Vishal, as far as i remember, with Castor 0.9.7 (or earlier, but I am not sure) we have introduced a patch for problems where in very specific situations locks didn't get released. And as far as I can tell by the stack trace quoted below, this might be the case in your example given. Can you please give either 0.9.7 or 0.9.9M1 a try, and see whether you still get the same problem ?
Werner -----Ursprüngliche Nachricht----- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Gesendet: Montag, 05. September 2005 14:11 An: [email protected] Betreff: [castor-dev] Having trouble with implementing a retrieve retry Hi, I have a requirement for my application that in some cases when we get a retrieve timeout from the database we should retry the retrieve. We do this by catching the PersistenceException from the call to query.execute and retrying the retrieve after having rolled back and re-begun the transaction (The test program and associated artifacts are attached). This normally works just fine, but I have run into a situation where when trying to retrieve an object that is related to another object, and if the related object is locked by some other process, then I run into fatal exceptions from Castor while trying to rollback the transaction and my subsequent attempts to retry the retrieve fail. Is this a know bug? I am currently using Castor 0.9.5.3 with MySQL 4.0.25. Regards, Vishal. e.g. I have a sample class CounterVar which has a reference to the class CounterType. When trying to retrieve CounterVar (when I have locked the corresponding CounterType object in another process) I get the following exception during the rollback and subsequent retry: [test]# java Test Current Time:: 1125909746547 Sep 5, 2005 3:47:27 AM org.exolab.castor.jdo.engine.SQLEngine load SEVERE: A fatal error occurred while loading CounterType using SQL: SELECT COUNTER_TYPE.counter_type_desc FROM COUNTER_TYPE WHERE COUNTER_TYPE.counter_type_id=? FOR UPDATE PERSISTENCE EXCEPTION!!! Current Time:: 1125909746547 java.sql.SQLException: Deadlock found when trying to get lock; Try restarting transaction message from server: "Lock wait timeout exceeded; Try restarting transaction" at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:1997) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1167) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1278) at com.mysql.jdbc.Connection.execSQL(Connection.java:2251) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:158 6) at org.exolab.castor.jdo.engine.SQLEngine.load(SQLEngine.java:1049) at org.exolab.castor.persist.ClassMolder.load(ClassMolder.java:708) at org.exolab.castor.persist.LockEngine.load(LockEngine.java:357) at org.exolab.castor.persist.TransactionContext.load(TransactionContext.jav a:651) at org.exolab.castor.persist.TransactionContext.load(TransactionContext.jav a:556) at org.exolab.castor.persist.ClassMolder.load(ClassMolder.java:795) at org.exolab.castor.persist.LockEngine.load(LockEngine.java:357) at org.exolab.castor.persist.TransactionContext.load(TransactionContext.jav a:651) at org.exolab.castor.persist.QueryResults.fetch(QueryResults.java:229) at org.exolab.castor.jdo.engine.OQLQueryImpl$OQLEnumeration.hasMore(OQLQuer yImpl.java:631) at org.exolab.castor.jdo.engine.OQLQueryImpl$OQLEnumeration.hasMore(OQLQuer yImpl.java:614) at Test.main(Test.java:48) java.lang.NullPointerException at org.exolab.castor.persist.ClassMolder.revertObject(ClassMolder.java:2518 ) at org.exolab.castor.persist.LockEngine.revertObject(LockEngine.java:861) at org.exolab.castor.persist.TransactionContext.rollback(TransactionContext .java:1722) at org.exolab.castor.jdo.engine.DatabaseImpl.rollback(DatabaseImpl.java:546 ) at Test.main(Test.java:81) java.lang.IllegalStateException: Transaction [EMAIL PROTECTED] does not hold the read lock: CounterType/1/1 -/-! at org.exolab.castor.persist.LockEngine$TypeInfo.assure(LockEngine.java:129 8) at org.exolab.castor.persist.LockEngine$TypeInfo.access$500(LockEngine.java :1030) at org.exolab.castor.persist.LockEngine.revertObject(LockEngine.java:860) at org.exolab.castor.persist.TransactionContext.rollback(TransactionContext .java:1722) at org.exolab.castor.jdo.engine.DatabaseImpl.rollback(DatabaseImpl.java:546 ) at Test.main(Test.java:81) GENERAL EXCEPTION!!! Current Time:: 1125909746547 java.lang.NullPointerException at org.exolab.castor.jdo.engine.DatabaseImpl.getLockEngine(DatabaseImpl.jav a:202) at org.exolab.castor.jdo.engine.OQLQueryImpl.create(OQLQueryImpl.java:257) at org.exolab.castor.jdo.engine.DatabaseImpl.getOQLQuery(DatabaseImpl.java: 445) at Test.main(Test.java:38) [test]# *************************************** How to run the attached program: *************************************** After having done the setup (create DB etc) login into the DB and lock the COUNTER_TYPE row (id=1 in this case): mysql> begin; mysql> select * from COUNTER_TYPE where COUNTER_TYPE_ID=1 for UPDATE; Then execute the attached Test program. The retrieve will eventually timeout (depending on the timeout value set in the DB). That is when the errors are observed. 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