Home Original page

[Python-Dev] Python 3.6 dict becomes compact and gets a private version; and keywords become ordered

Maciej Fijalkowski fijall at gmail.com
Tue Sep 20 15:01:16 EDT 2016 
On Thu, Sep 15, 2016 at 1:27 PM, Paul Moore <p.f.moore at gmail.com> wrote:
> On 15 September 2016 at 10:43, Raymond Hettinger
> <raymond.hettinger at gmail.com> wrote:
>> Something like this will reveal the true and massive improvement in iteration speed:
>>
>>      $ ./python.exe -m timeit -s "d=dict.fromkeys(map(str,range(10**6)))" "list(d)"
>
>>py -3.5 -m timeit -s "d=dict.fromkeys(map(str,range(10**6)))" "list(d)"
> 10 loops, best of 3: 66.2 msec per loop
>>py -3.6 -m timeit -s "d=dict.fromkeys(map(str,range(10**6)))" "list(d)"
> 10 loops, best of 3: 27.8 msec per loop
>
> And for Victor:
>
>>py -3.5 -m perf timeit -s "d=dict.fromkeys(map(str,range(10**6)))" "list(d)"
> ....................
> Median +- std dev: 65.7 ms +- 3.8 ms
>>py -3.6 -m perf timeit -s "d=dict.fromkeys(map(str,range(10**6)))" "list(d)"
> ....................
> Median +- std dev: 27.9 ms +- 1.2 ms
>
> Just as a side point, perf provided essentially identical results but
> took 2 minutes as opposed to 8 seconds for timeit to do so. I
> understand why perf is better, and I appreciate all the work Victor
> did to create it, and analyze the results, but for getting a quick
> impression of how a microbenchmark performs, I don't see timeit as
> being *quite* as bad as Victor is claiming.
>
> I will tend to use perf now that I have it installed, and now that I
> know how to run a published timeit invocation using perf. It's a
> really cool tool. But I certainly won't object to seeing people
> publish timeit results (any more than I'd object to *any*
> mirobenchmark).
>
> Paul

How about we just make timeit show average and not disable the GC then
(two of the complaints that will not change the execution time)?
More information about the Python-Dev mailing list