Martin Ritter added the comment: Dear Davin, Thanks for the input, I was perfectly aware that the "solution" I proposed is not realistic. But the feedback that multiprocessing is using threads internally is useful as I can quickly abandon the idea to do something like the check I proposed in our code base without spending time on it. I was aware of the Gil, I just did not anticipate that big a problem when mixing threads and processes with rather simple python code. My bad, sorry for the noise. Cheers, Martin ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue27422> _______________________________________