Python multiprocessing Process（创建子进程）

原因：了解进程的运行活动，只能实例化子进程。

# coding=utf-8
import logging
import os
import time
from multiprocessing import Process

x1, x2 = 3, 7
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [*] %(processName)s %(message)s"
)


def run_add (x1, x2):
    time.sleep(5)
    logging.info(f"子进程ID:{os.getpid()}")
    logging.info(f'x1 + x2 = {x1 + x2}')
    logging.info("----------the end------[*]")


if __name__ == '__main__':
    logging.info("--------starting-----[*]")
    p = Process(target=run_add, args=(x1, x2))
    p.daemon = True  # 如果没有join()方法，当主进程退出时，它会尝试终止其所有守护进程的子进程。
    logging.info(f"子进程是否存活：{p.is_alive()}")
    p.start()
    logging.info(f"子进程是否存活：{p.is_alive()}")
    logging.info(f"子进程ID：{p.pid}")
    logging.info(f"子进程的身份验证密钥：{p.authkey}")
    logging.info(f"子进程系统对象的数字句柄：{p.sentinel}")
    # p.terminate()  # 终止子进程
    p.join()  # 等待子进程结束后再继续往下运行，通常用于进程间的同步。
    logging.info(f"主进程ID:{os.getpid()}")
    logging.info(f'x1 * x2 = {x1 * x2}', )
    logging.info("--------the end------[*]")

输出：

2019-10-03 14:43:41,554 [*] MainProcess --------starting-----[*]
2019-10-03 14:43:41,554 [*] MainProcess 子进程是否存活：False
2019-10-03 14:43:41,570 [*] MainProcess 子进程是否存活：True
2019-10-03 14:43:41,570 [*] MainProcess 子进程ID：3704
2019-10-03 14:43:41,570 [*] MainProcess 子进程的身份验证密钥：b'V_\xe3\xce7\xa3\xa2r0iy-\xd6\xcf)"\x84\x0c\xbd\x13h\xe8\x90\xb8\x064\xa9\x8c\x1c0\xc7%'
2019-10-03 14:43:41,570 [*] MainProcess 子进程系统对象的数字句柄：440
2019-10-03 14:43:46,639 [*] Process-1 子进程ID:3704
2019-10-03 14:43:46,639 [*] Process-1 x1 + x2 = 10
2019-10-03 14:43:46,639 [*] Process-1 ----------the end------[*]
2019-10-03 14:43:46,660 [*] MainProcess 主进程ID:7344
2019-10-03 14:43:46,660 [*] MainProcess x1 * x2 = 21
2019-10-03 14:43:46,660 [*] MainProcess --------the end------[*]