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From "Naganarasimha G R (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6720) Inconsistent values of counters across tasks and job reported to timeline service.
Date Tue, 21 Jun 2016 17:02:58 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6720?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15342184#comment-15342184
] 

Naganarasimha G R commented on MAPREDUCE-6720:
----------------------------------------------

bq. Please note that these metrics will be reported as part of task counters as well.
well what we are doing at the end is publishing the aggregated map and/or Reduce counters
as application metrics so task counters are of no significance and retrospectively if suppose
we go ahead with map and reduce perspective app metrics would it be of any use for aggregation
across flows ? but definitely useful for analyzing for a given app. Either we keep this information
as part of event or we need to append  with Map/Reduce and keep it as app metric.

> Inconsistent values of counters across tasks and job reported to timeline service.
> ----------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-6720
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6720
>             Project: Hadoop Map/Reduce
>          Issue Type: Sub-task
>          Components: applicationmaster
>    Affects Versions: YARN-2928
>            Reporter: Varun Saxena
>            Assignee: Varun Saxena
>              Labels: yarn-2928-1st-milestone
>         Attachments: Counters For Job.png, Counters for Tasks.png, MAPREDUCE-6720-YARN-2928.01.patch
>
>
> While testing found below issue. For some of the task counters, we do not have consistent
values. This is not the case with every counter though.
> Consider the case of counter "org.apache.hadoop.mapreduce.FileSystemCounter:FILE_BYTES_WRITTEN".
> I found that its value for a flow I ran, was 936018 bytes. For the 3 apps associated
with this flow run, the values were 312006 bytes each (which equals to value for a flow run
i.e. 3 * 312006 = 936018). Drilling further down I found though that for one of the apps,
the 4 tasks(2 mappers and 2 reducers) had values as 155918 bytes each for the 2 reducers and
156003 bytes each for the 2 mappers.
> This means the value reported for the app should be (2 * 156003 + 2* 155918) or 623842
bytes but it is only 312006 bytes which indicates that only counter value of mappers is being
picked up.



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