进程间的通信

进程间的通信方式有 管道，消息队列 ，共享内存，信号(不太会)，套接字(用于web)

管道方式：一个放入一个取出

def ps(c,msg):
    print("child start")
    c.send("hello"+str(msg))
    print(os.getpid())
if __name__=="__main__":
    c,pa=Pipe()
    li=[]
    for i in range(5):
        p=Process(target=ps,args=(c,"王"))
        li.append(p)
        p.start()
    for i in range(5):
        data=pa.recv()
        print(data)
    for i in range(5):
        p.join()

消息队列：先放入消息再取出消息

def ps(c,msg):
    c.put("hello"+str(msg))
if __name__=="__main__":
    q=Queue()
    l=[]
    for i in range(5):
        p=Process(target=ps,args=(q,"_--"))
        l.append(p)
        p.start()
    for i in l:
        i.join()
    while not q.empty():
        print(q.get())

共享内存：

def ps(msg):
    for i in range(5):
        if msg.value==100:
            msg.value=0
        else:
            msg.value=100
        print(msg.value)
        sleep(1)
if __name__=="__main__":
    msg=Value("i",100)
    p1=Process(target=one,args=(msg,))
    p2=Process(target=one,args=(msg,))
    p1.start()
    p2.start()
    p1.join()
    p2.join()