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Posted to dev@lucene.apache.org by "Uwe Schindler (JIRA)" <ji...@apache.org> on 2013/03/20 20:11:17 UTC
[jira] [Updated] (LUCENE-4864) Add AsyncFSDirectory to work around
Windows issues with NIOFS (Lucene 5.0 only)
[ https://issues.apache.org/jira/browse/LUCENE-4864?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Uwe Schindler updated LUCENE-4864:
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Description:
On LUCENE-4848 a new directory implementation was proposed that uses AsyncFileChannel to make a sync-less directory implementation (only needed for IndexInput). The problem on Windows is that positional reads are impossible without overlapping (async) I/O, so FileChannel in the JDK has to syncronize all reads, because they consist of an atomic seek and atomic read.
AsyncFSDirectoty would not have this issue, but has to take care of thread management, because you need a separate thread to get notified when the read is done. This involves overhead, but might still be better than the synchronization.
was:
On LUCENE-4848 a new directory implementation was proposed that uses AsyncFileChannel to make a sync-less directory implementation (only needed for IndexInput). The problem on Windows is that positional reads are impossible without overlapping (async I/O), so FileChannel in the JDK has to syncronize all reads, because they consist of an atomic seek and atomic read.
AsyncFSDirectoty would not have this issue, but has to take care of thread management.
> Add AsyncFSDirectory to work around Windows issues with NIOFS (Lucene 5.0 only)
> -------------------------------------------------------------------------------
>
> Key: LUCENE-4864
> URL: https://issues.apache.org/jira/browse/LUCENE-4864
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/store
> Reporter: Uwe Schindler
>
> On LUCENE-4848 a new directory implementation was proposed that uses AsyncFileChannel to make a sync-less directory implementation (only needed for IndexInput). The problem on Windows is that positional reads are impossible without overlapping (async) I/O, so FileChannel in the JDK has to syncronize all reads, because they consist of an atomic seek and atomic read.
> AsyncFSDirectoty would not have this issue, but has to take care of thread management, because you need a separate thread to get notified when the read is done. This involves overhead, but might still be better than the synchronization.
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