asyncio服务器客户端提前终止而没有输出

Question

我正在学习使用async def和await的py3.5语法中的asyncio库，并尝试编写简单的服务器/客户端架构。

由于某种原因，客户端从未收到消息并提前终止：

客户端

IP = ''
PORT = 8880

import asyncio
import multiprocessing
import ssl

async def start_client(loop):
    reader, writer = await asyncio.open_connection(IP, PORT, loop=loop)
    writer.write("Gimme gimme gimme".encode())
    writer.close()
    data = await reader.read()
    print(data.decode())

loop = asyncio.get_event_loop()
loop.run_until_complete(start_client(loop))
loop.close()

服务器

IP = ''
PORT = 8880

import asyncio
import requests
import json

async def handle_echo(reader, writer):
    data = await reader.read()
    response = await whatsup()
    print(response)
    writer.write(response.encode())
    writer.write_eof()
    await writer.drain()
    writer.close()

async def whatsup():
    return "Hello there!"

loop = asyncio.get_event_loop()
server = asyncio.start_server(handle_echo,
            IP,
            PORT,
            loop=loop)
server = loop.run_until_complete(server)

try:
    loop.run_forever()
except:
    pass

server.close()
loop.run_until_complete(server.wait_closed())
loop.close()

我观察到的是服务器能够打印出＆＃34; Hello world！＆＃34;并成功返回，但是从我可以收集的内容中，客户端总共读取0个字节并且只退出

我已经尝试了什么

我尝试过：

while not reader.at_eof():
    data = await reader.read(100)
    print(data.decode())

但它评估at_eof()为真，并且也提前退出。

Answer 1

好的，我找到了解决方案：

read()会一直读到eof标记。我们需要双方都writer.write_eof()才能阅读read()。

这是解决方案代码：

async def handle_echo(reader, writer):
    data = await reader.read()
    response = await whatsup()
    print(response)
    writer.write(response.encode())
    writer.write_eof()
    await writer.drain()
    writer.close()

async def start_client(loop):
    reader, writer = await asyncio.open_connection(IP, PORT, loop=loop)
    writer.write("Gimme gimme gimme".encode())
    writer.write_eof() # crucial here
    writer.close()
    data = await reader.read()
    print(data.decode())