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Subject: Re: [OMPI users] Java binding requirements
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-10-24 12:23:38


On Oct 23, 2012, at 9:51 PM, Yoshiki SATO <yoshiki_at_[hidden]> wrote:

> Hi,
>
> Recently, I tried to use Java bindings in Open MPI released this February. As far as mentioned in the Java FAQ ( http://www.open-mpi.org/faq/?category=java ), the Java binding implementation doesn't cause any performance degradation because of just wrapping native Open MPI with mpiJava-based APIs. I believe this means no Java code is required to run on all processing nodes (workers) but it has only to run on a master node. Is this understanding correct?

Not sure I fully understand, but I believe the answer is no - Java code is going to run on all nodes where there are processes.

>
> If so, my question is if I need NOT to install JDK to the all nodes. In other words is it possible to have a machine used as a worker without JDK installed?
>

You do not need JDK installed on worker nodes - it only has to be on the node where you compile your code. However, we launch a JVM for each process, so you must at least have the JVM installed on each worker. This is typically included in a base Linux installation (just look for the "java" command, usually in /usr/bin), so you usually don't have to do anything special (as opposed to installing the JDK, which doesn't usually come in the base install)

HTH
Ralph

> Thanks a lot for any comment in advance.
>
> Regards,
> --yoshiki
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