> I was thinking about a run time warning that is emitted if you call
> os.fork() while multiple threads are active. It is ugly, but at least
> it tells you you are doing something that will in most cases not work
> correctly.

The problem is that multiprocessing itself, by construction, uses fork()
with multiple threads. Perhaps there's a way to use only non-blocking
communication instead (rendering the helper threads useless), but that's
not a trivial change.