OpenJPA
  1. OpenJPA
  2. OPENJPA-1609

PessimisticLockException instead of LockTimeoutException thrown on DB2V9 for ZOS

    Details

    • Type: Bug Bug
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: 2.0.0
    • Fix Version/s: 2.0.0, 2.1.0
    • Component/s: None
    • Labels:
      None
    • Environment:
      DB2V91 on z/OS
    • Patch Info:
      Patch Available

      Description

      I am observing the following problem while working with OpenJPA 2.x on DB2v91 for z/OS:

      When performing a EntityManager.find() with a lock timeout property set, I'm expecting to receive a LockTimeoutException if my find operation fails to fetch the data from the database within the specified timeout period. Instead of getting the LockTimeoutException, I am getting a PessimisticLockException – an Exception that is considerably more severe then is expected.

      I looked at the stack trace, and found the following information:

      **Exception: Caught unexpected exception from find.
      org.apache.openjpa.persistence.PessimisticLockException:Unable to obtain an object lock on "null [java.lang.String]".
      FailedObject: 1 [org.apache.openjpa.util.IntId] [java.lang.String]
      at org.apache.openjpa.jdbc.sql.DBDictionary.narrow(DBDictionary.java:4809)
      at org.apache.openjpa.jdbc.sql.DBDictionary.newStoreException(DBDictionary.java:4787)
      at org.apache.openjpa.jdbc.sql.DB2Dictionary.newStoreException(DB2Dictionary.java:563)
      at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:136)
      at org.apache.openjpa.jdbc.sql.SQLExceptions.getStore(SQLExceptions.java:86)
      at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.initialize(JDBCStoreManager.java:339)
      at com.ibm.ws.persistence.jdbc.kernel.WsJpaJDBCStoreManager.initialize(WsJpaJDBCStoreManager.java:147)
      at org.apache.openjpa.kernel.DelegatingStoreManager.initialize(DelegatingStoreManager.java:111)
      at org.apache.openjpa.kernel.ROPStoreManager.initialize(ROPStoreManager.java:57)
      at org.apache.openjpa.kernel.BrokerImpl.initialize(BrokerImpl.java:1005)
      at org.apache.openjpa.kernel.BrokerImpl.find(BrokerImpl.java:963)
      at org.apache.openjpa.kernel.BrokerImpl.find(BrokerImpl.java:880)
      at org.apache.openjpa.kernel.DelegatingBroker.find(DelegatingBroker.java:222)
      at org.apache.openjpa.persistence.EntityManagerImpl.find(EntityManagerImpl.java:496)
      at suite.r80.base.jpaspec.entitymanager.testlogic.FindLockTestLogic.testScenarioL009(FindLockTestLogic.java:2150)
      ...
      Caused by: org.apache.openjpa.lib.jdbc.ReportingSQLException: DB2 SQL Error: SQLCODE=-913, SQLSTATE=57033, SQLERRMC=00C9008E;00000304;DSN00292.JPA20EME.X'00000002'.X'01', DRIVER=3.57.91

      {prepstmnt 2135785293 SELECT t0.version, t1.id, t1.version, t1.ENTITYALAZY_ID, t1.strData, t0.strData FROM JPA20EMEntityA t0 LEFT OUTER JOIN JPA20EMEntityC t1 ON t0.id = t1.ENTITYA_ID WHERE t0.id = ? optimize for 1 row FOR READ ONLY WITH RR USE AND KEEP UPDATE LOCKS [params=(int) 1]}

      [code=-913, state=57033]
      at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.wrap(LoggingConnectionDecorator.java:257)
      at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.wrap(LoggingConnectionDecorator.java:241)
      at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.access$700(LoggingConnectionDecorator.java:70)
      at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator$LoggingConnection$LoggingPreparedStatement.executeQuery(LoggingConnectionDecorator.java:1063)
      at org.apache.openjpa.lib.jdbc.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:278)
      at org.apache.openjpa.jdbc.kernel.JDBCStoreManager$CancelPreparedStatement.executeQuery(JDBCStoreManager.java:1706)
      at org.apache.openjpa.lib.jdbc.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:268)
      at org.apache.openjpa.jdbc.sql.SelectImpl.executeQuery(SelectImpl.java:471)
      at org.apache.openjpa.jdbc.sql.SelectImpl.execute(SelectImpl.java:396)
      at com.ibm.ws.persistence.jdbc.sql.SelectImpl.execute(SelectImpl.java:77)
      at org.apache.openjpa.jdbc.sql.SelectImpl.execute(SelectImpl.java:354)
      at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.getInitializeStateResult(JDBCStoreManager.java:577)
      at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.initializeState(JDBCStoreManager.java:379)
      at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.initialize(JDBCStoreManager.java:334)
      ... 43 more

      The problem is that OpenJPA does not properly process the combination of SQLCODE=-913, SQLSTATE=57033, and SQLERRMC=00C9008E.
      The RedBook "DB2 for z/OS Stored Procedures: Through the CALL and Beyond" page 188 states:

      -913
      UNSUCCESSFUL EXECUTION CAUSED BY DEADLOCK OR TIMEOUT. REASON CODE reason-code, TYPE
      OF RESOURCE resource-type, AND RESOURCE NAME resource-name

      Explanation: The application was the victim in a deadlock or experienced a time-out. The
      reason code indicates whether a deadlock or time-out occurred.

      SQLERRD(3) also contains the reason-code which indicates whether a deadlock or time-out
      occurred. The most common reason codes are:

      00C90088 - deadlock
      00C9008E - time-out

      Response: The application should either commit or roll back to the previous COMMIT. Then,
      generally, the application should terminate. See message DSNT376I in DB2 UDB for z/OS
      Version 8 Messages and Codes, GC18-7422, for possible ways to avoid future deadlocks or
      time-outs.

      The error being reported by DB2V9 on zOS is "SQLCODE=-913, SQLSTATE=57033, SQLERRMC=00C9008E", which indicates that
      the reason for the unsuccessful execution is a Timeout, not a Deadlock.

      Presently, the DB2Dictionary.isFatalException() method does not support that combination.

      I've made a change to the isFatalException() method that considers that error combination, and the expected LockTimeoutException now surfaces. I will post the patch on to this JIRA in a few minutes.

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            • Assignee:
              Jody Grassel
              Reporter:
              Jody Grassel
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              Dates

              • Created:
                Updated:
                Resolved:

                Development