1 /* 2 * Copyright (c) 2001, 2011, 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 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" 28 #include "gc_implementation/g1/g1CollectorPolicy.hpp" 29 #include "gc_implementation/g1/g1MMUTracker.hpp" 30 #include "gc_implementation/g1/vm_operations_g1.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "runtime/vmThread.hpp" 33 34 // ======= Concurrent Mark Thread ======== 35 36 // The CM thread is created when the G1 garbage collector is used 37 38 SurrogateLockerThread* 39 ConcurrentMarkThread::_slt = NULL; 40 41 ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) : 42 ConcurrentGCThread(), 43 _cm(cm), 44 _started(false), 45 _in_progress(false), 46 _vtime_accum(0.0), 47 _vtime_mark_accum(0.0) 48 { 49 create_and_start(); 50 } 51 52 class CMCheckpointRootsFinalClosure: public VoidClosure { 53 54 ConcurrentMark* _cm; 55 public: 56 57 CMCheckpointRootsFinalClosure(ConcurrentMark* cm) : 58 _cm(cm) {} 59 60 void do_void(){ 61 _cm->checkpointRootsFinal(false); // !clear_all_soft_refs 62 } 63 }; 64 65 class CMCleanUp: public VoidClosure { 66 ConcurrentMark* _cm; 67 public: 68 69 CMCleanUp(ConcurrentMark* cm) : 70 _cm(cm) {} 71 72 void do_void(){ 73 _cm->cleanup(); 74 } 75 }; 76 77 78 79 void ConcurrentMarkThread::run() { 80 initialize_in_thread(); 81 _vtime_start = os::elapsedVTime(); 82 wait_for_universe_init(); 83 84 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 85 G1CollectorPolicy* g1_policy = g1h->g1_policy(); 86 G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker(); 87 Thread *current_thread = Thread::current(); 88 89 while (!_should_terminate) { 90 // wait until started is set. 91 sleepBeforeNextCycle(); 92 { 93 ResourceMark rm; 94 HandleMark hm; 95 double cycle_start = os::elapsedVTime(); 96 double mark_start_sec = os::elapsedTime(); 97 char verbose_str[128]; 98 99 if (PrintGC) { 100 gclog_or_tty->date_stamp(PrintGCDateStamps); 101 gclog_or_tty->stamp(PrintGCTimeStamps); 102 gclog_or_tty->print_cr("[GC concurrent-mark-start]"); 103 } 104 105 int iter = 0; 106 do { 107 iter++; 108 if (!cm()->has_aborted()) { 109 _cm->markFromRoots(); 110 } 111 112 double mark_end_time = os::elapsedVTime(); 113 double mark_end_sec = os::elapsedTime(); 114 _vtime_mark_accum += (mark_end_time - cycle_start); 115 if (!cm()->has_aborted()) { 116 if (g1_policy->adaptive_young_list_length()) { 117 double now = os::elapsedTime(); 118 double remark_prediction_ms = g1_policy->predict_remark_time_ms(); 119 jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms); 120 os::sleep(current_thread, sleep_time_ms, false); 121 } 122 123 if (PrintGC) { 124 gclog_or_tty->date_stamp(PrintGCDateStamps); 125 gclog_or_tty->stamp(PrintGCTimeStamps); 126 gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf sec]", 127 mark_end_sec - mark_start_sec); 128 } 129 130 CMCheckpointRootsFinalClosure final_cl(_cm); 131 sprintf(verbose_str, "GC remark"); 132 VM_CGC_Operation op(&final_cl, verbose_str); 133 VMThread::execute(&op); 134 } 135 if (cm()->restart_for_overflow() && 136 G1TraceMarkStackOverflow) { 137 gclog_or_tty->print_cr("Restarting conc marking because of MS overflow " 138 "in remark (restart #%d).", iter); 139 } 140 141 if (cm()->restart_for_overflow()) { 142 if (PrintGC) { 143 gclog_or_tty->date_stamp(PrintGCDateStamps); 144 gclog_or_tty->stamp(PrintGCTimeStamps); 145 gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]"); 146 } 147 } 148 } while (cm()->restart_for_overflow()); 149 150 // YSR: These look dubious (i.e. redundant) !!! FIX ME 151 slt()->manipulatePLL(SurrogateLockerThread::acquirePLL); 152 slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); 153 154 double end_time = os::elapsedVTime(); 155 // Update the total virtual time before doing this, since it will try 156 // to measure it to get the vtime for this marking. We purposely 157 // neglect the presumably-short "completeCleanup" phase here. 158 _vtime_accum = (end_time - _vtime_start); 159 160 if (!cm()->has_aborted()) { 161 if (g1_policy->adaptive_young_list_length()) { 162 double now = os::elapsedTime(); 163 double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms(); 164 jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms); 165 os::sleep(current_thread, sleep_time_ms, false); 166 } 167 168 CMCleanUp cl_cl(_cm); 169 sprintf(verbose_str, "GC