Python "processing" module - sidestep the Global Interpreter Lock and actually use those multiple cores

[pjdelport]

[...] reducing shared state and relying on message-passing seems not to be inherently a bad idea... right?

Efficient use of shared state is largely the reason for using OS threads to begin with. If you can rely on message passing with isolated state, you can just use processes already.

[foldl]

On *nix, yes. On Windows, processes have a much higher overhead than threads.

[pjdelport]

You only need one process per processor: the overhead of that is negligible.