[ale] listen()

[Chuck Huber]

On Tue, Feb 11, 2003 at 09:29:16AM -0700, Joe wrote:
> cfowler <cfowler at outpostsentinel.com> writes:
> 
> > I'm writing a server that will only accept one connection at a time.  IT
> > will only service one.  It will then accept a new one after the one
> > being serviced has terminated.  My questions is that listen(int socket,
> > int backlog) does not do this for me.  I'm setting backlog to 0 and I've
> > got clients waiting in the wings to be accept()ed.

That's your problem.  Setting a backlog of zero will cause an error to be
issued to clients trying to connect (resource busy, if I recall correctly).
The value of the backlog passed to listen() is dependent on how fast you
can accept() a connection and how fast you expect connect requests to
arrive balanced with system resources.  A typical value is 5.  

As Joe mentioned, forking a child to accept the connection gets the
parent back to an accept() quicker.

In your single-threaded scenario, there could be a long period before
you arrive back at an accept().  As such, the backlog for listen()
needs to be larger - perhaps 10 - to allow connection requests to be
queued rather than errored.

Enjoy,
    - Chuck
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