socket module's listen backlog problem

Graham Dumpleton grahamd at
Tue Apr 29 09:17:17 CEST 2003

SOMAXCONN value of 0x7fffffff means use the largest value the OS supports.
Problem is that Micro$oft differentiates their products and low end products
only support  a backlog of 5. You will need Windows 2000 Server in order
to get more than 5 to work. I can't remember what the actual number the
Server version of their product supports though.

janeaustine50 at (Jane Austine) wrote in message news:<ba1e306f.0304281519.1304ce5a at>...
> I'm running Python 2.3b1, which has been downloaded from as
> binary, on my Win XP Pro machine.
> socket.SOMAXCONN is 5. I want it to be higher. However, listen with
> higher backlog number doesn't work.
> I'm using asyncore and removed the following code but it still doesn't
> work with more than 5 backlogs.
> #from asyncore
>         if == 'nt' and num > 5:
>             num = 1
> I suppose the socket module uses winsock2.h and it's SOMAXCONN is
> 0x7fffffff.
> What's wrong? What can I do to increase listen backlog?

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