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From "Earwin Burrfoot (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-1658) Absorb NIOFSDirectory into FSDirectory
Date Mon, 01 Jun 2009 10:58:07 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-1658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12715057#action_12715057
] 

Earwin Burrfoot commented on LUCENE-1658:
-----------------------------------------

bq. I'm a bit nervous about creating MMapDirectory automatically for any OS, not just Windows.
It's almost okay for 64bit systems.

bq. The "hack" also saves transient disk space, on all systems, right?
That's a nice catch. Now I have some of the non-buggy-but-weird behaviour my app exhibits
explained.

bq. But they have a 64 bit buffer, so you could use it instead of many buffers.
They don't. When NIO2 project was merged into OpenJDK, they left some stuff unmerged, including
64bit buffers. Currently they aren't present in OpenJDK and Java7 preview builds, and not
even a rough estimate is given on whether they are going to make it through, and when.

bq. Maybe we should move this hack to contrib ( a class that extends MMapDirectory by adding
a close method) with a big warning!
I support this. The hack has some merits if carefully applied, but is outright too dangerous
to ship it as default.

> Absorb NIOFSDirectory into FSDirectory
> --------------------------------------
>
>                 Key: LUCENE-1658
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1658
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Store
>            Reporter: Michael McCandless
>            Assignee: Uwe Schindler
>            Priority: Minor
>             Fix For: 2.9
>
>         Attachments: LUCENE-1658-take2.patch, LUCENE-1658-take2.patch, LUCENE-1658-take3.patch,
LUCENE-1658-take3.patch, LUCENE-1658-take3.patch, LUCENE-1658-take3.patch, LUCENE-1658-take3.patch,
LUCENE-1658.patch, LUCENE-1658.patch, LUCENE-1658.patch
>
>
> I think whether one uses java.io.* vs java.nio.* or eventually
> java.nio2.*, or some other means, is an under-the-hood implementation
> detail of FSDirectory and doesn't merit a whole separate class.
> I think FSDirectory should be the core class one uses when one's index
> is in the filesystem.
> So, I'd like to deprecate NIOFSDirectory, absorbing it into
> FSDirectory, and add a setting "useNIO" to FSDirectory.  It should
> default to "true" for non-Windows OSs, because it gives far better
> concurrent performance on all platforms but Windows (due to known Sun
> JRE issue http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6265734).

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