There is a way to hook up a development too called a profiler to OH and it will tell you how many threads are active. Beyond that I don’t think there is. Worrying about threads isn’t usually something users have to worry about.
There might be a way to get some logs from Quartz that might be informative.
But beyond knowing these things are possible I’m not much help. I haven’t used a profiler in a decade.
Karaf may have something built in.