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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>
To: python-list@python.org
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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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<div dir=3D"ltr"><div><div><div><div><div>Hi,<br><br></div>I&#39;m working =
on auto-generated python code with the exec function. I&#39;ve done some pe=
rformance benches :<br><br>% python -m timeit &#39;1 + 1&#39;<br>10000000 l=
oops, best of 3: 0.0229 usec per loop<br><br>% python -m timeit &quot;exec(=
&#39;1 + 1&#39;)&quot;=C2=A0 <br>100000 loops, best of 3: 11.6 usec per loo=
p<br><br></div>-&gt; Maybe creating an exec environnement (I don&#39;t know=
 how it works) takes time. But :<br><br>% python -m timeit &quot;1 + 1; 1 +=
 1&quot;=C2=A0=C2=A0 <br>10000000 loops, best of 3: 0.042 usec per loop<br>=
<br>% python -m timeit &quot;exec(&#39;1 + 1; 1 + 1&#39;)&quot;<br>100000 l=
oops, best of 3: 15.7 usec per loop<br><br></div>-&gt; As if executing one =
more 1 + 1 would take 4 more seconds (100000 iterations) in an exec environ=
nement.<br><br></div>Am I missing something or should I expect that result =
? What does using exec imply that causes such a difference ?<br><br></div>J=
ean-Baptiste Braun<br></div>

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