我见过许多项目使用simplejson模块而不是标准库中的json模块。此外,还有许多不同的simplejson模块。为什么要使用这些替代品,而不是标准库中的替代品?
当前回答
我一直在测试json, simplejson和cjson。
json是最快的 Simplejson几乎等同于cjson Json比simplejson慢10倍
http://pastie.org/1507411:
$ python test_serialization_speed.py
--------------------
Encoding Tests
--------------------
Encoding: 100000 x {'m': 'asdsasdqwqw', 't': 3}
[ json] 1.12385 seconds for 100000 runs. avg: 0.011239ms
[simplejson] 0.44356 seconds for 100000 runs. avg: 0.004436ms
[ cjson] 0.09593 seconds for 100000 runs. avg: 0.000959ms
Encoding: 10000 x {'m': [['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19], ['0', 1, '2', 3, '4', 5, '6', 7, '8', 9, '10', 11, '12', 13, '14', 15, '16', 17, '18', 19]], 't': 3}
[ json] 7.76628 seconds for 10000 runs. avg: 0.776628ms
[simplejson] 0.51179 seconds for 10000 runs. avg: 0.051179ms
[ cjson] 0.44362 seconds for 10000 runs. avg: 0.044362ms
--------------------
Decoding Tests
--------------------
Decoding: 100000 x {"m": "asdsasdqwqw", "t": 3}
[ json] 3.32861 seconds for 100000 runs. avg: 0.033286ms
[simplejson] 0.37164 seconds for 100000 runs. avg: 0.003716ms
[ cjson] 0.03893 seconds for 100000 runs. avg: 0.000389ms
Decoding: 10000 x {"m": [["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19], ["0", 1, "2", 3, "4", 5, "6", 7, "8", 9, "10", 11, "12", 13, "14", 15, "16", 17, "18", 19]], "t": 3}
[ json] 37.26270 seconds for 10000 runs. avg: 3.726270ms
[simplejson] 0.56643 seconds for 10000 runs. avg: 0.056643ms
[ cjson] 0.33007 seconds for 10000 runs. avg: 0.033007ms
其他回答
在最新版本中,Json在加载和转储两种情况下都比simplejson快
测试版本:
python: 3.6.8 json: 2.0.9 simplejson: 3.16.0
结果:
>>> def test(obj, call, data, times):
... s = datetime.now()
... print("calling: ", call, " in ", obj, " ", times, " times")
... for _ in range(times):
... r = getattr(obj, call)(data)
... e = datetime.now()
... print("total time: ", str(e-s))
... return r
>>> test(json, "dumps", data, 10000)
calling: dumps in <module 'json' from 'C:\\Users\\jophine.antony\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\json\\__init__.py'> 10000 times
total time: 0:00:00.054857
>>> test(simplejson, "dumps", data, 10000)
calling: dumps in <module 'simplejson' from 'C:\\Users\\jophine.antony\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\site-packages\\simplejson\\__init__.py'> 10000 times
total time: 0:00:00.419895
'{"1": 100, "2": "acs", "3.5": 3.5567, "d": [1, "23"], "e": {"a": "A"}}'
>>> test(json, "loads", strdata, 1000)
calling: loads in <module 'json' from 'C:\\Users\\jophine.antony\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\json\\__init__.py'> 1000 times
total time: 0:00:00.004985
{'1': 100, '2': 'acs', '3.5': 3.5567, 'd': [1, '23'], 'e': {'a': 'A'}}
>>> test(simplejson, "loads", strdata, 1000)
calling: loads in <module 'simplejson' from 'C:\\Users\\jophine.antony\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\site-packages\\simplejson\\__init__.py'> 1000 times
total time: 0:00:00.040890
{'1': 100, '2': 'acs', '3.5': 3.5567, 'd': [1, '23'], 'e': {'a': 'A'}}
版本:
python: 3.7.4 json: 2.0.9 simplejson: 3.17.0
Json在转储操作中比simplejson快,但在加载操作中两者保持相同的速度
我发现Python 2.7与simplejson 3.3.1的API不兼容在于输出是生成str对象还是unicode对象。 如。
>>> from json import JSONDecoder
>>> jd = JSONDecoder()
>>> jd.decode("""{ "a":"b" }""")
{u'a': u'b'}
vs
>>> from simplejson import JSONDecoder
>>> jd = JSONDecoder()
>>> jd.decode("""{ "a":"b" }""")
{'a': 'b'}
如果首选使用simplejson,则可以通过将参数字符串强制转换为unicode来解决,如下所示:
>>> from simplejson import JSONDecoder
>>> jd = JSONDecoder()
>>> jd.decode(unicode("""{ "a":"b" }""", "utf-8"))
{u'a': u'b'}
强制转换确实需要知道原始字符集,例如:
>>> jd.decode(unicode("""{ "a": "ξηθννββωφρες" }"""))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xce in position 8: ordinal not in range(128)
这是第40个问题
项目使用simplejson的另一个原因是内置json最初不包括它的C加速,所以性能差异是显而易见的。
在python3中,如果你有一个b'bytes'的字符串,使用json你必须在加载它之前解码()内容。Simplejson会处理这个问题,所以你可以只做Simplejson .loads(byte_string)。
内置json模块被包含在Python 2.6中。任何支持Python < 2.6版本的项目都需要有一个备份。在很多情况下,这种退路很简单。
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