[Mongrel] Mongrel error : EMFILE too many open files

Ed Hickey bassnode at gmail.com
Mon Dec 17 12:20:35 EST 2007

On Dec 17, 2007 11:05 AM, Scott Derrick <lists at ruby-forum.com> wrote:
> The reason why I think this is a mongrel reliability issue is that when
> my mongrel server stops responding, its stops responding to everybody!
> Any browser from any client machine that trys to access any page on the
> website gets "nada", no response..

I don't have your original post, so you may have outlined these details, but:
Are you running more than 1 mongrel?  What are you using to balance:
Apache's mod_proxy, hardware load balancer, or something else (nginx,
etc)?  Last time I checked, Nginx and Apache use round-robin for
rotating through your mongrel ports.  So, if one mongrel process is
taking awhile to respond, the balancer can't tell and could send a new
user to that port causing a hanging request.  There are alternatives
that will allow the hung/slow ports to be skipped after a certain
threshold, but nothing that uses apache (to my knowledge).  Here's a
recent one for Nginx:
If you're just using one mongrel, then this won't apply.

What Kirk is explaining is that it's not mongrel that is hanging on
the request, it's the (single-threaded) Rails code.  He should know
all about that seeing as he wrote Swiftiply (which you might look into
as a solution). http://swiftiply.swiftcore.org/


> I can't even get a page not found 404 error if I feed it a bad address,
> the mongrel server is locked up and not responding, to anybody.
> Maybe I don't understand the linkage between my web app and the web
> server, I didn't think my application by running a periodic update could
> cause the server to refuse any new connections? Its not like its really
> busy with a couple hundred requests a second, its 5 requests a second,
> on a fast server?
> Scott
> Scott
> --
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