Thu, 13 Oct 2011 13:54:29 -0400
7098085: G1: partially-young GCs not initiated under certain circumstances
Reviewed-by: ysr, brutisso
ysr@777 | 1 | /* |
tonyp@2472 | 2 | * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. |
ysr@777 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
ysr@777 | 4 | * |
ysr@777 | 5 | * This code is free software; you can redistribute it and/or modify it |
ysr@777 | 6 | * under the terms of the GNU General Public License version 2 only, as |
ysr@777 | 7 | * published by the Free Software Foundation. |
ysr@777 | 8 | * |
ysr@777 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
ysr@777 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
ysr@777 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
ysr@777 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
ysr@777 | 13 | * accompanied this code). |
ysr@777 | 14 | * |
ysr@777 | 15 | * You should have received a copy of the GNU General Public License version |
ysr@777 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
ysr@777 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
ysr@777 | 18 | * |
trims@1907 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
trims@1907 | 20 | * or visit www.oracle.com if you need additional information or have any |
trims@1907 | 21 | * questions. |
ysr@777 | 22 | * |
ysr@777 | 23 | */ |
ysr@777 | 24 | |
stefank@2314 | 25 | #include "precompiled.hpp" |
stefank@2314 | 26 | #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" |
stefank@2314 | 27 | #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" |
stefank@2314 | 28 | #include "gc_implementation/g1/g1CollectorPolicy.hpp" |
stefank@2314 | 29 | #include "gc_implementation/g1/g1MMUTracker.hpp" |
stefank@2314 | 30 | #include "gc_implementation/g1/vm_operations_g1.hpp" |
stefank@2314 | 31 | #include "memory/resourceArea.hpp" |
stefank@2314 | 32 | #include "runtime/vmThread.hpp" |
ysr@777 | 33 | |
ysr@777 | 34 | // ======= Concurrent Mark Thread ======== |
ysr@777 | 35 | |
ysr@777 | 36 | // The CM thread is created when the G1 garbage collector is used |
ysr@777 | 37 | |
ysr@777 | 38 | SurrogateLockerThread* |
ysr@777 | 39 | ConcurrentMarkThread::_slt = NULL; |
ysr@777 | 40 | |
ysr@777 | 41 | ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) : |
ysr@777 | 42 | ConcurrentGCThread(), |
ysr@777 | 43 | _cm(cm), |
ysr@777 | 44 | _started(false), |
ysr@777 | 45 | _in_progress(false), |
ysr@777 | 46 | _vtime_accum(0.0), |
ysr@777 | 47 | _vtime_mark_accum(0.0), |
ysr@777 | 48 | _vtime_count_accum(0.0) |
ysr@777 | 49 | { |
ysr@777 | 50 | create_and_start(); |
ysr@777 | 51 | } |
ysr@777 | 52 | |
ysr@777 | 53 | class CMCheckpointRootsFinalClosure: public VoidClosure { |
ysr@777 | 54 | |
ysr@777 | 55 | ConcurrentMark* _cm; |
ysr@777 | 56 | public: |
ysr@777 | 57 | |
ysr@777 | 58 | CMCheckpointRootsFinalClosure(ConcurrentMark* cm) : |
ysr@777 | 59 | _cm(cm) {} |
ysr@777 | 60 | |
ysr@777 | 61 | void do_void(){ |
ysr@777 | 62 | _cm->checkpointRootsFinal(false); // !clear_all_soft_refs |
ysr@777 | 63 | } |
ysr@777 | 64 | }; |
ysr@777 | 65 | |
ysr@777 | 66 | class CMCleanUp: public VoidClosure { |
ysr@777 | 67 | ConcurrentMark* _cm; |
ysr@777 | 68 | public: |
ysr@777 | 69 | |
ysr@777 | 70 | CMCleanUp(ConcurrentMark* cm) : |
ysr@777 | 71 | _cm(cm) {} |
ysr@777 | 72 | |
ysr@777 | 73 | void do_void(){ |
ysr@777 | 74 | _cm->cleanup(); |
ysr@777 | 75 | } |
ysr@777 | 76 | }; |
ysr@777 | 77 | |
ysr@777 | 78 | |
