fix for: https://issues.apache.org/jira/browse/AMQ-3454 Use a read / write lock on the destination mutex as many of the access points are simply reads of the underlying maps or a quite copy to another Collection. The only time a write is done is during addDestination and removeDestination.
activemq/trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/AbstractRegion.java