We have been observing the Thread count in Dynatrace for Tomcat, the numbers vary quite widely ranging from showing 34 total with a various number listed as busy to 150, which is the defined maximum for our installation, with a various number listed as busy.
I am presuming that the Busy vs Idle threads means just that, these are working, and these are not. That said, I am wondering if someone can provide some insight into the wide variation of the number of total threads being reported by Dynatrace?
Idle and Active threads are things related directly to tomcat, not dynatrace. DT is only fetching metrics:
look on minSpareThreads parameter for example.
In general idle thread is the one that was active before. Now it is keeping idle forconfigured amount of time (maxIdleTime). During this time thread can be reused. After this it's killed and has to be stared again.