Performance in exec environnements

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Date	Tue, 13 Jan 2015 18:02:17 +0100
Subject	Performance in exec environnements
From	Jean-Baptiste Braun <jbaptiste.braun@gmail.com>
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Hi,

I'm working on auto-generated python code with the exec function. I've done
some performance benches :

% python -m timeit '1 + 1'
10000000 loops, best of 3: 0.0229 usec per loop

% python -m timeit "exec('1 + 1')"
100000 loops, best of 3: 11.6 usec per loop

-> Maybe creating an exec environnement (I don't know how it works) takes
time. But :

% python -m timeit "1 + 1; 1 + 1"
10000000 loops, best of 3: 0.042 usec per loop

% python -m timeit "exec('1 + 1; 1 + 1')"
100000 loops, best of 3: 15.7 usec per loop

-> As if executing one more 1 + 1 would take 4 more seconds (100000
iterations) in an exec environnement.

Am I missing something or should I expect that result ? What does using
exec imply that causes such a difference ?

Jean-Baptiste Braun

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Performance in exec environnements Jean-Baptiste Braun <jbaptiste.braun@gmail.com> - 2015-01-13 18:02 +0100
  Re: Performance in exec environnements Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-14 08:48 +1100
    Re: Performance in exec environnements Jean-Baptiste Braun <jbaptiste.braun@gmail.com> - 2015-01-14 10:02 +0100
      Re: Performance in exec environnements Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-15 12:51 +1100
    Re: Performance in exec environnements Chris Angelico <rosuav@gmail.com> - 2015-01-14 22:14 +1100
    Re: Performance in exec environnements Jean-Baptiste Braun <jbaptiste.braun@gmail.com> - 2015-01-14 14:38 +0100
    Re: Performance in exec environnements Chris Angelico <rosuav@gmail.com> - 2015-01-15 00:43 +1100
    Re: Performance in exec environnements Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-14 10:11 -0700

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