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https://issues.apache.org/jira/browse/HADOOP-1077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12478836
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David Bowen commented on HADOOP-1077:
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It is nice to see a patch with such good comments!
At the risk of being a coding-style bore, here are a couple of very minor
suggestions: (1) long synchronized blocks are a bit hard to read given the
two-space indentation style - it may be preferable to break them out into
separate methods; (2) some may disagree, but I see no need to write method
arguments like "new Integer(loc.getMapId())" when you can now write just
"loc.getMapId()" and the compiler will automatically do the conversion.
> Race condition in fetching map outputs (might lead to hung reduces)
> -------------------------------------------------------------------
>
> Key: HADOOP-1077
> URL: https://issues.apache.org/jira/browse/HADOOP-1077
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Reporter: Devaraj Das
> Assigned To: Devaraj Das
> Attachments: 1077.patch
>
>
> Sometimes when a map task is lost while the map-output fetch is happening
> from the TT for that task, and the lost map has successfully executed on some
> other node, the event for that successful execution is lost at the fetching
> TT. The fetching TT might eventually fail to fetch the output for the lost
> task, but then since the event for the new run of the lost map might also
> have been lost, the fetching TT might hang.
> This "hung" problem was discovered while working on HADOOP-1060.
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