2 Replies Latest reply on Aug 22, 2002 6:22 PM by David Jencks

    Transaction Isolation level issues

    Shane Newbie

      I'm running some tests with JBoss where I'm spawning two threads within a 'test client'. The first thread updates a complex object and the second thread which is started half a second later simply attempts to read the same object. What I'm testing for is that the read thread returns the updated values not the initial values.

      I have changed the transaction isolation levels within the database (SQL2K) configuration each of the following: TRANSACTION_SERIALIZABLE, TRANSACTION_REPEATABLE_READ, TRANSACTION_READ_COMMITTED, TRANSACTION_READ_UNCOMMITTED

      When I set to either TRANSACTION_READ_COMMITTED or TRANSACTION_READ_UNCOMMITTED, my test runs through successfully and the results returned by the read thread are the updated values in the object thus it is not allowing a 'dirty read'.

      However, when I set it to either TRANSACTION_SERIALIZABLE or TRANSACTION_REPEATABLE_READ the "read" thread hangs and eventually times out.

      Does anyone know why I'm getting this kind of behaviour?