socket.listen() backlog value

Sinang, Danny D.Sinang at
Sat Mar 12 01:31:02 CET 2005

Most of the socket articles I've read say that 5 is the normal value for
socket.listen() backlog parameter.
We're running a server (written in Python) with the value set to 10, but
during peak periods, users complain that their clients (also written in
Python) "hang".
Here's the server code :
import os
import time
import string
import LoginParser
import struct
from socket import *
import thread
class Start:
    def startserver(self):
        s = socket(AF_INET, SOCK_STREAM)
        s.bind(('', 7878))
        print 'Login Server started on port 7878' 
        while 1:
            client,addr = s.accept()
            cl =  "Got a conection from " + str(addr)
            print cl
            ipaddress = addr[0]
                msg = client.recv(1024).split("~~")
                p = LoginParser.Start(msg[0],ipaddress)
    def exitprog(self,event):
    def __init__(self):
The LoginParserver.Start ( ... ) queries a database to see if the
username, password given by the client is valid and returns some
pertinent information to the client.
The server runs on a Pentium 4 with 512 MB of memory, running WhiteBox
linux and Python 2.2 .
We've got about 1,000 employees / users all logging on / off during
shift change and this is when the problems are reported.
My question is, is our socket.listen(10) enough ? Should I increase it ?
What is the maximum value for our particular server operating system ?

Danny Sinang
Business Process Reengineering

Tel: +632-855-8686  Fax: +632-855-8630 <> 

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