2017-07-17 9:45 GMT-07:00 Steven D'Aprano <st...@pearwood.info>: > On Mon, Jul 17, 2017 at 02:43:19PM +0200, Antoine Pitrou wrote: > > > > Hello, > > > > Cost of creating a namedtuple has been identified as a contributor to > > Python startup time. Not only Python core and the stdlib, but any > > third-party library creating namedtuple classes (there are many of > > them). An issue was created for this: > > https://bugs.python.org/issue28638 > > Some time ago, I needed to backport a version of namedtuple to Python > 2.4, so I started with Raymond's recipe on Activestate and modified it > to only exec the code needed for __new__. The rest of the class is an > ordinary inner class: > > # a short sketch > def namedtuple(...): > class Inner(tuple): > ... > exec(source, ns) > Inner.__new__ = ns['__new__'] > return Inner > > > Here's my fork of Raymond's recipe: > > https://code.activestate.com/recipes/578918-yet-another-namedtuple/ > > > Out of curiosity, I took that recipe, updated it to work in Python 3, > and compared it to the std lib version. Here are some representative > timings: > > [steve@ando ~]$ python3.5 -m timeit -s "from collections import > namedtuple" "K = namedtuple('K', 'a b c')" > 1000 loops, best of 3: 1.02 msec per loop > > [steve@ando ~]$ python3.5 -m timeit -s "from nt3 import namedtuple" "K = > namedtuple('K', 'a b c')" > 1000 loops, best of 3: 255 usec per loop > > > I think that proves that this approach is viable and can lead to a big > speed up. > > I have an open pull request implementing this approach: https://github.com/python/cpython/pull/2736. We can discuss the exact form the code should take there (Ivan already added some good suggestions).
> I don't think that merely dropping the _source attribute will save much > time. It might save a bit of memory, but in my experiements dropping it > only saves about 10µs more. I think the real bottleneck is the cost of > exec'ing the entire class. > > > > -- > Steve > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/ > jelle.zijlstra%40gmail.com >
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
