无法在python3异步IO中正确接收数据报

我编写了简单的udp客户端程序，但无法正确接收数据报。
我的代码如下

import asyncio

class EchoClientProtocol:
    def __init__(self, message, loop):
        self.message = message
        self.loop = loop
        self.transport = None

    def connection_made(self, transport):
        self.transport = transport
        print('Send:', self.message)
        self.transport.sendto(self.message.encode())

    def datagram_received(self, data, addr):
        print('Received:', data.decode())

async def sendChar(transport, msg):
    print('send: ', msg)
    transport.sendto(msg.encode())

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    message = 'Hello World!'
    connect = loop.create_datagram_endpoint(
            lambda: EchoClientProtocol(message, loop),
            remote_addr=('127.0.0.1', 9999)
            )
    transport, protocol = loop.run_until_complete(connect)
    while (True):
        try:
            ch = input()
        except KeyboardInterrupt:
            break
        loop.run_until_complete(sendChar(transport, ch))
    loop.run_forever()
    transport.close()
    loop.close()

我在asyncio文档中编写UDP echo服务器协议程序。
（）

运行这些程序，我想结果是这样的

Send: Hello World!
Received: Hello World!
1
send: 1
Received: 1
2
send: 2
Received: 2

但结果是这样的

Send: Hello World!
1
send: 1
Received: Hello World!
2
send: 2
Received: 1

为什么结果会发生变化？

---

我搜索asyncio模块，但无法解决此问题。

这是因为

而True

循环在下一次发送调用之前不会将控制权返回给ioloop-

输入

被阻塞。只需添加一些异步睡眠，这样ioloop就可以处理事件来接收数据

while (True):
    try:
        loop.run_until_complete(asyncio.sleep(0.001))
        ch = input()
    except KeyboardInterrupt:
        break
    loop.run_until_complete(sendChar(transport, ch))

由于

input

也会在此处阻塞，因此最好将其移动到单独的线程：

import threading
import asyncio

class EchoClientProtocol:
    def __init__(self, message, loop):
        self.message = message
        self.loop = loop
        self.transport = None

    def connection_made(self, transport):
        self.transport = transport
        print('Send:', self.message)
        self.transport.sendto(self.message.encode())

    def datagram_received(self, data, addr):
        print('Received:', data.decode())

    def error_received(self, data, addr=None):
        raise data

async def sendChar(transport, msg):
    print('send: ', msg)
    transport.sendto(msg.encode())

user_input = [None]

# spawn a new thread to wait for input 
def get_user_input(user_input_ref):
    while True:
        user_input_ref[0] = input()

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    message = 'Hello World!'
    connect = loop.create_datagram_endpoint(
            lambda: EchoClientProtocol(message, loop),
            remote_addr=('127.0.0.1', 9999)
            )
    transport, protocol = loop.run_until_complete(connect)
    input_thread = threading.Thread(target=get_user_input, args=(user_input,))
    input_thread.daemon = True
    input_thread.start()
    while (True):
        if user_input[0] is not None:
            loop.run_until_complete(sendChar(transport, user_input[0]))
            user_input[0] = None
        loop.run_until_complete(asyncio.sleep(1))
    loop.run_forever()
    transport.close()
    loop.close()

---

我将您的代码与（当然是重构）混合在一起：）

谢谢您的回答。我试着运行你的代码，可以得到正确的结果！我没有使用线程模块，所以我没有想到它。我将学习线程模块。