Here is a potentially disruptive change to Cayenne core: http://svn.apache.org/viewvc?view=revision&revision=1292437 (also see https://issues.apache.org/jira/browse/CAY-1670 )
This removes the major global lock and has a potential to significantly increase throughput (which is an issue, see CAY-1124 by Tore for instance). The implementation is based on a previously untried by us data structure - ConcurrentLinkedHashMap - http://code.google.com/p/concurrentlinkedhashmap/ . It is used by Apache Cassandra, so presumably it works and can handle the load. I internalized this code, placing it under org.apache.cayenne.util.concurrentlinkedhashmap. I need help with testing though... Maybe someone has any kind of load tests that can emulate multiple DataContexts attached to a single ServerRuntime and performing various select/modify operations? Or maybe you are daring enough to place this in production? I will do the same on my end. To give some reassurance, our single-threaded unit tests pass 100% with no changes after I swapped commons-collections LRUMap to ConcurrentLinkedHashMap. Appreciate feedback on this feature! Thanks, Andrus
