Felipe Almeida Lessa wrote: > Em Qua, 2006-04-12 às 11:36 +1000, Steven D'Aprano escreveu: > > On Tue, 11 Apr 2006 19:15:18 +0200, Martin v. Löwis wrote: > > > > > Felipe Almeida Lessa wrote: > > >> I love benchmarks, so as I was testing the options, I saw something very > > >> strange: > > >> > > >> $ python2.4 -mtimeit 'x = range(100000); ' > > >> 100 loops, best of 3: 6.7 msec per loop > > >> $ python2.4 -mtimeit 'x = range(100000); del x[:]' > > >> 100 loops, best of 3: 6.35 msec per loop > > >> $ python2.4 -mtimeit 'x = range(100000); x[:] = []' > > >> 100 loops, best of 3: 6.36 msec per loop > > >> $ python2.4 -mtimeit 'x = range(100000); del x' > > >> 100 loops, best of 3: 6.46 msec per loop > > >> > > >> Why the first benchmark is the slowest? I don't get it... could someone > > >> test this, too? > > > > > > In the first benchmark, you need space for two lists: the old one and > > > the new one; > > > > Er, what new list? I see only one list, x = range(100000), which is merely > > created then nothing done to it. Have I missed something? > > He's talking about the garbage collector.
To be exact the reason for two array is timeit.py. It doesn't place the code to time into a separate namespace but injects it into a for loop, so the actual code timed is: for _i in _it: x = range(100000) and that makes two arrays with 100.000 items exist for a short time starting from second iteration. -- http://mail.python.org/mailman/listinfo/python-list