Maybe this has been improved in the last 10 years but heap management imho is one of the not-great things about the JVM when I was using it. What is happening is quite invisible to sysadmins used to monitoring traditional unix processes. To them it looks like a giant memory hog, non-cooperative, when in reality the program might only be using a small % of what top is showing allocated to the process.

The original JVM philosophy seemed to be to cohost a bunch of stuff in one monolithic JVM process, rather than run a bunch of separate communicating processes. And in fact this "container" philosophy is what the original J2EE servers operated with.