Logged into YF 

Active Session Report
21/04/2020 4:01 PM	Stephen 

Logged as Gemma 

Active Session Report
21/04/2020 4:01 PM	Stephen 
21/04/2020 4:02 PM	Gemma 

Gemma Clicked Logout button

Active Session Report
21/04/2020 4:01 PM	Stephen 

This suggests that the ActiveSession table is updated real-time

Logged as Gemma 

Active Session Report
21/04/2020 4:01 PM	Stephen 
21/04/2020 4:05 PM	Gemma 

Quit Firefox browser

Active Session Report
21/04/2020 4:01 PM	Stephen 
21/04/2020 4:05 PM	Gemma 

In this instance the ActiveSession record was not removed

Logged as Leah 

Active Session Report
21/04/2020 4:01 PM	Stephen 
21/04/2020 4:05 PM	Gemma 
21/04/2020 4:06 PM	Leah 

Quit Firefox browser

Logged as Gemma 

Active Session Report
21/04/2020 4:01 PM	Stephen 
21/04/2020 4:05 PM	Gemma 
21/04/2020 4:06 PM	Leah 
21/04/2020 4:08 PM	Gemma 

Gemma Clicked Logout button

Active Session Report
21/04/2020 4:01 PM	Stephen 
21/04/2020 4:05 PM	Gemma 
21/04/2020 4:06 PM	Leah 

This suggests that the action of the Logout button removes the ActiveSession record for that user based on the Session Start time, but it doesn't delete previous records for the same user.

Is it also possible that stopping the tomcat service(s) is meant to do a full cleanup ?