Re: epoll behaviour after running out of descriptors

["Olaf van der Spek" <olafvdspek@gmail.com>]

On Sun, Nov 2, 2008 at 8:10 PM, Eric Dumazet <dada1@cosmosbay.com> wrote:
> On listen queue, socket is still ready for an accept().

True, but not handy.

> Since you use edge trigered epoll, you'll only reveive new notification.

The strace shows I receive 10+.
If a return with EMFILE is indeed a no-op, I should receive only one.

> You probably had in you app a : listen(sock, 10), so after 10 notifications,
> your listen queue is full and TCP stack refuses to handle new connections.

I've got listen(l, SOMAXCONN);
IIRC SOMAXCONN is 128.

>  close(newfd); /* forget this incoming connection, we dont have enough fd */

Why not keep them in the queue until you do have enough descriptors?

> Of course, if your application is multi-threaded, you might adapt (and
> eventually reserve
> one emergency fd per thread)

Sounds like a great recipe for race conditions. ;)