[SOLVED] DLL load failed: The specified module could not be found when doing "from mpi4py import MPI"

DLL load failed: The specified module could not be found when doing "from mpi4py import MPI"

I am trying to use Mpi4py 1.3 with python 2.7 on Windows 7 64bits. I downloaded the installable version from here which includes OpenMPI 1.6.3 so in the installed directory (*/Python27\Lib\site-packages\mpi4py\lib) following libraries exist: libmpi.lib, libmpi_cxx.lib, libopen-pal.lib, and libopen-rte.lib. Now in my codes when trying to import it:

from mpi4py import MPI

It returns following error:

ImportError: DLL load failed: The specified module could not be found.

I tried to copy a bove lib files alongside the */Python27\Lib\site-packages\mpi4py\MPI.pyd and even to Windows/System32, but it didn't work. I appreciate your help on what DLL is missing and how to fix the error?

Solution

Use sys.prefix\lib\site-packages\mpi4py\bin\python-mpi.exe or add the following code to sys.prefix\lib\site-packages\mpi4py\__init__.py around line 37:

def _init_openmpi():
    """Pre-load libmpi.dll and register OpenMPI distribution."""
    import os
    import ctypes
    if os.name != 'nt' or 'OPENMPI_HOME' in os.environ:
        return
    try:
        openmpi_home = os.path.abspath(os.path.dirname(__file__))
        openmpi_bin = os.path.join(openmpi_home, 'bin')
        os.environ['OPENMPI_HOME'] = openmpi_home
        os.environ['PATH'] = ';'.join((openmpi_bin, os.environ['PATH']))
        ctypes.cdll.LoadLibrary(os.path.join(openmpi_bin, 'libmpi.dll'))
    except Exception:
        pass

_init_openmpi()