MQTT Mosquito broker slow

[Thedude]

My Mosquito broker is slowing down MQTT communications occasionally (not all the time) from 10 to 100 sec and more. This is quite unusual and I'm wondering what to do. My Mosquito is running on a tiny computer called Intel Stick Computer. It has minimal resources and runs Ubuntu. On the other hand it is dedicated to Mosquito only. I haven't had any problems with it for 3-4 years since I started it. So the question is does Mosquito need maintenance? Do I need to delete old files? Does Mosquito store all the historical data that I don't need at all?
Thanks,
TheDude

[Michael McSharry]

My understanding is that is store only the topic that have been identified with the retain property and in that case it is only the most recent publication of that topic. It does store to the memory device so if you are using something like an SD which is designed for occasional store of photos etc. then it could be wearing out. Copy the files to a new one and see if that helps.

[Thedude]

Michael McSharry Thanks.

[Thedude]

Michael McSharry

How about too many topics slowing down Mosquito ? Does Mosquito keep all topics (names of topics not the payload) on file? I've been quite conservative using just few topics until recently when I started experimenting with some Tasmota devices that create new topics quite generously. Is it possible to delete unused topics? Thanks.

[Michael McSharry]

You can delete the entire Mosquitto database and it will recreate it as needed. Google to find the location of Mosquitto's database. My understanding is that only RAM is used unless the Retain flag is set. What is more likely than too many messages is that the QOS has been set to Level 2 rather than Level 0. This means that there is much more traffic to manage doing all the handshakes to assure the client receives each message.