Mercurial > hg > graal-jvmci-8
annotate src/share/vm/runtime/sweeper.hpp @ 1887:cd3ef3fd20dd
6992998: CMSWaitDuration=0 causes hangs with +ExplicitGCInvokesConcurrent
Summary: Closed a timing hole during which concurrent full gc requests can be missed. The hole can increase the latency of the response to a full gc request by up to the value of CMSWaitDuration. If CMSWaitDuration=0 is, as currently, interpreted as an unbounded wait, suitable in certain tuning scenarios, the application can potentially hang. Made two obscure tunables, including CMSWaitDuration, manageable.
Reviewed-by: jcoomes, tonyp
author | ysr |
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date | Thu, 21 Oct 2010 17:29:24 -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 }; |