Hi Trent, On Sat, Nov 16, 2013 at 7:13 PM, Trent Nelson <trent@snakebite.org> wrote:

Slides are here: https://speakerdeck.com/trent/pyparallel-how-we-removed-the-gil-and-exploite...

Please stop me if I'm wrong. This allows the Python programmer to run a bunch of new threads in parallel; each new thread has read-only access to all pre-existing objects; all objects created by this new thread must die at the end. Disregarding issues of performance, this seems to be exactly the same model as "multiprocessing": the new thread (or process) cannot have any direct impact on the objects seen by the parent thread (or process). In fact, multiprocessing's capabilities are a superset of PyParallel's: e.g. you can change existing objects. That will not be reflected in the parent process, but will be visible in the future in the same process. This seems like a very useful thing to do in some cases. The performance benefits of PyParallel are probably only relevant on Windows (because it has no fork()), but I agree it's interesting if you're on Windows. However, the main issue I have with the whole approach of PyParallel is that it seems to be giving a subset of "multiprocessing" in terms of programming model. I already hate multiprocessing for giving the programmer a large set of constrains to work around; I suppose I don't have to explain my opinion of PyParallel... But more importantly, why would we want to hack at the source code of CPython like you did in order to get a result that was already done? Please tell me where I'm wrong. A bientôt, Armin.