...

2. Arrange for the epoll object (or FD) to be closed after fork, but before exec, so that the child process can't fiddle with it

See also:

http://bugs.python.org/issue8713

...which suggests Python 3.4 added fork+exec support to multiprocessing. On Unix and older Python versions, you're stuck with plain fork and all the attendant horribleness.

This is a multiprocessing bug IMHO.

Hi again, I've found this discussion https://lkml.org/lkml/2007/10/27/25 the scenarios discussed are a bit different but it sounds to me related to the same problem. which makes me think this is not a python bug but may be an epoll design poblem with fork !