Mercurial > hg > graal-jvmci-8
annotate src/share/vm/runtime/sweeper.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 |
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date | Mon, 16 Aug 2010 15:58:42 -0700 |
parents | 2a47bd84841f |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2010, 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 // An NmethodSweeper is an incremental cleaner for: | |
26 // - cleanup inline caches | |
27 // - reclamation of unreferences zombie nmethods | |
28 // | |
29 | |
30 class NMethodSweeper : public AllStatic { | |
31 static long _traversals; // Stack traversal count | |
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32 static nmethod* _current; // Current nmethod |
0 | 33 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache |
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34 |
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35 static volatile int _invocations; // No. of invocations left until we are completed with this pass |
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36 static volatile int _sweep_started; // Flag to control conc sweeper |
0 | 37 |
38 static bool _rescan; // Indicates that we should do a full rescan of the | |
39 // of the code cache looking for work to do. | |
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40 static bool _do_sweep; // Flag to skip the conc sweep if no stack scan happened |
0 | 41 static int _locked_seen; // Number of locked nmethods encountered during the scan |
42 static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack | |
43 | |
1202 | 44 static bool _was_full; // remember if we did emergency unloading |
45 static jint _advise_to_sweep; // flag to indicate code cache getting full | |
46 static jlong _last_was_full; // timestamp of last emergency unloading | |
47 static uint _highest_marked; // highest compile id dumped at last emergency unloading | |
48 static long _was_full_traversal; // trav number at last emergency unloading | |
0 | 49 |
50 static void process_nmethod(nmethod *nm); | |
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51 |
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52 static void log_sweep(const char* msg, const char* format = NULL, ...); |
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53 |
0 | 54 public: |
55 static long traversal_count() { return _traversals; } | |
56 | |
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57 static void scan_stacks(); // Invoked at the end of each safepoint |
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58 static void sweep_code_cache(); // Concurrent part of sweep job |
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59 static void possibly_sweep(); // Compiler threads call this to sweep |
0 | 60 |
61 static void notify(nmethod* nm) { | |
62 // Perform a full scan of the code cache from the beginning. No | |
63 // need to synchronize the setting of this flag since it only | |
64 // changes to false at safepoint so we can never overwrite it with false. | |
65 _rescan = true; | |
66 } | |
1202 | 67 |
68 static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate | |
69 static void speculative_disconnect_nmethods(bool was_full); // Called by vm op to deal with alloc failure | |
70 | |
71 static void set_was_full(bool state) { _was_full = state; } | |
72 static bool was_full() { return _was_full; } | |
0 | 73 }; |