在Python中从Socket.IO服务器向客户端发送数据时遇到问题

Question

我目前正在使用 Python 开发 Socket.IO 实现，其中为我的服务器使用了 socketio 和 eventlet，为我的客户端使用了 socketio。尽管客户端和服务器之间的连接成功，但我面临着一个问题，即客户端控制台中未接收/显示从服务器发送的数据。

这是我的服务器（server.py）的简化版本：

import socketio
import eventlet
from threading import Thread
import redis
import time

sio = socketio.Server()
app = socketio.WSGIApp(sio)

redis_conn = None


def initialize_redis_conn():
    global redis_conn
    if redis_conn is None:
        redis_conn = redis.StrictRedis(host='localhost', port=6379, decode_responses=True)
        print("redis connection init")


def insert_update_sid(sid, unique_id):
    """
    Inserts or updates the sid and uniqueId of the client into the Redis cache.
    """
    initialize_redis_conn()
    key = f"DATA_KEY_{unique_id}"
    expiry_in_seconds = 1800
    redis_conn.setex(key, expiry_in_seconds, sid)
    print("Data inserted into Redis successfully")


def get_sid_by_unique_id(unique_id):
    """
    Returns the sessionId (sid) of a client using the uniqueId.
    """
    initialize_redis_conn()
    print("fetching sid")
    key = f"DATA_KEY_{unique_id}"
    sid = redis_conn.get(key)
    if sid:
        print(f"Got sid {sid} using uid {unique_id}")
        return sid
    else:
        return None


def listen_sqs_queue():
    """
    this func is just to mimic the sqs, when sqs receives the message it should send that to client 
    """

    data = {
        "communicationStatus": "OKAY",
        "status": "Complete"
    }
    unique_id = "123789"
    if unique_id:
        print("inside sqs impl is : ", unique_id)
        sid = get_sid_by_unique_id(unique_id=unique_id)
        if sid:
            print("calling send response to client")
            send_response_to_client(sid, data)
            print(
                f"Response has been sent to the client with sessionId: {sid} and uniqueId : {unique_id}")
        else:
            print(f"Client not found for the given uniqueId: {unique_id}")


def send_response_to_client(sid, resp):
    """
    this func sends the response to the client
    """

    sio.emit('response_from_server', f'response : {resp}')
    print("data sent to client ")


@sio.event
def connect(sid, environ):

    print(f"client {sid} connected")
    print("sid type is: ", type(sid))
    token = environ.get('HTTP_TOKEN')
    sio.emit("acknowledge", "ack recevied from server", room=sid)
    if token:
        auth_status_code = 200
        if auth_status_code == 200:
            unique_id = "123789"
            # insert the sid and uniqueId into redis cache 
            insert_update_sid(sid, unique_id)


@sio.event
def disconnect(sid):
    """
    this is a disconnect event which disconnects the client from server
    """
    print(f"client {sid} disconnected")


def start_server():
    initialize_redis_conn()

    # Start the server in a separate thread
    # eventlet.wsgi.server(eventlet.listen(('0.0.0.0', 5000)), app)


    sqs_listen_thread = Thread(target=listen_sqs_queue)
    sqs_listen_thread.start()

    server_thread = Thread(target=eventlet.wsgi.server(eventlet.listen(('localhost', 5000)), app))
    server_thread.start()


    sqs_listen_thread.join()
    server_thread.join()


if __name__ == '__main__':
    start_server()

还有我的客户（client.py）：

import requests
import socketio

PORT = "5000"

IP = "localhost"

sio = socketio.Client()


@sio.event
def connect():
    print("connection established to server connect event")


@sio.event
def disconnect():
    print("client disconnected from server")


@sio.event
def server_response(response):
    print("response from server recived")
    print(f"response received from server: {response}")


@sio.event
def acknowledge(ack):
    print(ack)


if __name__ == '__main__':
    data = {}
    stage = "dev"
    token = get_token(stage)
    token = "Radom_token"
    if token:
        print("Token has been generated.")

        url = f"http://{IP}:{PORT}"

        # sio.connect(url, transports=['websocket', 'polling'], headers={'token': token})
        sio.connect(url=url)
        sio.wait()

    else:
        print("Token has not been generated ")

我已经验证服务端和客户端都连接成功，但是客户端没有触发response_from_server事件。我怀疑我发出事件的方式或线程设置可能存在问题。

任何有关如何排查和解决此问题的见解或建议将不胜感激。谢谢！

Answer 1

您正在将线程与 eventlet 混合。 Eventlet 是一个单线程异步平台，您必须留在主线程中才能工作。

一个相对简单的解决方案是对 Python 标准库进行猴子补丁，以便许多线程/网络调用被 greenlet 友好的等效项替换。您不仅需要它用于后台线程，还需要使 Redis 在 eventlet 下工作。