From: Francis Cianfrocca <garbagecat10@...>
Date: 2007-12-16T01:37:43+09:00
Subject: Re: Question about sockets/listeners

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On Dec 15, 2007 9:38 AM, James Croft <crofty_james@hotmail.com> wrote:

> hi, i'm very new to ruby and so i'd be very grateful of any help on
> this.  I am writing a script that listens for UDP packets on a
> particular port.  This is very easy using 'socket'.  I then want to make
> a script that simulates lots of clients sending UDP packets to the
> listener.  These clients should send a UDP packet from a particular port
> and then listen for a response on that same port.  For this reason, I am
> trying to run each simulated client in a different thread.  A simplified
> version of what i have done so far is shown below, however, when I run
> this, the client stops sending packets after the 66th one.  Can someone
> explain this to me please?  why is it stopping at 66?  which limit am i
> hitting?
>
> Also, any suggestions on how to improve the code will be gratefully
> received.  Thanks
>


Using a nonthreaded approach, I got up to about 360 packets through on a
single run. (This program requires the Ruby/EventMachine library):

#-----------------------------------------
require 'rubygems'
require 'eventmachine'

EM.epoll

SERVER = "127.0.0.1"
PORT = 1500

module Server
        def receive_data data
                send_data "I saw your #{data}"
        end
end

module Client
        def post_init
                @@counter ||= 0
                @@counter += 1
                send_datagram "Data packet #{@@counter}", SERVER, PORT
        end
        def receive_data data
                @@received ||= 0
                @@received += 1
                p "Received #{@@received}: #{data}"
        end
end

EM.run {
        EM.open_datagram_socket SERVER, PORT, Server
        (60000..60400).each {|n|
                EM.open_datagram_socket SERVER, n, Client
        }
}

#-------------------------------

I did two things differently: first, I didn't introduce a delay between each
new socket. If I had, then this program would probably have scaled much
farther. And second, I used sequential port numbers rather than random ones,
to avoid trying to open an already-open port, and to avoid trying to open a
privileged one.

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