Mercurial > hg > graal-compiler
annotate src/share/vm/memory/referencePolicy.hpp @ 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 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 25 // referencePolicy is used to determine when soft reference objects | |
| 26 // should be cleared. | |
| 27 | |
| 28 | |
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29 class ReferencePolicy : public CHeapObj { |
| 0 | 30 public: |
| 31 virtual bool should_clear_reference(oop p) { ShouldNotReachHere(); return true; } | |
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32 // Capture state (of-the-VM) information needed to evaluate the policy |
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33 virtual void setup() { /* do nothing */ } |
| 0 | 34 }; |
| 35 | |
| 36 class NeverClearPolicy : public ReferencePolicy { | |
| 37 public: | |
| 38 bool should_clear_reference(oop p) { return false; } | |
| 39 }; | |
| 40 | |
| 41 class AlwaysClearPolicy : public ReferencePolicy { | |
| 42 public: | |
| 43 bool should_clear_reference(oop p) { return true; } | |
| 44 }; | |
| 45 | |
| 46 class LRUCurrentHeapPolicy : public ReferencePolicy { | |
| 47 private: | |
| 48 jlong _max_interval; | |
| 49 | |
| 50 public: | |
| 51 LRUCurrentHeapPolicy(); | |
| 52 | |
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53 // Capture state (of-the-VM) information needed to evaluate the policy |
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54 void setup(); |
| 0 | 55 bool should_clear_reference(oop p); |
| 56 }; | |
| 57 | |
| 58 class LRUMaxHeapPolicy : public ReferencePolicy { | |
| 59 private: | |
| 60 jlong _max_interval; | |
| 61 | |
| 62 public: | |
| 63 LRUMaxHeapPolicy(); | |
| 64 | |
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65 // Capture state (of-the-VM) information needed to evaluate the policy |
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66 void setup(); |
| 0 | 67 bool should_clear_reference(oop p); |
| 68 }; |