Hui,

Thanks for the reply.   I am spawning the new process using MPI_COMM_SELF instead of MPI_COMM_WORLD.    Maybe that is my problem!

Thanks,

Kurt

From: Zhou, Hui <zhouh@anl.gov>
Sent: Wednesday, December 4, 2019 1:43 PM
To: discuss@mpich.org
Cc: Mccall, Kurt E. (MSFC-EV41) <kurt.e.mccall@nasa.gov>
Subject: [EXTERNAL] Re: [mpich-discuss] What is the best way to connect to a spawned process?

Hi Kurt,

Let’s say you have a communicator of 10 processes (MPI_COMM_WORLD or any derivatives), and if you use that communicator to spawn process P, the result inter-communicator will be between your original comm (10 processes) and P’s MPI_COMM_WORLD (1 process), right? All original 10 processes should be already connected to P. Did I miss anything?

— 

Hui Zhou

On Dec 4, 2019, at 1:31 PM, Mccall, Kurt E. (MSFC-EV41) via discuss <discuss@mpich.org> wrote:

Hi,

My job creates 10 processes, and the rank 0 one spawns a distinct process P to function as a master.   I’d like to share P’s inter-communicator with the other 9 processes, but it seems that I can’t pass it directly to them through function arguments to those processes (very weird errors happen involving the inter-communicator).   What is an efficient way to connect all 10 processes to P? I’ve looked into MPI_Open_port / MPI_Comm_accept / MPI_Comm_connect, but was wondering if there is more streamlined way.

(I can’t make rank 0 become the master directly, due to the peculiarities of my PBS/Torque node allocations).

Thanks,

Kurt

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