[Python-Dev] s/hotshot/lsprof

Armin Rigo arigo at tunes.org
Mon Nov 21 22:15:56 CET 2005

Hi Floris,

On Mon, Nov 21, 2005 at 04:41:04PM +0000, Floris Bruynooghe wrote:
> > Now Brett's
> > student, Floris, extended hotshot to allow custom timers.  This is
> > essential, because it enables testing.  The timing parts of hotshot were
> > not tested previously.
> Don't be too enthousiastic here.

Testing is done by feeding the profiler something that is not a real
timer function, but gives easy to predict answers.  Then we check that
the profiler accounted all this pseudo-time to the correct functions in
the correct way.  This is one of the few way to reliably test a
profiler, that's why it is essential.

> Iirc I did compare the output of test_profile between profile and my
> wrapper.  This was one of my checks to make sure it was wrapped
> correctly.  So could you tell me how they are different?

test_profile works as I explained above.  Running it with hotshot shows
different numbers, which means that there is a bug (and not just some
difference in real speed).   More precisely, a specific number of the
pseudo-clock-ticks are dropped for no reason other than a bug, and
doesn't show up in the final results at all.

A bientot,


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