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From "Mahadev konar (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2489) Jobsplits with random hostnames can make the queue unusable
Date Mon, 01 Aug 2011 22:39:49 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13073838#comment-13073838
] 

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

Jeffrey,
 One minor nit, 

 The method:

{code}

  static void verifyHostnames(String[] names) throws UnknownHostException {
{code}

does not seem appropriate for JobInProgress class. It needs to be moved out to some helper
class. NetUtils seems more appropriate for this helper method. What do you think?


> 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.patch,
MAPREDUCE-2489-mapred-v2.patch, MAPREDUCE-2489-mapred-v3.patch, MAPREDUCE-2489-mapred-v4.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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