Below information is captured from JMX (Tomcat Status). The question is the max spare threads (idle) is configured to 200. As per below threads busy is only 28. It still shows current thread count as 300 instead of 200 (which is max spare thread configuration). One time we did reach that busy thread mark but after threads died, it is still retaining 300 threads in memory instead of 200.
Max threads: 300 Min spare threads: 50 Max spare threads: 200 Current thread count: 300 Current thread busy: 28 Max processing time: 982691 ms Processing time: 656313.7 s Request count: 5127910 Error count: 6189 Bytes received: 1913.45 MB Bytes sent: 29500.69 MB