关于程序员:Python日学壹技性能分析

导读

置信日常应用 Python 作为生产力的读者，肯定会存在想要剖析代码中每一行的运行工夫与变量占用内存大小的需要，本文次要剖析两个模块，用于剖析每行代码的内存应用状况和运行工夫状况。

内存应用

• memory-profiler

装置

pip install memory-profiler

应用办法一

1. 在须要剖析的函数上，增加装璜器 @profile

@profile
def test1():
    c=0
    for item in xrange(100000):
         c+=1
     print (c)
        

2. 应用上面的命令运行

python -m memory_profiler memory_profiler_test.py     

应用办法二

 from memory_profiler import profile
 
 @profile(precision=4,stream=open('memory_profiler.log','w+'))
# @profile
def test1():
     c=0
     for item in xrange(100000):
         c+=1
     print c

# 间接运行即可    

后果

Filename: memory_profiler_test.py

Line #    Mem usage    Increment   Line Contents
================================================
     5   21.492 MiB   21.492 MiB   @profile
     6                             def test1():
     7   21.492 MiB    0.000 MiB       c=0
     8   21.492 MiB    0.000 MiB       for item in xrange(100000):
     9   21.492 MiB    0.000 MiB           c+=1
    10   21.492 MiB    0.000 MiB       print c

• Mem usage: 内存占用状况
• Increment: 执行该行代码后新增的内存

运行工夫

• line-profiler

装置

pip install line-profiler

应用

1. 在须要剖析的函数上，增加装璜器 @profile

@profile
def slow_function(a, b, c):
    ...

2. 运行

python -m line_profiler script_to_profile.py.lprof

后果

Pystone(1.1) time for 50000 passes = 2.48
This machine benchmarks at 20161.3 pystones/second
Wrote profile results to pystone.py.lprof
Timer unit: 1e-06 s

File: pystone.py
Function: Proc2 at line 149
Total time: 0.606656 s

Line #      Hits         Time  Per Hit   % Time  Line Contents
==============================================================
   149                                           @profile
   150                                           def Proc2(IntParIO):
   151     50000        82003      1.6     13.5      IntLoc = IntParIO + 10
   152     50000        63162      1.3     10.4      while 1:
   153     50000        69065      1.4     11.4          if Char1Glob == 'A':
   154     50000        66354      1.3     10.9              IntLoc = IntLoc - 1
   155     50000        67263      1.3     11.1              IntParIO = IntLoc - IntGlob
   156     50000        65494      1.3     10.8              EnumLoc = Ident1
   157     50000        68001      1.4     11.2          if EnumLoc == Ident1:
   158     50000        63739      1.3     10.5              break
   159     50000        61575      1.2     10.1      return IntParIO

• 每列含意

  > - Line #: The line number in the file.
  > - Hits: The number of times that line was executed.
  > - Time: The total amount of time spent executing the line in the timer's units. In the header information before the tables, you will see a line"Timer unit:" giving the conversion factor to seconds. It may be different on different systems.
  > - Per Hit: The average amount of time spent executing the line once in the timer's units.
  > - % Time: The percentage of time spent on that line relative to the total amount of recorded time spent in the function.
  > - Line Contents: The actual source code. Note that this is always read from disk when the formatted results are viewed, *not* when the code was executed. If you have edited the file in the meantime, the lines will not match up, and the formatter may not even be able to locate the function for display.

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