I am using EJB3 PFD with the included ejb3-entity cache.
I very often get error messages like
2006-02-20 08:51:17,645 ERROR [org.jboss.cache.lock.IdentityLock] write lock for /bla/nla/Bean/bla.bla.Bean#cKLUYAUkrWS2YV could not be acquired after 0 ms. Locks: Read lock owners: [<192.168.0.252:32778>:367] Write lock owner: null (caller=Thread[http-192.168.0.252-8080-3,5,jboss], lock info: read owners=[<192.168.0.252:32778>:367] (activeReaders=1, activeWriter=null, waitingReaders=0, waitingWriters=0, waitingUpgrader=0))