> caf -o hello_world hello_world.f90
> cafrun -np 2 ./hello_world
 Hello world from 1 of 2
 Hello world from 2 of 2
Abort(5328655) on node 0 (rank 0 in comm 0): Fatal error in internal_Comm_free: Other MPI error, error stack:
internal_Comm_free(87).........: MPI_Comm_free(comm=0x1083962b8) failed
MPIR_Comm_free_impl(809).......:
MPIR_Comm_delete_internal(1224): Communicator (handle=84000002) being freed has 1 unmatched message(s)
Abort(407981839) on node 1 (rank 1 in comm 0): Fatal error in internal_Comm_free: Other MPI error, error stack:
internal_Comm_free(87).........: MPI_Comm_free(comm=0x100d842b8) failed
MPIR_Comm_free_impl(809).......:
MPIR_Comm_delete_internal(1224): Communicator (handle=84000001) being freed has 1 unmatched message(s)
Error: Command:
 `$HOME/opt/usr/local/mpich/mpich-4.1.2-gcc-13.2.0/bin/mpiexec -n 2 ./hello_world`
failed to run.

OpenCoarrays Coarray Fortran Compiler Wrapper (caf version 2.10.1)
Copyright (C) 2015-2022 Sourcery Institute
Copyright (C) 2015-2022 Archaeologic Inc.
OpenCoarrays comes with NO WARRANTY, to the extent permitted by law.
You may redistribute copies of OpenCoarrays under the terms of the
BSD 3-Clause License. For more information about these matters, see
the file named LICENSE that is distributed with OpenCoarrays.

mpiexec --version
HYDRA build details:
 Version: 4.1.2
 Release Date: Wed Jun 7 15:22:45 CDT 2023
 CC: $HOME/opt/usr/local/gcc/gcc-13.2.0/bin/gcc-13.2.0
 Configure options: '--disable-option-checking' '--prefix=$HOME/opt/usr/local/mpich/mpich-4.1.2-gcc-13.2.0' '--with-hwloc=embedded' 'CC=$HOME/opt/usr/local/gcc/gcc-13.2.0/bin/gcc-13.2.0' 'CXX=$HOME/opt/usr/local/gcc/gcc-13.2.0/bin/g++-13.2.0' 'FC=$HOME/opt/usr/local/gcc/gcc-13.2.0/bin/gfortran-13.2.0' '--cache-file=/dev/null' '--srcdir=.' 'CFLAGS= -fno-common -O2' 'LDFLAGS=' 'LIBS=' 'CPPFLAGS= -DNETMOD_INLINE=__netmod_inline_ofi__ -I$HOME/opt/src/mpich-4.1.2/src/mpl/include -I$HOME/opt/src/mpich-4.1.2/modules/json-c -I$HOME/opt/src/mpich-4.1.2/modules/hwloc/include -D_REENTRANT -I$HOME/opt/src/mpich-4.1.2/src/mpi/romio/include -I$HOME/opt/src/mpich-4.1.2/src/pmi/include -I$HOME/opt/src/mpich-4.1.2/modules/yaksa/src/frontend/include -I$HOME/opt/src/mpich-4.1.2/modules/libfabric/include'
 Process Manager: pmi
 Launchers available: ssh rsh fork slurm ll lsf sge manual persist
 Topology libraries available: hwloc
 Resource management kernels available: user slurm ll lsf sge pbs cobalt
 Demux engines available: poll select

> cat hello_world.f90
program hello_world
implicit none
 write(*,*) 'Hello world from ', &
 this_image() , 'of', num_images()
end program hello_world