I’ve just upgraded my 2.5 installation to the new OH 3.0.
I’m really impressed of the new GUI and features and especially of the fact that the system is running very stable.
I have one MQTT device which publishes about 30 values every 3 seconds (temperature, humidity, status, …). If I add them as items to the MQTT thing is litters my logfile very fast and actually it’s hard to find the really intesting log messages.
Did you every think about adding a switch “exclude from logging” in every item where logging could be disabled?
Maybe it’s worth thinking about adding this to one of the future versions
However, this last tutorial is for OH 2. The log4j config was moved to the log4j.xml file and is now in XML format. See Logging | openHAB for some more info on that and Log4j – Log4j Filters should give you the information necessary to translate that tutorial to the new format.