Hello rodola

Here's detail:

In the server, we use multiprocess to handle the request with share the same FD. 

OK, when a request comes, all the process wake up and try to accept the request but only one process will accept success and the others will raise an Exception if we use the epoll without EPOLLEXCLUSIVE.

That means there will waste the performance. This effect is named thundering herd.

But if we use epoll with EPOLLEXCLUSIVE, when the envents happen, only one process will wake and try to handle the event.

So, I think it's necessary to support the EPOLLEXCLUSIVE in selectors.EpollSelector

Actually, Python support EPOLLEXCLUSIVE official since 3.7. It's time to support it in selectors