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From "Mathieu Poumeyrol (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-201) BufferedPositionedInputStream is not buffered
Date Thu, 10 Apr 2008 09:52:06 GMT

    [ https://issues.apache.org/jira/browse/PIG-201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12587558#action_12587558
] 

Mathieu Poumeyrol commented on PIG-201:
---------------------------------------

Ho ! The 8Kb buffer size is just plain guess. I honestly have no idea about the "right" value.

> BufferedPositionedInputStream is not buffered
> ---------------------------------------------
>
>                 Key: PIG-201
>                 URL: https://issues.apache.org/jira/browse/PIG-201
>             Project: Pig
>          Issue Type: Bug
>            Reporter: Mathieu Poumeyrol
>         Attachments: BufferedPositionedInputStream.patch
>
>
> BufferedPositionedInputStream is actualy not buffered, leading (I guess) to constant
round trip to dfs as byte are read one by one. I just wrapped the provided input stream in
the constructor in a good old BufferedInputStream.
> I measured a 40% performance boost on a script that reads and writes 3.7GB in dfs through
PigStorage on one node. I guess the impact may be greater on a real hdfs cluster with actual
network roundtrips.
> FYI, the issue was found while profiling with Yourkit java profiler. Usefull toy...

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