ysr@777 | 79 | |
ysr@777 | 80 | void ConcurrentMarkThread::run() { |
ysr@777 | 81 | initialize_in_thread(); |
ysr@777 | 82 | _vtime_start = os::elapsedVTime(); |
ysr@777 | 83 | wait_for_universe_init(); |
ysr@777 | 84 | |
tonyp@2472 | 85 | G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
tonyp@2472 | 86 | G1CollectorPolicy* g1_policy = g1h->g1_policy(); |
ysr@777 | 87 | G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker(); |
ysr@777 | 88 | Thread *current_thread = Thread::current(); |
ysr@777 | 89 | |
ysr@777 | 90 | while (!_should_terminate) { |
ysr@777 | 91 | // wait until started is set. |
ysr@777 | 92 | sleepBeforeNextCycle(); |
ysr@777 | 93 | { |
ysr@777 | 94 | ResourceMark rm; |
ysr@777 | 95 | HandleMark hm; |
ysr@777 | 96 | double cycle_start = os::elapsedVTime(); |
ysr@777 | 97 | double mark_start_sec = os::elapsedTime(); |
ysr@777 | 98 | char verbose_str[128]; |
ysr@777 | 99 | |
ysr@777 | 100 | if (PrintGC) { |
ysr@777 | 101 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 102 | gclog_or_tty->stamp(PrintGCTimeStamps); |
tonyp@1054 | 103 | gclog_or_tty->print_cr("[GC concurrent-mark-start]"); |
ysr@777 | 104 | } |
ysr@777 | 105 | |
ysr@777 | 106 | int iter = 0; |
ysr@777 | 107 | do { |
ysr@777 | 108 | iter++; |
ysr@777 | 109 | if (!cm()->has_aborted()) { |
ysr@777 | 110 | _cm->markFromRoots(); |
ysr@777 | 111 | } |
ysr@777 | 112 | |
ysr@777 | 113 | double mark_end_time = os::elapsedVTime(); |
ysr@777 | 114 | double mark_end_sec = os::elapsedTime(); |
ysr@777 | 115 | _vtime_mark_accum += (mark_end_time - cycle_start); |
ysr@777 | 116 | if (!cm()->has_aborted()) { |
ysr@777 | 117 | if (g1_policy->adaptive_young_list_length()) { |
ysr@777 | 118 | double now = os::elapsedTime(); |
ysr@777 | 119 | double remark_prediction_ms = g1_policy->predict_remark_time_ms(); |
ysr@777 | 120 | jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms); |
ysr@777 | 121 | os::sleep(current_thread, sleep_time_ms, false); |
ysr@777 | 122 | } |
ysr@777 | 123 | |
ysr@777 | 124 | if (PrintGC) { |
ysr@777 | 125 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 126 | gclog_or_tty->stamp(PrintGCTimeStamps); |
ysr@777 | 127 | gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf sec]", |
ysr@777 | 128 | mark_end_sec - mark_start_sec); |
ysr@777 | 129 | } |
ysr@777 | 130 | |
ysr@777 | 131 | CMCheckpointRootsFinalClosure final_cl(_cm); |
ysr@777 | 132 | sprintf(verbose_str, "GC remark"); |
ysr@777 | 133 | VM_CGC_Operation op(&final_cl, verbose_str); |
ysr@777 | 134 | VMThread::execute(&op); |
ysr@777 | 135 | } |
ysr@777 | 136 | if (cm()->restart_for_overflow() && |
ysr@777 | 137 | G1TraceMarkStackOverflow) { |
ysr@777 | 138 | gclog_or_tty->print_cr("Restarting conc marking because of MS overflow " |
ysr@777 | 139 | "in remark (restart #%d).", iter); |
ysr@777 | 140 | } |
ysr@777 | 141 | |
ysr@777 | 142 | if (cm()->restart_for_overflow()) { |
ysr@777 | 143 | if (PrintGC) { |
ysr@777 | 144 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 145 | gclog_or_tty->stamp(PrintGCTimeStamps); |
ysr@777 | 146 | gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]"); |
ysr@777 | 147 | } |
ysr@777 | 148 | } |
ysr@777 | 149 | } while (cm()->restart_for_overflow()); |
ysr@777 | 150 | double counting_start_time = os::elapsedVTime(); |
ysr@777 | 151 | |
ysr@777 | 152 | // YSR: These look dubious (i.e. redundant) !!! FIX ME |
ysr@777 | 153 | slt()->manipulatePLL(SurrogateLockerThread::acquirePLL); |
