多進程的基本使用

1 subprocess 常用函數示例

首先定義一個子進程調用的程序，用於打印一個輸出語句，並獲取命令行參數

1 import sys
2 print(‘Called_Function.py called, Hello world.‘)
3 try:
4     print(‘Got para‘, sys.argv[1:])
5 except:
6     pass

再定義主函數，即父進程，分別測試 run() / call() / check_call() / getstatusoutput() / getoutput() / ckeck_output函數。

 1 import
 
 subprocess
 2 
 3 # subprocess.run()
 4 print(‘---------subprocess.run------------‘)
 5 re = subprocess.run([‘python‘, ‘Called_Function.py‘, ‘para_1‘, ‘para_2‘])
 6 print(‘subprocess.run() test returns obj:‘, re)
 7 print(‘Return code is: {0}, stdout is: {1}, stderr is: {2}‘.format(re.returncode, re.stdout, re.stderr))
 
 8 
 9 # subprocess.call()
10 print(‘\n---------subprocess.call------------‘)
11 print(‘subprocess.call() test returns code:‘, subprocess.call([‘python‘, ‘Called_Function.py‘, ‘para_1‘, ‘para_2‘]))
12 
13 # subprocess.ckeck_call()
14 print(‘\n---------subprocess.check_call------------‘)
15 try:
16     print
 
(‘subprocess.check_call() test returns code:‘, subprocess.check_call([‘python‘, ‘Called_Function.py‘]))
17 except subprocess.CalledProcessError:
18     print(‘Failed to call.‘)
19 
20 # subprocess.getstatusoutput()
21 print(‘\n---------subprocess.getstatusoutput------------‘)
22 print(‘subprocess.getstatusoutput() test returns:‘, subprocess.getstatusoutput([‘python‘, ‘Called_Function.py‘]))
23 
24 # subprocess.getoutput()
25 print(‘\n---------subprocess.getstatusoutput------------‘)
26 print(‘subprocess.getoutput() test returns:‘, subprocess.getoutput([‘python‘, ‘Called_Function.py‘]))
27 
28 # subprocess.check_output()
29 print(‘\n---------subprocess.check_output------------‘)
30 print(‘subprocess.check_output() test returns:‘, subprocess.check_output([‘python‘, ‘Called_Function.py‘]))

2 利用Popen類與子進程交互

首先定義一個子進程調用的函數，函數中需求一個輸入

1 x = input(‘Please input something.‘)
2 print(x, ‘Hello World!‘)
3 # Raise an error
4 print(y)

再定義父進程的函數

 1 import subprocess
 2 
 3 prcs = subprocess.Popen([‘python‘, ‘Called_Function_Popen.py‘],
 4                         stdout=subprocess.PIPE,
 5                         stdin=subprocess.PIPE,
 6                         stderr=subprocess.PIPE,
 7                         universal_newlines=True,
 8                         shell=True)
 9 
10 print(‘subprocess pid:‘, prcs.pid)
11 
12 re = prcs.communicate(‘These string are from stdin‘)
13 print(‘\nSTDOUT:‘, re[0])
14 print(‘\nSTDERR:‘, re[1])
15 if prcs.poll():
16     print(‘\nThe subprocess has been done‘)

相關閱讀

1. subprocess 模塊

Python的線程&進程&協程[2] -> 進程 -> 多進程的基本使用