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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-2216) speculation should normalize progress rates based on amount of input data
Date Fri, 10 Dec 2010 02:21:02 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12970055#action_12970055
] 

Devaraj Das commented on MAPREDUCE-2216:
----------------------------------------

MAPREDUCE-718?

> speculation should normalize progress rates based on amount of input data
> -------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-2216
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2216
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: jobtracker
>            Reporter: Joydeep Sen Sarma
>
> We frequently see skews in data distribution both on the mappers and reducers. The small
ones finish quickly and the longer ones immediately get speculated. We should normalize progress
rates used by speculation with some metric correlated to the amount of data processed by the
task (like bytes read of rows processed). That will prevent these unnecessary speculations.

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