I've recently updated from hibernate 3.3.1.GA to hibernate 3.5.0 and I'm having a lot of performance issues. As a test, I added around 8000 entities to my DB (which in turn cause other entities to be saved). These entities are saved in batches of 20 so that the transactions aren't too large for performance reasons.

When using hibernate 3.3.1.GA all 8000 entities get saved in about 3 minutes. When using hibernate 3.5.0 it starts out slower than with hibernate 3.3.1. But it gets slower and slower. At around 4,000 entities, it sometimes takes 5 minutes just to save a batch of 20. If I then go to a mysql console and manually type in an insert statement from the mysql general query log, half of them run perfect in 0.00 seconds. And half of them take a long time (maybe 40 seconds) or timeout with "ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction" from MySQL.

Has something changed in hibernate's transaction management in version 3.5.0 that I should be aware of? The ONLY thing I changed to experience these unusable performance issues is replace the following hibernate 3.3.1.GA jar files: com.springsource.org.hibernate-3.3.1.GA.jar, com.springsource.org.hibernate.annotations-3.4.0.GA.jar, com.springsource.org.hibernate.annotations.common-3.3.0.ga.jar, com.springsource.javassist-3.3.0.ga.jar with the new hibernate 3.5.0 release hibernate3.jar and javassist-3.9.0.GA.jar.

Thanks.