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https://issues.apache.org/jira/browse/MAPREDUCE-6020?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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zhihai xu updated MAPREDUCE-6020:
---------------------------------

    Attachment: MAPREDUCE-6020.branch1.patch

> Too many threads blocking on the global JobTracker lock from getJobCounters, 
> optimize getJobCounters to release global JobTracker lock before access the 
> per job counter in JobInProgress
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-6020
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6020
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>    Affects Versions: 0.23.10
>            Reporter: zhihai xu
>            Assignee: zhihai xu
>         Attachments: MAPREDUCE-6020.branch1.patch
>
>
> Too many threads blocking on the global JobTracker lock from getJobCounters, 
> optimize getJobCounters to release global JobTracker lock before access the 
> per job counter in JobInProgress. It may be a lot of JobClients to call 
> getJobCounters in JobTracker at the same time, Current code will lock the 
> JobTracker to block all the threads to get counter from JobInProgress. It is 
> better to unlock the JobTracker when get counter from 
> JobInProgress(job.getCounters(counters)). So all the theads can run parallel 
> when access its own job counter.



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