Python的并发并行[3] -> 进程[1] -> 多进程的基本使用

多进程的基本使用

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1 subprocess 常用函数示例

首先定义一个子进程调用的程序，用于打印一个输出语句，并获取命令行参数

import sys
print('Called_Function.py called, Hello world.')
try:
    print('Got para', sys.argv[1:])
except:
    pass

再定义主函数，即父进程，分别测试 run() / call() / check_call() / getstatusoutput() / getoutput() / ckeck_output函数。

import subprocess

# subprocess.run()
print('---------subprocess.run------------')
re = subprocess.run(['python', 'Called_Function.py', 'para_1', 'para_2'])
print('subprocess.run() test returns obj:', re)
print('Return code is: {0}, stdout is: {1}, stderr is: {2}'.format(re.returncode, re.stdout, re.stderr))

# subprocess.call()
print('
---------subprocess.call------------')
print('subprocess.call() test returns code:', subprocess.call(['python', 'Called_Function.py', 'para_1', 'para_2']))

# subprocess.ckeck_call()
print('
---------subprocess.check_call------------')
try:
    print('subprocess.check_call() test returns code:', subprocess.check_call(['python', 'Called_Function.py']))
except subprocess.CalledProcessError:
    print('Failed to call.')

# subprocess.getstatusoutput()
print('
---------subprocess.getstatusoutput------------')
print('subprocess.getstatusoutput() test returns:', subprocess.getstatusoutput(['python', 'Called_Function.py']))

# subprocess.getoutput()
print('
---------subprocess.getstatusoutput------------')
print('subprocess.getoutput() test returns:', subprocess.getoutput(['python', 'Called_Function.py']))

# subprocess.check_output()
print('
---------subprocess.check_output------------')
print('subprocess.check_output() test returns:', subprocess.check_output(['python', 'Called_Function.py']))

 

2 利用Popen类与子进程交互

首先定义一个子进程调用的函数，函数中需求一个输入

x = input('Please input something.')
print(x, 'Hello World!')
# Raise an error
print(y)

再定义父进程的函数

import subprocess

prcs = subprocess.Popen(['python', 'Called_Function_Popen.py'],
                        stdout=subprocess.PIPE,
                        stdin=subprocess.PIPE,
                        stderr=subprocess.PIPE,
                        universal_newlines=True,
                        shell=True)

print('subprocess pid:', prcs.pid)

re = prcs.communicate('These string are from stdin')
print('
STDOUT:', re[0])
print('
STDERR:', re[1])
if prcs.poll():
    print('
The subprocess has been done')

相关阅读

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1. subprocess 模块