In a node doesn't respond anymore, but the process is still running, we need two things for debugging:
- jstack <pid>
- jmap -histo:live <pid>
The two tools above are included in the Java SE Development Kit, you can download here for your system: http://www.oracle.com/technetwork/java/javase/downloads/index.html
Please copy the output of both commands into a file, compress it and send it to us then.