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Date: Wed, 10 Aug 2011 21:17:28 +0000 (UTC)
From: "Jeffrey Naisbitt (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
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Subject: [jira] [Updated] (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:all-tabpanel ]

Jeffrey Naisbitt updated MAPREDUCE-2489:
----------------------------------------

    Status: Open  (was: Patch Available)

So, we discovered that the interface change is incompatible.  So, we are removing the incompatible change and the corresponding portion of code relying on that change and implementing the sanity check only.

> 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-v6.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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