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rev 2896 : 6484965: G1: piggy-back liveness accounting phase on marking
Summary: Remove the separate counting phase of concurrent marking by tracking the amount of marked bytes and the cards spanned by marked objects in marking task/worker thread local data structures, which are updated as individual objects are marked.
Reviewed-by: brutisso
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--- old/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp
+++ new/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp
1 1 /*
2 2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation.
8 8 *
9 9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 12 * version 2 for more details (a copy is included in the LICENSE file that
13 13 * accompanied this code).
14 14 *
15 15 * You should have received a copy of the GNU General Public License version
16 16 * 2 along with this work; if not, write to the Free Software Foundation,
17 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 18 *
19 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 20 * or visit www.oracle.com if you need additional information or have any
21 21 * questions.
22 22 *
23 23 */
24 24
25 25 #include "precompiled.hpp"
26 26 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
27 27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 28 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
29 29 #include "gc_implementation/g1/g1MMUTracker.hpp"
30 30 #include "gc_implementation/g1/vm_operations_g1.hpp"
31 31 #include "memory/resourceArea.hpp"
32 32 #include "runtime/vmThread.hpp"
33 33
34 34 // ======= Concurrent Mark Thread ========
35 35
36 36 // The CM thread is created when the G1 garbage collector is used
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37 37
38 38 SurrogateLockerThread*
39 39 ConcurrentMarkThread::_slt = NULL;
40 40
41 41 ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) :
42 42 ConcurrentGCThread(),
43 43 _cm(cm),
44 44 _started(false),
45 45 _in_progress(false),
46 46 _vtime_accum(0.0),
47 - _vtime_mark_accum(0.0),
48 - _vtime_count_accum(0.0)
47 + _vtime_mark_accum(0.0)
49 48 {
50 49 create_and_start();
51 50 }
52 51
53 52 class CMCheckpointRootsFinalClosure: public VoidClosure {
54 53
55 54 ConcurrentMark* _cm;
56 55 public:
57 56
58 57 CMCheckpointRootsFinalClosure(ConcurrentMark* cm) :
59 58 _cm(cm) {}
60 59
61 60 void do_void(){
62 61 _cm->checkpointRootsFinal(false); // !clear_all_soft_refs
63 62 }
64 63 };
65 64
66 65 class CMCleanUp: public VoidClosure {
67 66 ConcurrentMark* _cm;
68 67 public:
69 68
70 69 CMCleanUp(ConcurrentMark* cm) :
71 70 _cm(cm) {}
72 71
73 72 void do_void(){
74 73 _cm->cleanup();
75 74 }
76 75 };
77 76
78 77
79 78
80 79 void ConcurrentMarkThread::run() {
81 80 initialize_in_thread();
82 81 _vtime_start = os::elapsedVTime();
83 82 wait_for_universe_init();
84 83
85 84 G1CollectedHeap* g1h = G1CollectedHeap::heap();
86 85 G1CollectorPolicy* g1_policy = g1h->g1_policy();
87 86 G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
88 87 Thread *current_thread = Thread::current();
89 88
90 89 while (!_should_terminate) {
91 90 // wait until started is set.
92 91 sleepBeforeNextCycle();
93 92 {
94 93 ResourceMark rm;
95 94 HandleMark hm;
96 95 double cycle_start = os::elapsedVTime();
97 96 double mark_start_sec = os::elapsedTime();
98 97 char verbose_str[128];
99 98
100 99 if (PrintGC) {
101 100 gclog_or_tty->date_stamp(PrintGCDateStamps);
102 101 gclog_or_tty->stamp(PrintGCTimeStamps);
103 102 gclog_or_tty->print_cr("[GC concurrent-mark-start]");
104 103 }
105 104
106 105 int iter = 0;
107 106 do {
108 107 iter++;
109 108 if (!cm()->has_aborted()) {
110 109 _cm->markFromRoots();
111 110 }
112 111
113 112 double mark_end_time = os::elapsedVTime();
114 113 double mark_end_sec = os::elapsedTime();
115 114 _vtime_mark_accum += (mark_end_time - cycle_start);
116 115 if (!cm()->has_aborted()) {
117 116 if (g1_policy->adaptive_young_list_length()) {
118 117 double now = os::elapsedTime();
119 118 double remark_prediction_ms = g1_policy->predict_remark_time_ms();
120 119 jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
121 120 os::sleep(current_thread, sleep_time_ms, false);
122 121 }
123 122
124 123 if (PrintGC) {
125 124 gclog_or_tty->date_stamp(PrintGCDateStamps);
