The plugin gather various JVM informations. It creates graphs every 5 minutes which consumes some CPU. So one should not run it in production currently. If the debug.log is enabled it writes a list of threads there every minute. This list is quite interesting as it contains also the used CPU cycles - a looping thread can be identified very easy.
It uses RRD and a local RRD database, so it does not affect the Openfire database.
This is an experimental plugin, so there's nothing to configure.
It creates a directory OPENFIRE_HOME/jvmmonitor/ - there the 15 MB RRD database is stored. It writes the graphs to OPENFIRE_HOME/jvmmonitor/graph/ - one can not use the web gui to display them.
A lot of things can be configured, the # values (concurrent online users, number of MUCs, ...) which the monitoring and loadstat plugin do monitor are also stored by it. The graphs are only displayed when needed.
The web gui will display the graphs and it will allow to create a stack trace and a heap dump.
(zip file contains the source code)