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https://issues.apache.org/jira/browse/HADOOP-4018?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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dhruba borthakur updated HADOOP-4018:
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Attachment: maxSplits2.patch
This patch fails a job if the jobtracker detects that the number of splits for
the job exceeds a configures upper limit. Please let me know of any gotchas
that this patch might have.
I like the idea of having an upper limit of all tasks for the entire
jobtracker. But I have not yet implemented it. Do you think I should implement
it as part of this patch?
BTW, in our cluster, we have set mapred.jobtracker.completeuserjobs.maximum to
20 already.
> limit memory usage in jobtracker
> --------------------------------
>
> Key: HADOOP-4018
> URL: https://issues.apache.org/jira/browse/HADOOP-4018
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: maxSplits.patch, maxSplits2.patch
>
>
> We have seen instances when a user submitted a job with many thousands of
> mappers. The JobTracker was running with 3GB heap, but it was still not
> enough to prevent memory trashing from Garbage collection; effectively the
> Job Tracker was not able to serve jobs and had to be restarted.
> One simple proposal would be to limit the maximum number of tasks per job.
> This can be a configurable parameter. Is there other things that eat huge
> globs of memory in job Tracker?
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