1 /*
2 * Copyright (c) 2015, 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 "classfile/stringTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "code/codeCache.hpp"
30 #include "gc_implementation/g1/bufferingOopClosure.hpp"
31 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
32 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
33 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
34 #include "gc_implementation/g1/g1RemSet.inline.hpp"
35 #include "gc_implementation/g1/g1RootProcessor.hpp"
36 #include "memory/allocation.inline.hpp"
37 #include "runtime/fprofiler.hpp"
38 #include "runtime/mutex.hpp"
39 #include "services/management.hpp"
40
41 class G1CodeBlobClosure : public CodeBlobClosure {
42 class HeapRegionGatheringOopClosure : public OopClosure {
43 G1CollectedHeap* _g1h;
44 OopClosure* _work;
45 nmethod* _nm;
46
47 template <typename T>
48 void do_oop_work(T* p) {
49 _work->do_oop(p);
50 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
51 if (!oopDesc::is_null(oop_or_narrowoop)) {
52 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
53 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
54 assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset");
55 hr->add_strong_code_root(_nm);
56 }
57 }
58
59 public:
60 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
61
62 void do_oop(oop* o) {
63 do_oop_work(o);
64 }
65
66 void do_oop(narrowOop* o) {
67 do_oop_work(o);
68 }
69
70 void set_nm(nmethod* nm) {
71 _nm = nm;
72 }
73 };
74
75 HeapRegionGatheringOopClosure _oc;
76 public:
77 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
78
79 void do_code_blob(CodeBlob* cb) {
80 nmethod* nm = cb->as_nmethod_or_null();
81 if (nm != NULL) {
82 if (!nm->test_set_oops_do_mark()) {
83 _oc.set_nm(nm);
84 nm->oops_do(&_oc);
85 nm->fix_oop_relocations();
86 }
87 }
88 }
89 };
90
91
92 void G1RootProcessor::worker_has_discovered_all_strong_classes() {
93 uint n_workers = _g1h->n_par_threads();
94 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
95
96 uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes);
97 if (new_value == n_workers) {
98 // This thread is last. Notify the others.
99 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
100 _lock.notify_all();
101 }
102 }
103
104 void G1RootProcessor::wait_until_all_strong_classes_discovered() {
105 uint n_workers = _g1h->n_par_threads();
106 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
107
108 if ((uint)_n_workers_discovered_strong_classes != n_workers) {
109 MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);
110 while ((uint)_n_workers_discovered_strong_classes != n_workers) {
111 _lock.wait(Mutex::_no_safepoint_check_flag, 0, false);
112 }
113 }
114 }
115
116 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h, bool trace_metadata) :
117 _g1h(g1h),
118 _process_strong_tasks(new SubTasksDone(G1RP_PS_NumElements)),
119 _srs(g1h),
120 _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false, Monitor::_safepoint_check_never),
121 _n_workers_discovered_strong_classes(0),
122 _trace_metadata(trace_metadata) {}
123
124 void G1RootProcessor::evacuate_roots(OopClosure* scan_non_heap_roots,
125 OopClosure* scan_non_heap_weak_roots,
126 CLDClosure* scan_strong_clds,
127 CLDClosure* scan_weak_clds,
128 uint worker_i) {
129 // First scan the shared roots.
130 double ext_roots_start = os::elapsedTime();
131
132 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
133 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
134
135 OopClosure* const weak_roots = &buf_scan_non_heap_weak_roots;
136 OopClosure* const strong_roots = &buf_scan_non_heap_roots;
137
138 // CodeBlobClosures are not interoperable with BufferingOopClosures
139 G1CodeBlobClosure root_code_blobs(scan_non_heap_roots);
140
141 process_java_roots(strong_roots,
142 _trace_metadata ? scan_strong_clds : NULL,
143 scan_strong_clds,
144 _trace_metadata ? NULL : scan_weak_clds,
145 &root_code_blobs);
146
147 // This is the point where this worker thread will not find more strong CLDs/nmethods.
148 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
149 if (_trace_metadata) {
150 worker_has_discovered_all_strong_classes();
151 }
152
153 process_vm_roots(strong_roots, weak_roots);
154
155 // Now the CM ref_processor roots.
