Subject: Re: New sysctl "net.listen_backlog"?
To: Jonathan Stone <jonathan@DSG.Stanford.EDU>
From: Marc Slemko <>
List: tech-net
Date: 09/14/1998 19:11:42
On Mon, 14 Sep 1998, Jonathan Stone wrote:

> My take is, if the app writer uses SOMAXCONN, they're asking for a big
> a backlog as they can get, or perhaps jus tbeing lazy about "large backlog".

Yes, most of them are being lazy about a "large backlog".   

> If we leave SOMAXCONN at 128, then that limits the app to 128 even if
> that's too small (_or_ even too big, for a slow machine). But bumping
> the sysctl can't get beyond 128.  

Of course it can.  If you have an app that needs more than 128, make it
properly configurable so you can set the number properly.  You simply say
that SOMAXCONN isn't the absolute max, but simply a reasonable default

That is how FreeBSD does it (SOMAXCONN == 128, max is sysctl configurable
configurable). That is how Solaris does it (SOMAXCONN == 5, max is
unlimited).  That is how IRIX does it (SOMAXCONN == 1000, max is 1024).

Defaulting SOMAXCONN to INT_MAX would result in the horrible impact that
all apps using SOMAXCONN would get an immense backlog if one ever needed
it.  That is not acceptable.