asyncio聊天客户端使用aioconsole的实现难点：input()与asyncio不兼容

以下两种方案均适配最新版asyncio，无需依赖aioconsole：

方案1：Python 3.9+ 原生实现（推荐） #

通过asyncio.to_thread将同步input()包装为异步调用，无需额外安装依赖，代码最简：

async def asynchronous_input(prompt: str = "") -> str:
    return await asyncio.to_thread(input, prompt)

方案2：兼容Python 3.7/3.8 版本实现 #

如果运行环境Python版本低于3.9，使用线程池执行器实现：

import concurrent.futures

# 单例线程池，避免重复创建开销
_input_executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
async def asynchronous_input(prompt: str = "") -> str:
    loop = asyncio.get_running_loop()
    return await loop.run_in_executor(_input_executor, input, prompt)

原有代码修正 #

现有代码中存在协程无法并行的问题：chat_client函数内按顺序await message_sender和await message_reciever会导致message_sender的死循环永远阻塞接收逻辑，需要修改为并行运行：

async def chat_client():
    reader, writer = await asyncio.open_connection("xxx.xxx.xxx.xxx", xxx)
    # 同时启动收发两个协程
    await asyncio.gather(
        message_sender(writer),
        message_reciever(reader)
    )

最终message_sender函数修改 #

替换占位的异步输入调用即可：

async def message_sender(writer):
    try:
        while True:
            # 可自定义输入提示符，比如改成"你: "
            message = await asynchronous_input("")
            await message_writer(message, writer)
    except asyncio.TimeoutError:
        print("----------- You lost your connection -----------")
        writer.close()
        await writer.wait_closed()
        quit()

完整修改后代码示例 #

import asyncio
import struct
import concurrent.futures

# 兼容全版本的异步输入实现
_input_executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
async def asynchronous_input(prompt: str = "") -> str:
    loop = asyncio.get_running_loop()
    return await loop.run_in_executor(_input_executor, input, prompt)

async def chat_client():
    reader, writer = await asyncio.open_connection("xxx.xxx.xxx.xxx", xxx)
    await asyncio.gather(
        message_sender(writer),
        message_reciever(reader)
    )

async def message_sender(writer):
    try:
        while True:
            message = await asynchronous_input("你: ")
            await message_writer(message, writer)
    except asyncio.TimeoutError:
        print("----------- You lost your connection -----------")
        writer.close()
        await writer.wait_closed()
        quit()

async def message_reciever(reader):
        while True:
            size, = struct.unpack('<L', await reader.readexactly(4)) 
            rcv_message = await reader.readexactly(size)
            # 打印收到的消息时添加前缀区分
            print(f"\n对方: {rcv_message.decode()}\n你: ", end="")

async def message_writer(message, writer):
        data = message.encode()
        writer.write(struct.pack('<L', len(data)))
        writer.write(data)
        await writer.drain()

try:
    asyncio.run(chat_client())
except KeyboardInterrupt:
    print("\n----------- You left the Chat. -----------")
    quit()

内容的提问来源于stack exchange，提问作者SoccerFan