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我有多个 python 文件。一个文件包含与 MQTT 相关的所有代码并具有一些功能，而另一个文件导入 MQTT 文件并在事件发生时调用函数。MQTT 文件仅发布一些 QoS 0 和一些 QoS 1 的消息，并连接到安装在本地机器中的 mosquitto 代理。MQTT 代码如下

import paho.mqtt.client as mqtt
from threading import current_thread
import datetime
import cv2 as cv2
import time

# Define Variables
MQTT_HOST = "127.0.0.1"
MQTT_PORT = 1883
MQTT_KEEPALIVE_INTERVAL = 60


def send_something():
    try:
        mqttc.publish("topic", "hello", 1, False)  # QoS =1 Retain = False
    except Exception as e:
        print(str(e))          
def send_something_else():
    mqttc.publish("anothertopic", CombinedByteArr, 0, False) 
            
            
def on_connect(mqttc, userdata, flags, rc):    
    print("[INFO]  : MQTT : Connection returned result: " + mqtt.connack_string(rc))
    if(rc == 0):
        print("[INFO]  : MQTT : Connection Successful")
    else:
        print(rc)

def on_disconnect(mqttc, userdata, rc):
    if rc != 0:
        print(" Unexpected disconnection")
    while(True):
        try:
            print("Trying to Reconnect")
            mqttc.connect(MQTT_HOST, MQTT_PORT, MQTT_KEEPALIVE_INTERVAL)
            break
        except:
            print("Error in Retrying to Connect with Broker")
            continue

# Initiate MQTT Client

ThreadID = str(current_thread().ident)
mqttc = mqtt.Client(client_id= ThreadID, clean_session=False)


mqttc.on_publish = on_publish
mqttc.on_connect = on_connect
mqttc.on_message = on_message
mqttc.on_disconnect = on_disconnect

while(True):
    try:
        mqttc.connect(MQTT_HOST, MQTT_PORT, MQTT_KEEPALIVE_INTERVAL)
        print("[INFO]  : MQTT : MQTT Connect Complete")
        break
    except:
        print("ERROR Occurred")


mqttc.loop_start()  # Start A Thread

我运行多个 python 文件，这意味着运行了多个 MQTT 副本。在 mosquitto 日志中，它总是显示客户端继续断开连接然后重新连接。一段时间后，我在蚊子日志中不断得到这些：-

1518788230: New client connected from 127.0.0.1 as MQTT2225 (c0, k60).
1518788230: Sending CONNACK to MQTT2225 (0, 0)
1518788230: Socket error on client MQTT2225, disconnecting.
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1 回答 1

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您需要更改mqttc.loop_start()为mqttc.loop_forever()以停止程序在启动后台线程后退出。

编辑：在考虑了更多之后，问题不是循环，而是客户端 ID

假设您始终实例化您从主线程提供的代码中描述的对象的实例，那么线程 ID 将始终相同，这意味着代理将踢除最后一个实例之外的所有实例以进行连接。

而且，由于您有逻辑在一个紧密循环中重新连接，只要您有多个 MQTT 客户端，它们将始终保持相互启动

于 2018-02-16T13:52:25.520 回答