Re: Fw: epoll and fork()

[Davide Libenzi <davidel@xmailserver.org>]

>
> Is there a defined behaviour for what happens when a process with an epoll
> fd forks?
> 
> I've an app that inherits an epoll fd from its parent, and then
> unregisters some file descriptors from the epoll set. This seems to have
> the nasty side effect of unregistering the same file descriptors from the
> parent process as well. Surely this can't be right?

epoll does register the underlying file* not the fd, so this is the 
expected behaviour. Inheriting an fd, and epoll is no exception, simply 
bumps a counter, so both parent and child epoll fd shares the same context. 
Sorry but what behaviour do you expect by unregistering an fd pushed by 
the parent from inside a child? Events work exactly the same. Since the 
context is shared, events are delivered only once.



- Davide