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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1213) TaskTrackers restart is very slow because it deletes distributed cache directory synchronously
Date Thu, 10 Dec 2009 22:58:18 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12788995#action_12788995
] 

Todd Lipcon commented on MAPREDUCE-1213:
----------------------------------------

Given that this almost duplicates the async disk service from the DN, could we move it into
o.a.h.io in Common? The duplication seems a bit ugly since this is a nontrivial class.

> TaskTrackers restart is very slow because it deletes distributed cache directory synchronously
> ----------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1213
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1213
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 0.20.1
>            Reporter: dhruba borthakur
>            Assignee: Zheng Shao
>         Attachments: MAPREDUCE-1213.1.patch
>
>
> We are seeing that when we restart a tasktracker, it tries to recursively delete all
the file in the distributed cache. It invoked FileUtil.fullyDelete() which is very very slow.
This means that the TaskTracker cannot join the cluster for an extended period of time (upto
2 hours for us). The problem is acute if the number of files in a distributed cache is a few-thousands.

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