cleanup"); 170 VM_CGC_Operation op(&cl_cl, verbose_str); 171 VMThread::execute(&op); 172 } else { 173 g1h->set_marking_complete(); 174 } 175 176 // Check if cleanup set the free_regions_coming flag. If it 177 // hasn't, we can just skip the next step. 178 if (g1h->free_regions_coming()) { 179 // The following will finish freeing up any regions that we 180 // found to be empty during cleanup. We'll do this part 181 // without joining the suspendible set. If an evacuation pause 182 // takes place, then we would carry on freeing regions in 183 // case they are needed by the pause. If a Full GC takes 184 // place, it would wait for us to process the regions 185 // reclaimed by cleanup. 186 187 double cleanup_start_sec = os::elapsedTime(); 188 if (PrintGC) { 189 gclog_or_tty->date_stamp(PrintGCDateStamps); 190 gclog_or_tty->stamp(PrintGCTimeStamps); 191 gclog_or_tty->print_cr("[GC concurrent-cleanup-start]"); 192 } 193 194 // Now do the remainder of the cleanup operation. 195 _cm->completeCleanup(); 196 // Notify anyone who's waiting that there are no more free 197 // regions coming. We have to do this before we join the STS, 198 // otherwise we might deadlock: a GC worker could be blocked 199 // waiting for the notification whereas this thread will be 200 // blocked for the pause to finish while it's trying to join 201 // the STS, which is conditional on the GC workers finishing. 202 g1h->reset_free_regions_coming(); 203 204 _sts.join(); 205 g1_policy->record_concurrent_mark_cleanup_completed(); 206 _sts.leave(); 207 208 double cleanup_end_sec = os::elapsedTime(); 209 if (PrintGC) { 210 gclog_or_tty->date_stamp(PrintGCDateStamps); 211 gclog_or_tty->stamp(PrintGCTimeStamps); 212 gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]", 213 cleanup_end_sec - cleanup_start_sec); 214 } 215 } 216 guarantee(cm()->cleanup_list_is_empty(), 217 "at this point there should be no regions on the cleanup list"); 218 219 if (cm()->has_aborted()) { 220 if (PrintGC) { 221 gclog_or_tty->date_stamp(PrintGCDateStamps); 222 gclog_or_tty->stamp(PrintGCTimeStamps); 223 gclog_or_tty->print_cr("[GC concurrent-mark-abort]"); 224 } 225 } 226 227 // we now want to allow clearing of the marking bitmap to be 228 // suspended by a collection pause. 229 _sts.join(); 230 _cm->clearNextBitmap(); 231 _sts.leave(); 232 } 233 234 // Update the number of full collections that have been 235 // completed. This will also notify the FullGCCount_lock in case a 236 // Java thread is waiting for a full GC to happen (e.g., it 237 // called System.gc() with +ExplicitGCInvokesConcurrent). 238 _sts.join(); 239 g1h->increment_full_collections_completed(true /* concurrent */); 240 _sts.leave(); 241 } 242 assert(_should_terminate, "just checking"); 243 244 terminate(); 245 } 246 247 248 void ConcurrentMarkThread::yield() { 249 _sts.yield("Concurrent Mark"); 250 } 251 252 void ConcurrentMarkThread::stop() { 253 // it is ok to take late safepoints here, if needed 254 MutexLockerEx mu(Terminator_lock); 255 _should_terminate = true; 256 while (!_has_terminated) { 257 Terminator_lock->wait(); 258 } 259 } 260 261 void ConcurrentMarkThread::print() const { 262 print_on(tty); 263 } 264 265 void ConcurrentMarkThread::print_on(outputStream* st) const { 266 st->print("\"G1 Main Concurrent Mark GC Thread\" "); 267 Thread::print_on(st); 268 st->cr(); 269 } 270 271 void ConcurrentMarkThread::sleepBeforeNextCycle() { 272 // We join here because we don't want to do the "shouldConcurrentMark()" 273 // below while the world is otherwise stopped. 274 assert(!in_progress(), "should have been cleared"); 275 276 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 277 while (!started()) { 278 CGC_lock->wait(Mutex::_no_safepoint_check_flag); 279 } 280 set_in_progress(); 281 clear_started(); 282 } 283 284 // Note: this method, although exported by the ConcurrentMarkSweepThread, 285 // which is a non-JavaThread, can only be called by a JavaThread. 286 // Currently this is done at vm creation time (post-vm-init) by the 287 // main/Primordial (Java)Thread. 288 // XXX Consider changing this in the future to allow the CMS thread 289 // itself to create this thread? 290 void ConcurrentMarkThread::makeSurrogateLockerThread(TRAPS) { 291 assert(_slt == NULL, "SLT already created"); 292 _slt = SurrogateLockerThread::make(THREAD); 293 }