[yt-users] Running yt in parallel on a subset of available processes

[Matthew Turk]

Hi Dan,

I've done this before by modifying how the global communicator is
created.  The way they work in yt is through pushing new communicators
onto a stack, which can vary based on which processors you're on.  I
don't think I ever wrote it up in a PR, but I think it could be done
without too much work.

On Wed, Dec 3, 2014 at 11:47 AM, Daniel Fenn <dsfenn at gmail.com> wrote:
> Is there a way to restrict yt to only use a subset of the available
> processes when it's running in parallel? I have a set of ipython engines
> running, and I'm trying to launch a yt script on a subset of them, but it
> just hangs. It works fine if I launch the same script on all the processes.
>
> Printing out MPI.COMM_WORLD.Get_size() from the script gives the total
> number of engines, not the size of the subset I'm trying to use.
>
> I haven't done a lot of parallel programming, but I would guess that the
> running processes are waiting on one that's not running a yt script, since
> they can see the total number of processes available, but not the size of
> the subset of processes that are actually running a yt script.
>
> Does anyone have any thoughts on how to do this?
>
> Thanks,
>
> Dan
>
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