MQTT Socket error after 4 consecutive MQTT connect/disconnect

[Balamurugan]

Hi,

we are using MQTT to push the sensor and GPS data with 1 hour interval. After 4 consecutive connect and disconnect, MQTT is returning socket error. It requires the device reboot to connect again, so rebooting the device after every 4 MQTT connections. Because of reboot the device is taking longer time to get GPS fix for first time.

It is 100% reproducible. we are using our own MQTT broker and also tried the other brokers as well and behavior is same.

Error log returned by MQTT is "ERROR: mqtt_connect -12".

Please help us to resolve the issue.

[Didrik Rokhaug]

Hi.

I have reported this problem internally and requested help from our developers.

I'll keep you updated about any progress.

Best regards,

Didrik

[Balamurugan]

Sure.. Thanks!!!

[Didrik Rokhaug]

Turns out it is easier than I thought.

You need to call mqtt_live() after mqtt_disconnect() for the mqtt library to close the socket.

If not, you will run out of sockets, and get ENOMEM (-12).

[Balamurugan]

Interesting!!

Tested with the changes  as you mentioned and MQTT working as expected after consecutive MQTT connect/disconnect

printk("Disconnecting MQTT client...\n");
err = mqtt_disconnect(&client);
if (err) {
printk("Could not disconnect MQTT client. Error: %d\n", err);
}

err = mqtt_live(&client);
if (err != 0) {
printk("ERROR: mqtt_live %d\n", err);
}

Thanks for your support.