[Python-Dev] Startup time (original) (raw)

Jeff Epler jepler@unpythonic.net
Wed, 7 May 2003 14:42:17 -0500

On Wed, May 07, 2003 at 02:05:06PM -0500, Skip Montanaro wrote:

I don't know if this still holds true, but at one point during the 2.x series I think it was pretty expensive to perform imports inside functions, much more expensive than in 1.5.2 at least (maybe right after nested scopes were introduced?). If that is still true, moving the import might be false economy.

$ ./python Lib/timeit.py -s "def f(): import sys" "f()" 100000 loops, best of 3: 3.34 usec per loop $ ./python Lib/timeit.py -s "def f(): pass" "import sys; f()" 100000 loops, best of 3: 3.3 usec per loop $ ./python Lib/timeit.py -s "def f(): pass" "f()" 1000000 loops, best of 3: 0.451 usec per loop $ ./python Lib/timeit.py 'import sys' 100000 loops, best of 3: 2.88 usec per loop

About 2.8usec would be added to each invocation of the functions in question, about the same as the cost of a global-scope import. This means that you lose overall as soon as the function is called twice.

.. but this was about speeding python startup, not just speeding python. <.0375 wink>

Jeff