How do I import mpi4py.MPI in a frozen executable?

Question

I have a Python module that I would like to be able to run from the console, hence why I'm using pyinstaller. My module uses MPI and runs fine normally. Then I run the following:

pyinstaller my_script.py --hidden-import _mpi_dll_path

When I try to run the executable, I just get ImportError: cannot import name 'MPI' from 'mpi4py'. After a (slightly shameful) consultation of an LLM, I've got the impression that the problem is that import mpi4py builds the MPI class dynamically, and thus from mpi4py import MPI doesn't work in frozen executables.

I've also tried adding --collect-all mpi4py, but that doesn't help.

What is the fix here? If I can't use MPI directly, is there a function to get it after it has been built? Is there even a way to build it in an .exe?

I'm on Windows 11, with Python 3.13.7, mpi4py 4.1.1, and pyinstaller 6.16.0.

Full error:

Traceback (most recent call last):
  File "cli.py", line 1, in <module>
    from src.solver.__main__ import main, floor_plan_getters
  File "pyimod02_importers.py", line 457, in exec_module
  File "src\solver\__init__.py", line 1, in <module>
    from .boundarycondition import BoundaryCondition, Dirichlet, Neumann, ConstantDirichlet, ConstantNeumann
  File "pyimod02_importers.py", line 457, in exec_module
  File "src\solver\boundarycondition.py", line 4, in <module>
    from .types import Temperatures1D, MPI
  File "pyimod02_importers.py", line 457, in exec_module
  File "src\solver\types.py", line 5, in <module>
    from mpi4py import MPI
ImportError: cannot import name 'MPI' from 'mpi4py' (C:\[redacted]\dist\solvefloorplan\_internal\mpi4py\__init__.py)

always put full error message (traceback) because there are other useful information. — furas
– furas, Commented Oct 10 at 22:39
First you need to install the python mpi4py package. This package is built on top of a MPI library so make sure you install one that is compatible with the one used to build mpi4py. — Gilles Gouaillardet
– Gilles Gouaillardet, Commented Oct 11 at 5:06
As I said, my program runs fine normally, multithreaded or not. It's not that I haven't installed mpi4py. — Truls Henriksson
– Truls Henriksson, Commented Oct 11 at 14:28

Truls Henriksson · Accepted Answer · 2025-10-11 15:54:18Z

0

This is not a complete solution, but for my purposes (being able to run the module from the command line with arguments) I found a workaround. I found out that calling python script.py [options...] forwards those given options to sys.argv in script.py, which I could then read normally using argparser. That was my real objective, not necessarily making a distributable executable, so this worked out fine.

I'm still open for a solution to my original question though.

answered Oct 11 at 15:54

Truls Henriksson

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