[Mongrel] Excessive CLOSE_WAIT sockets, pound

Zed Shaw zedshaw at zedshaw.com
Wed Aug 23 16:59:47 EDT 2006

On Wed, 2006-08-23 at 11:47 -0700, John Butler wrote:
> Hello,
> I'm experiencing a strange, but very bad behavior with Mongrel
> and Pound 1.8. Every 6 hours or so one of our nine (not
> consistent on which one) application servers ( each one running
> several mongrel processes ) will start leaving lots of socket
> connections with pound open. This leads to "Too many open files"
> errors. I've set pound to close connections after 60 seconds ( after
> doing analysis of our Rails logs and finding that all requests end
> under 60 seconds, and only 0.12% take over 1 second ). Pound closes
> these, but mongrel apparently isn't getting the message and I end up
> with rapidly increasing socket connections on the app server all left
> in CLOSE_WAIT state ( which is when the remote end, pound, closes the
> connection, and the OS is waiting for the app, mongrel, to close it on
> its end ). Before setting Pound to kill these, one app server could
> effectively take out our web server, because of "Too many open files".
> The plagued app server still responds, and has low load, CPU usage,
> and memory usage. I can even access the mongrels on their individual
> ports. Nothing ( I could see ) shows up in the mongrel log and the
> Rails logs all show it completing requests in a very timely manner.
> Therefore I don't think its a code issue or resource issue. But it's
> very odd and disturbing.

Hey Jon, is it possible for you to come trouble shoot this with me in
the unofficial mongrel support room:


It'll be easier for me to have you run through some tests that way.

Zed A. Shaw
http://www.lingr.com/room/3yXhqKbfPy8 -- Come get help.

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