Example #1
0
void ConcurrentMarkSweepThread::run() {
  assert(this == cmst(), "just checking");

  this->record_stack_base_and_size();
  this->initialize_thread_local_storage();
  this->set_active_handles(JNIHandleBlock::allocate_block());
  // From this time Thread::current() should be working.
  assert(this == Thread::current(), "just checking");
  if (BindCMSThreadToCPU && !os::bind_to_processor(CPUForCMSThread)) {
    warning("Couldn't bind CMS thread to processor %u", CPUForCMSThread);
  }
  // Wait until Universe::is_fully_initialized()
  {
    CMSLoopCountWarn loopX("CMS::run", "waiting for "
                           "Universe::is_fully_initialized()", 2);
    MutexLockerEx x(CGC_lock, true);
    set_CMS_flag(CMS_cms_wants_token);
    // Wait until Universe is initialized and all initialization is completed.
    while (!is_init_completed() && !Universe::is_fully_initialized() &&
           !_should_terminate) {
      CGC_lock->wait(true, 200);
      loopX.tick();
    }
    // Wait until the surrogate locker thread that will do
    // pending list locking on our behalf has been created.
    // We cannot start the SLT thread ourselves since we need
    // to be a JavaThread to do so.
    CMSLoopCountWarn loopY("CMS::run", "waiting for SLT installation", 2);
    while (_slt == NULL && !_should_terminate) {
      CGC_lock->wait(true, 200);
      loopY.tick();
    }
    clear_CMS_flag(CMS_cms_wants_token);
  }

  while (!_should_terminate) {
    sleepBeforeNextCycle();
    if (_should_terminate) break;
    GCCause::Cause cause = _collector->_full_gc_requested ?
      _collector->_full_gc_cause : GCCause::_cms_concurrent_mark;
    _collector->collect_in_background(false, cause);
  }
  assert(_should_terminate, "just checking");
  // Check that the state of any protocol for synchronization
  // between background (CMS) and foreground collector is "clean"
  // (i.e. will not potentially block the foreground collector,
  // requiring action by us).
  verify_ok_to_terminate();
  // Signal that it is terminated
  {
    MutexLockerEx mu(Terminator_lock,
                     Mutex::_no_safepoint_check_flag);
    assert(_cmst == this, "Weird!");
    _cmst = NULL;
    Terminator_lock->notify();
  }

  // Thread destructor usually does this..
  ThreadLocalStorage::set_thread(NULL);
}
void ConcurrentMarkThread::run() {
  initialize_in_thread();
  _vtime_start = os::elapsedVTime();
  wait_for_universe_init();

  G1CollectedHeap* g1h = G1CollectedHeap::heap();
  G1CollectorPolicy* g1_policy = g1h->g1_policy();
  G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
  Thread *current_thread = Thread::current();

  while (!_should_terminate) {
    // wait until started is set.
    sleepBeforeNextCycle();
    if (_should_terminate) {
      break;
    }

    {
      ResourceMark rm;
      HandleMark   hm;
      double cycle_start = os::elapsedVTime();

      // We have to ensure that we finish scanning the root regions
      // before the next GC takes place. To ensure this we have to
      // make sure that we do not join the STS until the root regions
      // have been scanned. If we did then it's possible that a
      // subsequent GC could block us from joining the STS and proceed
      // without the root regions have been scanned which would be a
      // correctness issue.

      if (!cm()->has_aborted()) {
        _cm->scanRootRegions();
      }

      double mark_start_sec = os::elapsedTime();
      cm_log(G1Log::fine(), true, "[GC concurrent-mark-start]");

      int iter = 0;
      do {
        iter++;
        if (!cm()->has_aborted()) {
          _cm->markFromRoots();
        }

        double mark_end_time = os::elapsedVTime();
        double mark_end_sec = os::elapsedTime();
        _vtime_mark_accum += (mark_end_time - cycle_start);
        if (!cm()->has_aborted()) {
          if (g1_policy->adaptive_young_list_length()) {
            double now = os::elapsedTime();
            double remark_prediction_ms = g1_policy->predict_remark_time_ms();
            jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
            os::sleep(current_thread, sleep_time_ms, false);
          }

          cm_log(G1Log::fine(), true, "[GC concurrent-mark-end, %1.7lf secs]", mark_end_sec - mark_start_sec);

