I’ve been using openHAB with MQTT to monitor seven water meters, and it’s been a fantastic setup for keeping track of water usage. However, I recently noticed that the memory usage of openHAB was slowly increasing, which eventually caused some of my water meters to stop showing data. The logs indicated that MQTT messages were being dropped, which was concerning since the system had been running smoothly for months.
After some research and troubleshooting, I discovered that the issue might be related to how the rules were processing the MQTT messages. I decided to simplify the rules and reduce the number of calculations being performed in real-time. This change helped stabilize the system and brought the memory usage back down to a manageable level.
To further optimize, I also adjusted the persistence settings for the water flow calculations. Instead of persisting every update, I now use a strategy that saves data at regular intervals, which has significantly reduced the load on the system. This tweak not only improved performance but also made the data more consistent for long-term analysis.
I’m happy to share that these adjustments have been working well for the past few weeks. The water meters are now reliably reporting data, and the memory usage remains stable. If anyone else is dealing with similar issues, I’d recommend reviewing your rules and persistence settings as potential areas for optimization. Happy tinkering! 
