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https://issues.apache.org/jira/browse/HADOOP-3140?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12585273#action_12585273
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Devaraj Das commented on HADOOP-3140:
-------------------------------------

Dhruba, is that a documented exception. I didn't see it in the 
FileSystem.getContentSummary API doc. So if it is not documented is it 
advisable to bank client code on the exception? For e.g., what if 
getContentSummary, later on, returns null for non existent paths? So, unless 
FileSystem provides a guarantee that an exception will be thrown for 
non-existent paths, i'd like to go in the lines of what Amar mentioned in the 
code snippet. Thoughts?

> JobTracker should not try to promote a (map) task if it does not write to DFS 
> at all
> ------------------------------------------------------------------------------------
>
>                 Key: HADOOP-3140
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3140
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Runping Qi
>            Assignee: Amar Kamat
>             Fix For: 0.17.0
>
>         Attachments: HADOOP-3140-v1.patch, HADOOP-3140-v2.patch
>
>
> In most cases, map tasks do not write to dfs.
> Thus, when they complete, they should not be put into commit_pending queue at 
> all.
> This will improve the task promotion significantly.
>  

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