- · Jexpresso.jl

Setup with CPUs

>> cd $JEXPRESSO_HOME
>> julia --project=. -e "using Pkg; Pkg.instantiate(); Pkg.API.precompile()"

followed by the following:

Push problem name to ARGS You need to do this only when you run a new problem

push!(empty!(ARGS), EQUATIONS::String, EQUATIONS_CASE_NAME::String);
include("./src/Jexpresso.jl")

PROBLEMNAME is the name of your problem directory as JEXPRESSO/problems/equations/problemname
PROBLEMCASENAME is the name of the subdirectory containing the specific setup that you want to run:

The path would look like $JEXPRESSO/problems/equations/PROBLEM_NAME/PROBLEM_CASE_NAME

Some examples available in this branch:

Example 1: to solve the 2D Euler equations with buyoancy and two passive tracers defined in problems/equations/CompEuler/thetaTracers you would do the following:

push!(empty!(ARGS), "CompEuler", "thetaTracers");
include("./src/Jexpresso.jl")

Example 2: to solve the 3D Euler equations with buyoancy defined in problems/equations/CompEuler/3d you would do the following:

push!(empty!(ARGS), "CompEuler", "3d");
include("./src/Jexpresso.jl")

Setup and Run with MPI

JEXPRESSO supports parallel execution using either OpenMPI or MPICH. Follow these steps to configure and run with your preferred MPI implementation.

1. Install MPI Implementation

Choose either OpenMPI or MPICH:

OpenMPI Installation

# Ubuntu/Debian
sudo apt install libopenmpi-dev openmpi-bin

# macOS (Homebrew)
brew install open-mpi

# Verify installation
mpiexec --version

MPICH Installation

# Ubuntu/Debian
sudo apt install mpich libmpich-dev

# macOS (Homebrew) 
brew install mpich

# Verify installation
mpiexec --version

2. Configure MPI Preferences

Automatic Configuration (Default Path)

Use this command when MPI (OpenMPI/MPICH) is installed in standard system paths (/usr/bin, /usr/local/bin, etc.):

julia --project=. -e 'using Pkg; Pkg.add("MPIPreferences"); using MPIPreferences; MPIPreferences.use_system_binary()'

Manual Configuration (For Multiple MPI Installations or MPI not in Default Path)

For MPI installations in non-standard locations (e.g., /opt/openmpi, or custom paths):

julia --project=. -e 'using Pkg; Pkg.add("MPIPreferences"); using MPIPreferences; MPIPreferences.use_system_binary(;extra_paths = ["/where/your/mpi/lib"])'

If MPI is installed via homebrew on macOS, the MPI lib path is:

/opt/homebrew/lib

3. Running with MPI

Basic Execution

mpiexec -n <NPROCS> julia --project=. -e 'push!(empty!(ARGS), "<EQUATIONS>", "<CASE_NAME>"); include("./src/Jexpresso.jl")'

Implementation-Specific Examples

mpiexec -n 4 julia --project=. -e 'push!(empty!(ARGS), "CompEuler", "3d"); include("./src/Jexpresso.jl")'

Troubleshooting

Library conflicts: Clear existing preferences:
```
rm -f LocalPreferences.toml
```

Path issues: Verify paths with:

which mpiexec
which mpirun

You may have to use the full aboslute path to mpiexec or mpirun and to julia like this if necessary:

/opt/homebrew/Cellar/open-mpi/5.0.6/bin/mpirun -n 4 /Applications/Julia-1.11.app/Contents/Resources/julia/bin/julia --project=. -e 'push!(empty!(ARGS), "CompEuler", "theta"); include("./src/Jexpresso.jl")'

Version mismatches: Ensure consistent versions:
```
mpicc --version
mpif90 --version
```