Installation

Prerequisites

MPI

MultiGridBarrierMPI.jl requires an MPI implementation. When you install the package, Julia automatically provides MPI.jl with MPI_jll (bundled MPI implementation).

For HPC environments, you may want to configure MPI.jl to use your system's MPI installation. See the MPI.jl documentation for details.

MUMPS

The package uses MUMPS for sparse direct solves through LinearAlgebraMPI.jl. MUMPS is typically available through your system's package manager or HPC module system.

Package Installation

Basic Installation

using Pkg
Pkg.add(url="https://github.com/sloisel/MultiGridBarrierMPI.jl")

Development Installation

To install the development version:

git clone https://github.com/sloisel/MultiGridBarrierMPI.jl
cd MultiGridBarrierMPI.jl
julia --project -e 'using Pkg; Pkg.instantiate()'

Verification

Test your installation with MPI:

cd MultiGridBarrierMPI.jl
mpiexec -n 2 julia --project test/runtests.jl

All tests should pass. Expected output:

Test Summary:          | Pass  Total
MultiGridBarrierMPI.jl |    2      2

Initialization Pattern

Initialize MPI first, then load the package:

# CORRECT
using MPI
MPI.Init()

using MultiGridBarrierMPI
# Now you can use the package

# WRONG - MPI must be initialized before using MPI types
using MultiGridBarrierMPI
# Missing MPI.Init() - will fail when calling functions

Running MPI Programs

Multi-Rank Execution

For distributed execution, create a script file (e.g., my_program.jl):

using MPI
MPI.Init()

using MultiGridBarrierMPI
using LinearAlgebraMPI

# Your parallel code here
sol = fem2d_mpi_solve(Float64; L=3, p=1.0)
println(io0(), "Solution computed!")

Run with MPI:

mpiexec -n 4 julia --project my_program.jl

Output from Rank 0 Only

Use io0() from LinearAlgebraMPI for output to avoid duplicate messages:

println(io0(), "This prints once from rank 0")

Troubleshooting

MPI Issues

If you see MPI-related errors, try rebuilding MPI.jl:

using Pkg; Pkg.build("MPI")

MUMPS Issues

If MUMPS fails to load, ensure it's properly installed on your system and that LinearAlgebraMPI.jl can find it.

Test Failures

If tests fail:

Ensure you're using at least Julia 1.10 (LTS version)
Check all dependencies are installed: Pkg.status()
Run with verbose output to see detailed errors

Next Steps

Once installed, proceed to the User Guide to learn how to use the package.