61 CMCheckpointRootsFinalClosure(ConcurrentMark* cm) :
62 _cm(cm) {}
63
64 void do_void(){
65 _cm->checkpointRootsFinal(false); // !clear_all_soft_refs
66 }
67 };
68
69 class CMCleanUp: public VoidClosure {
70 ConcurrentMark* _cm;
71 public:
72
73 CMCleanUp(ConcurrentMark* cm) :
74 _cm(cm) {}
75
76 void do_void(){
77 _cm->cleanup();
78 }
79 };
80
81
82
83 void ConcurrentMarkThread::run() {
84 initialize_in_thread();
85 _vtime_start = os::elapsedVTime();
86 wait_for_universe_init();
87
88 G1CollectedHeap* g1h = G1CollectedHeap::heap();
89 G1CollectorPolicy* g1_policy = g1h->g1_policy();
90 G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
91 Thread *current_thread = Thread::current();
92
93 while (!_should_terminate) {
94 // wait until started is set.
95 sleepBeforeNextCycle();
96 if (_should_terminate) {
97 break;
98 }
99
100 {
101 ResourceMark rm;
102 HandleMark hm;
103 double cycle_start = os::elapsedVTime();
104
105 // We have to ensure that we finish scanning the root regions
106 // before the next GC takes place. To ensure this we have to
107 // make sure that we do not join the STS until the root regions
108 // have been scanned. If we did then it's possible that a
109 // subsequent GC could block us from joining the STS and proceed
110 // without the root regions have been scanned which would be a
111 // correctness issue.
112
113 double scan_start = os::elapsedTime();
114 if (!cm()->has_aborted()) {
115 if (G1Log::fine()) {
116 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
117 gclog_or_tty->print_cr("[GC concurrent-root-region-scan-start]");
118 }
119
120 _cm->scanRootRegions();
121
122 double scan_end = os::elapsedTime();
123 if (G1Log::fine()) {
124 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
125 gclog_or_tty->print_cr("[GC concurrent-root-region-scan-end, %1.7lf secs]",
126 scan_end - scan_start);
127 }
128 }
129
130 double mark_start_sec = os::elapsedTime();
131 if (G1Log::fine()) {
132 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
133 gclog_or_tty->print_cr("[GC concurrent-mark-start]");
134 }
135
136 int iter = 0;
137 do {
138 iter++;
139 if (!cm()->has_aborted()) {
140 _cm->markFromRoots();
141 }
142
143 double mark_end_time = os::elapsedVTime();
144 double mark_end_sec = os::elapsedTime();
145 _vtime_mark_accum += (mark_end_time - cycle_start);
146 if (!cm()->has_aborted()) {
147 if (g1_policy->adaptive_young_list_length()) {
148 double now = os::elapsedTime();
149 double remark_prediction_ms = g1_policy->predict_remark_time_ms();
150 jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
151 os::sleep(current_thread, sleep_time_ms, false);
152 }
153
154 if (G1Log::fine()) {
155 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
156 gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf secs]",
157 mark_end_sec - mark_start_sec);
158 }
159
160 CMCheckpointRootsFinalClosure final_cl(_cm);
161 VM_CGC_Operation op(&final_cl, "GC remark", true /* needs_pll */);
162 VMThread::execute(&op);
163 }
164 if (cm()->restart_for_overflow()) {
165 if (G1TraceMarkStackOverflow) {
166 gclog_or_tty->print_cr("Restarting conc marking because of MS overflow "
167 "in remark (restart #%d).", iter);
168 }
169 if (G1Log::fine()) {
170 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
171 gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
172 }
173 }
174 } while (cm()->restart_for_overflow());
175
176 double end_time = os::elapsedVTime();
177 // Update the total virtual time before doing this, since it will try
178 // to measure it to get the vtime for this marking. We purposely
179 // neglect the presumably-short "completeCleanup" phase here.
180 _vtime_accum = (end_time - _vtime_start);
181
182 if (!cm()->has_aborted()) {
183 if (g1_policy->adaptive_young_list_length()) {
184 double now = os::elapsedTime();
185 double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
186 jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
187 os::sleep(current_thread, sleep_time_ms, false);
188 }
189
190 CMCleanUp cl_cl(_cm);
191 VM_CGC_Operation op(&cl_cl, "GC cleanup", false /* needs_pll */);
192 VMThread::execute(&op);
193 } else {
194 // We don't want to update the marking status if a GC pause
195 // is already underway.
196 SuspendibleThreadSetJoiner sts_join;
197 g1h->collector_state()->set_mark_in_progress(false);
198 }
199
200 // Check if cleanup set the free_regions_coming flag. If it
201 // hasn't, we can just skip the next step.
202 if (g1h->free_regions_coming()) {
203 // The following will finish freeing up any regions that we
204 // found to be empty during cleanup. We'll do this part
205 // without joining the suspendible set. If an evacuation pause
206 // takes place, then we would carry on freeing regions in
207 // case they are needed by the pause. If a Full GC takes
208 // place, it would wait for us to process the regions
209 // reclaimed by cleanup.
210
211 double cleanup_start_sec = os::elapsedTime();
212 if (G1Log::fine()) {
213 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
214 gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
215 }
216
217 // Now do the concurrent cleanup operation.
218 _cm->completeCleanup();
219
220 // Notify anyone who's waiting that there are no more free
221 // regions coming. We have to do this before we join the STS
222 // (in fact, we should not attempt to join the STS in the
223 // interval between finishing the cleanup pause and clearing
224 // the free_regions_coming flag) otherwise we might deadlock:
225 // a GC worker could be blocked waiting for the notification
226 // whereas this thread will be blocked for the pause to finish
227 // while it's trying to join the STS, which is conditional on
228 // the GC workers finishing.
229 g1h->reset_free_regions_coming();
230
231 double cleanup_end_sec = os::elapsedTime();
232 if (G1Log::fine()) {
233 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
234 gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf secs]",
235 cleanup_end_sec - cleanup_start_sec);
236 }
237 }
238 guarantee(cm()->cleanup_list_is_empty(),
239 "at this point there should be no regions on the cleanup list");
240
241 // There is a tricky race before recording that the concurrent
242 // cleanup has completed and a potential Full GC starting around
243 // the same time. We want to make sure that the Full GC calls
244 // abort() on concurrent mark after
245 // record_concurrent_mark_cleanup_completed(), since abort() is
246 // the method that will reset the concurrent mark state. If we
247 // end up calling record_concurrent_mark_cleanup_completed()
248 // after abort() then we might incorrectly undo some of the work
249 // abort() did. Checking the has_aborted() flag after joining
250 // the STS allows the correct ordering of the two methods. There
251 // are two scenarios:
252 //
253 // a) If we reach here before the Full GC, the fact that we have
254 // joined the STS means that the Full GC cannot start until we
255 // leave the STS, so record_concurrent_mark_cleanup_completed()
256 // will complete before abort() is called.
257 //
258 // b) If we reach here during the Full GC, we'll be held up from
259 // joining the STS until the Full GC is done, which means that
260 // abort() will have completed and has_aborted() will return
261 // true to prevent us from calling
262 // record_concurrent_mark_cleanup_completed() (and, in fact, it's
263 // not needed any more as the concurrent mark state has been
264 // already reset).
265 {
266 SuspendibleThreadSetJoiner sts_join;
267 if (!cm()->has_aborted()) {
268 g1_policy->record_concurrent_mark_cleanup_completed();
269 }
270 }
271
272 if (cm()->has_aborted()) {
273 if (G1Log::fine()) {
274 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
275 gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
276 }
277 }
278
279 // We now want to allow clearing of the marking bitmap to be
280 // suspended by a collection pause.
281 // We may have aborted just before the remark. Do not bother clearing the
282 // bitmap then, as it has been done during mark abort.
283 if (!cm()->has_aborted()) {
284 _cm->clearNextBitmap();
285 } else {
286 assert(!G1VerifyBitmaps || _cm->nextMarkBitmapIsClear(), "Next mark bitmap must be clear");
287 }
288 }
289
290 // Update the number of full collections that have been
291 // completed. This will also notify the FullGCCount_lock in case a
292 // Java thread is waiting for a full GC to happen (e.g., it
293 // called System.gc() with +ExplicitGCInvokesConcurrent).
