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Joydeep Sen Sarma commented on MAPREDUCE-2026:
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yeah - i think we have this patch in production for many months now - let me regenerate the
patch since it's been a long while.
> JobTracker.getJobCounters() should not hold JobTracker lock while calling JobInProgress.getCounters()
> -----------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-2026
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2026
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: Scott Chen
> Assignee: Joydeep Sen Sarma
> Attachments: 2026.1.patch, MAPREDUCE-2026.txt
>
>
> JobTracker.getJobCounter() will lock JobTracker and call JobInProgress.getCounters().
> JobInProgress.getCounters() can be very expensive because it aggregates all the task
counters.
> We found that from the JobTracker jstacks that this method is one of the bottleneck of
the JobTracker performance.
> JobInProgress.getCounters() should be able to be called out side the JobTracker lock
because it already has JobInProgress lock.
> For example, it is used by jobdetails.jsp without a JobTracker lock.
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