jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp@b7a938236e43 (annotated)

src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp@b7a938236e43 (annotated)

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

Mon, 31 Jan 2011 16:28:40 -0500

author: tonyp
date: Mon, 31 Jan 2011 16:28:40 -0500
changeset 2501: b7a938236e43
parent 2492: a672e43650cc
child 2643: 1216415d8e35
permissions: -rw-r--r--

7014679: G1: deadlock during concurrent cleanup
Summary: There's a potential deadlock between the concurrent cleanup thread and the GC workers that are trying to allocate and waiting for more free regions to be made available.
Reviewed-by: iveresov, jcoomes

 /*
  * 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 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* 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::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@b7a938236e43 (annotated)

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