294 {
295 SuspendibleThreadSetJoiner sts_join;
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61 CMCheckpointRootsFinalClosure(ConcurrentMark* cm) :
62 _cm(cm) {}
63
64 void do_void(){
65 _cm->checkpointRootsFinal(false); // !clear_all_soft_refs
66 }
67 };
68
69 class CMCleanUp: public VoidClosure {
70 ConcurrentMark* _cm;
71 public:
72
73 CMCleanUp(ConcurrentMark* cm) :
74 _cm(cm) {}
75
76 void do_void(){
77 _cm->cleanup();
78 }
79 };
80
81 // We want to avoid that the logging from the concurrent thread is mixed
82 // with the logging from a STW GC. So, if necessary join the STS to ensure
83 // that the logging is done either before or after the STW logging.
84 void ConcurrentMarkThread::cm_log(bool doit, bool join_sts, const char* fmt, ...) {
85 if (doit) {
86 SuspendibleThreadSetJoiner sts_joiner(join_sts);
87 va_list args;
88 va_start(args, fmt);
89 gclog_or_tty->gclog_stamp(cm()->concurrent_gc_id());
90 gclog_or_tty->vprint_cr(fmt, args);
91 va_end(args);
92 }
93 }
94
95 void ConcurrentMarkThread::run() {
96 initialize_in_thread();
97 _vtime_start = os::elapsedVTime();
98 wait_for_universe_init();
99
100 G1CollectedHeap* g1h = G1CollectedHeap::heap();
101 G1CollectorPolicy* g1_policy = g1h->g1_policy();
102 G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
103 Thread *current_thread = Thread::current();
104
105 while (!_should_terminate) {
106 // wait until started is set.
107 sleepBeforeNextCycle();
108 if (_should_terminate) {
109 break;
110 }
111
112 {
113 ResourceMark rm;
114 HandleMark hm;
115 double cycle_start = os::elapsedVTime();
116
117 // We have to ensure that we finish scanning the root regions
118 // before the next GC takes place. To ensure this we have to
119 // make sure that we do not join the STS until the root regions
120 // have been scanned. If we did then it's possible that a
121 // subsequent GC could block us from joining the STS and proceed
122 // without the root regions have been scanned which would be a
123 // correctness issue.
124
125 double scan_start = os::elapsedTime();
126 if (!cm()->has_aborted()) {
127 cm_log(G1Log::fine(), false, "[GC concurrent-root-region-scan-start]");
128
129 _cm->scanRootRegions();
130
131 cm_log(G1Log::fine(), false, "[GC concurrent-root-region-scan-end, %1.7lf secs]", os::elapsedTime() - scan_start);
132 }
133
134 double mark_start_sec = os::elapsedTime();
135 cm_log(G1Log::fine(), true, "[GC concurrent-mark-start]");
136
137 int iter = 0;
138 do {
139 iter++;
140 if (!cm()->has_aborted()) {
141 _cm->markFromRoots();
142 }
143
144 double mark_end_time = os::elapsedVTime();
145 double mark_end_sec = os::elapsedTime();
146 _vtime_mark_accum += (mark_end_time - cycle_start);
147 if (!cm()->has_aborted()) {
148 if (g1_policy->adaptive_young_list_length()) {
149 double now = os::elapsedTime();
150 double remark_prediction_ms = g1_policy->predict_remark_time_ms();
151 jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
152 os::sleep(current_thread, sleep_time_ms, false);
153 }
154
155 cm_log(G1Log::fine(), true, "[GC concurrent-mark-end, %1.7lf secs]", mark_end_sec - mark_start_sec);
156
157 CMCheckpointRootsFinalClosure final_cl(_cm);
158 VM_CGC_Operation op(&final_cl, "GC remark", true /* needs_pll */);
159 VMThread::execute(&op);
160 }
161 if (cm()->restart_for_overflow()) {
162 cm_log(G1TraceMarkStackOverflow, true, "Restarting conc marking because of MS overflow in remark (restart #%d).", iter);
163 cm_log(G1Log::fine(), true, "[GC concurrent-mark-restart-for-overflow]");
164 }
165 } while (cm()->restart_for_overflow());
166
167 double end_time = os::elapsedVTime();
168 // Update the total virtual time before doing this, since it will try
169 // to measure it to get the vtime for this marking. We purposely
170 // neglect the presumably-short "completeCleanup" phase here.
