Handle fork safely.

[ioquatix]

Forking with an active scheduler is unlikely to work as expected.

It would make sense to detect this (e.g. pthread_atfork) and either (1) invalidate the scheduler or (2) recreate the scheduler.

[jpcamara]

This couldn't utilize Process._fork?

[ioquatix]

There are ways to detect and recreate the file monitors, libev does something like this.