          CMCheckpointRootsFinalClosure final_cl(_cm);
          VM_CGC_Operation op(&final_cl, "GC remark", true /* needs_pll */);
          VMThread::execute(&op);
        }
        if (cm()->restart_for_overflow()) {
          cm_log(G1TraceMarkStackOverflow, true, "Restarting conc marking because of MS overflow in remark (restart #%d).", iter);
          cm_log(G1Log::fine(), true, "[GC concurrent-mark-restart-for-overflow]");
        }
      } while (cm()->restart_for_overflow());

      double end_time = os::elapsedVTime();
      // Update the total virtual time before doing this, since it will try
      // to measure it to get the vtime for this marking.  We purposely
      // neglect the presumably-short "completeCleanup" phase here.
      _vtime_accum = (end_time - _vtime_start);

      if (!cm()->has_aborted()) {
        if (g1_policy->adaptive_young_list_length()) {
          double now = os::elapsedTime();
          double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
          jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
          os::sleep(current_thread, sleep_time_ms, false);
        }

        CMCleanUp cl_cl(_cm);
        VM_CGC_Operation op(&cl_cl, "GC cleanup", false /* needs_pll */);
        VMThread::execute(&op);
      } else {
        // We don't want to update the marking status if a GC pause
        // is already underway.
        SuspendibleThreadSetJoiner sts_join;
        g1h->collector_state()->set_mark_in_progress(false);
      }

      // Check if cleanup set the free_regions_coming flag. If it
      // hasn't, we can just skip the next step.
      if (g1h->free_regions_coming()) {
        // The following will finish freeing up any regions that we
        // found to be empty during cleanup. We'll do this part
        // without joining the suspendible set. If an evacuation pause
        // takes place, then we would carry on freeing regions in
        // case they are needed by the pause. If a Full GC takes
        // place, it would wait for us to process the regions
        // reclaimed by cleanup.

        double cleanup_start_sec = os::elapsedTime();
        cm_log(G1Log::fine(), true, "[GC concurrent-cleanup-start]");

        // Now do the concurrent cleanup operation.
        _cm->completeCleanup();

        // Notify anyone who's waiting that there are no more free
        // regions coming. We have to do this before we join the STS
        // (in fact, we should not attempt to join the STS in the
        // interval between finishing the cleanup pause and clearing
        // the free_regions_coming flag) otherwise we might deadlock:
        // a GC worker could be blocked waiting for the notification
        // whereas this thread will be blocked for the pause to finish
        // while it's trying to join the STS, which is conditional on
        // the GC workers finishing.
        g1h->reset_free_regions_coming();

        double cleanup_end_sec = os::elapsedTime();
        cm_log(G1Log::fine(), true, "[GC concurrent-cleanup-end, %1.7lf secs]", cleanup_end_sec - cleanup_start_sec);
      }
      guarantee(cm()->cleanup_list_is_empty(),
                "at this point there should be no regions on the cleanup list");

      // There is a tricky race before recording that the concurrent
      // cleanup has completed and a potential Full GC starting around
      // the same time. We want to make sure that the Full GC calls
      // abort() on concurrent mark after
      // record_concurrent_mark_cleanup_completed(), since abort() is
      // the method that will reset the concurrent mark state. If we
      // end up calling record_concurrent_mark_cleanup_completed()
      // after abort() then we might incorrectly undo some of the work
      // abort() did. Checking the has_aborted() flag after joining
      // the STS allows the correct ordering of the two methods. There
      // are two scenarios:
      //
      // a) If we reach here before the Full GC, the fact that we have
      // joined the STS means that the Full GC cannot start until we
      // leave the STS, so record_concurrent_mark_cleanup_completed()
      // will complete before abort() is called.
      //
      // b) If we reach here during the Full GC, we'll be held up from
      // joining the STS until the Full GC is done, which means that
      // abort() will have completed and has_aborted() will return
      // true to prevent us from calling
      // record_concurrent_mark_cleanup_completed() (and, in fact, it's
      // not needed any more as the concurrent mark state has been
      // already reset).
      {
        SuspendibleThreadSetJoiner sts_join;
        if (!cm()->has_aborted()) {
          g1_policy->record_concurrent_mark_cleanup_completed();
        } else {
          cm_log(G1Log::fine(), false, "[GC concurrent-mark-abort]");
        }
      }

