[Python-Dev] Usage of += on strings in loops in stdlib (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Wed Feb 13 08:24:22 CET 2013

On Wed, 13 Feb 2013 08:16:21 +0100 Antoine Pitrou <solipsis at pitrou.net> wrote:

On Wed, 13 Feb 2013 09:39:23 +1000 Nick Coghlan <ncoghlan at gmail.com> wrote: > On 13 Feb 2013 07:08, "Maciej Fijalkowski" <fijall at gmail.com> wrote: > > > > Hi > > > > We recently encountered a performance issue in stdlib for pypy. It > > turned out that someone commited a performance "fix" that uses += for > > strings instead of "".join() that was there before. > > > > Now this hurts pypy (we can mitigate it to some degree though) and > > possible Jython and IronPython too. > > > > How people feel about generally not having += on long strings in > > stdlib (since the refcount = 1 thing is a hack)? > > > > What about other performance improvements in stdlib that are > > problematic for pypy or others? > > > > Personally I would like cleaner code in stdlib vs speeding up CPython. > > For the specific case of "Don't rely on the fragile refcounting hack in > CPython's string concatenation" I strongly agree. However, as a general > principle, I can't agree until speed.python.org is a going concern and we > can get a reasonable overview of any resulting performance implications.

Anybody can run the benchmark suite for himself, speed.p.o is (fortunately) not a roadblock: http://bugs.python.org/issue17170

And I meant to paste the repo URL actually: http://hg.python.org/benchmarks/

Regards

Antoine.

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