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From "Eric Payne (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-6166) Reducers do not catch corrupted map output transfers during shuffle if data shuffled directly to disk
Date Thu, 11 Dec 2014 17:10:15 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-6166?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Eric Payne updated MAPREDUCE-6166:
----------------------------------
    Summary: Reducers do not catch corrupted map output transfers during shuffle if data shuffled
directly to disk  (was: Reducers do not catch bad map output transfers during shuffle if data
shuffled directly to disk)

> Reducers do not catch corrupted map output transfers during shuffle if data shuffled
directly to disk
> -----------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-6166
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6166
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv2
>    Affects Versions: 2.6.0
>            Reporter: Eric Payne
>            Assignee: Eric Payne
>         Attachments: MAPREDUCE-6166.v1.201411221941.txt, MAPREDUCE-6166.v2.201411251627.txt,
MAPREDUCE-6166.v3.txt, MAPREDUCE-6166.v4.txt, MAPREDUCE-6166.v5.txt
>
>
> In very large map/reduce jobs (50000 maps, 2500 reducers), the intermediate map partition
output gets corrupted on disk on the map side. If this corrupted map output is too large to
shuffle in memory, the reducer streams it to disk without validating the checksum. In jobs
this large, it could take hours before the reducer finally tries to read the corrupted file
and fails. Since retries of the failed reduce attempt will also take hours, this delay in
discovering the failure is multiplied greatly.



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