public synchronized static ConsistencyMonitor getInstance() {
        if (INSTANCE == null) {
            INSTANCE = new ConsistencyMonitor();
            INSTANCE.reinitialize();
        }
        return INSTANCE;
    }
Caches, especially clustered caches, have various supporting data structures that allow them to work properly in
certain conditions. The content of these caches and their supporting data structures are expected to be in a certain
consistent state. This monitor periodically performs a check if this is true.

Note that validation of consistency is a resource intensive process. Enabling the monitor might have severe effects
on the availability and performance of the Openfire domain.

@author Guus der Kinderen, guus.der.kinderen@gmail.com
xmppserver/src/main/java/org/jivesoftware/util/cache/ConsistencyMonitor.java