[Zope] z2.py -i

[Brian Lloyd]

>     Set the interpreter check interval. This integer value
>     determines how often the interpreter checks for periodic things
>     such as thread switches and signal handlers. The Zope default
>     is 120, but you may want to experiment with other values that
>     may increase performance in your particular environment.    
> 
> can anybody explain in plain english please.  if i decrease the number, 
> what'll happen?  if i increase it?  what the heck is it anyway?

Roughly: 

The Python interpreter has a "main loop", and the 
check interval controls how often (in terms of times 
through the loop) the interpreter checks for certain 
housekeeping things. In a fairly large application 
like Zope, you can get a speedup by decreasing the 
interval that the runtime has to stop running user 
code to do housekeeping.

Exactly how much speedup you get seems to be very 
dependent on your exact environment (platform, 
processor speed, memory, etc.) The default that Zope 
sets (of 120) seems to give a measurable speedup on 
the limited platforms that we have available to test. 

It is configurable so that people who like to tweak 
can try different values on their particular platform 
and see if there is a number that gives a better speedup 
on that platform (usually they use 'ab' or a similar tool
to test requests per second on a given url). 

Hope this helps!


Brian Lloyd        brian@digicool.com
Software Engineer  540.371.6909              
Digital Creations  http://www.digicool.com