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https://issues.apache.org/jira/browse/HADOOP-5049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12666424#action_12666424
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Owen O'Malley commented on HADOOP-5049:
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No, I'm saying that the correct behavior should be to run the init, reduce, and
cleanup tasks, even when there are 0 maps. Think of a system that wants to run
every 5 minutes to do roll ups. I think it makes more sense to have a directory
with empty output files than a missing one if there was no input data.
In terms of the fix to the immediate problem, I think that all changes to the
job state should be set to the listeners. Doesn't that solve the original
problem?
> Jobs with 0 maps will never get removed from the default scheduler
> ------------------------------------------------------------------
>
> Key: HADOOP-5049
> URL: https://issues.apache.org/jira/browse/HADOOP-5049
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Reporter: Amar Kamat
> Assignee: Amar Kamat
> Priority: Blocker
> Fix For: 0.20.0
>
> Attachments: HADOOP-5049-v1.1.patch
>
>
> Jobs' with 0 maps finish/succeed in the init phase i.e while the job is in
> the _PREP_ state. {{EagerTaskInitializationListener}} removes the job after
> initing but {{JobQueueJobInProgressListener}} waits for a job-state change
> event to be raised and aonly then removes the job from the queue and hence
> the job will stay forever with the {{JobQueueJobInProgressListener}}. Looks
> like {{FairScheduler}} periodically scans the job list and removes completed
> jobs. {{CapacityScheduler}} has a concept of waiting jobs and scans waiting
> queue for completed jobs and purges them.
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