1 /*
2 * Copyright (c) 2001, 2009, 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 "incls/_precompiled.incl"
26 #include "incls/_concurrentMarkThread.cpp.incl"
27
28 // ======= Concurrent Mark Thread ========
29
30 // The CM thread is created when the G1 garbage collector is used
31
32 SurrogateLockerThread*
33 ConcurrentMarkThread::_slt = NULL;
34
35 ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) :
36 ConcurrentGCThread(),
37 _cm(cm),
38 _started(false),
39 _in_progress(false),
40 _vtime_accum(0.0),
41 _vtime_mark_accum(0.0),
42 _vtime_count_accum(0.0)
43 {
44 create_and_start();
45 }
46
47 class CMCheckpointRootsInitialClosure: public VoidClosure {
48
49 ConcurrentMark* _cm;
50 public:
51
52 CMCheckpointRootsInitialClosure(ConcurrentMark* cm) :
53 _cm(cm) {}
54
55 void do_void(){
56 _cm->checkpointRootsInitial();
57 }
58 };
59
60 class CMCheckpointRootsFinalClosure: public VoidClosure {
61
62 ConcurrentMark* _cm;
63 public:
64
65 CMCheckpointRootsFinalClosure(ConcurrentMark* cm) :
66 _cm(cm) {}
67
68 void do_void(){
69 _cm->checkpointRootsFinal(false); // !clear_all_soft_refs
70 }
71 };
72
73 class CMCleanUp: public VoidClosure {
74 ConcurrentMark* _cm;
75 public:
76
77 CMCleanUp(ConcurrentMark* cm) :
78 _cm(cm) {}
79
80 void do_void(){
81 _cm->cleanup();
82 }
83 };
84
85
86
87 void ConcurrentMarkThread::run() {
88 initialize_in_thread();
89 _vtime_start = os::elapsedVTime();
90 wait_for_universe_init();
91
92 G1CollectedHeap* g1 = G1CollectedHeap::heap();
93 G1CollectorPolicy* g1_policy = g1->g1_policy();
94 G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
95 Thread *current_thread = Thread::current();
96
97 while (!_should_terminate) {
98 // wait until started is set.
99 sleepBeforeNextCycle();
100 {
101 ResourceMark rm;
102 HandleMark hm;
103 double cycle_start = os::elapsedVTime();
104 double mark_start_sec = os::elapsedTime();
105 char verbose_str[128];
106
107 if (PrintGC) {
108 gclog_or_tty->date_stamp(PrintGCDateStamps);
109 gclog_or_tty->stamp(PrintGCTimeStamps);
110 gclog_or_tty->print_cr("[GC concurrent-mark-start]");
111 }
112
113 if (!g1_policy->in_young_gc_mode()) {
114 // this ensures the flag is not set if we bail out of the marking
115 // cycle; normally the flag is cleared immediately after cleanup
116 g1->set_marking_complete();
117
118 if (g1_policy->adaptive_young_list_length()) {
119 double now = os::elapsedTime();
120 double init_prediction_ms = g1_policy->predict_init_time_ms();
121 jlong sleep_time_ms = mmu_tracker->when_ms(now, init_prediction_ms);
122 os::sleep(current_thread, sleep_time_ms, false);
123 }
124
125 // We don't have to skip here if we've been asked to restart, because
126 // in the worst case we just enqueue a new VM operation to start a
127 // marking. Note that the init operation resets has_aborted()
128 CMCheckpointRootsInitialClosure init_cl(_cm);
129 strcpy(verbose_str, "GC initial-mark");
130 VM_CGC_Operation op(&init_cl, verbose_str);
131 VMThread::execute(&op);
132 }
133
134 int iter = 0;
135 do {
136 iter++;
137 if (!cm()->has_aborted()) {
138 _cm->markFromRoots();
139 }
140
141 double mark_end_time = os::elapsedVTime();
142 double mark_end_sec = os::elapsedTime();
143 _vtime_mark_accum += (mark_end_time - cycle_start);
144 if (!cm()->has_aborted()) {
145 if (g1_policy->adaptive_young_list_length()) {
146 double now = os::elapsedTime();
147 double remark_prediction_ms = g1_policy->predict_remark_time_ms();
148 jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
149 os::sleep(current_thread, sleep_time_ms, false);
150 }
151
152 if (PrintGC) {
153 gclog_or_tty->date_stamp(PrintGCDateStamps);
154 gclog_or_tty->stamp(PrintGCTimeStamps);
155 gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf sec]",
156 mark_end_sec - mark_start_sec);
157 }
158
159 CMCheckpointRootsFinalClosure final_cl(_cm);
160 sprintf(verbose_str, "GC remark");
161 VM_CGC_Operation op(&final_cl, verbose_str);
162 VMThread::execute(&op);
163 }
164 if (cm()->restart_for_overflow() &&
165 G1TraceMarkStackOverflow) {
166 gclog_or_tty->print_cr("Restarting conc marking because of MS overflow "
167 "in remark (restart #%d).", iter);
168 }
169
170 if (cm()->restart_for_overflow()) {
171 if (PrintGC) {
172 gclog_or_tty->date_stamp(PrintGCDateStamps);
173 gclog_or_tty->stamp(PrintGCTimeStamps);
174 gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
175 }
176 }
177 } while (cm()->restart_for_overflow());
178 double counting_start_time = os::elapsedVTime();
179
180 // YSR: These look dubious (i.e. redundant) !!! FIX ME
181 slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
182 slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
183
184 if (!cm()->has_aborted()) {
185 double count_start_sec = os::elapsedTime();
186 if (PrintGC) {
187 gclog_or_tty->date_stamp(PrintGCDateStamps);
188 gclog_or_tty->stamp(PrintGCTimeStamps);
189 gclog_or_tty->print_cr("[GC concurrent-count-start]");
190 }
191
192 _sts.join();
193 _cm->calcDesiredRegions();
194 _sts.leave();
195
196 if (!cm()->has_aborted()) {
197 double count_end_sec = os::elapsedTime();
198 if (PrintGC) {
199 gclog_or_tty->date_stamp(PrintGCDateStamps);
200 gclog_or_tty->stamp(PrintGCTimeStamps);
201 gclog_or_tty->print_cr("[GC concurrent-count-end, %1.7lf]",
202 count_end_sec - count_start_sec);
203 }
204 }
205 }
206 double end_time = os::elapsedVTime();
207 _vtime_count_accum += (end_time - counting_start_time);
208 // Update the total virtual time before doing this, since it will try
209 // to measure it to get the vtime for this marking. We purposely
210 // neglect the presumably-short "completeCleanup" phase here.
