[jbosscache-dev] Problems with node locking semantics in JBC 1.4.1.GA

In 1.4.1.GA, we introduced node locking semantics that weren't there in the previous few releases (and maybe never were there). This is causing significant integration issues. Specifically, before inserting or removing a child node, we acquire a WL on the parent. Previously, only a RL was acquired. I'm concerned about anomalies this might cause in apps that intentionally or unintentionally depends on the old behavior. For example, the AS http session repl code assumes it has freedom to add/remove cache nodes that represent a session underneath the parent that represents the webapp. Now these activities will block until any activity on any other session is complete. With FIELD granularity, that's a big issue, as locks are held throughout the web request. It will likely cause issues with other granularities as well. (We already saw a minor issue in a support case when a customer tried to upgrade 4.0.5 to 1.4.1). This definitely breaks the Hibernate (and thus EJB3 entity bean clustering) integration with 1.4.1.GA. Basically, assume there is an entity Person, with a child collection "children". Hibernate caches the entity, and later caches the child collection in a child node. 1) Transaction tx = tm.begin(); 2) cache.get("/Person/Person#1/children", ITEM); // returns null -- not cached yet 3) read db to get the ids of the collection elements 4) tx.suspend(); 5) cache.putFailFast("/Person/Person#1/children", ITEM, data); 6) tx.resume(); This fails in step 5, because with the tx suspended, the putFailFast() call cannot acquire the WL on /Person/Person#1 that it needs to insert /Person/Person#1/children. Hmm, an EJB3 unit test shows that problem occuring, but I assume even simple entity caching will break: 1) Transaction tx = tm.begin(); 2) cache.get("/Person/Person#2", ITEM); // returns null -- not cached yet 3) read db to get the Person 4) tx.suspend(); 5) cache.putFailFast("/Person/Person#1", ITEM, data); 6) tx.resume(); We need a quick workaround for this in the 1.4 branch, as it's a blocker for EJB3 RC10 and AS 4.2. Brian Stansberry Lead, AS Clustering JBoss, a division of Red Hat Ph: 510-396-3864 skype: bstansberry