jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp@4dfb2df418f2 (annotated)

src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp@4dfb2df418f2 (annotated)

src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp

Thu, 22 Sep 2011 10:57:37 -0700

author: johnc
date: Thu, 22 Sep 2011 10:57:37 -0700
changeset 3175: 4dfb2df418f2
parent 3065: ff53346271fe
child 3208: ec4b032a4977
permissions: -rw-r--r--

6484982: G1: process references during evacuation pauses
Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

 /*
  * Copyright (c) 2001, 2011, 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 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* 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]");
       }
       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 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();
         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::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);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp@4dfb2df418f2 (annotated)

src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp