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python - 一次做更多的迭代python

问题描述

我有一个阻塞 for 循环，我尝试将套接字连接到服务器。我想做一个非阻塞循环，因为它需要很多时间，比如重叠连接。
这是我的示例代码：

import socket

for _ in range(100):
    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
        s.connect(('', 4444))

标签： pythonfor-loop

解决方案

正如 MLAlex 所建议的，使用 asyncio 库是有意义的。

这个怎么样，灵感来自asyncio 文档：

import asyncio

async def tcp_echo_client(message):
    reader, writer = await asyncio.open_connection(
        '127.0.0.1', 8888)

    print(f'Send: {message!r}')
    writer.write(message.encode())

    await asyncio.sleep(randint(1,3))

    data = await reader.read(100)
    print(f'Received: {data.decode()!r}')

    print('Close the connection')
    writer.close()
    await writer.wait_closed()

    return data.decode()


async def main():
    requests = [
            tcp_echo_client(f"msg {i}") for i in range(10)
    ]
    echoes = await asyncio.gather(*requests)
    print(echoes)


asyncio.run(main())

例如，与这个回显服务器结合（需要三秒钟来回显一条消息）：

import asyncio

async def handle_echo(reader, writer):
    data = await reader.read(100)
    message = data.decode()
    addr = writer.get_extra_info('peername')

    print(f"Received {message!r} from {addr!r}")

    await asyncio.sleep(3)

    print(f"Send: {message!r}")
    writer.write(data)
    await writer.drain()

    print("Close the connection")
    writer.close()

async def main():
    server = await asyncio.start_server(
        handle_echo, '127.0.0.1', 8888)

    addr = server.sockets[0].getsockname()
    print(f'Serving on {addr}')

    async with server:
        await server.serve_forever()

asyncio.run(main())

产生：

Send: 'msg 0'
Send: 'msg 1'
Send: 'msg 2'
Send: 'msg 3'
Send: 'msg 4'
Send: 'msg 5'
Send: 'msg 6'
Send: 'msg 7'
Send: 'msg 8'
Send: 'msg 9'
Received: 'msg 0'
Close the connection
Received: 'msg 1'
Close the connection
Received: 'msg 2'
Close the connection
Received: 'msg 3'
Close the connection
Received: 'msg 4'
Close the connection
Received: 'msg 5'
Close the connection
Received: 'msg 6'
Close the connection
Received: 'msg 7'
Close the connection
Received: 'msg 8'
Close the connection
Received: 'msg 9'
Close the connection
['msg 0', 'msg 1', 'msg 2', 'msg 3', 'msg 4', 'msg 5', 'msg 6', 'msg 7', 'msg 8', 'msg 9']

三秒左右，即只满足一个请求所需的时间

real    0m3,169s
user    0m0,044s
sys     0m0,084s

如果我们在服务器回复的时间上引入一些差异，我们可以看到客户端收到的结果是乱序的。例如在第 10 行：

await asyncio.sleep(randint(3,4))

那么客户端的输出变为：

(tih1) SO $ time python aio_cnx.py 
Send: 'msg 0'
Send: 'msg 1'
Send: 'msg 2'
Send: 'msg 3'
Send: 'msg 4'
Send: 'msg 5'
Send: 'msg 6'
Send: 'msg 7'
Send: 'msg 8'
Send: 'msg 9'
Received: 'msg 1'
Close the connection
Received: 'msg 2'
Close the connection
Received: 'msg 3'
Close the connection
Received: 'msg 7'
Close the connection
Received: 'msg 8'
Close the connection
Received: 'msg 9'
Close the connection
Received: 'msg 0'
Close the connection
Received: 'msg 4'
Close the connection
Received: 'msg 5'
Close the connection
Received: 'msg 6'
Close the connection
['msg 0', 'msg 1', 'msg 2', 'msg 3', 'msg 4', 'msg 5', 'msg 6', 'msg 7', 'msg 8', 'msg 9']

real    0m4,135s
user    0m0,059s
sys     0m0,013s

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