When does session is considered as inactive in websphere server


The session time out of the application is set programatically via the method setMaxInactiveInterval(timeValue). The timeValue is being retrived from the database. In the web.xml, the heartbeatInterval is set to -1 and there is a filter set. Looks like this:

       <description>Vaadin heartbeat</description>

The session time out is set for 10 minutes. However, the application that is deployed on a websphere environment, times out after 11 minutes. Compared to the application deployed on a wildfly environment, it times out roughly after 10 mins and 30 seconds.

May I know why this happens? Thanks in advanced for your help.