This is a known issue with MPICH. There’s no portable way to detect this, but for MPICH you can look for PMI variables in the environment. — Pavan

On Oct 20, 2014, at 11:34 AM, Jeff Hammond <[email protected]> wrote:

I wrote a trivial program that uses MPI_Comm_spawn. It works when I launch with mpiexec but not if I run directly.

1) Is this a bug in MPICH? 2) What is the proper way for the program to detect how the program was launched? I would like to provide a helpful warning message...

Thanks!

Jeff

jrhammon-mac01:comm_spawn jrhammon$ ./parent I am 0 of 1 for the parent program. [[email protected]] match_arg (../../../../src/pm/hydra/utils/args/args.c:159): unrecognized argument pmi_args [[email protected]] HYDU_parse_array (../../../../src/pm/hydra/utils/args/args.c:174): argument matching returned error [[email protected]] parse_args (../../../../src/pm/hydra/ui/mpich/utils.c:1596): error parsing input array [[email protected]] HYD_uii_mpx_get_parameters (../../../../src/pm/hydra/ui/mpich/utils.c:1648): unable to parse user arguments [[email protected]] main (../../../../src/pm/hydra/ui/mpich/mpiexec.c:153): error parsing parameters ^C

jrhammon-mac01:comm_spawn jrhammon$ mpiexec -n 1 ./parent I am 0 of 1 for the parent program. I am 0 of 1 for the child program.

==> parent.c <== #include <stdio.h> #include <mpi.h>

int main(int argc, char * argv[]) { MPI_Init(&argc,&argv);

int size, rank; MPI_Comm_size(MPI_COMM_WORLD, &size); MPI_Comm_rank(MPI_COMM_WORLD, &rank);

printf("I am %d of %d for the parent program.\n", rank, size);

MPI_Comm intercomm; int errors[size]; MPI_Comm_spawn( (char*)"./child", MPI_ARGV_NULL, 1, MPI_INFO_NULL, 0 /* root */, MPI_COMM_WORLD, &intercomm, errors);

MPI_Finalize(); return 0; }

==> child.c <== #include <stdio.h> #include <mpi.h>

int main(int argc, char * argv[]) { MPI_Init(&argc,&argv);

int size, rank; MPI_Comm_size(MPI_COMM_WORLD, &size); MPI_Comm_rank(MPI_COMM_WORLD, &rank);

printf("I am %d of %d for the child program.\n", rank, size);

MPI_Finalize(); return 0; }

==> Makefile <== CC = mpicc CFLAGS = -g -O2 -Wall -std=c99

LD = $(CC) LDFLAGS = $(COPT)

LIBS =

TESTS= parent child

all: $(TESTS)

%: %.o $(CC) $(CFLAGS) $< $(LIBS) -o $@

clean: -rm -f *.o -rm -f $(TESTS)

-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/devel

-- Pavan Balaji ✉️ http://www.mcs.anl.gov/~balaji