[Python-Dev] default of returning None hurts performance? (original) (raw)

Gregory P. Smith greg at krypto.org
Tue Sep 1 00:07:49 CEST 2009

On Mon, Aug 31, 2009 at 2:20 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

Gregory P. Smith <greg krypto.org> writes: > > food for thought as noticed by a coworker who has been profiling some hot code to optimize a library...If a function does not have a return statement we return None. Ironically this makes the foo2 function below faster than the bar2 function at least as measured using bytecode size

I would be surprised if this "bytecode size" difference made a significant difference in runtimes, given that function call cost should dwarf the cumulated cost of POPTOP and LOADCONST (two of the simplest opcodes you could find). the attached sample code repeatably shows that it makes a difference though its really not much of one (2-3%).

I was just wondering if a bytecode for a superinstruction of the common sequence:

         6 POP_TOP
          7 LOAD_CONST               0 (None)
         10 RETURN_VALUE

might be worth it. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20090831/48320427/attachment-0001.htm> -------------- next part -------------- A non-text attachment was scrubbed... Name: none_speed.py Type: text/x-python Size: 619 bytes Desc: not available URL: <http://mail.python.org/pipermail/python-dev/attachments/20090831/48320427/attachment-0001.py>

More information about the Python-Dev mailing list