Installation

Requirements

You need to have the following software properly installed in order to build MPI for Python:

  • A working MPI implementation, preferably supporting MPI-3 and built with shared/dynamic libraries.

    Note

    If you want to build some MPI implementation from sources, check the instructions at Building MPI from sources in the appendix.

  • Python 3.6 or above.

    Note

    Some MPI-1 implementations do require the actual command line arguments to be passed in MPI_Init(). In this case, you will need to use a rebuilt, MPI-enabled, Python interpreter executable. MPI for Python has some support for alleviating you from this task. Check the instructions at MPI-enabled Python interpreter in the appendix.

Using pip

If you already have a working MPI (either if you installed it from sources or by using a pre-built package from your favourite GNU/Linux distribution) and the mpicc compiler wrapper is on your search path, you can use pip:

$ python -m pip install mpi4py

Note

If the mpicc compiler wrapper is not on your search path (or if it has a different name) you can use env to pass the environment variable MPICC providing the full path to the MPI compiler wrapper executable:

$ env MPICC=/path/to/mpicc python -m pip install mpi4py

Warning

pip keeps previouly built wheel files on its cache for future reuse. If you want to reinstall the mpi4py package using a different or updated MPI implementation, you have to either first remove the cached wheel file with:

$ python -m pip cache remove mpi4py

or ask pip to disable the cache:

$ python -m pip install --no-cache-dir mpi4py

Using distutils

The MPI for Python package is available for download at the project website generously hosted by GitHub. You can use curl or wget to get a release tarball.

  • Using curl:

    $ curl -O https://github.com/mpi4py/mpi4py/releases/download/X.Y.Z/mpi4py-X.Y.Z.tar.gz
    
  • Using wget:

    $ wget https://github.com/mpi4py/mpi4py/releases/download/X.Y.Z/mpi4py-X.Y.Z.tar.gz
    

After unpacking the release tarball:

$ tar -zxf mpi4py-X.Y.Z.tar.gz
$ cd mpi4py-X.Y.Z

the package is ready for building.

MPI for Python uses a standard distutils-based build system. However, some distutils commands (like build) have additional options:

--mpicc=

Lets you specify a special location or name for the mpicc compiler wrapper.

--mpi=

Lets you pass a section with MPI configuration within a special configuration file.

--configure

Runs exhaustive tests for checking about missing MPI types, constants, and functions. This option should be passed in order to build MPI for Python against old MPI-1 or MPI-2 implementations, possibly providing a subset of MPI-3.

If you use a MPI implementation providing a mpicc compiler wrapper (e.g., MPICH, Open MPI), it will be used for compilation and linking. This is the preferred and easiest way of building MPI for Python.

If mpicc is located somewhere in your search path, simply run the build command:

$ python setup.py build

If mpicc is not in your search path or the compiler wrapper has a different name, you can run the build command specifying its location:

$ python setup.py build --mpicc=/where/you/have/mpicc

Alternatively, you can provide all the relevant information about your MPI implementation by editing the file called mpi.cfg. You can use the default section [mpi] or add a new, custom section, for example [other_mpi] (see the examples provided in the mpi.cfg file as a starting point to write your own section):

[mpi]

include_dirs         = /usr/local/mpi/include
libraries            = mpi
library_dirs         = /usr/local/mpi/lib
runtime_library_dirs = /usr/local/mpi/lib

[other_mpi]

include_dirs         = /opt/mpi/include ...
libraries            = mpi ...
library_dirs         = /opt/mpi/lib ...
runtime_library_dirs = /op/mpi/lib ...

...

and then run the build command, perhaps specifying you custom configuration section:

$ python setup.py build --mpi=other_mpi

After building, the package is ready for install.

If you have root privileges (either by log-in as the root user of by using sudo) and you want to install MPI for Python in your system for all users, just do:

$ python setup.py install

The previous steps will install the mpi4py package at standard location prefix/lib/pythonX.X/site-packages.

If you do not have root privileges or you want to install MPI for Python for your private use, just do:

$ python setup.py install --user

Testing

To quickly test the installation:

$ mpiexec -n 5 python -m mpi4py.bench helloworld
Hello, World! I am process 0 of 5 on localhost.
Hello, World! I am process 1 of 5 on localhost.
Hello, World! I am process 2 of 5 on localhost.
Hello, World! I am process 3 of 5 on localhost.
Hello, World! I am process 4 of 5 on localhost.

If you installed from source, issuing at the command line:

$ mpiexec -n 5 python demo/helloworld.py

or (in the case of ancient MPI-1 implementations):

$ mpirun -np 5 python `pwd`/demo/helloworld.py

will launch a five-process run of the Python interpreter and run the test script demo/helloworld.py from the source distribution.

You can also run all the unittest scripts:

$ mpiexec -n 5 python test/runtests.py

or, if you have nose unit testing framework installed:

$ mpiexec -n 5 nosetests -w test

or, if you have py.test unit testing framework installed:

$ mpiexec -n 5 py.test test/