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From Omkar Joshi <ojo...@hortonworks.com>
Subject Re: How to make hadoop use all nodes?
Date Thu, 19 Sep 2013 23:49:36 GMT

Let me clarify few things.
1) you are making container requests which are not explicitly looking for
certain nodes. (No white listing).
2) All nodes are identical in terms of resources (memory/cores) and every
container requires same amount of resources.
3) All nodes have capacity to run say 2 containers.
4) You have 20 nodes.

Now if an application is running and is requesting 20 containers then you
can not say that you will get all on different nodes (uniformly
distributed). It more depends on which node heartbeated to the Resource
manager at what time and how much memory is available with it and also how
many applications are present in queue and how much they are requesting at
what request priorities. If it has say sufficient memory to run 2
containers then they will get allocated (This allocation is quite complex
..I am assuming very simple "*" reuqest). So you may see few running 2, few
running 1 where as few with 0 containers.

I hope it clarifies your doubt.

Omkar Joshi
*Hortonworks Inc.* <http://www.hortonworks.com>

On Thu, Sep 19, 2013 at 7:19 AM, Vandecreme, Antoine <
antoine.vandecreme@nist.gov> wrote:

>  Hi all,
> I am working with Hadoop 2.0.5 (I plan to migrate to 2.1.0 soon).
> When I am starting a Job, I notice that some nodes are not used or
> partially used.
> For example, if my nodes can hold 2 containers, I notice that some nodes
> are not running any or just 1 while others are running 2.
> All my nodes are configured the same way.
> Is this an expected behavior (maybe in case others jobs are started) ?
> Is there a configuration to change this behavior?
> Thanks,
> Antoine

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