How to inspect File descriptors leaks in a heap dump hprof file

Question

I have an instance of an app server's heap dump (hprof). How do I use visualvm or any other tool to inspect leaking File descriptors?

I did check the file descriptors in use by running

sudo lsof | grep java | wc -l

When I run the following OOQL I get a list of FileDescriptors

select x from java.io.FileDescriptor x

But how do I approach finding the abusing classes using the heap dump analysis?

Carrot