      // We now want to allow clearing of the marking bitmap to be
      // suspended by a collection pause.
      // We may have aborted just before the remark. Do not bother clearing the
      // bitmap then, as it has been done during mark abort.
      if (!cm()->has_aborted()) {
        _cm->clearNextBitmap();
      } else {
        assert(!G1VerifyBitmaps || _cm->nextMarkBitmapIsClear(), "Next mark bitmap must be clear");
      }
    }

    // Update the number of full collections that have been
    // completed. This will also notify the FullGCCount_lock in case a
    // Java thread is waiting for a full GC to happen (e.g., it
    // called System.gc() with +ExplicitGCInvokesConcurrent).
    {
      SuspendibleThreadSetJoiner sts_join;
      g1h->increment_old_marking_cycles_completed(true /* concurrent */);
      g1h->register_concurrent_cycle_end();
    }
  }
  assert(_should_terminate, "just checking");

  terminate();
}
void ConcurrentMarkThread::run() {
  initialize_in_thread();
  _vtime_start = os::elapsedVTime();
  wait_for_universe_init();

  G1CollectedHeap* g1h = G1CollectedHeap::heap();
  G1CollectorPolicy* g1_policy = g1h->g1_policy();
  G1MMUTracker *mmu_tracker = g1_policy->mmu_tracker();
  Thread *current_thread = Thread::current();

  while (!_should_terminate) {
    // wait until started is set.
    sleepBeforeNextCycle();
    {
      ResourceMark rm;
      HandleMark   hm;
      double cycle_start = os::elapsedVTime();
      double mark_start_sec = os::elapsedTime();
      char verbose_str[128];

      if (PrintGC) {
        gclog_or_tty->date_stamp(PrintGCDateStamps);
        gclog_or_tty->stamp(PrintGCTimeStamps);
        gclog_or_tty->print_cr("[GC concurrent-mark-start]");
      }

      if (!g1_policy->in_young_gc_mode()) {
        // this ensures the flag is not set if we bail out of the marking
        // cycle; normally the flag is cleared immediately after cleanup
        g1h->set_marking_complete();

        if (g1_policy->adaptive_young_list_length()) {
          double now = os::elapsedTime();
          double init_prediction_ms = g1_policy->predict_init_time_ms();
          jlong sleep_time_ms = mmu_tracker->when_ms(now, init_prediction_ms);
          os::sleep(current_thread, sleep_time_ms, false);
        }

        // We don't have to skip here if we've been asked to restart, because
        // in the worst case we just enqueue a new VM operation to start a
        // marking.  Note that the init operation resets has_aborted()
        CMCheckpointRootsInitialClosure init_cl(_cm);
        strcpy(verbose_str, "GC initial-mark");
        VM_CGC_Operation op(&init_cl, verbose_str);
        VMThread::execute(&op);
      }

      int iter = 0;
      do {
        iter++;
        if (!cm()->has_aborted()) {
          _cm->markFromRoots();
        }

        double mark_end_time = os::elapsedVTime();
        double mark_end_sec = os::elapsedTime();
        _vtime_mark_accum += (mark_end_time - cycle_start);
        if (!cm()->has_aborted()) {
          if (g1_policy->adaptive_young_list_length()) {
            double now = os::elapsedTime();
            double remark_prediction_ms = g1_policy->predict_remark_time_ms();
            jlong sleep_time_ms = mmu_tracker->when_ms(now, remark_prediction_ms);
            os::sleep(current_thread, sleep_time_ms, false);
          }

          if (PrintGC) {
            gclog_or_tty->date_stamp(PrintGCDateStamps);
            gclog_or_tty->stamp(PrintGCTimeStamps);
            gclog_or_tty->print_cr("[GC concurrent-mark-end, %1.7lf sec]",
                                      mark_end_sec - mark_start_sec);
          }