ysr@777 | 154 | slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); |
ysr@777 | 155 | |
ysr@777 | 156 | if (!cm()->has_aborted()) { |
ysr@777 | 157 | double count_start_sec = os::elapsedTime(); |
ysr@777 | 158 | if (PrintGC) { |
ysr@777 | 159 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 160 | gclog_or_tty->stamp(PrintGCTimeStamps); |
ysr@777 | 161 | gclog_or_tty->print_cr("[GC concurrent-count-start]"); |
ysr@777 | 162 | } |
ysr@777 | 163 | |
ysr@777 | 164 | _sts.join(); |
ysr@777 | 165 | _cm->calcDesiredRegions(); |
ysr@777 | 166 | _sts.leave(); |
ysr@777 | 167 | |
ysr@777 | 168 | if (!cm()->has_aborted()) { |
ysr@777 | 169 | double count_end_sec = os::elapsedTime(); |
ysr@777 | 170 | if (PrintGC) { |
ysr@777 | 171 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 172 | gclog_or_tty->stamp(PrintGCTimeStamps); |
ysr@777 | 173 | gclog_or_tty->print_cr("[GC concurrent-count-end, %1.7lf]", |
ysr@777 | 174 | count_end_sec - count_start_sec); |
ysr@777 | 175 | } |
ysr@777 | 176 | } |
ysr@777 | 177 | } |
ysr@777 | 178 | double end_time = os::elapsedVTime(); |
ysr@777 | 179 | _vtime_count_accum += (end_time - counting_start_time); |
ysr@777 | 180 | // Update the total virtual time before doing this, since it will try |
ysr@777 | 181 | // to measure it to get the vtime for this marking. We purposely |
ysr@777 | 182 | // neglect the presumably-short "completeCleanup" phase here. |
ysr@777 | 183 | _vtime_accum = (end_time - _vtime_start); |
ysr@777 | 184 | if (!cm()->has_aborted()) { |
ysr@777 | 185 | if (g1_policy->adaptive_young_list_length()) { |
ysr@777 | 186 | double now = os::elapsedTime(); |
ysr@777 | 187 | double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms(); |
ysr@777 | 188 | jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms); |
ysr@777 | 189 | os::sleep(current_thread, sleep_time_ms, false); |
ysr@777 | 190 | } |
ysr@777 | 191 | |
ysr@777 | 192 | CMCleanUp cl_cl(_cm); |
ysr@777 | 193 | sprintf(verbose_str, "GC cleanup"); |
ysr@777 | 194 | VM_CGC_Operation op(&cl_cl, verbose_str); |
ysr@777 | 195 | VMThread::execute(&op); |
ysr@777 | 196 | } else { |
tonyp@2472 | 197 | g1h->set_marking_complete(); |
ysr@777 | 198 | } |
ysr@777 | 199 | |
tonyp@2472 | 200 | // Check if cleanup set the free_regions_coming flag. If it |
tonyp@2472 | 201 | // hasn't, we can just skip the next step. |
tonyp@2472 | 202 | if (g1h->free_regions_coming()) { |
tonyp@2472 | 203 | // The following will finish freeing up any regions that we |
tonyp@2472 | 204 | // found to be empty during cleanup. We'll do this part |
tonyp@2472 | 205 | // without joining the suspendible set. If an evacuation pause |
tonyp@2643 | 206 | // takes place, then we would carry on freeing regions in |
tonyp@2472 | 207 | // case they are needed by the pause. If a Full GC takes |
tonyp@2643 | 208 | // place, it would wait for us to process the regions |
tonyp@2472 | 209 | // reclaimed by cleanup. |
tonyp@2472 | 210 | |
ysr@777 | 211 | double cleanup_start_sec = os::elapsedTime(); |
ysr@777 | 212 | if (PrintGC) { |
ysr@777 | 213 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 214 | gclog_or_tty->stamp(PrintGCTimeStamps); |
ysr@777 | 215 | gclog_or_tty->print_cr("[GC concurrent-cleanup-start]"); |
ysr@777 | 216 | } |
ysr@777 | 217 | |
tonyp@3208 | 218 | // Now do the concurrent cleanup operation. |
ysr@777 | 219 | _cm->completeCleanup(); |
tonyp@3208 | 220 | |