171 _vtime_accum = (end_time - _vtime_start);
172
173 if (!cm()->has_aborted()) {
174 if (g1_policy->adaptive_young_list_length()) {
175 double now = os::elapsedTime();
176 double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
177 jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
178 os::sleep(current_thread, sleep_time_ms, false);
179 }
180
181 CMCleanUp cl_cl(_cm);
182 VM_CGC_Operation op(&cl_cl, "GC cleanup", false /* needs_pll */);
183 VMThread::execute(&op);
184 } else {
185 // We don't want to update the marking status if a GC pause
186 // is already underway.
187 SuspendibleThreadSetJoiner sts_join;
188 g1h->collector_state()->set_mark_in_progress(false);
189 }
190
191 // Check if cleanup set the free_regions_coming flag. If it
192 // hasn't, we can just skip the next step.
193 if (g1h->free_regions_coming()) {
194 // The following will finish freeing up any regions that we
195 // found to be empty during cleanup. We'll do this part
196 // without joining the suspendible set. If an evacuation pause
197 // takes place, then we would carry on freeing regions in
198 // case they are needed by the pause. If a Full GC takes
199 // place, it would wait for us to process the regions
200 // reclaimed by cleanup.
201
202 double cleanup_start_sec = os::elapsedTime();
203 cm_log(G1Log::fine(), true, "[GC concurrent-cleanup-start]");
204
205 // Now do the concurrent cleanup operation.
206 _cm->completeCleanup();
207
208 // Notify anyone who's waiting that there are no more free
209 // regions coming. We have to do this before we join the STS
210 // (in fact, we should not attempt to join the STS in the
211 // interval between finishing the cleanup pause and clearing
212 // the free_regions_coming flag) otherwise we might deadlock:
213 // a GC worker could be blocked waiting for the notification
214 // whereas this thread will be blocked for the pause to finish
215 // while it's trying to join the STS, which is conditional on
216 // the GC workers finishing.
217 g1h->reset_free_regions_coming();
218
219 double cleanup_end_sec = os::elapsedTime();
220 cm_log(G1Log::fine(), true, "[GC concurrent-cleanup-end, %1.7lf secs]", cleanup_end_sec - cleanup_start_sec);
221 }
222 guarantee(cm()->cleanup_list_is_empty(),
223 "at this point there should be no regions on the cleanup list");
224
225 // There is a tricky race before recording that the concurrent
226 // cleanup has completed and a potential Full GC starting around
227 // the same time. We want to make sure that the Full GC calls
228 // abort() on concurrent mark after
229 // record_concurrent_mark_cleanup_completed(), since abort() is
230 // the method that will reset the concurrent mark state. If we
231 // end up calling record_concurrent_mark_cleanup_completed()
232 // after abort() then we might incorrectly undo some of the work
233 // abort() did. Checking the has_aborted() flag after joining
234 // the STS allows the correct ordering of the two methods. There
235 // are two scenarios:
236 //
237 // a) If we reach here before the Full GC, the fact that we have
238 // joined the STS means that the Full GC cannot start until we
239 // leave the STS, so record_concurrent_mark_cleanup_completed()
240 // will complete before abort() is called.
241 //
242 // b) If we reach here during the Full GC, we'll be held up from
243 // joining the STS until the Full GC is done, which means that
244 // abort() will have completed and has_aborted() will return
245 // true to prevent us from calling
246 // record_concurrent_mark_cleanup_completed() (and, in fact, it's
247 // not needed any more as the concurrent mark state has been
248 // already reset).
249 {
250 SuspendibleThreadSetJoiner sts_join;
251 if (!cm()->has_aborted()) {
252 g1_policy->record_concurrent_mark_cleanup_completed();
253 } else {
254 cm_log(G1Log::fine(), false, "[GC concurrent-mark-abort]");
255 }
256 }
257
258 // We now want to allow clearing of the marking bitmap to be
259 // suspended by a collection pause.
260 // We may have aborted just before the remark. Do not bother clearing the
261 // bitmap then, as it has been done during mark abort.
262 if (!cm()->has_aborted()) {
263 _cm->clearNextBitmap();
264 } else {
265 assert(!G1VerifyBitmaps || _cm->nextMarkBitmapIsClear(), "Next mark bitmap must be clear");
266 }
267 }
268
269 // Update the number of full collections that have been
270 // completed. This will also notify the FullGCCount_lock in case a
271 // Java thread is waiting for a full GC to happen (e.g., it
272 // called System.gc() with +ExplicitGCInvokesConcurrent).
273 {
274 SuspendibleThreadSetJoiner sts_join;
|