clds; }
189 CLDClosure* strong_clds() { return _clds; }
190
191 // We don't want to visit code blobs more than once, so we return NULL for the
192 // strong case and walk the entire code cache as a separate step.
193 CodeBlobClosure* strong_codeblobs() { return NULL; }
194 };
195
196 void G1RootProcessor::process_all_roots(OopClosure* oops,
197 CLDClosure* clds,
198 CodeBlobClosure* blobs,
199 bool process_string_table) {
200 AllRootsClosures closures(oops, clds);
201
202 process_java_roots(&closures, NULL, 0);
203 process_vm_roots(&closures, NULL, 0);
204
205 if (process_string_table) {
206 process_string_table_roots(&closures, NULL, 0);
207 }
208 process_code_cache_roots(blobs, NULL, 0);
209
210 _process_strong_tasks.all_tasks_completed(n_workers());
211 }
212
213 void G1RootProcessor::process_all_roots(OopClosure* oops,
214 CLDClosure* clds,
215 CodeBlobClosure* blobs) {
216 process_all_roots(oops, clds, blobs, true);
217 }
218
219 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops,
220 CLDClosure* clds,
221 CodeBlobClosure* blobs) {
222 assert(!ClassUnloading, "Should only be used when class unloading is disabled");
223 process_all_roots(oops, clds, blobs, false);
224 }
225
226 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
227 G1GCPhaseTimes* phase_times,
228 uint worker_i) {
229 // Iterating over the CLDG and the Threads are done early to allow us to
230 // first process the strong CLDs and nmethods and then, after a barrier,
231 // let the thread process the weak CLDs and nmethods.
232 {
233 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
234 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
235 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
236 }
237 }
238
239 {
240 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
241 bool is_par = n_workers() > 1;
242 Threads::possibly_parallel_oops_do(is_par,
243 closures->strong_oops(),
244 closures->strong_codeblobs());
245 }
246 }
247
248 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
249 G1GCPhaseTimes* phase_times,
250 uint worker_i) {
251 OopClosure* strong_roots = closures->strong_oops();
252
253 {
254 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i);
255 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) {
256 Universe::oops_do(strong_roots);
257 }
258 }
259
260 {
261 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i);
262 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {
263 JNIHandles::oops_do(strong_roots);
264 }
265 }
266
267 {
268 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i);
269 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {
270 ObjectSynchronizer::oops_do(strong_roots);
271 }
272 }
273
274 {
275 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i);
276 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) {
277 Management::oops_do(strong_roots);
278 }
279 }
280
281 {
282 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i);
283 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) {
284 JvmtiExport::oops_do(strong_roots);
285 }
286 }
287
288 #if INCLUDE_AOT
289 if (UseAOT) {
290 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i);
291 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) {
292 AOTLoader::oops_do(strong_roots);
293 }
294 }
295 #endif
296
297 {
298 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i);
299 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {
300 SystemDictionary::oops_do(strong_roots);
301 }
302 }
303 }
304
305 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures,
306 G1GCPhaseTimes* phase_times,
307 uint worker_i) {
308 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed");
309 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i);
310 // All threads execute the following. A specific chunk of buckets
311 // from the StringTable are the individual tasks.
312 StringTable::possibly_parallel_oops_do(&_par_state_string, closures->weak_oops());
313 }
314
315 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
316 G1GCPhaseTimes* phase_times,
317 uint worker_i) {
318 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) {
319 CodeCache::blobs_do(code_closure);
320 }
321 }
322
323 void G1RootProcessor::process_full_gc_weak_roots(OopClosure* oops) {
324 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
325 _g1h->ref_processor_stw()->weak_oops_do(oops);
326 }
327
328 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_weakProcessor_oops_do)) {
329 WeakProcessor::oops_do(oops);
330 }
331 }
332
333 uint G1RootProcessor::n_workers() const {
334 return _srs.n_threads();
335 }