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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2982) Startup performance suffers when there are many edit log segments
Date Fri, 18 May 2012 05:53:05 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2982?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13278591#comment-13278591
] 

Todd Lipcon commented on HDFS-2982:
-----------------------------------

Hi Colin. Many of my comments from HDFS-3049 still apply (eg about the lazy initialization
of the reader stream)

Are the changes to validateEditLog necessary here? And the change to how corrupt files are
handled? It seems like they fit more appropriately into HDFS-3049. I think you should be able
to separate those out from this performance fix.

The new test case is missing the @Test annotation so it won't run.


                
> Startup performance suffers when there are many edit log segments
> -----------------------------------------------------------------
>
>                 Key: HDFS-2982
>                 URL: https://issues.apache.org/jira/browse/HDFS-2982
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 2.0.0
>            Reporter: Todd Lipcon
>            Assignee: Colin Patrick McCabe
>            Priority: Critical
>         Attachments: HDFS-2982.001.patch
>
>
> For every one of the edit log segments, it seems like we are calling listFiles on the
edit log directory inside of {{findMaxTransaction}}. This is killing performance, especially
when there are many log segments and the directory is stored on NFS. It is taking several
minutes to start up the NN when there are several thousand log segments present.

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