[Python-Dev] Re: Fast access to builtins (original) (raw)

Raymond Hettinger python@rcn.com
Fri, 28 Mar 2003 18:05:17 -0500

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[Raymond]

> I've already tried out a pure python proof-of-concept

[Michael Chermside]

Does that mean that you can give us some idea what kind of performance boost this actually resulted in?

It depends on what you're timing but it is not a big win.

Speed doubles in demo code that just makes references to globals but is much more modest when the builtins are called. This shows that the call time is more significant than the reference time:
```
  def f(i):
      dict; hasattr; float; pow; list; range   # speed more than doubles
      hex(i); str(i); oct(i); int(i); float(i)    # 12% gain
```
Contrived examples show the best gains while code from real apps show smaller improvements:

def shuffle(random=random.random): # 6% gain x = list('abcdefghijklmnopqrstuvwyz0123456789') for i in xrange(len(x)-1, 0, -1): j = int(random() * (i+1)) x[i], x[j] = x[j], x[i]
PyStone does not use any builtins.
Scanning my own sources, it looks like some of the builtins almost never appear inside loops (dir, map, filter, zip, dict, range). The ones that are in loops usually do something simple (int, str, chr, len). Either way, builtin access never seems to dominate the running time. OTOH, maybe that's just the way I write code.

Raymond Hettinger

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