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Posted to common-issues@hadoop.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2009/11/05 01:47:32 UTC

[jira] Commented: (HADOOP-3205) Read multiple chunks directly from FSInputChecker subclass into user buffers

    [ https://issues.apache.org/jira/browse/HADOOP-3205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12773731#action_12773731 ] 

Todd Lipcon commented on HADOOP-3205:
-------------------------------------

Just reran benchmarks with 128K io.file.buffer.size. All of the improvements stayed practically identical, percentage-wise.

> Read multiple chunks directly from FSInputChecker subclass into user buffers
> ----------------------------------------------------------------------------
>
>                 Key: HADOOP-3205
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3205
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: fs
>            Reporter: Raghu Angadi
>            Assignee: Todd Lipcon
>         Attachments: hadoop-3205.txt
>
>
> Implementations of FSInputChecker and FSOutputSummer like DFS do not have access to full user buffer. At any time DFS can access only up to 512 bytes even though user usually reads with a much larger buffer (often controlled by io.file.buffer.size). This requires implementations to double buffer data if an implementation wants to read or write larger chunks of data from underlying storage.
> We could separate changes for FSInputChecker and FSOutputSummer into two separate jiras.

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