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https://issues.apache.org/jira/browse/YARN-389?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13611037#comment-13611037
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Bikas Saha commented on YARN-389:
---------------------------------

bq. I've checked reason why the requested AM size is larger than 
yarn.scheduler.maximum-allocation-mb. In fact, the AM size is not checked 
before requesting a container. It is because MR jobs are submitted through 
ResourceMgrDelegate and managed by MRAppMaster, while checking AM size against 
the maximum resource capability is only implemented in Client and 
ApplicationMaster of the distributed shell.

The AM launcher checking limits is great but its the RM's responsibility to not 
accept requests that it cannot fulfill. From reading the comments, it not clear 
to me what exactly the root issue is in the RM itself. Is it that the RM is 
accepting container requests that are greater than the maximum resource 
available on any 1 node? I dont think we should be comparing against the entire 
cluster resource since a container request needs to be satisfied within a 
single node.
                
> Infinitely assigning containers when the required resource exceeds the 
> cluster's absolute capacity
> --------------------------------------------------------------------------------------------------
>
>                 Key: YARN-389
>                 URL: https://issues.apache.org/jira/browse/YARN-389
>             Project: Hadoop YARN
>          Issue Type: Bug
>            Reporter: Zhijie Shen
>            Assignee: Zhijie Shen
>
> I've run wordcount example on branch-2 and trunk. I've set 
> yarn.nodemanager.resource.memory-mb to 1G and 
> yarn.app.mapreduce.am.resource.mb to 1.5G. Therefore, resourcemanager is to 
> assign a 2G AM container for AM. However, the nodemanager doesn't have enough 
> memory to assign the container. The problem is that the assignment operation 
> will be repeated infinitely, if the assignment cannot be accomplished. Logs 
> follow.

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