          CMCheckpointRootsFinalClosure final_cl(_cm);
          sprintf(verbose_str, "GC remark");
          VM_CGC_Operation op(&final_cl, verbose_str);
          VMThread::execute(&op);
        }
        if (cm()->restart_for_overflow() &&
            G1TraceMarkStackOverflow) {
          gclog_or_tty->print_cr("Restarting conc marking because of MS overflow "
                                 "in remark (restart #%d).", iter);
        }

        if (cm()->restart_for_overflow()) {
          if (PrintGC) {
            gclog_or_tty->date_stamp(PrintGCDateStamps);
            gclog_or_tty->stamp(PrintGCTimeStamps);
            gclog_or_tty->print_cr("[GC concurrent-mark-restart-for-overflow]");
          }
        }
      } while (cm()->restart_for_overflow());
      double counting_start_time = os::elapsedVTime();

      // YSR: These look dubious (i.e. redundant) !!! FIX ME
      slt()->manipulatePLL(SurrogateLockerThread::acquirePLL);
      slt()->manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);

      if (!cm()->has_aborted()) {
        double count_start_sec = os::elapsedTime();
        if (PrintGC) {
          gclog_or_tty->date_stamp(PrintGCDateStamps);
          gclog_or_tty->stamp(PrintGCTimeStamps);
          gclog_or_tty->print_cr("[GC concurrent-count-start]");
        }

        _sts.join();
        _cm->calcDesiredRegions();
        _sts.leave();

        if (!cm()->has_aborted()) {
          double count_end_sec = os::elapsedTime();
          if (PrintGC) {
            gclog_or_tty->date_stamp(PrintGCDateStamps);
            gclog_or_tty->stamp(PrintGCTimeStamps);
            gclog_or_tty->print_cr("[GC concurrent-count-end, %1.7lf]",
                                   count_end_sec - count_start_sec);
          }
        }
      }
      double end_time = os::elapsedVTime();
      _vtime_count_accum += (end_time - counting_start_time);
      // Update the total virtual time before doing this, since it will try
      // to measure it to get the vtime for this marking.  We purposely
      // neglect the presumably-short "completeCleanup" phase here.
      _vtime_accum = (end_time - _vtime_start);
      if (!cm()->has_aborted()) {
        if (g1_policy->adaptive_young_list_length()) {
          double now = os::elapsedTime();
          double cleanup_prediction_ms = g1_policy->predict_cleanup_time_ms();
          jlong sleep_time_ms = mmu_tracker->when_ms(now, cleanup_prediction_ms);
          os::sleep(current_thread, sleep_time_ms, false);
        }

        CMCleanUp cl_cl(_cm);
        sprintf(verbose_str, "GC cleanup");
        VM_CGC_Operation op(&cl_cl, verbose_str);
        VMThread::execute(&op);
      } else {
        g1h->set_marking_complete();
      }

      // Check if cleanup set the free_regions_coming flag. If it
      // hasn't, we can just skip the next step.
      if (g1h->free_regions_coming()) {
        // The following will finish freeing up any regions that we
        // found to be empty during cleanup. We'll do this part
        // without joining the suspendible set. If an evacuation pause
        // takes places, then we would carry on freeing regions in
        // case they are needed by the pause. If a Full GC takes
        // places, it would wait for us to process the regions
        // reclaimed by cleanup.

        double cleanup_start_sec = os::elapsedTime();
        if (PrintGC) {
          gclog_or_tty->date_stamp(PrintGCDateStamps);
          gclog_or_tty->stamp(PrintGCTimeStamps);
          gclog_or_tty->print_cr("[GC concurrent-cleanup-start]");
        }

        // Now do the remainder of the cleanup operation.
        _cm->completeCleanup();
        // Notify anyone who's waiting that there are no more free
        // regions coming. We have to do this before we join the STS,
        // otherwise we might deadlock: a GC worker could be blocked
        // waiting for the notification whereas this thread will be
        // blocked for the pause to finish while it's trying to join
        // the STS, which is conditional on the GC workers finishing.
        g1h->reset_free_regions_coming();

