如何在同一个 paho-mqtt 脚本下运行多个设备

Question

I am writing a script which will log more than one device with different credentials using paho-mqtt. All the client is running in the same address and with the same port. If I change the username and pass then I get the different feeds depending upon the credentials. It's working fine if I write for different devices different script. But I want to log all the devices in on_connet. I have written the script but it's working only for one device. Here is the script:

import paho.mqtt.client as mqtt
import time, json, threading, logging,ssl 

clients=[
   {"ursername":"username1","password": 'password1'},
   {"ursername":"username2","password":'password2'},
   {"ursername":"username3","password":'password3'}
]
nclients=len(clients)
run = True

def Create_connections():
   for i in range(nclients):
      t=int(time.time())
      client_id = "client" + str(t)
      client = mqtt.Client(client_id)
      
      username = credentials[i]["ursername"]
      password = credentials[i]["password"]
      
      client.on_log=on_log
      client.on_connect = on_connect
      client.on_subscribe=on_subscribe
      client.on_message = on_message
      client.on_disconnect = on_disconnect
      print("connecting to broker")
      
      client.tls_set("CXXXXX.crt", tls_version=ssl.PROTOCOL_TLSv1_2)
      client.tls_insecure_set(True)
      client.username_pw_set(username, password)
      client.loop_start()
      client.connect("XXXXX", XXXX, XX)
      print("Loop pass ")


def on_log(client, userdata, level, buf):
   print("message:" + str(buf))
   print("userdata:" + str(userdata))

   
def on_message(client, userdata, message):
   msg="message received",str(message.payload.decode("utf-8"))
   print(msg)

def on_connect(client, userdata, flags, rc):
   print("Connected with result code:"+str(rc))
   client.subscribe('v3/+/devices/+/up')


def on_disconnect(client, userdata, rc):
   pass

def on_publish(client, userdata, mid):
   print("mid: " + str(mid) + '\n')

def on_subscribe(mosq, obj, mid, granted_qos):
    print("Subscribed: " + str(mid) + " " + str(granted_qos))

mqtt.Client.connected_flag=False
no_threads=threading.active_count()
print("current threads =",no_threads)
print("Creating  Connections ",nclients," clients")

   
Create_connections()

Response

current threads = 1
Creating  Connections  2  clients
____________________________________________________________________________
client01597648398
<paho.mqtt.client.Client object at 0x7f73c0a5b1d0>
username1
connecting to broker
message:Sending CONNECT (u1, p1, wr0, wq0, wf0, c1, k60) client_id=b'client01597648398'
userdata:None
message:Received CONNACK (0, 0)
userdata:None
Connected with result code:0
message:Sending SUBSCRIBE (d0, m1) [(b'XX/+/devices/+/XX', 0)]
userdata:None
message:Received SUBACK
userdata:None
Subscribed: 1 (0,)
message:Sending PINGREQ
userdata:None
message:Received PINGRESP
userdata:None

Any help will be highly appreciated. Thanks in advance

Answer 1

Your problem lies here:

while run:
    client.loop_forever()

loop_forever() is a blocking call which will only return when the associated client is disconnected:

This is a blocking form of the network loop and will not return until the client calls disconnect(). It automatically handles reconnecting. paho-mqtt

So your other clients never get initialized/connected. You might want to use loop_start instead - this will use a separate thread to handle communication for every client:

def Create_connections():
   for i in range(nclients):
      # ...
      client.loop_start()
      client.connect("XXXXXXXXXX", XXXX, XX)

# ...
Create_connections()

while run:
   pass