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comparison src/share/vm/oops/markOop.cpp @ 6725:da91efe96a93

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6964458: Reimplement class meta-data storage to use native memory Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>
author coleenp
date Sat, 01 Sep 2012 13:25:18 -0400
parents f08d439fab8c
children f34d701e952e
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6724:36d1d483d5d6 6725:da91efe96a93
1 /* 1 /*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. 2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 * 4 *
5 * This code is free software; you can redistribute it and/or modify it 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 6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. 7 * published by the Free Software Foundation.
48 if (has_bias_pattern()) st->print("biased,"); 48 if (has_bias_pattern()) st->print("biased,");
49 st->print("hash %#lx,", hash()); 49 st->print("hash %#lx,", hash());
50 st->print("age %d)", age()); 50 st->print("age %d)", age());
51 } 51 }
52 } 52 }
53
54
55 // Give advice about whether the oop that contains this markOop
56 // should be cached or not.
57 bool markOopDesc::should_not_be_cached() const {
58 // the cast is because decode_pointer() isn't marked const
59 if (is_marked() && ((markOopDesc *)this)->decode_pointer() != NULL) {
60 // If the oop containing this markOop is being forwarded, then
61 // we are in the middle of GC and we do not want the containing
62 // oop to be added to a cache. We have no way of knowing whether
63 // the cache has already been visited by the current GC phase so
64 // we don't know whether the forwarded oop will be properly
65 // processed in this phase. If the forwarded oop is not properly
66 // processed, then we'll see strange crashes or asserts during
67 // the next GC run because the markOop will contain an unexpected
68 // value.
69 //
70 // This situation has been seen when we are GC'ing a methodOop
71 // because we use the methodOop while we're GC'ing it. Scary
72 // stuff. Some of the uses the methodOop cause the methodOop to
73 // be added to the OopMapCache in the instanceKlass as a side
74 // effect. This check lets the cache maintainer know when a
75 // cache addition would not be safe.
76 return true;
77 }
78
79 // caching the containing oop should be just fine
80 return false;
81 }