FWIW: the “better” solution is to move Hadoop to an HPC-like RM such as Slurm. 
We did this as Pivotal as well as at Intel, but in both cases business moves at 
the very end of the project (Greenplum becoming Pivotal, and Intel moving its 
Hadoop work into Cloudera) blocked its release. Frustrating, as all the work 
was done in both cases :-(



> On Oct 27, 2014, at 10:28 AM, Brock Palen <bro...@umich.edu> wrote:
> 
> Thanks this is good feedback.
> 
> I was worried with the dynamic nature of Yarn containers that it would be 
> hard to coordinate wire up, and you have confirmed that.
> 
> Thanks
> 
> Brock Palen
> www.umich.edu/~brockp
> CAEN Advanced Computing
> XSEDE Campus Champion
> bro...@umich.edu
> (734)936-1985
> 
> 
> 
>> On Oct 27, 2014, at 11:25 AM, Ralph Castain <r...@open-mpi.org> wrote:
>> 
>> 
>>> On Oct 26, 2014, at 9:56 PM, Brock Palen <bro...@umich.edu> wrote:
>>> 
>>> We are starting to look at supporting MPI on our Hadoop/Spark YARN based 
>>> cluster.
>> 
>> You poor soul…
>> 
>>> I found a bunch of referneces to Hamster, but what I don't find is if it 
>>> was ever merged into regular OpenMPI, and if so is it just another RM 
>>> integration?  Or does it need more setup?
>> 
>> When I left Pivotal, it was based on a copy of the OMPI trunk that sat 
>> somewhere in the 1.7 series, I believe. Last contact I had indicated they 
>> were trying to update, but I’m not sure they were successful.
>> 
>>> 
>>> I found this:
>>> http://pivotalhd.docs.pivotal.io/doc/2100/Hamster.html
>> 
>> Didn’t know they had actually (finally) released it, so good to know. Just 
>> so you are aware, there are major problems running MPI under Yarn as it just 
>> isn’t designed for MPI support. What we did back then was add a JNI layer so 
>> that ORTE could run underneath it, and then added a PMI-like service to 
>> provide the wireup support (since Yarn couldn’t be used to exchange the info 
>> itself). You also have the issue that Yarn doesn’t understand the need for 
>> all the procs to be launched together, and so you have to modify Yarn so it 
>> will ensure that the MPI procs are all running or else you’ll hang in 
>> MPI_Init.
>> 
>>> 
>>> Which appears to imply extra setup required.  Is this documented anywhere 
>>> for OpenMPI?
>> 
>> I’m afraid you’ll just have to stick with the Pivotal-provided version as 
>> the integration is rather complicated. Don’t expect much in the way of 
>> performance! This was purely intended as a way for “casual” MPI users to 
>> make use of “free” time on their Hadoop cluster, not for any serious 
>> technical programming.
>> 
>>> 
>>> Brock Palen
>>> www.umich.edu/~brockp
>>> CAEN Advanced Computing
>>> XSEDE Campus Champion
>>> bro...@umich.edu
>>> (734)936-1985
>>> 
>>> 
>>> 
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