This message was deleted.

forget it! I have tried with grails 6 and devtools, and for controllers it seems to be working correctly

Yeah the dev tool have worked since Grails rebased on top of spring boot from spring mvc. It does an automatic app restart, which is quicker than a manual restart. This works well as long as you don't allow your app to get too big before breaking it up into services/micro services. Some people have had success with the hotswap agent, and some have not. The other option is jrebel which will work, but is expensive and for huge projects the initial compile/start time can be doubled.