1 /*
2 * Copyright (c) 2015, 2016, 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/bufferingOopClosure.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/g1Policy.hpp"
37 #include "gc/g1/g1RootClosures.hpp"
38 #include "gc/g1/g1RootProcessor.hpp"
39 #include "gc/g1/heapRegion.inline.hpp"
40 #include "memory/allocation.inline.hpp"
41 #include "runtime/fprofiler.hpp"
42 #include "runtime/mutex.hpp"
43 #include "services/management.hpp"
44
45 void G1RootProcessor::worker_has_discovered_all_strong_classes() {
46 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
47
48 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes);
49 if (new_value == n_workers()) {
50 // This thread is last. Notify the others.
51 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
52 _lock.notify_all();
53 }
54 }
55
56 void G1RootProcessor::wait_until_all_strong_classes_discovered() {
57 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
58
59 if ((uint)_n_workers_discovered_strong_classes != n_workers()) {
60 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
61 while ((uint)_n_workers_discovered_strong_classes != n_workers()) {
62 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false);
63 }
64 }
65 }
66
67 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, uint n_workers) :
68 _g1h(g1h),
69 _process_strong_tasks(G1RP_PS_NumElements),
70 _srs(n_workers),
71 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
72 _n_workers_discovered_strong_classes(0) {}
73
74 void G1RootProcessor::evacuate_roots(G1EvacuationRootClosures* closures, uint worker_i) {
75 double ext_roots_start = os::elapsedTime();
76 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
77
78 process_java_roots(closures, phase_times, worker_i);
79
80 // This is the point where this worker thread will not find more strong CLDs/nmethods.
81 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
82 if (closures->trace_metadata()) {
83 worker_has_discovered_all_strong_classes();
84 }
85
86 process_vm_roots(closures, phase_times, worker_i);
87 process_string_table_roots(closures, phase_times, worker_i);
88
89 {
90 // Now the CM ref_processor roots.
91 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CMRefRoots, worker_i);
92 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
93 // We need to treat the discovered reference lists of the
94 // concurrent mark ref processor as roots and keep entries
95 // (which are added by the marking threads) on them live
96 // until they can be processed at the end of marking.
97 _g1h->ref_processor_cm()->weak_oops_do(closures->strong_oops());
98 }
99 }
100
101 if (closures->trace_metadata()) {
102 {
103 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WaitForStrongCLD, worker_i);
104 // Barrier to make sure all workers passed
105 // the strong CLD and strong nmethods phases.
106 wait_until_all_strong_classes_discovered();
107 }
108
109 // Now take the complement of the strong CLDs.
110 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::WeakCLDRoots, worker_i);
111 assert(closures->second_pass_weak_clds() != NULL, "Should be non-null if we are tracing metadata.");
112 ClassLoaderDataGraph::roots_cld_do(NULL, closures->second_pass_weak_clds());
113 } else {
114 phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);
115 phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);
116 assert(closures->second_pass_weak_clds() == NULL, "Should be null if not tracing metadata.");
117 }
118
119 // Finish up any enqueued closure apps (attributed as object copy time).
120 closures->flush();
121
122 double obj_copy_time_sec = closures->closure_app_seconds();
123
124 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec);
125
126 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec;
127
128 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec);
129
130 // During conc marking we have to filter the per-thread SATB buffers
131 // to make sure we remove any oops into the CSet (which will show up
132 // as implicitly live).
133 {
134 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);
135 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->collector_state()->mark_in_progress()) {
136 JavaThread::satb_mark_queue_set().filter_thread_buffers();
137 }
138 }
139
140 _process_strong_tasks.all_tasks_completed(n_workers());
141 }
142
143 // Adaptor to pass the closures to the strong roots in the VM.
144 class StrongRootsClosures : public G1RootClosures {
145 OopClosure* _roots;
146 CLDClosure* _clds;
147 CodeBlobClosure* _blobs;
148 public:
149 StrongRootsClosures(OopClosure* roots, CLDClosure* clds, CodeBlobClosure* blobs) :
150 _roots(roots), _clds(clds), _blobs(blobs) {}
151
152 OopClosure* weak_oops() { return NULL; }
153 OopClosure* strong_oops() { return _roots; }
154
155 CLDClosure* weak_clds() { return NULL; }
156 CLDClosure* strong_clds() { return _clds; }
157
158 CodeBlobClosure* strong_codeblobs() { return _blobs; }
159 };
160
161 void G1RootProcessor::process_strong_roots(OopClosure* oops,
162 CLDClosure* clds,
163 CodeBlobClosure* blobs) {
164 StrongRootsClosures closures(oops, clds, blobs);
165
166 process_java_roots(&closures, NULL, 0);
167 process_vm_roots(&closures, NULL, 0);
168
169 _process_strong_tasks.all_tasks_completed(n_workers());
170 }
171
172 // Adaptor to pass the closures to all the roots in the VM.