126 125 gclog_or_tty->stamp(PrintGCTimeStamps);
127 126 gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf sec]",
128 127 mark_end_sec - mark_start_sec);
129 128 }
130 129
131 130 CMCheckpointRootsFinalClosure final_cl(_cm);
132 131 sprintf(verbose_str, "GC remark");
133 132 VM_CGC_Operation op(&final_cl, verbose_str);
134 133 VMThread::execute(&op);
135 134 }
136 135 if (cm()->restart_for_overflow() &&
137 136 G1TraceMarkStackOverflow) {
138 137 gclog_or_tty->print_cr("Restarting conc marking because of MS overflow "
139 138 "in remark (restart #%d).", iter);
140 139 }
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141 140
142 141 if (cm()->restart_for_overflow()) {
143 142 if (PrintGC) {
144 143 gclog_or_tty->date_stamp(PrintGCDateStamps);
145 144 gclog_or_tty->stamp(PrintGCTimeStamps);
146 145 gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
147 146 }
148 147 }
149 148 } while (cm()->restart_for_overflow());
150 149
151 - double counting_start_time = os::elapsedVTime();
152 - if (!cm()->has_aborted()) {
153 - double count_start_sec = os::elapsedTime();
154 - if (PrintGC) {
155 - gclog_or_tty->date_stamp(PrintGCDateStamps);
156 - gclog_or_tty->stamp(PrintGCTimeStamps);
157 - gclog_or_tty->print_cr("[GC concurrent-count-start]");
158 - }
159 -
160 - _sts.join();
161 - _cm->calcDesiredRegions();
162 - _sts.leave();
163 -
164 - if (!cm()->has_aborted()) {
165 - double count_end_sec = os::elapsedTime();
166 - if (PrintGC) {
167 - gclog_or_tty->date_stamp(PrintGCDateStamps);
168 - gclog_or_tty->stamp(PrintGCTimeStamps);
169 - gclog_or_tty->print_cr("[GC concurrent-count-end, %1.7lf]",
170 - count_end_sec - count_start_sec);
171 - }
172 - }
173 - }
174 -
175 150 double end_time = os::elapsedVTime();
176 - _vtime_count_accum += (end_time - counting_start_time);
177 151 // Update the total virtual time before doing this, since it will try
178 152 // to measure it to get the vtime for this marking. We purposely
179 153 // neglect the presumably-short "completeCleanup" phase here.
180 154 _vtime_accum = (end_time - _vtime_start);
155 +
181 156 if (!cm()->has_aborted()) {
182 157 if (g1_policy->adaptive_young_list_length()) {
183 158 double now = os::elapsedTime();
184 159 double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
185 160 jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
186 161 os::sleep(current_thread, sleep_time_ms, false);
187 162 }
188 163
189 164 CMCleanUp cl_cl(_cm);
190 165 sprintf(verbose_str, "GC cleanup");
191 166 VM_CGC_Operation op(&cl_cl, verbose_str);
192 167 VMThread::execute(&op);
193 168 } else {
194 169 // We don't want to update the marking status if a GC pause
195 170 // is already underway.
196 171 _sts.join();
197 172 g1h->set_marking_complete();
198 173 _sts.leave();
199 174 }
200 175
201 176 // Check if cleanup set the free_regions_coming flag. If it
202 177 // hasn't, we can just skip the next step.
203 178 if (g1h->free_regions_coming()) {
204 179 // The following will finish freeing up any regions that we
205 180 // found to be empty during cleanup. We'll do this part
206 181 // without joining the suspendible set. If an evacuation pause
207 182 // takes place, then we would carry on freeing regions in
208 183 // case they are needed by the pause. If a Full GC takes
209 184 // place, it would wait for us to process the regions
210 185 // reclaimed by cleanup.
211 186
212 187 double cleanup_start_sec = os::elapsedTime();
213 188 if (PrintGC) {
214 189 gclog_or_tty->date_stamp(PrintGCDateStamps);
215 190 gclog_or_tty->stamp(PrintGCTimeStamps);
216 191 gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
217 192 }
218 193
219 194 // Now do the concurrent cleanup operation.
220 195 _cm->completeCleanup();
221 196
222 197 // Notify anyone who's waiting that there are no more free
223 198 // regions coming. We have to do this before we join the STS
224 199 // (in fact, we should not attempt to join the STS in the
225 200 // interval between finishing the cleanup pause and clearing
226 201 // the free_regions_coming flag) otherwise we might deadlock:
227 202 // a GC worker could be blocked waiting for the notification
228 203 // whereas this thread will be blocked for the pause to finish
229 204 // while it's trying to join the STS, which is conditional on
230 205 // the GC workers finishing.
