jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp@e1162778c1c8 (annotated)

src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp@e1162778c1c8 (annotated)

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

Thu, 07 Apr 2011 09:53:20 -0700

author: johnc
date: Thu, 07 Apr 2011 09:53:20 -0700
changeset 2781: e1162778c1c8
parent 2314: f95d63e2154a
child 3463: d30fa85f9994
permissions: -rw-r--r--

7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes

 /*
  * 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
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  */
 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP
 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP
 #include "gc_implementation/shared/concurrentGCThread.hpp"
 // The Concurrent Mark GC Thread (could be several in the future).
 // This is copied from the Concurrent Mark Sweep GC Thread
 // Still under construction.
 class ConcurrentMark;
 class ConcurrentMarkThread: public ConcurrentGCThread {
   friend class VMStructs;
   double _vtime_start;  // Initial virtual time.
   double _vtime_accum;  // Accumulated virtual time.
   double _vtime_mark_accum;
   double _vtime_count_accum;
  public:
   virtual void run();
  private:
   ConcurrentMark*                  _cm;
   volatile bool                    _started;
   volatile bool                    _in_progress;
   void sleepBeforeNextCycle();
   static SurrogateLockerThread*         _slt;
  public:
   // Constructor
   ConcurrentMarkThread(ConcurrentMark* cm);
   static void makeSurrogateLockerThread(TRAPS);
   static SurrogateLockerThread* slt() { return _slt; }
   // Printing
   void print_on(outputStream* st) const;
   void print() const;
   // Total virtual time so far.
   double vtime_accum();
   // Marking virtual time so far
   double vtime_mark_accum();
   // Counting virtual time so far.
   double vtime_count_accum() { return _vtime_count_accum; }
   ConcurrentMark* cm()     { return _cm; }
   void set_started()       { assert(!_in_progress, "cycle in progress"); _started = true;  }
   void clear_started()     { assert(_in_progress, "must be starting a cycle"); _started = false; }
   bool started()           { return _started;  }
   void set_in_progress()   { assert(_started, "must be starting a cycle"); _in_progress = true;  }
   void clear_in_progress() { assert(!_started, "must not be starting a new cycle"); _in_progress = false; }
   bool in_progress()       { return _in_progress;  }
   // This flag returns true from the moment a marking cycle is
   // initiated (during the initial-mark pause when started() is set)
   // to the moment when the cycle completes (just after the next
   // marking bitmap has been cleared and in_progress() is
   // cleared). While this flag is true we will not start another cycle
   // so that cycles do not overlap. We cannot use just in_progress()
   // as the CM thread might take some time to wake up before noticing
   // that started() is set and set in_progress().
   bool during_cycle()      { return started() || in_progress(); }
   // Yield for GC
   void            yield();
   // shutdown
   void stop();
 };
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP

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src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp@e1162778c1c8 (annotated)

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