tonyp@2501 | 221 | // Notify anyone who's waiting that there are no more free |
tonyp@3208 | 222 | // regions coming. We have to do this before we join the STS |
tonyp@3208 | 223 | // (in fact, we should not attempt to join the STS in the |
tonyp@3208 | 224 | // interval between finishing the cleanup pause and clearing |
tonyp@3208 | 225 | // the free_regions_coming flag) otherwise we might deadlock: |
tonyp@3208 | 226 | // a GC worker could be blocked waiting for the notification |
tonyp@3208 | 227 | // whereas this thread will be blocked for the pause to finish |
tonyp@3208 | 228 | // while it's trying to join the STS, which is conditional on |
tonyp@3208 | 229 | // the GC workers finishing. |
tonyp@2501 | 230 | g1h->reset_free_regions_coming(); |
tonyp@2501 | 231 | |
tonyp@2472 | 232 | double cleanup_end_sec = os::elapsedTime(); |
tonyp@2472 | 233 | if (PrintGC) { |
tonyp@2472 | 234 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
tonyp@2472 | 235 | gclog_or_tty->stamp(PrintGCTimeStamps); |
tonyp@2472 | 236 | gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]", |
tonyp@2472 | 237 | cleanup_end_sec - cleanup_start_sec); |
ysr@777 | 238 | } |
ysr@777 | 239 | } |
tonyp@2472 | 240 | guarantee(cm()->cleanup_list_is_empty(), |
tonyp@2472 | 241 | "at this point there should be no regions on the cleanup list"); |
ysr@777 | 242 | |
tonyp@3208 | 243 | // There is a tricky race before recording that the concurrent |
tonyp@3208 | 244 | // cleanup has completed and a potential Full GC starting around |
tonyp@3208 | 245 | // the same time. We want to make sure that the Full GC calls |
tonyp@3208 | 246 | // abort() on concurrent mark after |
tonyp@3208 | 247 | // record_concurrent_mark_cleanup_completed(), since abort() is |
tonyp@3208 | 248 | // the method that will reset the concurrent mark state. If we |
tonyp@3208 | 249 | // end up calling record_concurrent_mark_cleanup_completed() |
tonyp@3208 | 250 | // after abort() then we might incorrectly undo some of the work |
tonyp@3208 | 251 | // abort() did. Checking the has_aborted() flag after joining |
tonyp@3208 | 252 | // the STS allows the correct ordering of the two methods. There |
tonyp@3208 | 253 | // are two scenarios: |
tonyp@3208 | 254 | // |
tonyp@3208 | 255 | // a) If we reach here before the Full GC, the fact that we have |
tonyp@3208 | 256 | // joined the STS means that the Full GC cannot start until we |
tonyp@3208 | 257 | // leave the STS, so record_concurrent_mark_cleanup_completed() |
tonyp@3208 | 258 | // will complete before abort() is called. |
tonyp@3208 | 259 | // |
tonyp@3208 | 260 | // b) If we reach here during the Full GC, we'll be held up from |
tonyp@3208 | 261 | // joining the STS until the Full GC is done, which means that |
tonyp@3208 | 262 | // abort() will have completed and has_aborted() will return |
tonyp@3208 | 263 | // true to prevent us from calling |
tonyp@3208 | 264 | // record_concurrent_mark_cleanup_completed() (and, in fact, it's |
tonyp@3208 | 265 | // not needed any more as the concurrent mark state has been |
tonyp@3208 | 266 | // already reset). |
tonyp@3208 | 267 | _sts.join(); |
tonyp@3208 | 268 | if (!cm()->has_aborted()) { |
tonyp@3208 | 269 | g1_policy->record_concurrent_mark_cleanup_completed(); |
tonyp@3208 | 270 | } |
tonyp@3208 | 271 | _sts.leave(); |
tonyp@3208 | 272 | |
ysr@777 | 273 | if (cm()->has_aborted()) { |
ysr@777 | 274 | if (PrintGC) { |
