MPI on macOS

Repast4Py requires that a working MPI implementation be installed. On macOS, the MPICH MPI implementation can be installed using the Homebrew package manager, or compiled from source. In either case, first install the macOS Xcode command line tools, if necessary, by running the following in a terminal window.

xcode-select -install

This will start a dialog for the tools installation.

Homebrew

To install MPICH using the homebrew package manager, first install Homebrew by going to the Homebrew site, and follow the installation instructions. Once Homebrew is installed, install MPICH by running the following in a terminal window.

% /opt/homebrew/bin/brew install mpich

Check if the install was successful with by running one of the MPICH MPI compiler wrappers.

 % /opt/homebrew/bin/mpicxx --version
Apple clang version 14.0.0 (clang-1400.0.29.102)
Target: arm64-apple-darwin21.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

The version information might differ.

Compile MPICH from Source

Once the command line tool installation is complete, download the mpich source from here, any recent stable version will work. The source then needs to be unarchived, configured, and compiled in a terminal window.

# cd to wherever the mpich tar ball was downloaded (e.g, ~/Downloads)
% cd ~/Downloads
# Replace mpich-4.0.3.tar.gz with the downloaded version
% tar xf mpich-4.0.3.tar.gz
% cd mpich-4.0.3
# Replace $HOME/sfw/mpich-4.0.3 with where you want to install mpich
% ./configure --disable-fortran --prefix=$HOME/sfw/mpich-4.0.3
# Compile and install the source
% make install

The compilation will take a few minutes or more, depending on your machine.

Testing the MPI Installation

Once MPICH is installed, we can test the MPI installation by installing the mpi4py Python package which requires a MPI installation, and is itself a Repast4Py requirement. As part of its installation mpi4py needs to be able to find the MPI compilation wrappers installed as part of MPI implementation. To determine if the wrappers can be found, run the following in a terminal window.

% mpicc --version

If the wrappers are not found, you will see an error like zsh: command not found: mpicc, and you will need to add the wrapper location to the PATH environment variable. If you installed via Homebrew, this will be /opt/homebrew/bin. If you installed from source, this will be the install directory specified in the prefix argument plus /bin (e.g., $HOME/sfw/mpich-4.0.3/bin).

# Replace X with `opt/homebrew` for Hombrew or wherever you installed mpich
# for source
% export PATH=X/bin:$PATH
% mpicc --version
Apple clang version 14.0.0 (clang-1400.0.29.102)
Target: arm64-apple-darwin21.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

In the same terminal window, install and test mpi4py by importing it.

% pip3 install mpi4py
Collecting mpi4py
...
% python3
Python 3.9.6 (default, Aug  5 2022, 15:21:02)
[Clang 14.0.0 (clang-1400.0.29.102)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from mpi4py import MPI

Assuming the mpi4py install is successful, install Repast4Py and test it with an import.

% CC=mpicxx pip3 install repast4py
Collecting repast4py
...
% python3
Python 3.9.6 (default, Aug  5 2022, 15:21:02)
[Clang 14.0.0 (clang-1400.0.29.102)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from repast4py import space

The MPI compilation wrappers also need to be on the PATH for the repast4py install.