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From "Michael McCandless (JIRA)" <>
Subject [jira] Updated: (LUCENE-753) Use NIO positional read to avoid synchronization in FSIndexInput
Date Thu, 17 Jul 2008 18:19:31 GMT


Michael McCandless updated LUCENE-753:

    Attachment: FSDirectoryPool.patch

I attached FSDirectoryPool.patch, which adds, a Directory that will open a new file for
every unique thread.

This is intended only as a test (to see if shows consistent
improvement in concurrency) -- eg it does not close all these files,
nor make any effort to budget itself if there are too many threads,
it's not really a pool, etc.  But it should give us an upper bound on
the gains we could hope for.

I also added a "pool=true|false" config option to contrib/benchmark so
you can run tests with and without separate files.

I ran some quick initial tests but didn't see obvious gains.  I'll go
back & re-run more carefully to confirm, and post back.

> Use NIO positional read to avoid synchronization in FSIndexInput
> ----------------------------------------------------------------
>                 Key: LUCENE-753
>                 URL:
>             Project: Lucene - Java
>          Issue Type: New Feature
>          Components: Store
>            Reporter: Yonik Seeley
>         Attachments:,,,,,,, FSDirectoryPool.patch, FSIndexInput.patch,
FSIndexInput.patch, lucene-753.patch, lucene-753.patch
> As suggested by Doug, we could use NIO pread to avoid synchronization on the underlying
> This could mitigate any MT performance drop caused by reducing the number of files in
the index format.

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