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Date: Wed, 01 Aug 2012 13:07:23 +0200
From: Laszlo Nagy <gandalf@shopzeus.com>
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Subject: Re: Pass data to a subprocess
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>> The most effective IPC is usually through shared memory. But there is no
>> OS independent standard Python module that can communicate over shared
>> memory.
> It's true that shared memory is faster than serializing objects over a
> TCP connection.  On the other hand, it's hard to imagine anything
> written in Python where you would notice the difference.
Well, except in response times. ;-)

The TCP stack likes to wait after you call send() on a socket. Yes, you 
can use setsockopt/TCP_NOWAIT, but my experience is that response times 
with TCP can be long, especially when you have to do many 
request-response pairs.

It also depends on the protocol design - if you can reduce the number of 
request-response pairs then it helps a lot.