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From "Johan Oskarsson (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-2172) PositionCache was removed from FSDataInputStream, causes extremely bad MapFile performance
Date Thu, 08 Nov 2007 19:11:51 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-2172?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Johan Oskarsson updated HADOOP-2172:
------------------------------------

    Attachment: positioncache-v1.patch

This patch brings back the PositionCache from 0.13.1. It appears the position cache previously
did not keep track of long skip(long) or int read(). This has been added.

Passes all the tests on 0.14.3 and has been tested on a 35 node cluster.

> PositionCache was removed from FSDataInputStream, causes extremely bad MapFile performance
> ------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-2172
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2172
>             Project: Hadoop
>          Issue Type: Bug
>    Affects Versions: 0.14.3, 0.15.0
>            Reporter: Johan Oskarsson
>            Assignee: Johan Oskarsson
>            Priority: Blocker
>         Attachments: positioncache-v1.patch
>
>
> The PositionCache in FSDataInputStream seems to have been removed in HADOOP-1470. This
causes for example MapFile.get usage to be  extremely slow as the file position isn't cached
in memory.

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