James, what RDBMS are you using ? And with regards to your last question, let me just add that you should not create new JDO instances (or JDOManager instances, as they are named with more recent releases) in a multi-threaded, heavy-load application.
Just create a JDO instance once, and then call JDO.getDatabase() whenever you've got something to do against the database, e.g. pesist an entity, load an entity, etc. Werner James Abley wrote: > Hi, > > I am having some problems with deadlocks in my application. It works > fine with a single client and I have functional tests which exercise > this part of the application, but once I start cranking up the number of > clients, I rapidly see lots of these: > > Caused by: org.exolab.castor.jdo.TransactionAbortedException: Nested > error: org.exolab.castor.jdo.LockNotGrantedException: Deadlock has been > detected while attempting to acquire a lock: Deadlock has been detected > while attempting to acquire a lock > at > org.exolab.castor.persist.TransactionContext.prepare(TransactionContext.java:1654) > > at > org.exolab.castor.jdo.engine.DatabaseImpl.commit(DatabaseImpl.java:545) > vola ... 34 more > Caused by: org.exolab.castor.jdo.LockNotGrantedException: Deadlock has > been detected while attempting to acquire a lock > at > org.exolab.castor.persist.ObjectLock.detectDeadlock(ObjectLock.java:983) > at > org.exolab.castor.persist.ObjectLock.upgrade(ObjectLock.java:770) > at > org.exolab.castor.persist.LockEngine$TypeInfo.upgrade(LockEngine.java:1324) > at > org.exolab.castor.persist.LockEngine$TypeInfo.access$600(LockEngine.java:1055) > > at > org.exolab.castor.persist.LockEngine.writeLock(LockEngine.java:801) > at > org.exolab.castor.persist.TransactionContext.writeLock(TransactionContext.java:1344) > > at > org.exolab.castor.persist.ClassMolder.preStore(ClassMolder.java:1547) > at > org.exolab.castor.persist.LockEngine.preStore(LockEngine.java:718) > at > org.exolab.castor.persist.TransactionContext.prepare(TransactionContext.java:1521) > > ... 36 more > > I am using Castor 0.9.6. I tried upgrading to 1.0.3 but got > NullPointerExceptions (I'll create a test case separately to see if it's > a bug, or more probably, a problem with my mapping file), so I'm > sticking with 0.9.6 currently and trying to understand how I'm misusing > Castor and what I should do to eliminate, or at least minimise these > deadlocks. > > The only related thread that I have found so far on the mailing list > archive is this: > > http://www.mail-archive.com/[email protected]/msg00205.html > > There are a couple of the suggested issues present in the codebase that > I am currently working on fixing; notably a new JDO instance is being > created each request: > > JDO newJdo = new JDO(); > newJdo.setDatabaseName(databaseName); > > // We resolve the full config URI > URL u = getClass().getResource(configurationURI); > if (u == null) { > throw new RepositoryException( > "Unable to locate config file " + configurationURI); > } > > newJdo.setConfiguration(u.toString()); > > But I was wondering if people might be able to comment on any other > fruitful avenues to pursue? > > Regards, > > James > > --------------------------------------------------------------------- > To unsubscribe from this list please visit: > > http://xircles.codehaus.org/manage_email > > --------------------------------------------------------------------- To unsubscribe from this list please visit: http://xircles.codehaus.org/manage_email
