https://issues.apache.org/jira/browse/AMQ-4094 - offline durable subs with selectors can lead to page leaks in the index and bloat of db.data in kahadb - fix up page caching on overflow and btree free on remove. test that validates the inuse page count for specific intervals
activemq/trunk/activemq-core/src/test/java/org/apache/activemq/usecases/DurableSubsOfflineSelectorIndexUseTest.java