[Python-Dev] PEP 414 - Unicode Literals for Python 3 (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Tue Feb 28 10:02:46 CET 2012

Am 27.02.2012 22:35, schrieb Armin Ronacher:

Hi,

On 2/27/12 4:44 PM, martin at v.loewis.de wrote: Maybe I'm missing something, but there doesn't seem to be a benchmark that measures the 2to3 performance, supporting the claim that it runs "two orders of magnitude" slower (which I'd interpret as a factor of 100). My Jinja2+Werkzeug's testsuite combined takes 2 seconds to run (Werkzeug actually takes 3 because it pauses for two seconds in a cache expiration test). 2to3 takes 45 seconds to run. And those are small code bases (15K lines combined).

I'm not quite able to reproduce that. I don't know how to run the Jinja2 and Werkzeug test suites combined (Werkzeug's setup.py install gives SyntaxError on Python3). So taking Jinja2 alone, this is what I get:

So this is less than a factor of ten, but more importantly, much shorter than 45s.

I also claim that the example is atypical, in that the test suite completes so quickly. Taking distribute 0.6.24 as a counter-example:

So the test suite runs longer than the build process.

Therefore, even a claim "In many cases 2to3 runs 20 times slower than the testsuite for the library or application it's testing" cannot be substantiated, as cannot the claim "This for instance is the case for the Jinja2 library".

On the contrary, I'd expect that the build time using 2to3 is significantly shorter than the test suite run times, in particular for large projects. For example, for Django, 2to3 takes less than 3 minutes (IIRC), and the test suite runs an hour or so (depending on how many tests get skipped).

Regards, Martin

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