多进程以及join的用法

# # ************************************************
# # 创建多进程方式
# import os
# from multiprocessing import Process
#
# def task():
#     print('this is sub process')
#     print(f'sub process id {os.getpid()}')
#     print(f'my id {os.getpid()} ppid is {os.getppid()}')
#
#
# print(os.getpid(),__name__)
#
# if __name__ =='__main__':
#     # 注意开启进程的代码必须放在__main__下面
#     # 实例化一个进程对象，让他开启进程
#     p = Process(target=task)
#     p.start()
#     print('this is parent process')
#     print(f'parent process is:{os.getpid()}')
#     print('over')
#
# """
# 4280 __main__
# this is parent process
# parent process is:4280
# over
# 5576 __mp_main__
# this is sub process
# sub process id 5576
# my id 5576 ppid is 4280
# """
# # ************************************************
# from multiprocessing import Process
# import os
#
# class Downloarder(Process):
#     # def __init__(self,url,size,name):
#     #     super().__init()
#     #     self.url = url
#     #     self.size = size
#     #     self.name = name
#
#
#     def run(self):
#         print(os.getpid())
#         pass
#
#
# if __name__ == '__main__':
#     m = Downloarder()
#     m.start()
#     m.run()
#     print('parent over',os.getpid())
#
# """
# 1648
# parent over 1648
# 5684
#
# """
# ************************************************
# from multiprocessing import Process
# import os,time
#
# a = 257
#
# def task():
#     global a
#     print("2",a,id(a))
#     a = 200
#
# if __name__ == '__main__':
#     p = Process(target=task)
#
#     p.start()
#
#     time.sleep(5)
#     print(a)
#
# """
# 2 257 2903098186800
# 257
# """
# ************************************************
# from multiprocessing import Process
# import os,time
#
# a = 257
#
# def task():
#     while True:
#         print("子")
#
# if __name__ == '__main__':
#
#
#     p = Process(target=task)
#     p.start()
#     while True:
#         print('主')
#
#         time.sleep(4)
#         print(a)
#
# """
# 主
# 子
# 子
# 子
# 子
# 子
# ......(子)
#
# """
# ************************************************
# 5. join函数

# from multiprocessing import Process
# import os,time
#
# def task():
#     for i in range(100):
#         print('子 run')
#
# if __name__ == '__main__':
#     p = Process(target=task)
#     p.start()# 向操作系统发送指令
#     p.join()# 让主进程等待子进程执行完毕再继续执行
#
#     print('over')
#
#
# """
# 有p.join()
# 子 run
# ...(97个）...
# 子 run
# 子 run
# over
#
#
# 没有p.join()
# over
# 子 run
# 子 run
# 子 run
# .......(97个)
#
# """
# ************************************************
# from multiprocessing import Process
# import os,time
#
# def task1(time):
#     for i in range(1000):
#         print(f'{name} run')
#
# def task2(time):
#     for i in range(1000):
#         print(f'{name} run')
#
# if __name__ == '__main__':
#     p1 = Process(target=task1,args=("p1",))
#     p1.start()
#     p2 = Process(target=task2,args=("p2",))
#     p2.start()
#
#     p2.join() # 让主进程等待子进程执行完毕再执行
#     p1.join()
#
#
#     # 达到的效果是p1 ，p2两个程序是并发执行的，并且over一定是在所有程序执行完之后才打印的
#     print('over')
#
#
# ************************************************

# join的使用
# import os,time
# from multiprocessing import Process
#
# def task(name):
#     for i in range(4):
#         print(f'{name} run')
#
# if __name__ == '__main__': # args是给子进程传递的参数，必须是元祖
#
#
#     ps = []
#     for i in range(4):
#         p = Process(target=task,args=(i,))
#         p.start()
#         ps.append(p)
#
#     # 挨个join以下
#     for i in ps:
#         i.join()
#
#     print('over')
#
#
# """
# 0 run
# 0 run
# 0 run
# 0 run
# 1 run
# 1 run
# 1 run
# 1 run
# 2 run
# 2 run
# 2 run
# 2 run
# 3 run
# 3 run
# 3 run
# 3 run
# over
# """

# ************************************************
from multiprocessing import Process
import os,time

def task():
    while True:
        print('子 run',os.getpid())
        # os.getpid()本身的ID  os.getppid()父类的ID


if __name__ == '__main__':
    p = Process(target=task,args="老司机进程")
    p.start()
    p.join()
    print(p.name)

    # p.daemon # 守护进程
    # p.join()
    # print(p.exitcode)# 获取进程的退出码---用处：设置好例如0：无误，1：账户错误，2：密码错误，3，地址错误。。。
    # print(p.is_alive())# 查看进程是否存活
    # print('zi',p.pid) # 获取进程ID
    # p.terminate()# 终止进程 与start不同的是，不会立即终止，因为操作系统还有很多事情要做

if __name__ == '__main__':
    """
    1. 创建服务器socket对象，绑定IP，端口，开始监听  主进程
    
    2. 连接循环 主进程
    
    3. 通讯循环 子进程 来了一个客户端就要开启一个子进程
    """