On Fri, Nov 22, 2013 at 2:57 PM, John Ladasky <john_lada...@sbcglobal.net> wrote: > or, for that matter, why data needs to be pickled to pass it between > processes.
Oh, that part's easy. Let's leave the multiprocessing module out of it for the moment; imagine you spin up two completely separate instances of Python. Create some object in one of them; now, transfer it to the other. How are you going to do it? Ultimately, the operating system isn't going to give you facilities for moving complex objects around - what you almost exclusively get is streams of bytes (or occasionally messaged chunks with lengths, but still of bytes). Pickling is one method of turning an object into a stream of bytes, in such a way that it can be turned back into an equivalent object on the other side. And therein is the problem with exceptions; since the traceback includes references to stack frames and such, it's not as simple as saying "Two to beam up" and hearing the classic sound effect - somehow you need to transfer all the appropriate information across processes. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
