Common execution errors

MPI error on GPU execution on the Caltech GPU cluster (See CLIMA WIKI):

Executing julia --project=$CLIMA_HOME/env/gpu ./test/DGmethods/compressible_Navier_Stokes/rtb_visc.jl

may return the error below:

--------------------------------------------------------------------------
PMI2_Init failed to intialize.  Return code: 14

--------------------------------------------------------------------------
--------------------------------------------------------------------------
The application appears to have been direct launched using "srun",
but OMPI was not built with SLURM's PMI support and therefore cannot
execute. There are several options for building PMI support under
SLURM, depending upon the SLURM version you are using:

  version 16.05 or later: you can use SLURM's PMIx support. This
  requires that you configure and build SLURM --with-pmix.

  Versions earlier than 16.05: you must use either SLURM's PMI-1 or
  PMI-2 support. SLURM builds PMI-1 by default, or you can manually
  install PMI-2. You must then build Open MPI using --with-pmi pointing
  to the SLURM PMI library location.

Please configure as appropriate and try again.
--------------------------------------------------------------------------
*** An error occurred in MPI_Init
*** on a NULL communicator
*** MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort,
***    and potentially your MPI job)

Solution: see here

Building MPI on the Caltech GPU cluster

When using OpenMPI, upon build MPI in julia, some of the cluster nodes may return

Executing ERROR: LoadError: LoadError: could not open file ~/.julia/packages/MPI/hcbnk/deps/consts.jl

Solution:

1. make sure all modules are up to date, especially module load cuda/10.0 and openmpi/4.0.1_cuda-10.0
2. export JULIA_MPI_PATH=/central/software/OpenMPI/4.0.1 (some nodes delete this, so needs to be reset)