view src/share/vm/memory/generationSpec.cpp @ 1716:be3f9c242c9d

6948538: CMS: BOT walkers can fall into object allocation and initialization cracks Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode. Reviewed-by: chrisphi, johnc, poonam
author ysr
date Mon, 16 Aug 2010 15:58:42 -0700
parents c18cbe5936b8
children f95d63e2154a
line wrap: on
line source

/*
 * Copyright (c) 2001, 2005, 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 "incls/_precompiled.incl"
# include "incls/_generationSpec.cpp.incl"

Generation* GenerationSpec::init(ReservedSpace rs, int level,
                                 GenRemSet* remset) {
  switch (name()) {
    case Generation::DefNew:
      return new DefNewGeneration(rs, init_size(), level);

    case Generation::MarkSweepCompact:
      return new TenuredGeneration(rs, init_size(), level, remset);

#ifndef SERIALGC
    case Generation::ParNew:
      return new ParNewGeneration(rs, init_size(), level);

    case Generation::ASParNew:
      return new ASParNewGeneration(rs,
                                    init_size(),
                                    init_size() /* min size */,
                                    level);

    case Generation::ConcurrentMarkSweep: {
      assert(UseConcMarkSweepGC, "UseConcMarkSweepGC should be set");
      CardTableRS* ctrs = remset->as_CardTableRS();
      if (ctrs == NULL) {
        vm_exit_during_initialization("Rem set incompatibility.");
      }
      // Otherwise
      // The constructor creates the CMSCollector if needed,
      // else registers with an existing CMSCollector

      ConcurrentMarkSweepGeneration* g = NULL;
      g = new ConcurrentMarkSweepGeneration(rs,
                 init_size(), level, ctrs, UseCMSAdaptiveFreeLists,
                 (FreeBlockDictionary::DictionaryChoice)CMSDictionaryChoice);

      g->initialize_performance_counters();

      return g;
    }

    case Generation::ASConcurrentMarkSweep: {
      assert(UseConcMarkSweepGC, "UseConcMarkSweepGC should be set");
      CardTableRS* ctrs = remset->as_CardTableRS();
      if (ctrs == NULL) {
        vm_exit_during_initialization("Rem set incompatibility.");
      }
      // Otherwise
      // The constructor creates the CMSCollector if needed,
      // else registers with an existing CMSCollector

      ASConcurrentMarkSweepGeneration* g = NULL;
      g = new ASConcurrentMarkSweepGeneration(rs,
                 init_size(), level, ctrs, UseCMSAdaptiveFreeLists,
                 (FreeBlockDictionary::DictionaryChoice)CMSDictionaryChoice);

      g->initialize_performance_counters();

      return g;
    }
#endif // SERIALGC

    default:
      guarantee(false, "unrecognized GenerationName");
      return NULL;
  }
}


PermanentGenerationSpec::PermanentGenerationSpec(PermGen::Name name,
                      size_t init_size, size_t max_size,
                      size_t read_only_size, size_t read_write_size,
                      size_t misc_data_size, size_t misc_code_size) {
  _name = name;
  _init_size = init_size;

  if (UseSharedSpaces || DumpSharedSpaces) {
    _enable_shared_spaces = true;
    if (UseSharedSpaces) {
      // Override shared space sizes from those in the file.
      FileMapInfo* mapinfo = FileMapInfo::current_info();
      _read_only_size = mapinfo->space_capacity(CompactingPermGenGen::ro);
      _read_write_size = mapinfo->space_capacity(CompactingPermGenGen::rw);
      _misc_data_size = mapinfo->space_capacity(CompactingPermGenGen::md);
      _misc_code_size = mapinfo->space_capacity(CompactingPermGenGen::mc);
    } else {
      _read_only_size = read_only_size;
      _read_write_size = read_write_size;
      _misc_data_size = misc_data_size;
      _misc_code_size = misc_code_size;
    }
  } else {
    _enable_shared_spaces = false;
    _read_only_size = 0;
    _read_write_size = 0;
    _misc_data_size = 0;
    _misc_code_size = 0;
  }

  _max_size = max_size;
}


PermGen* PermanentGenerationSpec::init(ReservedSpace rs,
                                       size_t init_size,
                                       GenRemSet *remset) {

  // Break the reserved spaces into pieces for the permanent space
  // and the shared spaces.
  ReservedSpace perm_rs = rs.first_part(_max_size, UseSharedSpaces,
                                        UseSharedSpaces);
  ReservedSpace shared_rs = rs.last_part(_max_size);

  if (enable_shared_spaces()) {
    if (!perm_rs.is_reserved() ||
        perm_rs.base() + perm_rs.size() != shared_rs.base()) {
      FileMapInfo* mapinfo = FileMapInfo::current_info();
      mapinfo->fail_continue("Sharing disabled - unable to "
                                 "reserve address space.");
      shared_rs.release();
      disable_sharing();
    }
  }

  switch (name()) {
    case PermGen::MarkSweepCompact:
      return new CompactingPermGen(perm_rs, shared_rs, init_size, remset, this);

#ifndef SERIALGC
    case PermGen::MarkSweep:
      guarantee(false, "NYI");
      return NULL;

    case PermGen::ConcurrentMarkSweep: {
      assert(UseConcMarkSweepGC, "UseConcMarkSweepGC should be set");
      CardTableRS* ctrs = remset->as_CardTableRS();
      if (ctrs == NULL) {
        vm_exit_during_initialization("RemSet/generation incompatibility.");
      }
      // XXXPERM
      return new CMSPermGen(perm_rs, init_size, ctrs,
                   (FreeBlockDictionary::DictionaryChoice)CMSDictionaryChoice);
    }
#endif // SERIALGC
    default:
      guarantee(false, "unrecognized GenerationName");
      return NULL;
  }
}


// Alignment
void PermanentGenerationSpec::align(size_t alignment) {
  _init_size       = align_size_up(_init_size,       alignment);
  _max_size        = align_size_up(_max_size,        alignment);
  _read_only_size  = align_size_up(_read_only_size,  alignment);
  _read_write_size = align_size_up(_read_write_size, alignment);
  _misc_data_size  = align_size_up(_misc_data_size,  alignment);
  _misc_code_size  = align_size_up(_misc_code_size,  alignment);

  assert(enable_shared_spaces() || (_read_only_size + _read_write_size == 0),
         "Shared space when disabled?");
}