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Posted to dev@lucene.apache.org by "Michael McCandless (JIRA)" <ji...@apache.org> on 2008/11/17 11:30:44 UTC
[jira] Resolved: (LUCENE-1309) Using IndexSearcher in a
multithreaded context causes contention
[ https://issues.apache.org/jira/browse/LUCENE-1309?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael McCandless resolved LUCENE-1309.
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Resolution: Duplicate
Dup of LUCENE-1329 (readOnly IndexReader) and LUCENE-753 (NIOFSDirectory), at least on non-Windows platforms.
Based on this user report it seems like sharing an IndexReader across multiple threads in fact gives better performance than thread-private IndexReader instances:
http://www.nabble.com/IndexSearcher-and-multi-threaded-performance-td20449375.html
> Using IndexSearcher in a multithreaded context causes contention
> ----------------------------------------------------------------
>
> Key: LUCENE-1309
> URL: https://issues.apache.org/jira/browse/LUCENE-1309
> Project: Lucene - Java
> Issue Type: Bug
> Affects Versions: 2.3.1, 2.3.2
> Environment: * WinXP, Dual Core Centrino
> * Opensuse Linux, Dual Core AMD
> java version "1.6.0_06"
> Java(TM) SE Runtime Environment (build 1.6.0_06-b02)
> Java HotSpot(TM) Client VM (build 10.0-b22, mixed mode, sharing)
> Reporter: Rene Schwietzke
> Attachments: yad.zip
>
>
> The attached code allows to search with a single IndexSearcher across threads or with a single instance per Thread, additionally it allows to deals with String.intern in Field from LUCENE-1308.
> Really interesting is the behavior of the current implementation (Field String.intern) The performance improves dramatically.
> Is this by design? Because it is usually recommended to reuse the IndexSearcher. How about a version to supports mult-threading much better basically delivering a read-only view?
> The following results have been measured. The [main] part is a single threaded run. The following thread results
> _Field String.intern, Single Searcher_
> [main] Search took: 3453ms
> [Thread-2] Search took: 17812ms
> [Thread-3] Search took: 18313ms
> [Thread-1] Search took: 18234ms
> [Thread-0] Search took: 18562ms
> _Field WeakHashMap, Single Searcher_
> [main] Search took: 3156ms
> [Thread-3] Search took: 14953ms
> [Thread-1] Search took: 15593ms
> [Thread-0] Search took: 15656ms
> [Thread-2] Search took: 16188ms
> _Field ConcurrentHashMap, Single Searcher_
> [main] Search took: 2844ms
> [Thread-1] Search took: 14812ms
> [Thread-0] Search took: 14890ms
> [Thread-2] Search took: 15172ms
> [Thread-3] Search took: 14656ms
> _Field intern, Searcher per Thread_
> [main] Search took: 3687ms
> [Thread-2] Search took: 10766ms
> [Thread-1] Search took: 10734ms
> [Thread-0] Search took: 11047ms
> [Thread-3] Search took: 10938ms
> _Field Weak, Searcher per Thread_
> [main] Search took: 3187ms
> [Thread-3] Search took: 11625ms
> [Thread-2] Search took: 12484ms
> [Thread-1] Search took: 12609ms
> [Thread-0] Search took: 12391ms
> _Field Concurrent, Searcher per Thread_
> [main] Search took: 2938ms
> [Thread-3] Search took: 10203ms
> [Thread-2] Search took: 10360ms
> [Thread-1] Search took: 10406ms
> [Thread-0] Search took: 10719ms
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