[DRMAA-WG] About obtaining the machines names in a parallel job

[Peter Tröger]

Hi Yves,

thanks for a good discussion in Munich, I hope we can rely on your  
user perspective also in the future.

> I understand why you don't want to put a mean to get the  
> hostnamesfile for an
> MPI code, since it's should be transparently done in the configName  
> (correct
> name if my rememberings are well).
>
> But I thought of a different use case: a code is just launched on all
> machines. This code is a socket based one, thus it needs to know the  
> other
> machine names to be able to run correctly.
> Of course, this could be bypassed with the use of an external  
> machine where a
> daemon runs, and where running codes can register -- I think of it  
> like an
> omniNames running for example. Another solution is to encapsulate
> applications in an MPI code just to, maybe, have that information.

For me, it sounds like getting the information about allocated  
machines (for a job) on each of the execution hosts. I wonder if this  
information is provided by the different DRM systems. Does that depend  
on the parallelization technology, such as the chosen MPI library ?

Best,
Peter.

>
> But don't you think that the cost is very big (if possible: a lot of  
> policy is
> to not let run user code on the frontal, and a machine only knows  
> that itself
> is taking part to the parallel run) compared to the possibility to  
> at least
> having the possibility to copy the file containing the hostnames to  
> all
> reserved nodes?
>
> Bon courage for the discussions today!
> Cheers.
>
> .Yves.
>
> -- 
> Yves Caniou
> Associate Professor at Université Lyon 1,
> Member of the team project INRIA GRAAL in the LIP ENS-Lyon,
> Délégation CNRS in Japan French Laboratory of Informatics (JFLI),
>  * in Information Technology Center, The University of Tokyo,
>    2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8658, Japan
>    tel: +81-3-5841-0540
>  * in National Institute of Informatics
>    2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan
>    tel: +81-3-4212-2412
> http://graal.ens-lyon.fr/~ycaniou/
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