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Eric Payne commented on MAPREDUCE-6166: --------------------------------------- [~jira.shegalov], did that make sense? > Reducers do not catch bad 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 > > > 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)