100% CPU usage on one core

Hi,
I’m running Openhab 2.2 on Ubuntu 16.04 installed via OpenHABian script. The only thing constantly running is iCloud location synchronization every 5 mintues yet one of the Openhab Java processes are using 100% CPU. Frontail (events.log and openhab.log) only shows activity every ~5 minutes. How can i figure out what it is doing?

Thanks
Maciej

Ramp up openhab logging.
Possibly you (or something) is changing an items or rules file often, each touch or save causes a reprocessing run.