156 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_refProcessor_oops_do)) {
157 // We need to treat the discovered reference lists of the
158 // concurrent mark ref processor as roots and keep entries
159 // (which are added by the marking threads) on them live
160 // until they can be processed at the end of marking.
161 _g1h->ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
162 }
163
164 if (_trace_metadata) {
165 // Barrier to make sure all workers passed
166 // the strong CLD and strong nmethods phases.
167 wait_until_all_strong_classes_discovered();
168
169 // Now take the complement of the strong CLDs.
170 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
171 }
172
173 // Finish up any enqueued closure apps (attributed as object copy time).
174 buf_scan_non_heap_roots.done();
175 buf_scan_non_heap_weak_roots.done();
176
177 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
178 + buf_scan_non_heap_weak_roots.closure_app_seconds();
179
180 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
181 phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec);
182
183 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec;
184
185 phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec);
186
187 // During conc marking we have to filter the per-thread SATB buffers
188 // to make sure we remove any oops into the CSet (which will show up
189 // as implicitly live).
190 {
191 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);
192 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->mark_in_progress()) {
193 JavaThread::satb_mark_queue_set().filter_thread_buffers();
194 }
195 }
196
197 _process_strong_tasks->all_tasks_completed();
198 }
199
200 void G1RootProcessor::process_strong_roots(OopClosure* oops,
201 CLDClosure* clds,
202 CodeBlobClosure* blobs) {
203
204 process_java_roots(oops, clds, clds, NULL, blobs);
205 process_vm_roots(oops, NULL);
206
207 _process_strong_tasks->all_tasks_completed();
208 }
209
210 void G1RootProcessor::process_all_roots(OopClosure* oops,
211 CLDClosure* clds,
212 CodeBlobClosure* blobs) {
213
214 process_java_roots(oops, NULL, clds, clds, NULL);
215 process_vm_roots(oops, oops);
216
217 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_CodeCache_oops_do)) {
218 CodeCache::blobs_do(blobs);
219 }
220
221 _process_strong_tasks->all_tasks_completed();
222 }
223
224 void G1RootProcessor::process_java_roots(OopClosure* strong_roots,
225 CLDClosure* thread_stack_clds,
226 CLDClosure* strong_clds,
227 CLDClosure* weak_clds,
228 CodeBlobClosure* strong_code) {
229 assert(thread_stack_clds == NULL || weak_clds == NULL, "There is overlap between those, only one may be set");
230 // Iterating over the CLDG and the Threads are done early to allow us to
231 // first process the strong CLDs and nmethods and then, after a barrier,
232 // let the thread process the weak CLDs and nmethods.
233
234 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {
235 ClassLoaderDataGraph::roots_cld_do(strong_clds, weak_clds);
236 }
237
238 Threads::possibly_parallel_oops_do(strong_roots, thread_stack_clds, strong_code);
239 }
240
241 void G1RootProcessor::process_vm_roots(OopClosure* strong_roots,
242 OopClosure* weak_roots) {
243
244 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_Universe_oops_do)) {
245 Universe::oops_do(strong_roots);
246 }
247
248 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {
249 JNIHandles::oops_do(strong_roots);
250 }
251
252 if (!_process_strong_tasks-> is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {
253 ObjectSynchronizer::oops_do(strong_roots);
254 }
255
256 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) {
257 FlatProfiler::oops_do(strong_roots);
258 }
259
260 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_Management_oops_do)) {
261 Management::oops_do(strong_roots);
262 }
263
264 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_jvmti_oops_do)) {
265 JvmtiExport::oops_do(strong_roots);
266 }
267
268 if (!_process_strong_tasks->is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {
269 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
270 }
271
272 // All threads execute the following. A specific chunk of buckets
273 // from the StringTable are the individual tasks.
274 if (weak_roots != NULL) {
275 StringTable::possibly_parallel_oops_do(weak_roots);
276 }
277 }
278
279 void G1RootProcessor::scan_remembered_sets(G1ParPushHeapRSClosure* scan_rs,
280 OopClosure* scan_non_heap_weak_roots,
281 uint worker_i) {
282 // Now scan the complement of the collection set.
283 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
284
285 _g1h->g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
286 }
287
288 void G1RootProcessor::set_num_workers(int active_workers) {
289 _process_strong_tasks->set_n_threads(active_workers);
290 }