1. Add system property: cache.username2roster.maxLifetime = 419430400
2. Add system property: xmpp.pep.enabled = false
3. You can increase memory for Java. Add a line like this in file /etc/sysconfig/openfire : OPENFIRE_OPTS="-Xms256m -Xmx512m"
You can increase memory as much as you can, so if you have 2GB of memory you can set: OPENFIRE_OPTS="-Xms512m -Xmx1024m" .
Also you can do this by sending parameter to openfire.You must first find the command that starts Java and add this command line parameter:
For example, use
-Xmx256mto let Java use 256 MB of memory. The full command might be something like
/path/to/java -Xmx256m -jar openfire.jar
That should solve your issue with low memory in Java Openfire Jabber chat server.