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

[Antoine Pitrou]

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.

Antoine.