public class QueryMonitor
Provide a very simple low overhead means for measuring query executions, and cache hits.
This can be useful for performance analysis in a complex system.
This monitor is enabled through the System property "org.eclipse.persistence.querymonitor=true" or
through the persistence.xml property eclipselink.profiler=QueryMonitor.
It dumps the number of query cache hits, and executions (misses) once every 100s.