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Posted to common-dev@hadoop.apache.org by "Jothi Padmanabhan (JIRA)" <ji...@apache.org> on 2009/05/19 11:37:45 UTC

[jira] Commented: (HADOOP-5850) map/reduce doesn't run jobs with 0 maps

    [ https://issues.apache.org/jira/browse/HADOOP-5850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12710678#action_12710678 ] 

Jothi Padmanabhan commented on HADOOP-5850:
-------------------------------------------

Changes to JobInProgress looks fine.
Could you add an assertion to the test case to verify presence of empty output directories as well? That should fail without the patch and should pass with the patch.

> map/reduce doesn't run jobs with 0 maps
> ---------------------------------------
>
>                 Key: HADOOP-5850
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5850
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.20.0
>            Reporter: Owen O'Malley
>            Assignee: Vinod K V
>            Priority: Critical
>             Fix For: 0.20.1
>
>         Attachments: HADOOP-5850-20090519.txt
>
>
> Currently, the framework ignores jobs that have 0 maps. This is incorrect. Many pipelines need the job to run (if nothing else, to create the output directory!) so that subsequent jobs don't fail. Effectively, there will be no map tasks and the reduce tasks should immediately set up the Reducer and RecordWriter and then call close on both since there are no inputs to the reduce. I believe it should just work if we remove the check...

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