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From Sonja Koenig <sonja.koe...@uni-ulm.de>
Subject Re: Number of workers vs number of threads
Date Mon, 13 Jul 2015 09:30:21 GMT
Thanks for the info!


Am 13.07.2015 um 11:22 schrieb Arjun Sharma:
> I am not measuring RAM or CPU usage. I am just measuring the overall 
> time the job takes to finish on a large input. For assigning RAM to 
> the workers, I am using the job parameters 
> -Dmapreduce.map.memory.mb=9300 -Dmapreduce.map.java.opts="-Xms9G 
> -Xmx9G" (I am running on YARN).
>
> On Mon, Jul 13, 2015 at 2:05 AM, Sonja Koenig <sonja.koenig@uni-ulm.de 
> <mailto:sonja.koenig@uni-ulm.de>> wrote:
>
>     Hi there!
>
>     On a related matter:
>     May I ask you how you perform your measurements? Especially for
>     capturing RAM and CPU usage..
>     I also want to do some performance tests and I would be thankful
>     to hear how you succeeded on that issue ;)
>
>     Regards,
>     Sonja
>
>
>     Am 13.07.2015 um 10:56 schrieb Arjun Sharma:
>
>         Hi,
>
>         Many of the discussions on this forum suggest using one worker
>         per physical machine, and increasing the number of threads per
>         worker, versus using multiple workers per physical machine,
>         with a less number of threads. This does not seem to be the
>         case with my experiments.
>
>         The cluster I am using has 12 physical machines (used
>         exclusively for workers), 64 GB of RAM and 12 cores each. I
>         experimented with two setups:
>
>         Setup 1 runs 72 workers (i.e., 6 workers per machine), 72*72
>         partitions, which is the default, and 8 threads per worker.
>
>         Setup 2 tries to simulate Setup 1, but using threads instead
>         of workers. Therefore, it has 12 workers (1 worker per
>         machine), 72*72 partitions (using numUserPartitions), and
>         since the number of parallel tasks per machine in Setup 1 is 6
>         workers * 8 threads, then the number of compute, input, output
>         threads is set to 48.
>
>         In both cases 56 GB of RAM is assigned equally to all workers
>         on the machine (either given to the 1 worker on that machine
>         or divided among 6 of them).
>
>         In my case, Setup 1 performs significantly better (faster)
>         than Setup 2, which sounds counter intuitive, and not agreeing
>         with other suggestions of using less number of workers, and
>         more number of threads. Is there anything I am missing here?
>         Is there any kind of tuning or configuration parameter setting
>         that can make Setup 2 outperform Setup 1?
>
>         Thanks!
>
>
>


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