Re: CPU usage of Python interpreter doing empty while loop under XP

From: Peter Hansen (peter_at_engcorp.com)
Date: 04/27/04 

Date: Tue, 27 Apr 2004 14:24:03 -0400

Jon Perez wrote:
> Peter Hansen wrote:
>
>>How does that help your debugging? That will tell us whether
>>sleep(0) is a better alternative, or whether there is really
>>something else you should be doing instead.
>>
>>(I have never had occasion to use "while 1: pass" in Python, ever.)
>
> I'm trying to debug an event-driven framework I wrote myself and
> there are some iffy situations where a quick and dirty way to halt
> execution and view the state of some variables with print is to
> insert a while 1: pass (or sleep(0)).

Good, then what you are really looking for is to get away from the
print statement and learn to use "import pdb; pdb.set_trace()".

This will drop you into a convenient interpreter prompt right in
the frame where it executes (well, one level down, so just type "r"
to return from the set_trace() call to the calling level). From
this prompt you can inspect any variable in your program, execute
code by single-stepping, and so forth.

Very handy, and it completely obsoletes the "while 1: pass" idea. :-)

-Peter

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