view src/share/vm/gc_implementation/concurrentMarkSweep/cmsPermGen.hpp @ 452:00b023ae2d78

6722113: CMS: Incorrect overflow handling during precleaning of Reference lists Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery. Reviewed-by: apetrusenko, jcoomes
author ysr
date Thu, 20 Nov 2008 12:27:41 -0800
parents c0492d52d55b
children c18cbe5936b8
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/*
 * Copyright (c) 2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 */

class CardTableRS;   // fwd decl
class ConcurrentMarkSweepGeneration;

// A PermGen implemented with a CMS space, collected by a CMS collector.
class CMSPermGen:  public PermGen {
  friend class VMStructs;

 protected:
  // The "generation" view.
  ConcurrentMarkSweepGeneration* _gen;

 public:
  CMSPermGen(ReservedSpace rs, size_t initial_byte_size,
             CardTableRS* ct, FreeBlockDictionary::DictionaryChoice);

  HeapWord* mem_allocate(size_t size);

  void compute_new_size();

  Generation* as_gen() const { return _gen; }
};

// This is the "generation" view of a CMSPermGen.
class CMSPermGenGen: public ConcurrentMarkSweepGeneration {
  // Abstractly, this is a subtype that gets access to protected fields.
  friend class CMSPermGen;
public:
  CMSPermGenGen(ReservedSpace rs, size_t initial_byte_size,
                       int level, CardTableRS* ct):
    // See comments in the constructor for CompactibleFreeListSpace
    // regarding not using adaptive free lists for a perm gen.
    ConcurrentMarkSweepGeneration(rs, initial_byte_size, // MinPermHeapExapnsion
      level, ct, false /* use adaptive freelists */,
      (FreeBlockDictionary::DictionaryChoice)CMSDictionaryChoice)
  {}

  void initialize_performance_counters();

  const char* name() const {
    return "concurrent-mark-sweep perm gen";
  }

  const char* short_name() const {
    return "CMS Perm";
  }

  bool must_be_youngest() const { return false; }
  bool must_be_oldest() const { return false; }
};