How to reliably take Java Heap Dumps?
Solution 1:
Which is your operating system? (I can't add comments).
For Solaris we get better results first forcing a core dump (gcore <pid>) and then attaching jmap to the core dump file (jmap -heap:format=b <path to java bin> <path to core>)
gcore is a *nix utility to generate an image of a running program. See link.
Solution 2:
we have a JSP that queries ManagementFactory.getThreadMXBean() and produces a report. May not be useful when the app has crashed, but if you poll every minute or so, you'll get an idea of what's happening.
More info here.