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https://issues.apache.org/jira/browse/MAPREDUCE-802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12738834#action_12738834
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Sreekanth Ramakrishnan commented on MAPREDUCE-802:
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Also a part of this issue, I propose to have a single source of {{startTime}} 
and move the same to {{JobStatus}}.  As event {{START_TIME_CHANGED}} is raised 
on {{JobStatus}} so if a person changes only {{JobInProgress}} {{startTime}} 
field and forgets to change {{JobStatus.startTime}} we might run into issue of 
correct start time not being propagated.


> Simplify the job updated event notification between Jobtracker and schedulers
> -----------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-802
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-802
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: jobtracker
>            Reporter: Hemanth Yamijala
>            Assignee: Sreekanth Ramakrishnan
>
> HADOOP-4053 and HADOOP-4149 added events to take care of updates to the state 
> / property of a job like the run state / priority of a job notified to the 
> scheduler. We've seen some issues with this framework, such as the following:
> - Events are not raised correctly at all places. If a new code path is added 
> to kill a job, raising events is missed out.
> - Events are raised with incorrect event data. For e.g. typically start time 
> value is missed out.
> The resulting contract break between jobtracker and schedulers has lead to 
> problems in the capacity scheduler where jobs remain stuck in the queue 
> without being ever removed and so on.
> It has proven complicated to get this right in the framework and fixes have 
> typically still left dangling cases. Or new code paths introduce new bugs.
> This JIRA is about trying to simplify the interaction model so that it is 
> more robust and works well.

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