[Python-Dev] Startup time

[Raymond Hettinger]

> Guido, any chance you can quickly run the above two through the thirty-leven
> versions of Python you have laying about so we can narrow this down or
> refute my faulty memory?  I've seen some recent posts by you which had
> performance data as far back as 1.3.  I tried with 2.1, 2.2 and CVS but saw
> no discernable differences within versions:
> 
>     % python ~/local/bin/timeit.py -s'def f(): pass' 'import math; f()'
>     100000 loops, best of 3: 7.44 usec per loop
>     % python ~/local/bin/timeit.py -s'def f(): import math' 'f()'
>     100000 loops, best of 3: 7.6 usec per loop
> 
>     % python2.2 ~/local/bin/timeit.py -s'def f(): pass' 'import math; f()'
>     100000 loops, best of 3: 9.19 usec per loop
>     % python2.2 ~/local/bin/timeit.py -s'def f(): import math' 'f()'
>     100000 loops, best of 3: 9.05 usec per loop
> 
>     % python2.1 ~/local/bin/timeit.py -s'def f(): pass' 'import math; f()'
>     100000 loops, best of 3: 9.16 usec per loop
>     % python2.1 ~/local/bin/timeit.py -s'def f(): import math' 'f()'
>     100000 loops, best of 3: 9.12 usec per loop

I don't think timeit.py helps here.  It works by substituting *both* 
the setup and statement inside a compiled function.  

So, *none* of the above timings show the effect of a top level import 
versus one that is inside a function.  It does compare 1 deep nesting 
to 2 levels deep.

So, you'll likely have to roll your own minature timer if you want
a straight answer.


Raymond Hettinger