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https://issues.apache.org/jira/browse/MAPREDUCE-6166?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14248348#comment-14248348
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Hudson commented on MAPREDUCE-6166:
-----------------------------------
FAILURE: Integrated in Hadoop-Mapreduce-trunk-Java8 #44 (See
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk-Java8/44/])
MAPREDUCE-6166. Reducers do not validate checksum of map outputs when fetching
directly to disk. (Eric Payne via gera) (gera: rev
af006937e8ba82f98f468dc7375fe89c2e0a7912)
*
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/OnDiskMapOutput.java
* hadoop-mapreduce-project/CHANGES.txt
*
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestFetcher.java
> Reducers do not validate checksum of map outputs when fetching 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
> Fix For: 2.7.0
>
> 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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