How to know if you have memory size problems or if that's just the JVM growing empty?

Question

The question is the following :

I noticed on my server that the memory is 100% full.

Now does that mean that :

• my tomcat needs to much memory, and that I should either optimize my code or add some memory to my server
• the JVM has grown in anticipation of its content growth

The basic question is : should I be worried ?

Answer 1

..should I be worried ?

Start worrying when the app. gets OutOfMemoryErrors.

Answer 2

run jvisualvm, connect it to your application VM, perform a manual GC and see if there is any memory left?