[Python-Dev] file.readinto performance regression in Python 3.2 vs. 2.7? (original) (raw)

Amaury Forgeot d'Arc amauryfa at gmail.com
Fri Nov 25 16:07:59 CET 2011

2011/11/25 Paul Moore <p.f.moore at gmail.com>

The optimisation mentioned was an attempt (by mutating an existing string when the runtime determined that it was safe to do so) to hide the consequences of this fact from end-users who didn't fully understand the issues. It was relatively effective, but like any such case (floating point is another common example) it did some level of harm at the same time as it helped (by obscuring the issue further).

It would be nice to have the optimisation back if it's easy enough to do so, for quick-and-dirty code, but it is not a good idea to rely on it (and it's especially unwise to base benchmarks on it working :-))

Note that this string optimization hack is still present in Python 3, but it now acts on unicode strings, not bytes.

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