ysr@777 | 275 | gclog_or_tty->date_stamp(PrintGCDateStamps); |
ysr@777 | 276 | gclog_or_tty->stamp(PrintGCTimeStamps); |
ysr@777 | 277 | gclog_or_tty->print_cr("[GC concurrent-mark-abort]"); |
ysr@777 | 278 | } |
ysr@777 | 279 | } |
ysr@777 | 280 | |
tonyp@3208 | 281 | // We now want to allow clearing of the marking bitmap to be |
ysr@777 | 282 | // suspended by a collection pause. |
ysr@777 | 283 | _sts.join(); |
ysr@777 | 284 | _cm->clearNextBitmap(); |
ysr@777 | 285 | _sts.leave(); |
ysr@777 | 286 | } |
tonyp@2011 | 287 | |
tonyp@2011 | 288 | // Update the number of full collections that have been |
tonyp@2011 | 289 | // completed. This will also notify the FullGCCount_lock in case a |
tonyp@2011 | 290 | // Java thread is waiting for a full GC to happen (e.g., it |
tonyp@2011 | 291 | // called System.gc() with +ExplicitGCInvokesConcurrent). |
tonyp@2372 | 292 | _sts.join(); |
tonyp@2472 | 293 | g1h->increment_full_collections_completed(true /* concurrent */); |
tonyp@2372 | 294 | _sts.leave(); |
ysr@777 | 295 | } |
ysr@777 | 296 | assert(_should_terminate, "just checking"); |
ysr@777 | 297 | |
ysr@777 | 298 | terminate(); |
ysr@777 | 299 | } |
ysr@777 | 300 | |
ysr@777 | 301 | |
ysr@777 | 302 | void ConcurrentMarkThread::yield() { |
ysr@777 | 303 | _sts.yield("Concurrent Mark"); |
ysr@777 | 304 | } |
ysr@777 | 305 | |
ysr@777 | 306 | void ConcurrentMarkThread::stop() { |
ysr@777 | 307 | // it is ok to take late safepoints here, if needed |
ysr@777 | 308 | MutexLockerEx mu(Terminator_lock); |
ysr@777 | 309 | _should_terminate = true; |
ysr@777 | 310 | while (!_has_terminated) { |
ysr@777 | 311 | Terminator_lock->wait(); |
ysr@777 | 312 | } |
ysr@777 | 313 | } |
ysr@777 | 314 | |
tonyp@1454 | 315 | void ConcurrentMarkThread::print() const { |
tonyp@1454 | 316 | print_on(tty); |
tonyp@1454 | 317 | } |
tonyp@1454 | 318 | |
tonyp@1454 | 319 | void ConcurrentMarkThread::print_on(outputStream* st) const { |
tonyp@1454 | 320 | st->print("\"G1 Main Concurrent Mark GC Thread\" "); |
tonyp@1454 | 321 | Thread::print_on(st); |
tonyp@1454 | 322 | st->cr(); |
ysr@777 | 323 | } |
ysr@777 | 324 | |
ysr@777 | 325 | void ConcurrentMarkThread::sleepBeforeNextCycle() { |
ysr@777 | 326 | // We join here because we don't want to do the "shouldConcurrentMark()" |
ysr@777 | 327 | // below while the world is otherwise stopped. |
johnc@2195 | 328 | assert(!in_progress(), "should have been cleared"); |
johnc@2195 | 329 | |
ysr@777 | 330 | MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); |
ysr@777 | 331 | while (!started()) { |
ysr@777 | 332 | CGC_lock->wait(Mutex::_no_safepoint_check_flag); |
ysr@777 | 333 | } |
ysr@777 | 334 | set_in_progress(); |
ysr@777 | 335 | clear_started(); |
ysr@777 | 336 | } |
ysr@777 | 337 | |
ysr@777 | 338 | // Note: this method, although exported by the ConcurrentMarkSweepThread, |
ysr@777 | 339 | // which is a non-JavaThread, can only be called by a JavaThread. |
ysr@777 | 340 | // Currently this is done at vm creation time (post-vm-init) by the |
ysr@777 | 341 | // main/Primordial (Java)Thread. |
ysr@777 | 342 | // XXX Consider changing this in the future to allow the CMS thread |
ysr@777 | 343 | // itself to create this thread? |
ysr@777 | 344 | void ConcurrentMarkThread::makeSurrogateLockerThread(TRAPS) { |
ysr@777 | 345 | assert(_slt == NULL, "SLT already created"); |
ysr@777 | 346 | _slt = SurrogateLockerThread::make(THREAD); |
ysr@777 | 347 | } |