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

[Chris Withers]

On 13/02/2013 11:53, Steven D'Aprano wrote:
>> 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.
>
>
> I remember it well.
>
> http://mail.python.org/pipermail/python-dev/2009-August/091125.html
>
> I frequently link to this thread as an example of just how bad repeated
> string concatenation can be, how painful it can be to debug, and how
> even when the optimization is fast on one system, it may fail and be
> slow on another system.

Amusing is that 
http://mail.python.org/pipermail/python-dev/2009-August/thread.html#91125 doesn't 
even list the email where I found the problem...

Chris

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