Re: epoll with ONESHOT possibly fails to deliver events

[Phil Turmel]

On 12/13/2012 04:32 AM, Eric Wong wrote:
> Andreas Voellmy <andreas.voellmy@xxxxxxxx> wrote:

[trim /]

>>> Another thread, distinct from all of the threads serving particular
>>> sockets, is perfoming epoll_wait calls. When sockets are returned as
>>> being ready from an epoll_wait call, the thread signals to the
>>> condition variable for the socket.
> 
> Perhaps there is a bug in the way your epoll_wait thread
> uses the condition variable to notify other threads?

Have you considered the possibility that data is arriving between
epoll_ctl and pthread_cond_wait ?  If your monitoring thread returns
from epoll_wait within this race window, it will call
pthread_cond_signal while the first thread is not yet waiting for it.
With the one-shot flag, the next iteration of epoll_wait won't see that
socket's new data.

Phil
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