Benchmarking Python JSON serializers - json vs ujson vs orjson

Introduction

If you work with a large datasets in json inside your python code, then you might want to try using 3rd party libraries like ujson and orjson which are replacements to python’s json library.

As per their documentation

• ujson (UltraJSON) is an ultra fast JSON encoder and decoder written in pure C with bindings for Python 3.7+.

• orjson is a fast, correct JSON library for Python. It is the fastest python library for json encoding & decoding. It serializes dataclass, datetime, numpy, and UUID instances natively.

Benchmarking

I did a basic benchmark comparing json, ujson and orjson. The benchmarking results were interesting.

import time
import json
import orjson
import ujson


def benchmark(name, dumps, loads):
    start = time.time()
    for i in range(3000000):
        result = dumps(m)
        loads(result)
    print(name, time.time() - start)


if __name__ == "__main__":
    m = {
        "timestamp": 1556283673.1523004,
        "task_uuid": "0ed1a1c3-050c-4fb9-9426-a7e72d0acfc7",
        "task_level": [1, 2, 1],
        "action_status": "started",
        "action_type": "main",
        "key": "value",
        "another_key": 123,
        "and_another": ["a", "b"],
    }

    benchmark("Python", json.dumps, json.loads)
    benchmark("ujson", ujson.dumps, ujson.loads)

    # orjson only outputs bytes, but often we need unicode:
    benchmark("orjson", lambda s: str(orjson.dumps(s), "utf-8"), orjson.loads)

# OUTPUT:
# Python 12.502133846282959
# ujson 4.428200960159302
# orjson 2.3136467933654785

ujson is 3 times faster than the standard json library

orjson is over 6 times faster than the standard json library

Conclusion

For most cases, you would want to go with python’s standard json library which removes dependencies on other libraries. On other hand you could try out ujson which is simple replacement for python’s json library. If you want more speed and also want dataclass, datetime, numpy, and UUID instances and you are ready to deal with more complex code, then you can try your hands on orjson