        _sts.join();
        g1_policy->record_concurrent_mark_cleanup_completed();
        _sts.leave();

        double cleanup_end_sec = os::elapsedTime();
        if (PrintGC) {
          gclog_or_tty->date_stamp(PrintGCDateStamps);
          gclog_or_tty->stamp(PrintGCTimeStamps);
          gclog_or_tty->print_cr("[GC concurrent-cleanup-end, %1.7lf]",
                                 cleanup_end_sec - cleanup_start_sec);
        }
      }
      guarantee(cm()->cleanup_list_is_empty(),
                "at this point there should be no regions on the cleanup list");

      if (cm()->has_aborted()) {
        if (PrintGC) {
          gclog_or_tty->date_stamp(PrintGCDateStamps);
          gclog_or_tty->stamp(PrintGCTimeStamps);
          gclog_or_tty->print_cr("[GC concurrent-mark-abort]");
        }
      }

      // we now want to allow clearing of the marking bitmap to be
      // suspended by a collection pause.
      _sts.join();
      _cm->clearNextBitmap();
      _sts.leave();
    }

    // Update the number of full collections that have been
    // completed. This will also notify the FullGCCount_lock in case a
    // Java thread is waiting for a full GC to happen (e.g., it
    // called System.gc() with +ExplicitGCInvokesConcurrent).
    _sts.join();
    g1h->increment_full_collections_completed(true /* concurrent */);
    _sts.leave();
  }
  assert(_should_terminate, "just checking");

  terminate();
}
void ConcurrentMarkThread::run_service() {
    _vtime_start = os::elapsedVTime();

    G1CollectedHeap* g1h = G1CollectedHeap::heap();
    G1CollectorPolicy* g1_policy = g1h->g1_policy();

    while (!_should_terminate) {
        // wait until started is set.
        sleepBeforeNextCycle();
        if (_should_terminate) {
            break;
        }

        assert(GCId::current() != GCId::undefined(), "GC id should have been set up by the initial mark GC.");
        {
            ResourceMark rm;
            HandleMark   hm;
            double cycle_start = os::elapsedVTime();

            // We have to ensure that we finish scanning the root regions
            // before the next GC takes place. To ensure this we have to
            // make sure that we do not join the STS until the root regions
            // have been scanned. If we did then it's possible that a
            // subsequent GC could block us from joining the STS and proceed
            // without the root regions have been scanned which would be a
            // correctness issue.

            if (!cm()->has_aborted()) {
                GCConcPhaseTimer(_cm, "Concurrent Root Region Scanning");
                _cm->scanRootRegions();
            }

            // It would be nice to use the GCTraceConcTime class here but
            // the "end" logging is inside the loop and not at the end of
            // a scope. Mimicking the same log output as GCTraceConcTime instead.
            jlong mark_start = os::elapsed_counter();
            log_info(gc)("Concurrent Mark (%.3fs)", TimeHelper::counter_to_seconds(mark_start));

            int iter = 0;
            do {
                iter++;
                if (!cm()->has_aborted()) {
                    GCConcPhaseTimer(_cm, "Concurrent Mark");
                    _cm->markFromRoots();
                }

                double mark_end_time = os::elapsedVTime();
                jlong mark_end = os::elapsed_counter();
                _vtime_mark_accum += (mark_end_time - cycle_start);
                if (!cm()->has_aborted()) {
                    delay_to_keep_mmu(g1_policy, true /* remark */);
                    log_info(gc)("Concurrent Mark (%.3fs, %.3fs) %.3fms",
                                 TimeHelper::counter_to_seconds(mark_start),
                                 TimeHelper::counter_to_seconds(mark_end),
                                 TimeHelper::counter_to_millis(mark_end - mark_start));

                    CMCheckpointRootsFinalClosure final_cl(_cm);
                    VM_CGC_Operation op(&final_cl, "Pause Remark", true /* needs_pll */);
                    VMThread::execute(&op);
                }
                if (cm()->restart_for_overflow()) {
                    log_debug(gc)("Restarting conc marking because of MS overflow in remark (restart #%d).", iter);
                    log_info(gc)("Concurrent Mark restart for overflow");
                }
            } while (cm()->restart_for_overflow());

            double end_time = os::elapsedVTime();
            // Update the total virtual time before doing this, since it will try
            // to measure it to get the vtime for this marking.  We purposely
            // neglect the presumably-short "completeCleanup" phase here.
            _vtime_accum = (end_time - _vtime_start);

            if (!cm()->has_aborted()) {
                delay_to_keep_mmu(g1_policy, false /* cleanup */);

