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Hi Stanislav,<br>
<br>
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.<br>
<br>
Min<br>
<br>
<div class="moz-cite-prefix">On 8/11/17 1:31 PM, Stanislav Simko
wrote:<br>
</div>
<blockquote type="cite" cite="mid:1502454690.4363.18.camel@uu.nl">
<div>Dear all,</div>
<div><br>
</div>
<div>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:</div>
<div><br>
</div>
<div><br>
</div>
<div>______________________________________________</div>
<div>parent.py</div>
<div><br>
</div>
<div>from __future__ import print_function</div>
<div>from mpi4py import MPI</div>
<div>comm = MPI.COMM_WORLD</div>
<div>spawned =
MPI.COMM_SELF.Spawn(sys.executable,args=['child.py'],maxprocs=1)</div>
<div>print("parent process is waiting for child")</div>
<div>spawned.Barrier()</div>
<div><br>
</div>
<div><br>
</div>
<div>______________________________________________</div>
<div>child.py</div>
<div><br>
</div>
<div>from __future__ import print_function</div>
<div>from mpi4py import MPI</div>
<div>parent = MPI.Comm.Get_parent()</div>
<div># just do some stupid stuff that takes a bit of time</div>
<div>for i in range(5000000):</div>
<div> a = i*i+1-(i*10) + math.sin(math.pow(i,i%8))</div>
<div>parent.Barrier()</div>
<div><br>
</div>
<div>______________________________________________</div>
<div><br>
</div>
<div>I run with e.g.:</div>
<div>mpirun -n 1 python mpi.py</div>
<div><br>
</div>
<div>Do I miss something with SPAWN method?</div>
<div>(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)</div>
<div><br>
</div>
<div>thank you very much for suggestions.</div>
<div><br>
</div>
<div>Regards,</div>
<div>stanislav.</div>
<div><span></span></div>
<div><span></span></div>
<br>
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<br>
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