211 _vtime_accum = (end_time - _vtime_start);
212 if (!cm()->has_aborted()) {
213 if (g1_policy->adaptive_young_list_length()) {
214 double now = os::elapsedTime();
215 double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
216 jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
217 os::sleep(current_thread, sleep_time_ms, false);
218 }
219
220 CMCleanUp cl_cl(_cm);
221 sprintf(verbose_str, "GC cleanup");
222 VM_CGC_Operation op(&cl_cl, verbose_str);
223 VMThread::execute(&op);
224 } else {
225 G1CollectedHeap::heap()->set_marking_complete();
226 }
227
228 if (!cm()->has_aborted()) {
229 double cleanup_start_sec = os::elapsedTime();
230 if (PrintGC) {
231 gclog_or_tty->date_stamp(PrintGCDateStamps);
232 gclog_or_tty->stamp(PrintGCTimeStamps);
233 gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
234 }
235
236 // Now do the remainder of the cleanup operation.
237 _sts.join();
238 _cm->completeCleanup();
239 if (!cm()->has_aborted()) {
240 g1_policy->record_concurrent_mark_cleanup_completed();
241
242 double cleanup_end_sec = os::elapsedTime();
243 if (PrintGC) {
244 gclog_or_tty->date_stamp(PrintGCDateStamps);
245 gclog_or_tty->stamp(PrintGCTimeStamps);
246 gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]",
247 cleanup_end_sec - cleanup_start_sec);
248 }
249 }
250 _sts.leave();
251 }
252 // We're done: no more unclean regions coming.
253 G1CollectedHeap::heap()->set_unclean_regions_coming(false);
254
255 if (cm()->has_aborted()) {
256 if (PrintGC) {
257 gclog_or_tty->date_stamp(PrintGCDateStamps);
258 gclog_or_tty->stamp(PrintGCTimeStamps);
259 gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
260 }
261 }
262
263 // we now want to allow clearing of the marking bitmap to be
264 // suspended by a collection pause.
265 _sts.join();
266 _cm->clearNextBitmap();
267 _sts.leave();
268 }
269
270 // Update the number of full collections that have been
271 // completed. This will also notify the FullGCCount_lock in case a
272 // Java thread is waiting for a full GC to happen (e.g., it
273 // called System.gc() with +ExplicitGCInvokesConcurrent).
274 g1->increment_full_collections_completed(true /* outer */);
275 }
276 assert(_should_terminate, "just checking");
277
278 terminate();
279 }
280
281
282 void ConcurrentMarkThread::yield() {
283 _sts.yield("Concurrent Mark");
284 }
285
286 void ConcurrentMarkThread::stop() {
287 // it is ok to take late safepoints here, if needed
288 MutexLockerEx mu(Terminator_lock);
289 _should_terminate = true;
290 while (!_has_terminated) {
291 Terminator_lock->wait();
292 }
293 }
294
295 void ConcurrentMarkThread::print() const {
296 print_on(tty);
297 }
298
299 void ConcurrentMarkThread::print_on(outputStream* st) const {
300 st->print("\"G1 Main Concurrent Mark GC Thread\" ");
301 Thread::print_on(st);
302 st->cr();
303 }
304
305 void ConcurrentMarkThread::sleepBeforeNextCycle() {
306 // We join here because we don't want to do the "shouldConcurrentMark()"
307 // below while the world is otherwise stopped.
308 assert(!in_progress(), "should have been cleared");
309
310 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
311 while (!started()) {
312 CGC_lock->wait(Mutex::_no_safepoint_check_flag);
313 }
314 set_in_progress();
315 clear_started();
316 }
317
318 // Note: this method, although exported by the ConcurrentMarkSweepThread,
319 // which is a non-JavaThread, can only be called by a JavaThread.
320 // Currently this is done at vm creation time (post-vm-init) by the
321 // main/Primordial (Java)Thread.
322 // XXX Consider changing this in the future to allow the CMS thread
323 // itself to create this thread?
324 void ConcurrentMarkThread::makeSurrogateLockerThread(TRAPS) {
325 assert(_slt == NULL, "SLT already created");
326 _slt = SurrogateLockerThread::make(THREAD);
327 }