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https://issues.apache.org/jira/browse/HADOOP-492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12473552
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Runping Qi commented on HADOOP-492:
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As a user, I normally am interested only in the final accumulated values of my 
counters, and  don't need/want to know them as the job runs.
I think each task can do local aggregations for the counters. If I need to 
display during  it, I can explicitly get the values and call 
Reporter.setStatus() method (or LOG) for that purpose. That way, I can control 
the frequence of the refreshment.



> Global counters
> ---------------
>
>                 Key: HADOOP-492
>                 URL: https://issues.apache.org/jira/browse/HADOOP-492
>             Project: Hadoop
>          Issue Type: New Feature
>          Components: mapred
>            Reporter: arkady borkovsky
>         Assigned To: David Bowen
>
> It would be nice to have map / reduce job keep aggregated counts for 
> arbitrary events occuring in its tasks -- the numer of records processed, the 
> numer of exceptions of a specific type, the number of sentences in passive 
> voice, whatever the jobs finds useful.
> This can be implemented by tasks periodically sending <name, value> pairs to 
> the jobtracker (in some implementations such messages are piggy-backed on the 
> heartbeats), so that the job tracker stores all the latests values from each 
> task and aggregates them on a request.  It should also make the aggregated 
> values available at the job end.  The value for a task would be flushed when 
> the task fails.
> #491 and #490 may be related to this one.

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