listen backlog

Eric Wong normalperson at
Fri Dec 3 16:49:06 EST 2010

ghazel at wrote:
> On Thu, Dec 2, 2010 at 11:35 PM, Eric Wong <normalperson at> wrote:
> > UNIX sockets are faster for nginx <-> Unicorn, but Raindrops is slower
> > dealing with them since Linux doesn't export UNIX sockets stats to
> > netlink the same way it does for TCP sockets.  So there's always a
> > tradeoff :x
> When does that netlink speed difference matter - only when collecting stats?

Yes, the performance difference is only when collecting stats.

> Using "modprobe inet_diag" made the script spit out a new error:
>             address     active     queued
> linux-tcp-listener-stats.rb:42:in `tcp_listener_stats': NLMSG_ERROR
> (RuntimeError)
>         from linux-tcp-listener-stats.rb:42

I don't think I've ever seen NLMSG_ERROR before.  Are you running
this as the same user that originally bound the listener (the user
of the Unicorn master process)?

> $ sudo modprobe -l inet_diag
> /lib/modules/
> I dug in to raindrops a little bit, and it seems the error associated
> with the NLMSG_ERROR is -2,
> "No such file or directory".

Are you bound to and not  Use if you're bound to that (I had another user on the
raindrops mailing list with that problem).

Eric Wong

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