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From "Vinod K V (JIRA)" <j...@apache.org>
Subject [jira] Updated: (MAPREDUCE-1829) JobInProgress.findSpeculativeTask should use min() to find the candidate instead of sort()
Date Fri, 11 Jun 2010 07:32:15 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-1829?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Vinod K V updated MAPREDUCE-1829:
---------------------------------

    Status: Patch Available  (was: Open)

Yes, slowestTIP is actually reflective, we launch speculative attempts for TIPs which have
the slowest progress-rate.

> JobInProgress.findSpeculativeTask should use min() to find the candidate instead of sort()
> ------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1829
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1829
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: jobtracker
>    Affects Versions: 0.22.0
>            Reporter: Scott Chen
>            Assignee: Scott Chen
>             Fix For: 0.22.0
>
>         Attachments: MAPREDUCE-1829-20100610.txt, MAPREDUCE-1829.txt
>
>
> findSpeculativeTask needs only one candidate to speculate so it does not need to sort
the whole list. It may looks OK but someone can still submit big jobs with small slow task
thresholds. In this case, this sorting becomes expensive.

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