[jankedeen]

*...it's a total mess...theoretically it's possible....speculation on standard behavior based on platform behavior...namespace(x)<-threads->chosen implementation detail...functional language reference... -- Translation: Design is broken

[klodolph]

Well, then allow me to cite the standard for you.

> If a multi-threaded process calls fork() ... the child process may only execute async-signal-safe operations until such time as one of the exec functions is called.

IEEE Std 1003.1-2008, 2016 Edition

http://pubs.opengroup.org/onlinepubs/9699919799/

I don't know about "design is broken". I personally think the fork()/exec() model is a clumsy way to create a new process, but that's a matter of taste.