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From Wangda Tan <wheele...@gmail.com>
Subject Re: FW: Is it valid to use userLimit in calculating maxApplicationsPerUser ?
Date Fri, 17 Jul 2015 00:31:00 GMT
I think it's not valid. Multiply it by ULF seems not reasonable, I think it
should be:

max(1, maxApplications * max(userlimit/100, 1/#activeUsers))

Assuming admin setups a very large ULF (e.g. 100), maxApplicationsPerUser
can be much more than maxApplications of a queue.

Also, multiply ULF to compute userAMResourceLimit seems not valid too, it
can lead to a single user can run too much applications than expected,
which we should avoid.

Thoughts?

Thanks,
Wangda

On Thu, Jul 16, 2015 at 12:53 AM, Naganarasimha G R (Naga) <
garlanaganarasimha@huawei.com> wrote:

>   Hi Folks ,
>  Came across one scenario where in maxApplications @ cluster level(2
> node) was set to a low value like 10 and based on capacity configuration
> for a particular queue it was coming to 2 as value, but further while
> calculating maxApplicationsPerUser formula used is :
>
>  *maxApplicationsPerUser = (int)(maxApplications * (userLimit / 100.0f) *
> userLimitFactor);*
>
>  but the definition of *userLimit  *in the documentation is :
> *Each queue enforces a limit on the percentage of resources allocated to a
> user at any given time, if there is demand for resources. The user limit
> can vary between a minimum and maximum value. The the former (the minimum
> value) is set to this property value and the latter (the maximum value)
> depends on the number of users who have submitted applications. For e.g.,
> suppose the value of this property is 25. If two users have submitted
> applications to a queue, no single user can use more than 50% of the queue
> resources. If a third user submits an application, no single user can use
> more than 33% of the queue resources. With 4 or more users, no user can use
> more than 25% of the queues resources. A value of 100 implies no user
> limits are imposed. The default is 100. Value is specified as a integer.*
>
>  So was wondering how a* minimum limit is made used in a formula to
> calculate max applications for a user*, suppose i set "
> yarn.scheduler.capacity.<queue-path>.minimum-user-limit-percent" to *20 * assuming
> at least 20% of queue at the minimum is available for a queue but based on
> the formula *maxApplicationsPerUser * is getting set to *zero. *
> According to the definition of the property max is based on the current
> no. of active users, so i feel this formula is wrong.
> *P.S. *userLimitFactor was configured as default 1, but what i am
> wondering is whether its valid to use it in combination with userlimit to
> find max apps per user.
>
>  Please correct me if my understanding is wrong? if its a bug would like
> to raise and solve it .
>
>  + Naga
>

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