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https://issues.apache.org/jira/browse/MAPREDUCE-7169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17005468#comment-17005468
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Ahmed Hussein commented on MAPREDUCE-7169:
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[~BilwaST], the patch is not applicable anymore with the trunk. Can you please 
fix the compilation errors along with the java doc and checkstyle issues?

 

I see that you add the node hosting the original task to the blacklist of the 
speculative task. Wouldn't it be easier just to change the order of the 
dataLocalHosts so that the node will be picked last in the loop? In that case, 
the speculative task will run on the same node only if all other nodes cannot 
be assigned to the speculative task.

> Speculative attempts should not run on the same node
> ----------------------------------------------------
>
>                 Key: MAPREDUCE-7169
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-7169
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>          Components: yarn
>    Affects Versions: 2.7.2
>            Reporter: Lee chen
>            Assignee: Bilwa S T
>            Priority: Major
>         Attachments: MAPREDUCE-7169-001.patch, MAPREDUCE-7169-002.patch, 
> MAPREDUCE-7169-003.patch, image-2018-12-03-09-54-07-859.png
>
>
>           I found in all versions of yarn, Speculative Execution may set the 
> speculative task to the node of  original task.What i have read is only it 
> will try to have one more task attempt. haven't seen any place mentioning not 
> on same node.It is unreasonable.If the node have some problems lead to tasks 
> execution will be very slow. and then placement the speculative  task to same 
> node cannot help the  problematic task.
>          In our cluster (version 2.7.2,2700 nodes),this phenomenon appear 
> almost everyday.
>  !image-2018-12-03-09-54-07-859.png! 



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