OpenMP and Python

python parallel-processing openmp
user1132648 picture user1132648 · Jul 6, 2012 · Viewed 81.9k times · Source

I have experience in coding OpenMP for Shared Memory machines (in both C and FORTRAN) to carry out simple tasks like matrix addition, multiplication etc. (Just to see how it competes with LAPACK). I know OpenMP enough to carry out simple tasks without the need to look at documentation.

Recently, I shifted to Python for my projects and I don't have any experience with Python beyond the absolute basics.

My question is :

What is the easiest way to use OpenMP in Python? By easiest, I mean the one that takes least effort on the programmer side (even if it comes at the expense of added system time)?

The reason I use OpenMP is because a serial code can be converted to a working parallel code with a few !$OMPs scattered around. The time required to achieve a rough parallelization is fascinatingly small. Is there any way to replicate this feature in Python?

From browsing around on SO, I can find:

  • C extensions
  • StackLess Python

Are there more? Which aligns best with my question?

Answer

jfs picture jfs · Jul 6, 2012

Due to GIL there is no point to use threads for CPU intensive tasks in CPython. You need either multiprocessing (example) or use C extensions that release GIL during computations e.g., some of numpy functions, example.

You could easily write C extensions that use multiple threads in Cython, example.

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