Hi Christoph, can you please create a bug report at http://bugzilla.exolab.org, provide the same descriptive message as part of the bug report and attach the samples mentioned below. In addition, can you please provide us with
- information what RDBMS you are using. - instructions how to create the tables required. - etc. Thanks Werner > Hello, > > we have come to the conclusion that there is a bug in the rollback > mechanism > of Castor JDO. The problem occurs whenever you are doing a rollback on a > transaction which has touched two persistent objects of different types > (say > types A and B), which are both referring to an object of a third type (say > type C): > A -> C <- B > The problem only occurs if the access-mode is db-locked. > > What happens, when you now call rollback? > 1. Object A is reverted and released > 2. This means all of it's objects are reverted and released, so this > happens > also to object C > 3. Now object B is reverted, which means, all of it's objects are reverted > 4. This ends up in "case FieldMolder.PERSISTANCECAPABLE:" in the method > ClassMolder.revertObject() > 5. TransactionContext.fetch() is called for object C > 6. This method checks, if the accessMode is DbLocked (which is true for > us) > and if the current object (our object C) is locked. > 7. The object is not locked (it has been released in step 2), so the > > This is exactly what happens to us if we call rollback: > org.exolab.castor.jdo.PersistenceException: Lock conflict: attempt to load > object of type C with identity XXX in two different locks modes (exclusive > and non exclusive) in the same transaction > at > org.exolab.castor.persist.TransactionContext.fetch(TransactionContext.java:5 > 12) > at > org.exolab.castor.persist.ClassMolder.revertObject(ClassMolder.java:2532) > at > org.exolab.castor.persist.LockEngine.revertObject(LockEngine.java:855) > at > org.exolab.castor.persist.TransactionContext.rollback(TransactionContext.jav > a:1726) > at > org.exolab.castor.jdo.engine.DatabaseImpl.rollback(DatabaseImpl.java:519) > > Unfortunately the table row remains locked until the JVM (in our case the > application server) is stopped. In our application this happens quite > frequently. > > ==Workaround== > All of this will not happen if you do not revert the object after it has > already been reverted (or not modified at all). This workaround seems to > be > already included in the Castor source, but it is in comment signs: > In Revision 1.14 of org.exolab.castor.persist.TransactionContext just > activate the line 1793: //if ( entry.updateCacheNeeded > || > entry.updatePersistNeeded ) > We would like to recommend this as a fix for one of the next Castor > releases. See our questions below. > > ==Playback== > We have created a small scenario to reproduce the problem basing on the > src/examples/jdo/test: > - We added the type NewProduct, which is a smaller version of Product, but > like Product references the type ProductGroup > - All tables in mapping.xml are db-locked. > - Rollback does not work at all on the test class Product as it came, > because it has no methods setDetails( Vector details ) and setCategories( > Vector cats ) so we added them. (This might be considered a bug in the > test > type). > - We appended a small section to the Test.java class which creates a > NewProduct entry and connects it to the ProductGroup. In a following > transaction a Product and a NewProduct are db.loaded and then > db.rollback() > is called. > - If we execute this driver, the application crashes with the exception > described above. > > If you like I can provide these files. > > == Questions== > * Does anybody know, why the line "//if ( entry.updateCacheNeeded || > entry.updatePersistNeeded" in the method rollback() of > org.exolab.castor.persist.TransactionContext has been commented? It is out > since Revision 1.1 on your viewcvs. > * Does anybody have an idea, if there are any side-effects in our > "work-around", of activating this line. So far we have noticed none. > > If you confirm this bug and accept the workaround, please put it into one > of > the next releases. > > Sincerely, > Christoph Ernst > > -- > Christoph Ernst (sd&m AG) > dit - Deutscher Investment Trust, Applied Technology > Phone: +49-69-263-16125 > [EMAIL PROTECTED] > [EMAIL PROTECTED] > > > -- +++ Sparen Sie mit GMX DSL +++ http://www.gmx.net/de/go/dsl AKTION für Wechsler: DSL-Tarife ab 3,99 EUR/Monat + Startguthaben ----------------------------------------------------------- If you wish to unsubscribe from this mailing, send mail to [EMAIL PROTECTED] with a subject of: unsubscribe castor-dev