231 206 g1h->reset_free_regions_coming();
232 207
233 208 double cleanup_end_sec = os::elapsedTime();
234 209 if (PrintGC) {
235 210 gclog_or_tty->date_stamp(PrintGCDateStamps);
236 211 gclog_or_tty->stamp(PrintGCTimeStamps);
237 212 gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]",
238 213 cleanup_end_sec - cleanup_start_sec);
239 214 }
240 215 }
241 216 guarantee(cm()->cleanup_list_is_empty(),
242 217 "at this point there should be no regions on the cleanup list");
243 218
244 219 // There is a tricky race before recording that the concurrent
245 220 // cleanup has completed and a potential Full GC starting around
246 221 // the same time. We want to make sure that the Full GC calls
247 222 // abort() on concurrent mark after
248 223 // record_concurrent_mark_cleanup_completed(), since abort() is
249 224 // the method that will reset the concurrent mark state. If we
250 225 // end up calling record_concurrent_mark_cleanup_completed()
251 226 // after abort() then we might incorrectly undo some of the work
252 227 // abort() did. Checking the has_aborted() flag after joining
253 228 // the STS allows the correct ordering of the two methods. There
254 229 // are two scenarios:
255 230 //
256 231 // a) If we reach here before the Full GC, the fact that we have
257 232 // joined the STS means that the Full GC cannot start until we
258 233 // leave the STS, so record_concurrent_mark_cleanup_completed()
259 234 // will complete before abort() is called.
260 235 //
261 236 // b) If we reach here during the Full GC, we'll be held up from
262 237 // joining the STS until the Full GC is done, which means that
263 238 // abort() will have completed and has_aborted() will return
264 239 // true to prevent us from calling
265 240 // record_concurrent_mark_cleanup_completed() (and, in fact, it's
266 241 // not needed any more as the concurrent mark state has been
267 242 // already reset).
268 243 _sts.join();
269 244 if (!cm()->has_aborted()) {
270 245 g1_policy->record_concurrent_mark_cleanup_completed();
271 246 }
272 247 _sts.leave();
273 248
274 249 if (cm()->has_aborted()) {
275 250 if (PrintGC) {
276 251 gclog_or_tty->date_stamp(PrintGCDateStamps);
277 252 gclog_or_tty->stamp(PrintGCTimeStamps);
278 253 gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
279 254 }
280 255 }
281 256
282 257 // We now want to allow clearing of the marking bitmap to be
283 258 // suspended by a collection pause.
284 259 _sts.join();
285 260 _cm->clearNextBitmap();
286 261 _sts.leave();
287 262 }
288 263
289 264 // Update the number of full collections that have been
290 265 // completed. This will also notify the FullGCCount_lock in case a
291 266 // Java thread is waiting for a full GC to happen (e.g., it
292 267 // called System.gc() with +ExplicitGCInvokesConcurrent).
293 268 _sts.join();
294 269 g1h->increment_full_collections_completed(true /* concurrent */);
295 270 _sts.leave();
296 271 }
297 272 assert(_should_terminate, "just checking");
298 273
299 274 terminate();
300 275 }
301 276
302 277
303 278 void ConcurrentMarkThread::yield() {
304 279 _sts.yield("Concurrent Mark");
305 280 }
306 281
307 282 void ConcurrentMarkThread::stop() {
308 283 // it is ok to take late safepoints here, if needed
309 284 MutexLockerEx mu(Terminator_lock);
310 285 _should_terminate = true;
311 286 while (!_has_terminated) {
312 287 Terminator_lock->wait();
313 288 }
314 289 }
315 290
316 291 void ConcurrentMarkThread::print() const {
317 292 print_on(tty);
318 293 }
319 294
320 295 void ConcurrentMarkThread::print_on(outputStream* st) const {
321 296 st->print("\"G1 Main Concurrent Mark GC Thread\" ");
322 297 Thread::print_on(st);
323 298 st->cr();
324 299 }
325 300
326 301 void ConcurrentMarkThread::sleepBeforeNextCycle() {
327 302 // We join here because we don't want to do the "shouldConcurrentMark()"
328 303 // below while the world is otherwise stopped.
329 304 assert(!in_progress(), "should have been cleared");
330 305
331 306 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
332 307 while (!started()) {
333 308 CGC_lock->wait(Mutex::_no_safepoint_check_flag);
334 309 }
335 310 set_in_progress();
336 311 clear_started();
337 312 }
338 313
339 314 // Note: As is the case with CMS - this method, although exported
340 315 // by the ConcurrentMarkThread, which is a non-JavaThread, can only
341 316 // be called by a JavaThread. Currently this is done at vm creation
342 317 // time (post-vm-init) by the main/Primordial (Java)Thread.
343 318 // XXX Consider changing this in the future to allow the CM thread
344 319 // itself to create this thread?
345 320 void ConcurrentMarkThread::makeSurrogateLockerThread(TRAPS) {
346 321 assert(UseG1GC, "SLT thread needed only for concurrent GC");
347 322 assert(THREAD->is_Java_thread(), "must be a Java thread");
348 323 assert(_slt == NULL, "SLT already created");
349 324 _slt = SurrogateLockerThread::make(THREAD);
350 325 }
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