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From Yehia Elshater <y.z.elsha...@gmail.com>
Subject Re: fair scheduler not working as intended
Date Wed, 13 Aug 2014 17:06:17 GMT
Hi Henry,

I think FairScheduler is a better option for your case. As if you used
FifoScheduler, the latency of the short jobs will be worst (in case of any
of longrun jobs are currently running in your cluster). So I think your
queue layout is good to apply fairness between the long and short jobs.
Long run queue will gain more resources (more than its min share) just in
case that the short one does not have any jobs to run in the mean time.
These additional resources will be diminished gradually to its minimum
share again based on the short queue workload to ensure fairness.

I hope that helps you.

Yehia


On 13 August 2014 02:01, Henry Hung <YTHung1@winbond.com> wrote:

>  Hi Yehia,
>
>
>
> Oh? I thought that by using maxResources = 15360 mb (3072 mb * 5), vcores
> = 5, and maxMaps = 5, I already restricting the job to only use 5 maps at
> max.
>
>
>
> The reason is my long run job have 841 maps, and each map will process
> data for almost 2 hours.
>
> In the meantime there will be some short jobs that only need couple of
> minutes to complete.
>
> Hence why I use fair scheduler to split resources into 2 groups, one
> default and other one longrun.
>
> I want to make sure there always an available resources ready to be used
> by short jobs.
>
>
>
> If your explanation is true, then current fair scheduler behavior is not
> what I wanted.
>
> So is there any other ways to setup YARN resources to accommodate the
> short / long run jobs?
> Or do I need to create 2 separate YARN cluster? (I have been thinking
> about this approach)
>
>
>
> Best regards,
>
> Henry
>
>
>
> *From:* Yehia Elshater [mailto:y.z.elshater@gmail.com]
> *Sent:* Wednesday, August 13, 2014 11:27 AM
> *To:* user@hadoop.apache.org
> *Subject:* Re: fair scheduler not working as intended
>
>
>
> Hi Henry,
>
>
>
> Are there any applications (on different queues rather than longrun queue)
> are running in the same time ? I think FairScheduler is going to assign
> more resources to your "longrun" as long as there no other applications are
> running in the other queues.
>
>
>
> Thanks
>
> Yehia
>
>
>
> On 12 August 2014 20:30, Henry Hung <YTHung1@winbond.com> wrote:
>
>  Hi Everyone,
>
>
>
> I’m using Hadoop-2.2.0 with fair scheduler in my YARN cluster, but
> something is wrong with the fair scheduler.
>
>
>
> Here is my fair-scheduler.xml looks like:
>
>
>
> <allocations>
>
>   <queue name="longrun">
>
>     <maxResources>15360 mb, 5 vcores</maxResources>
>
>     <weight>0.5</weight>
>
>     <minMaps>2</minMaps>
>
>     <maxMaps>5</maxMaps>
>
>     <minReduces>1</minReduces>
>
>   </queue>
>
> </allocations>
>
>
>
> I create a “longrun” queue to ensure that huge MR application can only use
> 5 resources. My YARN setup for each resource memory is 3072 MB:
>
>
>
>   <property>
>
>     <name>mapreduce.map.memory.mb</name>
>
>     <value>3072</value>
>
>   </property>
>
>   <property>
>
>     <name>mapreduce.reduce.memory.mb</name>
>
>     <value>3072</value>
>
>   </property>
>
>
>
> When the huge application started, it works just fine and scheduler
> restrict it to only run 5 maps in parallel.
>
> But after running for some time, the application run 10 maps in parallel.
>
> The scheduler page show that the “longrun” queue used 66%, exceed the fair
> share 30%.
>
>
>
> Can anyone tell me why the application can get more than it deserved?
>
> Is the problem with my configuration? Or there is a bug?
>
>
>
> Best regards,
>
> Henry Hung
>
>
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