[Python-Dev] Patch to use dict subclasses in eval(), exec (original) (raw)

Jeff Epler jepler@unpythonic.net
Tue, 29 Oct 2002 11:10:25 -0600

Still working from the version which is missing DECREFs, I get these timings from a program intended to more directly measure the speed of local, global, and builtin name lookups:

Vanilla Python CVS. In effect these are three runs of the same thing, so you get some idea of the timing variations on my system. $ python-cvs/python lookup-speed.py Timing 4000000 name lookups type builtin global local overhead dict 2.74015 1.99215 1.21323 0.17610 D 2.69901 1.99129 1.24662 0.17832 E 2.73839 2.03171 1.25233 0.17843

CVS with my original patch (leaks references). "D" is a dict subclass which doesn't define getitem, "E" is a dict subclass which does (simply calling dict.getitem and returning the result) $ python-dict/python lookup-speed.py Timing 4000000 name lookups type builtin global local overhead dict 2.81268 2.04795 1.26585 0.18117 D 5.08308 2.85853 1.23625 0.17944 E 81.62213 64.60481 1.26524 0.17973 This is a ~3% slowdown on the test with the heaviest use of builtins and globals that I can think of offhand. Slowdown: builtin global dict 3% 3% D 80% 40% E *28 *31

I'm about done pretending to cheerlead for this patch, though if I fix the reference problem I'll post the revised diffs.

Jeff