                CMCleanUp cl_cl(_cm);
                VM_CGC_Operation op(&cl_cl, "Pause Cleanup", false /* needs_pll */);
                VMThread::execute(&op);
            } else {
                // We don't want to update the marking status if a GC pause
                // is already underway.
                SuspendibleThreadSetJoiner sts_join;
                g1h->collector_state()->set_mark_in_progress(false);
            }

            // Check if cleanup set the free_regions_coming flag. If it
            // hasn't, we can just skip the next step.
            if (g1h->free_regions_coming()) {
                // The following will finish freeing up any regions that we
                // found to be empty during cleanup. We'll do this part
                // without joining the suspendible set. If an evacuation pause
                // takes place, then we would carry on freeing regions in
                // case they are needed by the pause. If a Full GC takes
                // place, it would wait for us to process the regions
                // reclaimed by cleanup.

                GCTraceConcTime(Info, gc) tt("Concurrent Cleanup");
                GCConcPhaseTimer(_cm, "Concurrent Cleanup");

                // Now do the concurrent cleanup operation.
                _cm->completeCleanup();

                // Notify anyone who's waiting that there are no more free
                // regions coming. We have to do this before we join the STS
                // (in fact, we should not attempt to join the STS in the
                // interval between finishing the cleanup pause and clearing
                // the free_regions_coming flag) otherwise we might deadlock:
                // a GC worker could be blocked waiting for the notification
                // whereas this thread will be blocked for the pause to finish
                // while it's trying to join the STS, which is conditional on
                // the GC workers finishing.
                g1h->reset_free_regions_coming();
            }
            guarantee(cm()->cleanup_list_is_empty(),
                      "at this point there should be no regions on the cleanup list");

            // There is a tricky race before recording that the concurrent
            // cleanup has completed and a potential Full GC starting around
            // the same time. We want to make sure that the Full GC calls
            // abort() on concurrent mark after
            // record_concurrent_mark_cleanup_completed(), since abort() is
            // the method that will reset the concurrent mark state. If we
            // end up calling record_concurrent_mark_cleanup_completed()
            // after abort() then we might incorrectly undo some of the work
            // abort() did. Checking the has_aborted() flag after joining
            // the STS allows the correct ordering of the two methods. There
            // are two scenarios:
            //
            // a) If we reach here before the Full GC, the fact that we have
            // joined the STS means that the Full GC cannot start until we
            // leave the STS, so record_concurrent_mark_cleanup_completed()
            // will complete before abort() is called.
            //
            // b) If we reach here during the Full GC, we'll be held up from
            // joining the STS until the Full GC is done, which means that
            // abort() will have completed and has_aborted() will return
            // true to prevent us from calling
            // record_concurrent_mark_cleanup_completed() (and, in fact, it's
            // not needed any more as the concurrent mark state has been
            // already reset).
            {
                SuspendibleThreadSetJoiner sts_join;
                if (!cm()->has_aborted()) {
                    g1_policy->record_concurrent_mark_cleanup_completed();
                } else {
                    log_info(gc)("Concurrent Mark abort");
                }
            }

            // We now want to allow clearing of the marking bitmap to be
            // suspended by a collection pause.
            // We may have aborted just before the remark. Do not bother clearing the
            // bitmap then, as it has been done during mark abort.
            if (!cm()->has_aborted()) {
                GCConcPhaseTimer(_cm, "Concurrent Bitmap Clearing");
                _cm->clearNextBitmap();
            } else {
                assert(!G1VerifyBitmaps || _cm->nextMarkBitmapIsClear(), "Next mark bitmap must be clear");
            }
        }

        // Update the number of full collections that have been
        // completed. This will also notify the FullGCCount_lock in case a
        // Java thread is waiting for a full GC to happen (e.g., it
        // called System.gc() with +ExplicitGCInvokesConcurrent).
        {
            SuspendibleThreadSetJoiner sts_join;
            g1h->increment_old_marking_cycles_completed(true /* concurrent */);
            g1h->register_concurrent_cycle_end();
        }
    }
}