Hi guys

We are trying to use terracotta as second level cache for hibernate and while testing for performance in a case in which we are constantly reading and writing to a db i see a bottleneck.

I constantly see a thread acquiring the a lock shown in the thread dump below whenever there is an update operation due to which all other threads keep waiting.

at org.hibernate.cache.UpdateTimestampsCache.preinvalidate(UpdateTimestampsCache.java:70)
- locked <0x65e83449> (a org.hibernate.cache.UpdateTimestampsCache)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:275)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:263)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:170)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:50)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1027)
at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:304)

Can you guys give me a hint for why this lock is taken every time i try to update an object which is mapped to a db.