Sometimes we need to change the session timeout in our grails application.to set session time out we need web.xml,initially that is not available in our application. Firstly we run command:-

 grails install-templates 

Then we need to modify “src/templates/war/web.xml” and set session timeout as per requirement after servlet-mapping;

    <session-config>
       <session-timeout>45</session-timeout>
    </session-config>  

The value that you set in the session-timeout is in minutes. Now run application and check, it will work fine.