On 6/16/2012 8:03 AM, Roland Schulz wrote:
Hi,
I would like to start a single process without mpirun and then use
MPI_Comm_spawn to start up as many processes as required. I don't want
the parent process to take up any resources, so I tried to disconnect
the inter communicator and then finalize mpi and exit the parent. But
as soon as I do that the children exit too. Why is that? Can I somehow
change that behavior? Or can I wait on the children to exit without
the waiting taking up CPU time?
The reason I don't need the parent as soon as the children are
spawned, is that I need one intra-communicator over all processes. And
as far as I know I cannot join the parent and children to one
intra-communicator.
You could use MPI_Intercomm_merge to create an intra-communicator out of
the groups in an inter-communicator and pass the inter-communicator you
get back from the MPI_Comm_spawn call.
--td
The purpose of the whole exercise is that I want that my program to
use all cores of a node by default when executed without mpirun.
I have tested this with OpenMPI 1.4.5. A sample program is here:
http://pastebin.com/g2XSZwvY . "Child finalized" is only printed with
the sleep(2) in the parent not commented out.
Roland
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