173 class AllRootsClosures : public G1RootClosures {
174 OopClosure* _roots;
175 CLDClosure* _clds;
176 public:
177 AllRootsClosures(OopClosure* roots, CLDClosure* clds) :
178 _roots(roots), _clds(clds) {}
179
180 OopClosure* weak_oops() { return _roots; }
181 OopClosure* strong_oops() { return _roots; }
182
183 // By returning the same CLDClosure for both weak and strong CLDs we ensure
184 // that a single walk of the CLDG will invoke the closure on all CLDs i the
185 // system.
186 CLDClosure* weak_clds() { return _clds; }
187 CLDClosure* strong_clds() { return _clds; }
188
189 // We don't want to visit code blobs more than once, so we return NULL for the
190 // strong case and walk the entire code cache as a separate step.
191 CodeBlobClosure* strong_codeblobs() { return NULL; }
192 };
193
194 void G1RootProcessor::process_all_roots(OopClosure* oops,
195 CLDClosure* clds,
196 CodeBlobClosure* blobs,
197 bool process_string_table) {
198 AllRootsClosures closures(oops, clds);
199
200 process_java_roots(&closures, NULL, 0);
201 process_vm_roots(&closures, NULL, 0);
202
203 if (process_string_table) {
204 process_string_table_roots(&closures, NULL, 0);
205 }
206 process_code_cache_roots(blobs, NULL, 0);
207
208 _process_strong_tasks.all_tasks_completed(n_workers());
209 }
210
211 void G1RootProcessor::process_all_roots(OopClosure* oops,
212 CLDClosure* clds,
213 CodeBlobClosure* blobs) {
214 process_all_roots(oops, clds, blobs, true);
215 }
216
217 void G1RootProcessor::process_all_roots_no_string_table(OopClosure* oops,
218 CLDClosure* clds,
219 CodeBlobClosure* blobs) {
220 assert(!ClassUnloading, "Should only be used when class unloading is disabled");
221 process_all_roots(oops, clds, blobs, false);
222 }
223
224 void G1RootProcessor::process_java_roots(G1RootClosures* closures,
225 G1GCPhaseTimes* phase_times,
226 uint worker_i) {
227 // Iterating over the CLDG and the Threads are done early to allow us to
228 // first process the strong CLDs and nmethods and then, after a barrier,
229 // let the thread process the weak CLDs and nmethods.
230 {
231 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::CLDGRoots, worker_i);
232 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
233 ClassLoaderDataGraph::roots_cld_do(closures->strong_clds(), closures->weak_clds());
234 }
235 }
236
237 {
238 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ThreadRoots, worker_i);
239 bool is_par = n_workers() > 1;
240 Threads::possibly_parallel_oops_do(is_par,
241 closures->strong_oops(),
242 closures->strong_codeblobs());
243 }
244 }
245
246 void G1RootProcessor::process_vm_roots(G1RootClosures* closures,
247 G1GCPhaseTimes* phase_times,
248 uint worker_i) {
249 OopClosure* strong_roots = closures->strong_oops();
250 OopClosure* weak_roots = closures->weak_oops();
251
252 {
253 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::UniverseRoots, worker_i);
254 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Universe_oops_do)) {
255 Universe::oops_do(strong_roots);
256 }
257 }
258
259 {
260 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JNIRoots, worker_i);
261 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {
262 JNIHandles::oops_do(strong_roots);
263 }
264 }
265
266 {
267 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ObjectSynchronizerRoots, worker_i);
268 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {
269 ObjectSynchronizer::oops_do(strong_roots);
270 }
271 }
272
273 {
274 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::FlatProfilerRoots, worker_i);
275 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) {
276 FlatProfiler::oops_do(strong_roots);
277 }
278 }
279
280 {
281 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::ManagementRoots, worker_i);
282 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_Management_oops_do)) {
283 Management::oops_do(strong_roots);
284 }
285 }
286
287 {
288 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::JVMTIRoots, worker_i);
289 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_jvmti_oops_do)) {
290 JvmtiExport::oops_do(strong_roots);
291 }
292 }
293
294 #if INCLUDE_AOT
295 if (UseAOT) {
296 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::AOTCodeRoots, worker_i);
297 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_aot_oops_do)) {
298 AOTLoader::oops_do(strong_roots);
299 }
300 }
301 #endif
302
303 {
304 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SystemDictionaryRoots, worker_i);
305 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {
306 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
307 }
308 }
309 }
310
311 void G1RootProcessor::process_string_table_roots(G1RootClosures* closures,
312 G1GCPhaseTimes* phase_times,
313 uint worker_i) {
314 assert(closures->weak_oops() != NULL, "Should only be called when all roots are processed");
315 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::StringTableRoots, worker_i);
316 // All threads execute the following. A specific chunk of buckets
317 // from the StringTable are the individual tasks.
318 StringTable::possibly_parallel_oops_do(closures->weak_oops());
319 }
320
321 void G1RootProcessor::process_code_cache_roots(CodeBlobClosure* code_closure,
322 G1GCPhaseTimes* phase_times,
323 uint worker_i) {
324 if (!_process_strong_tasks.is_task_claimed(G1RP_PS_CodeCache_oops_do)) {
325 CodeCache::blobs_do(code_closure);
326 }
327 }
328
329 uint G1RootProcessor::n_workers() const {
330 return _srs.n_threads();
331 }