I am writing some Python code using the Message Passing Interface
(MPI), an API used in parallel computing. There exist a number of
Python implementations of MPI, but apparently they all rely on the
Numeric Python (numpy) package. I need to run my code on a particular
machine made available by my university, which does not have numpy and
will not be getting it.
So I am trying to write my own mini-wrapper for MPI in C to extend
my Python program.
There exists a special C compiler to use when compiling C programs
that use MPI, called mpicc.
Here is what I have tried:
I have written a minimal C program that uses MPI. It works correctly
when compiled with mpicc.
Then I've written Python boilerplate code and a Python script to
compile my C program into a Python-includable module. This does not
work a priori because the Python compilation script uses gcc rather
than mpicc. So I have taken the exact gcc command that the script uses
and replaced "gcc" with "mpicc".
This produces an *.so file that compiles without errors.
Unfortunately, it fails when I try to import it in Python. It can't
find the MPI library.
My MPI code looks like this (plus some boilerplate code):
/* Return the MPI rank of the current process. */
int rank(){
int argc;
char **argv;
int rank, size;
MPI_Init( &argc, &argv );
MPI_Comm_rank( MPI_COMM_WORLD, &rank );
MPI_Finalize();
return rank;
}
/* Main. A 'Hello World' function. */
int hello() {
int rankNumber = rank();
printf ("Hello, World. I am process %d.\n", rankNumber);
return rankNumber;
}
My Python program that includes it looks like this:
import ctest
ctest.hello()
My error message is this:
[EMAIL PROTECTED] Opgave03]$ mpiexec -n 1 python ctest.py
Traceback (most recent call last):
File "ctest.py", line 1, in <module>
import ctest
ImportError: /big/School/Cluster/Opgave03/ctest.so: undefined
symbol: ompi_mpi_comm_world
[EMAIL PROTECTED] Opgave03]$
Can anyone suggest anything? Can I get MPI to work in Python?
Last time I asked a similar question, someone recommended that I
check out Cython instead of C. Do MPI bindings for Cython exist?
Thanks in advance.
- Claus Appel
--
http://mail.python.org/mailman/listinfo/python-list
