最早见过手写的，类似于下面这种：
1 import datetime
2
3 def time_1():
4 begin = datetime.datetime.now()
5 sum = 0
6 for i in xrange(10000000):
7 sum = sum + i
8 end = datetime.datetime.now()
9 return end-begin
10
11 print time_1()
输出如下：
➜ Python python time_1.py
0:00:00.280797
另外一种方法是使用timeit模块，使用方法如下：
In [5]: import timeit
In [6]: timeit.timeit("sum(range(100))")
Out[6]: 1.2272648811340332
还可以在命令行上使用这种timeit模块，如下：
➜ Python python -m timeit -s"import time_1 as t" "t.time_1()"
0:00:00.282044
10 loops, best of 3: 279 msec per loop
注意：timeit模块会多次运行程序以获得更精确的时间，所以需要避免重复执行带来的影响。比方说x.sort()这种操作，因为第一次执行之后，后边已经是排好的了，准确性就收到了影响。
还有一种方法是使用cProfile模块，代码如下，名字为time_1.py:
1 import datetime
2
3 def time_1():
4 begin = datetime.datetime.now()
5 sum = 0
6 for i in xrange(10000000):
7 sum = sum + i
8 end = datetime.datetime.now()
9 return end-begin
10
11 if __name__ == '__main__':
12 print time_1()
13
14 import cProfile
15 cProfile.run('time_1()')
运行程序结果如下：
➜ Python python time_1.py
0:00:00.282828
2 function calls in 0.000 seconds
Ordered by: standard name
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 0.000 0.000 :1()
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}
Traceback (most recent call last):
File "time_1.py", line 15, in
cProfile.run('main()')
File "/usr/lib/python2.7/cProfile.py", line 29, in run
prof = prof.run(statement)
File "/usr/lib/python2.7/cProfile.py", line 135, in run
return self.runctx(cmd, dict, dict)
File "/usr/lib/python2.7/cProfile.py", line 140, in runctx
exec cmd in globals, locals
File "", line 1, in
NameError: name 'main' is not defined
➜ Python vi time_1.py
➜ Python python time_1.py
0:00:00.284642
5 function calls in 0.281 seconds
Ordered by: standard name
ncalls tottime percall cumtime percall filename:lineno(function)
1 0.000 0.000 0.281 0.281 :1()
1 0.281 0.281 0.281 0.281 time_1.py:3(time_1)
2 0.000 0.000 0.000 0.000 {built-in method now}
1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler' objects}
一开始代码里最后一行写的是cProfile.run('main()')，提示没有main（），将main（）改成函数名字就可以了
这里是最简单的应用，具体大家可以去看看文档，或者直接help(xxx)
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