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From Wangda Tan <wheele...@gmail.com>
Subject Re: Why return NULL_ASSIGNMENT when one app can not assign to this leaf queue?
Date Mon, 23 Feb 2015 20:57:43 GMT
Hi Steven,
For now, CapacityScheduler trying to solve is large batch job, it allocates
resource in FIFO manner, and adding capacity limits, etc. So if a job
submit later cannot get resource before previous job get satisfied. This is
to make big batch job can get resource quickly and finish quickly.

I don't think there's a way to disable reservation.

HTH,
Wangda

On Mon, Feb 23, 2015 at 3:37 AM, 杨逸帆Steven <me@legato.ninja> wrote:

> HI,
>
> I am learning Yarn source code, and have this confussion.
>
> In the assignContainers@LeafQueue.java, yarn will iterate all active
> applications and try to do the schedule work. however, I notive if one
> application's require is over queue limit, the function will return but not
> break.
>
> Say I have app#2 needs 500mb, and next app# needs 300mb. The queue now has
> only 400mb available left, so when app#2 canAssignToThisQueue fails,
> function return and leaves app#3 without schedule. And in this case, app#3
> is able to run.
>
> So, what is the reason to Return here?
>
>
> Thank you.
>
> P.S can I disable reservation? and how to do that?
>
> Sincerely,
> Steven
>

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