On 12/13/2012 07:08 PM, Phil Turmel wrote: > On 12/13/2012 04:32 AM, Eric Wong wrote: >> Andreas Voellmy <andreas.voel...@yale.edu> 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.
Let me clarify: The read thread must perform the epoll_ctl between pthread_mutex_lock and pthread_cond_wait, while the monitoring thread must hold the mutex lock when signaling. pthread_cond_signal and pthread_cond_broadcast don't require the caller to hold the mutex in general, but your app needs it. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
