It is important to be able to monitor the cache utilization of your application. You can collect cache metrics for further analysis. The Hibernate second-level cache API provides ways to obtain cache utilization data.
By collecting cache metrics, you can find out how many entities are put in cache regions, and how many cache hits and misses occurred. Furthermore, you can browse the content of cached data.
However, first you have to enable the generation of statistics in Hibernate and also make the cache content human readable. To do this, you would need to add the following two lines to your Hibernate configuration:
<property name="hibernate.generate_statistics">true</property> <property name="hibernate.cache.use_structured_entries"> true </property>
The first line ensures that cache statistics are collected. (It also forces Hibernate to collect other statistics; we will return to this in Chapter 7, Metrics and Statistics, when we discuss metrics and statistics...