I've noticed that for some test runs, when the test ends or I attempt to stop the test, I receive the message "Thread won't exit". After some troubleshooting, I noticed this was occurring when I have a thread waiting to enter a critical section controller.
Currently only samplers will get notified to stop. The controllers where considered to be short running things and left out originally. Patches are welcome, as usual :) (But should probably be discussed on the dev mailing list before digging to deep into this) I wondered, whether elements, that are potentially blocking, should be able to register themselves at the running JMeterThread/Engine to be notified when a stop is ordered.
This issue has been migrated to GitHub: https://github.com/apache/jmeter/issues/5441