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From "Joshua McKenzie (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6993) Windows: remove mmap'ed I/O for index files and force standard file access
Date Wed, 10 Dec 2014 16:38:12 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6993?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14241342#comment-14241342
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Joshua McKenzie commented on CASSANDRA-6993:
--------------------------------------------

Very good point.  Looking through the code-base, every place where we're using isUnix seems
to really mean 'isn't Windows' so I'd be comfortable with that distinction for now with the
ability to make it more complex/powerful in the future if necessary.   Also, right now we're
skipping early re-open on files based on that check for FBUtilities.isUnix (see CASSANDRA-7365)
so I'd prefer to get this modification in before 2.1.3 so we can get more coverage / usage
of the early re-open logic, at least on OSX-based dev machines.

> Windows: remove mmap'ed I/O for index files and force standard file access
> --------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6993
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6993
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Joshua McKenzie
>            Assignee: Joshua McKenzie
>            Priority: Minor
>              Labels: Windows
>             Fix For: 3.0, 2.1.3
>
>         Attachments: 6993_2.1_v1.txt, 6993_v1.txt, 6993_v2.txt
>
>
> Memory-mapped I/O on Windows causes issues with hard-links; we're unable to delete hard-links
to open files with memory-mapped segments even using nio.  We'll need to push for close to
performance parity between mmap'ed I/O and buffered going forward as the buffered / compressed
path offers other benefits.



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