[Libevent-users] Problem with epoll in Centos 5.9/6.4?

[Alex Agranovsky <alex@xxxxxxxxx>]

Are there known problems with either libevent or epoll mechanism in 
RHEL/Centos 5.9/6.4?

We have a stable integration with libevent (using epoll), that had been 
running trouble-free for a few years. With some systems being upgraded 
to Centos 5.9, we've noticed that every once in awhile a server socket 
receives a notification about incoming connection, the connection is 
accept()'ed and added to base event via event_new/event_add -- and never 
receives any further notifications, neither for incoming data, nor for 
the far end dropping the connection.

Packet capture shows both events (data incoming/connection closed) 
occurring. The following facts make me wonder if there's a problem:
- as I've mentioned, the code ran trouble free, and under significant 
loads for a couple of years at least
- neither libevent version, nor our code on top of it have changed
- Centos 5.9 release notes mention a change in the affected area 
(https://bugzilla.redhat.com/show_bug.cgi?id=681578)
- if we allocate enough base events to lighten the load on each, the 
problem goes away (we see the problem at about 60-70 sockets per base 
event; at about 30 it seems to never occur)

Have you seen anything similar? Is there a limit on how many sockets can 
be added to a single base event?
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