Python的線程&進程&協程[2] -> 進程 -> 多進程的基本使用

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多進程的基本使用

 

1 subprocess 常用函數樣本

首先定義一個子進程調用的程式，用於列印一個輸出語句，並擷取命令列參數

1 import sys2 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類與子進程互動

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 error4 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 模組

 

Python的線程&進程&協程[2] -> 進程 -> 多進程的基本使用