#!/usr/bin/perl -w
#New stable Thread module in 5.8
use IO::Socket;
use Thread;

$Server = new IO::Socket::INET(Listen => 0, LocalPort => 4000, Reuse => 0) || die('Can not open port 4000');


while(1) {
   $newClientSocket=$Server->accept;
   new Thread \&handleRequest,$newClientSocket;
}

sub handleRequest() {
   $clientSocket=shift;
   ...
}