python - Paho mqtt on internet disconnect not running callback

Question

I have this mqtt class

class MQTT():
    def __init__(self):
        # Observer.__init__(self) # DON'T FORGET THIS

        self.mqttClient = paho.Client(client_id=constants.MQTT_CLIENT_ID)
        self.mqttClient.username_pw_set(username=constants.MQTT_BROKER_USERNAME, password=constants.MQTT_BROKER_PASSWORD)

        # assign mqtt event callbacks
        self.mqttClient.on_message = self.on_message
        self.mqttClient.on_connect = self.on_connect
        self.mqttClient.on_disconnect = self.on_disconnect
        self.mqttClient.on_socket_close = self.on_disconnect
        self.mqttClient.on_log = self.on_log

   def on_disconnect(self,client, userdata, rc):
        log("MQTT DISCONNECT:",client, userdata, rc)

and then

mqtt = MQTT()

If i run my code it work perfectly but then i have to run some functions when internet connection is lost. So for that i am using on_disconnect and after running code if turn of network nothing happen. I want some call back to run on Internet connection lost. Do we have any ?

Answer 1

on_disconnect is the right callback for this - the question is when it gets called?

If the network connection is lost your client will only notice it at its next attempt of transmission. So if the client is not about to publish something (or acknowledge a subscription which was received just before the connection dropped) the next transmission will be the PINGREQ

By default keepalive is set to 60 - that means your client will send a PINGREQ every 60 seconds if no other control package was sent within this time interval.

So the on_disconnect callback will be called, it just does not happen as fast as you expected. Try a lower keepalive to improve on this