Tomcat sessions expiring unexpectedly

Question

We are running tomcat application server that handle over 100 concurrent sessions. In the last 2 months the most active users noticed that sometimes they are getting kicked

Answer 1

If there has been no code chance triggering this, I would look at memory usage. This might be the effect of Tomcat running out of memory and invalidating sessions to recover.

If at all possible monitor garbage collections, and/or put surveillance on with jconsole or jvisualvm.