>> We can't do that, it would break existing code.
>
> I would argue that such code is already broken.
>

- that's not necessarily true, if your code is carefully designed
- we can't forbid fork() in a multi-threaded application while it's
allowed by POSIX
- backward compatibility is *really* important

>> What do you mean by helper threads?
>
> multiprocessing uses threads behind the scenes to handle queue traffic and such for individual forked processes. It's something I also wasn't aware of until Antoine pointed it out. It also has its own implementation of atfork hooks in an attempt to handle the locking issue.
>

I'm curious as to how you'll manage to implement
multiprocessing.queues without threads.
Please open a dedicated issue for this.