Tomcat memory usage grows in IDLE

Question

I have problem with growing memory consuming on Tomcat. Just after start nothing happens,but if some user login, after this memory usage start growing in Edem. PermGen does not grow, but anyway, it anormal.

My analyze shows that thread RMI TCP Connection produces lot of Object[] char[] and String[] objects. I can not understand what's wrong and where to dig. Who starts this thread, is is postgres connections and what is this?

Answer 1

This is normal, and is NOT a memory leak. Objects are created and destroyed constantly by the threads used to manage the application. You see the memory increasing because the JVM garbage collector is not eagerly reclaiming unused memory. This happens periodically (based on previous statistics) or when memory is running low. If it were a real memory leak, you would not see the Eden memory usage drop down to almost zero after a collection. A memory leak is shown as the lowest point (right after a GC) increasing over time.

Answer 2

You are observing that you are observing:

The JVM gathers statistical information about itself and sends it to you. This consumes memory and uses the RMI transfer facilities.

What is RMI TCP Accept, Attach Listener, and Signal Dispatcher in Visual VM?

I also don't see a problem with what that image shows. Eden is basically always growing slowly since there is always a bit work that consumes memory.

Once Eden gets collected (~200MB worth towards the end) you can see that most of the memory is completely free and very little (~8MB) ends in the survivor spaces since there are probably still references to these objects. But they don't seem to leave survivor since OldGen is not growing, also the Histogram at the bottom shows that typical survivor objects make it to level 2 and are gone then.

This all looks pretty normal to me.