You need to create/lookup a separate EM in each thread - EMs are not thread safe.
Regards,
-marina
Allan Juul wrote:
> hi,
>
> from a servlet I start a transaction much like the code below.
> this code works beuatifully in the way that i get data inserted/updated
> into my database via my entities.
>
> my problem is that my updates will happen from 2 threads, so i am afraid
> that my transaction will not commit. for instance i will get this kind
> of errors.
>
> "Nested transaction not supported"
>
>
> so my question really is, how do i make sure this scenario is thread and
> transaction safe, ensuring that all transactions commit ok ?
>
>
> ./allan
>
> ************************* pseudo code **************************
>
>
> @PersistenceContext( name = "GFPU", unitName = "GFPU")
> public class myServlet extends HttpServlet {
> @Resource
> UserTransaction _utx;
> ...
>
>
> protected void doProcess(HttpServletRequest request, HttpServletResponse
> response) throws ServletException, IOException {
>
> String pc_jndi = "my_jndi_name";
> InitialContext ic = new InitialContext();
> Object ot = ic.lookup(pc_jndi);
> _em = (EntityManager) ot;
> ...
>
> ...
>
> MyThread instance1 = new AggregatorThread(_utx, _em, 1);
> Thread thread1 = new Thread( instance1 );
> thread1.start();
>
> MyThread instance2 = new AggregatorThread( _utx, _em, 2);
> Thread thread2 = new Thread( instance2 );
> thread2.start();
>
>
>
>