[Python-Dev] Status of json (simplejson) in cpython

[Bob Ippolito]

On Fri, Apr 15, 2011 at 4:12 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Fri, 15 Apr 2011 14:27:04 -0700
> Bob Ippolito <bob at redivi.com> wrote:
>> On Fri, Apr 15, 2011 at 2:20 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
>> > Le vendredi 15 avril 2011 à 14:18 -0700, Bob Ippolito a écrit :
>> >> On Friday, April 15, 2011, Antoine Pitrou <solipsis at pitrou.net> wrote:
>> >> >>
>> >> >> > Since the JSON spec is set in stone, the changes
>> >> >> > will mostly be about API (indentation, object conversion, etc)
>> >> >> > and optimization.  I presume the core parsing logic won't
>> >> >> > be changing much.
>> >> >>
>> >> >> Actually the core parsing logic is very different (and MUCH faster),
>> >> >
>> >> > Are you talking about the Python logic or the C logic?
>> >>
>> >> Both, actually. IIRC simplejson in pure python typically beats json
>> >> with it's C extension.
>> >
>> > Really? It would be nice to see some concrete benchmarks against both
>> > repo tips.
>>
>> Maybe in a few weeks or months when I have time to finish up the
>> benchmarks that I was working on... but it should be pretty easy for
>> anyone to show that the version in CPython is very slow (and uses a
>> lot more memory) in comparison to simplejson.
>
> Well, here's a crude microbenchmark. I'm comparing 2.6+simplejson 2.1.3
> to 3.3+json, so I'm avoiding integers:
>
> * json.dumps:
>
> $ python -m timeit -s "from simplejson import dumps, loads; \
>    d = dict((str(i), str(i)) for i in range(1000))" \
>   "dumps(d)"
>
> - 2.6+simplejson: 372 usec per loop
> - 3.2+json: 352 usec per loop
>
> * json.loads:
>
> $ python -m timeit -s "from simplejson import dumps, loads; \
>    d = dict((str(i), str(i)) for i in range(1000)); s = dumps(d)" \
>    "loads(s)"
>
> - 2.6+simplejson: 224 usec per loop
> - 3.2+json: 233 usec per loop
>
>
> The runtimes look quite similar.

That's the problem with trivial benchmarks. With more typical data
(for us, anyway) you should see very different results.

-bob