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https://issues.apache.org/jira/browse/TEZ-394?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16052192#comment-16052192
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Rohini Palaniswamy commented on TEZ-394:
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[~jlowe],
     [~gopalv] was mentioning in the Summit, that he tried the patch as Hive 
also has same problem. But he was running into lot more pre-emption of tasks in 
his case which was unnecessary and wasteful.

[~gopalv],
   Could you elaborate on the issue?

> Better scheduling for uneven DAGs
> ---------------------------------
>
>                 Key: TEZ-394
>                 URL: https://issues.apache.org/jira/browse/TEZ-394
>             Project: Apache Tez
>          Issue Type: Sub-task
>            Reporter: Rohini Palaniswamy
>            Assignee: Jason Lowe
>         Attachments: TEZ-394.001.patch, TEZ-394.002.patch, TEZ-394.003.patch
>
>
>   Consider a series of joins or group by on dataset A with few datasets that 
> takes 10 hours followed by a final join with a dataset X. The vertex that 
> loads dataset X will be one of the top vertexes and initialized early even 
> though its output is not consumed till the end after 10 hours. 
> 1) Could either use delayed start logic for better resource allocation
> 2) Else if they are started upfront, need to handle failure/recovery cases 
> where the nodes which executed the MapTask might have gone down when the 
> final join happens. 



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