[CentOS] Apache jserv monitoring?

In our environment we have many legacy application servers running
apache/jserv.  There is a web server front end, then a couple of
load-balanced java servers on the backside.  One of the problems we
are faced with is hung or stuck jvms.  I have looked at the java
process with the ps command, and there are many times when URL(s) do
not respond, yet the java looks healthy, at least from the OS point of
view.  The usual cure for this situation is to restart the JVM, then
the URLs come right back up.

Are any of you aware of tools for monitoring apache jserv, either from
localhost or by connecting to port 8008 over the network?  I really
want to find out if there is a way to detect a "sick" JVM other than
getting a bunch of down URL alerts on my phone.