python-fork()创建子进程

Linux系统提供了一个fork()函数创建子进程。当调用这个函数时，操作系统将当前的进程(父进程)复制一份(子进程)，然后分别在父进程和子进程内返回，子进程永远返回0，父进程返回子进程的PID
python中os模块提供了fork()函数

import os
import time

print("Before fork process pid=%s, ppid=%s" % (os.getpid(), os.getppid()))

pid = os.fork()
if pid == 0:
    print("I am child process pid=%s, ppid=%s" % (os.getpid(), os.getppid()))
    time.sleep(5)
else:
    print("I am parent process pid=%s, ppid=%s" % (os.getpid(), os.getppid()))
    time.sleep(5)

print( "After fork process pid=%s, ppid=%s" % (os.getpid(), os.getppid()))

运行结果:

Before fork process pid=8161, ppid=6182
I am parent process pid=8161, ppid=6182
I am child process pid=8162, ppid=8161
After fork process pid=8162, ppid=8161
After fork process pid=8161, ppid=6182