Python JSON decoding performance


I'm using the json module in Python 2.6 to load and decode JSON files. However I'm currently getting slower than expected performance. I'm using a test case which is 6MB in size and json.loads() is taking 20 seconds.

I thought the json module had some native code to speed up the decoding?

How do I check if this is being used?

As a comparison, I downloaded and installed the python-cjson module, and cjson.decode() is taking 1 second for the same test case.

I'd rather use the JSON module provided with Python 2.6 so that users of my code aren't required to install additional modules.

(I'm developing on Mac OS X, but I getting a similar result on Windows XP.)


The new Yajl - Yet Another JSON Library is very fast.

yajl        serialize: 0.180  deserialize: 0.182  total: 0.362
simplejson  serialize: 0.840  deserialize: 0.490  total: 1.331
stdlib json serialize: 2.812  deserialize: 8.725  total: 11.537

You can compare the libraries yourself.

Update: UltraJSON is even faster.

take a look UltraJSON

here my test (code from:

platform: OS X 10.8.3 MBP 2.2 GHz Intel Core i7







JSON Benchmark
2.7.2 (default, Oct 11 2012, 20:14:37)
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)]
simplejson: 0.293394s
cjson: 0.461517s
ujson: 0.222278s
jsonlib: 0.428641s
json: 0.759091s
yajl: 0.388836s

simplejson: 0.556367s
cjson: 0.42649s
ujson: 0.212396s
jsonlib: 0.265861s
json: 0.365553s
yajl: 0.361718s
By : TONy.W

I was parsing the same file 10x. File size was 1,856,944 bytes.

Python 2.6:

yajl        serialize: 0.294  deserialize: 0.334  total: 0.627
cjson       serialize: 0.494  deserialize: 0.276  total: 0.769
simplejson  serialize: 0.554  deserialize: 0.268  total: 0.823
stdlib json serialize: 3.917  deserialize: 17.508 total: 21.425

Python 2.7:

yajl        serialize: 0.289  deserialize: 0.312  total: 0.601
cjson       serialize: 0.232  deserialize: 0.254  total: 0.486
simplejson  serialize: 0.288  deserialize: 0.253  total: 0.540
stdlib json serialize: 0.273  deserialize: 0.256  total: 0.528

Not sure why numbers are disproportionate from your results. I guess, newer libraries?

By : Tomas

This video can help you solving your question :)
By: admin