[Python-Dev] Usage of += on strings in loops in stdlib

[Chris Withers]

On 12/02/2013 21:03, Maciej Fijalkowski wrote:
> 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.

That's... interesting.

I fixed a performance bug in httplib some years ago by doing the exact 
opposite; += -> ''.join(). In that case, it changed downloading a file 
from 20 minutes to 3 seconds. That was likely on Python 2.5.

> How people feel about generally not having += on long strings in
> stdlib (since the refcount = 1 thing is a hack)?

+1 from me.

Chris

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