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Posted to mapreduce-issues@hadoop.apache.org by "Nigel Daley (JIRA)" <ji...@apache.org> on 2010/12/13 20:00:17 UTC

[jira] Commented: (MAPREDUCE-2026) JobTracker.getJobCounters() should not hold JobTracker lock while calling JobInProgress.getCounters()

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2026?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12970960#action_12970960 ] 

Nigel Daley commented on MAPREDUCE-2026:
----------------------------------------

Hi Joydeep, I see you have a number of issues where this request seems to be ignored:
 
{quote}
[exec] Please justify why no new tests are needed for this patch.
[exec] Also please list what manual steps were performed to verify this patch.
{quote}

Can you please provide this info for your patches?

Thanks!

> 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
>             Fix For: 0.22.0
>
>         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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