Hi Stanislav, I apologize for the late update. After a while I finally find chance to try this test. I could not reproduce this problem on my side. Here is my environment: - MPICH version: version 3.3a2 (using the same configure options as shown in your config.log) - mpi4py: version 2.0.0 - platform: a Fedora25 VM and a Centos7 VM If you are still facing this problem, please try the following steps to narrow down: 1. Try remove the computation in child.py 2. Try MPICH test suite under <your MPICH build directory>/test/mpi/spawn/     make     make testing V=1 Regards, Min On 8/13/17 11:07 AM, Stanislav Simko wrote:

Hi Min, attached are configure and make logs for the build that I did for myself on our local cluster with Intel compilers. I.e., build is definitely not guaranteed to be perfect/optimal. But please keep in mind that I get the same behaviour with standard MPICH package in Fedora distribution - I think that configuration options should be available online, maybe prepared by someone from MPICH?

Also, I tested with simple c++ hello world like program and it's the same.

Thank you. best, stanislav.

On Sun, 2017-08-13 at 19:58 +0100, Min Si wrote:

...

Hi Stanislav,

This seems interesting. Could you please also attach the MPICH config.log ? You can find under the directory where you build MPICH. I will look into this problem then and keep you updated.

Min

On 8/11/17 1:31 PM, Stanislav Simko wrote:

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Dear all,

I'm just trying some very basic stuff with MPI_COMM_SPAWN in python (i.e. I use mpi4py package), but I see behaviour that I do not understand - the child process gets spawned, does its stuff and then "should" finish. I see though, that the process created for the child stays alive. I see this only with the MPICH, OPENMPI does what I would (naively) expect. In this way I can end up with N "ghost" process, after calling SPAWN N-times. My minimal working example is following:

______________________________________________ parent.py

from __future__ import print_function from mpi4py import MPI comm = MPI.COMM_WORLD spawned = MPI.COMM_SELF.Spawn(sys.executable,args=['child.py'],maxprocs=1) print("parent process is waiting for child") spawned.Barrier()

______________________________________________ child.py

from __future__ import print_function from mpi4py import MPI parent = MPI.Comm.Get_parent() # just do some stupid stuff that takes a bit of time for i in range(5000000):     a = i*i+1-(i*10) + math.sin(math.pow(i,i%8)) parent.Barrier()

______________________________________________

I run with e.g.: mpirun -n 1 python mpi.py

Do I miss something with SPAWN method? (I tested on two independent systems, our local cluster with mpich v3.0.4, and my laptop - fedora 26, mpich v3.2.8 from repositories)

thank you very much for suggestions.

Regards, stanislav.

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