libev epoll and EPOLLRDHUP

Marc Lehmann schmorp at
Thu Jun 13 01:31:17 CEST 2013

On Wed, Jun 12, 2013 at 05:19:31PM +0530, "Chaliha, Sayan" <sayan.chaliha at> wrote:
> I'd like a notification from libev when a TCP connection goes down. This
> works fine with poll backend, but with epoll backend it doesn't. My
> guess is because EPOLLRDHUP is not being handled. Could I have a patch
> for this please?

Hi - this doesn't make much sense: libev already notifies you when a tcp
connection goes down (for both read and write watcher depending on which
half is closed). It makes no obvious sense for libev to handle EPOLLRDHUP
in any way.

Could you describe:

- what behaviour you are seeing.
- what behaviour do you expect instead.
- what exactly you think should be changed.
- how poll differs from epoll in generated signals.

Also, since epoll is extremely badly designed and implemented, maybe you
are hitting a bug in your kernel - which kernel version do you see the
beahviour with?

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