R. David Murray added the comment: Heh, yeah. What I was really trying to do by that comment was clarify for any *other* readers that stumble on this issue later it is just the python code that *has* to be constrained by the GIL. I have no idea how much of the scipy stack drops the gil at strategic spots. I do seem to remember that the the Jupyter uses multiple processes for its parallelism, though. Anyway, this is pretty off topic now :) ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue27422> _______________________________________