view src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp @ 2034:7e37af9d69ef

7011379: G1: overly long concurrent marking cycles Summary: This changeset introduces filtering of SATB buffers at the point when they are about to be enqueued. If this filtering clears enough entries on each buffer, the buffer can then be re-used and not enqueued. This cuts down the number of SATB buffers that need to be processed by the concurrent marking threads. Reviewed-by: johnc, ysr
author tonyp
date Wed, 19 Jan 2011 09:35:17 -0500
parents f95d63e2154a
children 0fa27f37d4d4
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/*
 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
#include "gc_implementation/g1/g1CollectorPolicy.hpp"
#include "gc_implementation/g1/g1MMUTracker.hpp"
#include "gc_implementation/g1/vm_operations_g1.hpp"
#include "memory/resourceArea.hpp"
#include "runtime/vmThread.hpp"

// ======= Concurrent Mark Thread ========

// The CM thread is created when the G1 garbage collector is used

SurrogateLockerThread*
     ConcurrentMarkThread::_slt = NULL;

ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) :
  ConcurrentGCThread(),
  _cm(cm),
  _started(false),
  _in_progress(false),
  _vtime_accum(0.0),
  _vtime_mark_accum(0.0),
  _vtime_count_accum(0.0)
{
  create_and_start();
}

class CMCheckpointRootsInitialClosure: public VoidClosure {

  ConcurrentMark* _cm;
public:

  CMCheckpointRootsInitialClosure(ConcurrentMark* cm) :
    _cm(cm) {}

  void do_void(){
    _cm->checkpointRootsInitial();
  }
};

class CMCheckpointRootsFinalClosure: public VoidClosure {

  ConcurrentMark* _cm;
public:

  CMCheckpointRootsFinalClosure(ConcurrentMark* cm) :
    _cm(cm) {}

  void do_void(){
    _cm->checkpointRootsFinal(false); // !clear_all_soft_refs
  }
};

class CMCleanUp: public VoidClosure {
  ConcurrentMark* _cm;
public:

  CMCleanUp(ConcurrentMark* cm) :
    _cm(cm) {}

  void do_void(){
    _cm->cleanup();
  }
};



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

  G1CollectedHeap* g1 = G1CollectedHeap::heap();
  G1CollectorPolicy* g1_policy = g1->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
        g1->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 {
        G1CollectedHeap::heap()->set_marking_complete();
      }

      if (!cm()->has_aborted()) {
        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.
        _sts.join();
        _cm->completeCleanup();
        if (!cm()->has_aborted()) {
          g1_policy->record_concurrent_mark_cleanup_completed();

          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);
          }
        }
        _sts.leave();
      }
      // We're done: no more unclean regions coming.
      G1CollectedHeap::heap()->set_unclean_regions_coming(false);

      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();
    g1->increment_full_collections_completed(true /* concurrent */);
    _sts.leave();
  }
  assert(_should_terminate, "just checking");

  terminate();
}


void ConcurrentMarkThread::yield() {
  _sts.yield("Concurrent Mark");
}

void ConcurrentMarkThread::stop() {
  // it is ok to take late safepoints here, if needed
  MutexLockerEx mu(Terminator_lock);
  _should_terminate = true;
  while (!_has_terminated) {
    Terminator_lock->wait();
  }
}

void ConcurrentMarkThread::print() const {
  print_on(tty);
}

void ConcurrentMarkThread::print_on(outputStream* st) const {
  st->print("\"G1 Main Concurrent Mark GC Thread\" ");
  Thread::print_on(st);
  st->cr();
}

void ConcurrentMarkThread::sleepBeforeNextCycle() {
  // We join here because we don't want to do the "shouldConcurrentMark()"
  // below while the world is otherwise stopped.
  assert(!in_progress(), "should have been cleared");

  MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
  while (!started()) {
    CGC_lock->wait(Mutex::_no_safepoint_check_flag);
  }
  set_in_progress();
  clear_started();
}

// Note: this method, although exported by the ConcurrentMarkSweepThread,
// which is a non-JavaThread, can only be called by a JavaThread.
// Currently this is done at vm creation time (post-vm-init) by the
// main/Primordial (Java)Thread.
// XXX Consider changing this in the future to allow the CMS thread
// itself to create this thread?
void ConcurrentMarkThread::makeSurrogateLockerThread(TRAPS) {
  assert(_slt == NULL, "SLT already created");
  _slt = SurrogateLockerThread::make(THREAD);
}