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Date: Sat, 6 Aug 2011 18:04:27 +0000 (UTC)
From: "Mahadev konar (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
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Subject: [jira] [Commented] (MAPREDUCE-2489) Jobsplits with random hostnames
 can make the queue unusable
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-2489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080438#comment-13080438 ] 

Mahadev konar commented on MAPREDUCE-2489:
------------------------------------------

+1 for 0.20S patch. I have committed that to the branch. Thanks Jeffrey. I'll wait for the trunk common and mapred patches before closing this jira.


> Jobsplits with random hostnames can make the queue unusable
> -----------------------------------------------------------
>
>                 Key: MAPREDUCE-2489
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2489
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: jobtracker
>    Affects Versions: 0.20.205.0, 0.23.0
>            Reporter: Jeffrey Naisbitt
>            Assignee: Jeffrey Naisbitt
>             Fix For: 0.20.205.0, 0.23.0
>
>         Attachments: MAPREDUCE-2489-0.20s-v2.patch, MAPREDUCE-2489-0.20s-v3.patch, MAPREDUCE-2489-0.20s-v4.patch, MAPREDUCE-2489-0.20s-v5.patch, MAPREDUCE-2489-0.20s.patch, MAPREDUCE-2489-mapred-v2.patch, MAPREDUCE-2489-mapred-v3.patch, MAPREDUCE-2489-mapred-v4.patch, MAPREDUCE-2489-mapred-v5.patch, MAPREDUCE-2489-mapred.patch
>
>
> We saw an issue where a custom InputSplit was returning invalid hostnames for the splits that were then causing the JobTracker to attempt to excessively resolve host names.  This caused a major slowdown for the JobTracker.  We should prevent invalid InputSplit hostnames from affecting everyone else.
> I propose we implement some verification for the hostnames to try to ensure that we only do DNS lookups on valid hostnames (and fail otherwise).  We could also fail the job after a certain number of failures in the resolve.

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