[Twisted-Python] robust listenUDP with N clients?

Jean-Paul Calderone exarkun at divmod.com
Mon Dec 4 12:59:02 EST 2006

On Mon, 04 Dec 2006 12:05:29 -0500, marc bohlen <marcbohlen at acm.org> wrote:
>Jean-Paul Calderone wrote:
>>On Mon, 04 Dec 2006 10:28:57 -0500, marc bohlen <marcbohlen at acm.org> wrote:
>>>hi folks
>>>I am new to twisted and new to server programming. Nonetheless, I would 
>>>like to build a robust client-server looping mechanism in which a server 
>>>would listen for input from N clients, say 10, and react immediately when 
>>>it receives data from them. I have a sample (see below) that appears to 
>>>run well, but am not sure if it will scale under real network load and 
>>>larger N.
>>>(I am parsing the input data received from the clients and using it to 
>>>calculate a fibonnaci series, just for testing. The reactor can be stopped 
>>>with keyboard input (I am on a win32 platform)).
>>>If you see any problems with this approach, please let me know !
>>>Thanks, marc
>>You probably need to be more specific to get many useful responses.  What
>>do you expect N to go to?  Why do you use multiple ports?  Why are you
>>using UDP?  What do you mean by "robust"?  What does the Fibonnaci 
>>have to do with the application?  Is the keyboard input handling code
>>relevant or just part of the example?  Is win32 your development platform
>>or your deployment platform or both?
>Hi Jean-Paul
>I would want N no larger than 30.

30 is quite small.  There should be no performance issues related to
the network layer.

>I am testing only on localhost and have N ports instead of N computers for 

Okay.  So ultimately it will be 1 port communicating with N computers,
instead of the current N ports all communicating with 1 computer?

>Fibonnaci calculation: just a cpu cycle eating app for testing, will change.

I don't think your original example realistically represented CPU load.
It seems more likely that you will have some work to do in response to
each request, which corresponds to datagramReceived

>Keyboard handling is important.
>Win32 is development and deployment platform.

Win32 is pretty crummy.  I have no idea how well anything will work on
it.  I generally assume that it won't, at all.

>UDP choice: I would like the faster of the two protocols (UDP vs TCP), 
>although TCP has congestion
>control. Is TCP the better choice here?

If that's the primary metric, TCP is a better choice.

>Robust: will it work even under heavy network load

If _that's_ the primary metric, TCP is still a better choice. :)


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