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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: maxSplits6.patch
Thanks to Amar for your comments. I am attaching a new patch that looks at the
allocated tasks for each job and matches that with the specified limit. Amar:
can you pl review this latest patch? Thanks.
@Vinod: the proposed mapred.max.tasks.per.jobtracker is used to limit the
memory usage of the jobtracker. We need to count how many tasks (failed,
completed, running, etc) are resident in memory. I believe that
mapred.jobtracker.completeuserjobs.maximum does not satifsy that requirement. I
do not know much about org.apache.hadoop.mapred.LimitTasksPerJobTaskScheduler,
maybe Amar can comment on that,
> 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, maxSplits3.patch,
> maxSplits4.patch, maxSplits5.patch, maxSplits6.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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