Messages in this thread | | | Date | Tue, 25 Aug 2009 18:14:55 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: PROBLEM: Epoll frequently fails to notify connects at connect bursts |
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On Wed, 26 Aug 2009, Will Brown wrote:
> PLEASE CC: ME ON ANY REPLIES, thank you. > > *** 1. Epoll frequently fails to notify connects at connect bursts > > *** 2. Sometimes, when several connects come in quickly, epoll > establishes tcp connections (according to 'netstat') but then fails to > notify the application by returning from epoll_wait(). In those cases > a subsequent connection or an EPOLLIN or EPOLLOUT event can cause a > return from epoll_wait(), which then causes the previously ignored > connection to be reported. But then the more recent event is not > notified, the whole sequence lags and everything gets out of whack. > The problems can easily be reproduced on my Ubuntu machine which runs > a kernel version 2.6.28 using supplied test program. I also have a > Ubuntu hosted in VMWare running a 2.6.27 version kernel, which appears > to NOT have the same problem.
Multiple quasi-simultaneous events for the same fd are merged. This is why on POLLIN on accepting sockets you want to do something like:
while ((afd = accept(sfd, ...)) != -1) add_client(afd);
- Davide
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