Threading in python

[Peter Hansen]

Jean-Paul Calderone wrote:
> On 14 Dec 2005 10:15:08 -0800, Aahz <aahz at pythoncraft.com> wrote:
>>You either need to run multiple processes or run code that mostly calls
>>into C libraries that release the GIL.  For example, a threaded spider
>>scales nicely on SMP.
> 
> Yes.  Nearly as well as a single-threaded spider ;)

I'm confused about how a single-threaded spider -- even using Twisted! 
-- could "scale well" on a multiprocessor machine (that's what SMP 
means, right?) without using multiple processes.  I believe that's the 
scenario to which Aahz was referring.

-Peter