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Date: Fri, 12 Oct 2012 01:51:03 +0000 (UTC)
From: "Vinod Kumar Vavilapalli (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
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Subject: [jira] [Commented] (MAPREDUCE-4495) Workflow Application Master in
 YARN
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-4495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13474722#comment-13474722 ] 

Vinod Kumar Vavilapalli commented on MAPREDUCE-4495:
----------------------------------------------------

Just caught up with discussion.

I am willing to help with all the support and improvements that this AM will need from YARN side. Also willing to discuss and vet the design of the workflow AM, it clearly has many champions. I am generally +1 for a workflow idea, but don't quite agree on some of the design points, but we can argue about that separately.

Regarding the project home, I agree with the general sentiment here. I am sure there will be a proliferation of YARN frameworks and apps in the future. Burdening the hadoop YARN or MapReduce communities with the maintenance of all those projects is clearly a road that we should all look to avoid given our experience with the contrib projects in the past.

We have an opportunity to set a clear precedence here. In my opinion, this code is best hosted at oozie, but incubator is a clear alternative like others noted. Am willing to help with any efforts needed to push this into incubator. Others like PAAS, MPI should also follow suit. Tx.
                
> Workflow Application Master in YARN
> -----------------------------------
>
>                 Key: MAPREDUCE-4495
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4495
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>    Affects Versions: 2.0.0-alpha
>            Reporter: Bo Wang
>            Assignee: Bo Wang
>         Attachments: MAPREDUCE-4495-v1.1.patch, MAPREDUCE-4495-v1.patch, MapReduceWorkflowAM.pdf
>
>
> It is useful to have a workflow application master, which will be capable of running a DAG of jobs. The workflow client submits a DAG request to the AM and then the AM will manage the life cycle of this application in terms of requesting the needed resources from the RM, and starting, monitoring and retrying the application's individual tasks.
> Compared to running Oozie with the current MapReduce Application Master, these are some of the advantages:
>  - Less number of consumed resources, since only one application master will be spawned for the whole workflow.
>  - Reuse of resources, since the same resources can be used by multiple consecutive jobs in the workflow (no need to request/wait for resources for every individual job from the central RM).
>  - More optimization opportunities in terms of collective resource requests.
>  - Optimization opportunities in terms of rewriting and composing jobs in the workflow (e.g. pushing down Mappers).
>  - This Application Master can be reused/extended by higher systems like Pig and hive to provide an optimized way of running their workflows.

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