On Friday 14 November 2003 09:15, Adrian Brock wrote:
Hi,
> > JBoss 3.2.2, Commit Option A...
> >
> > I have a SLSB method something like...
> >
> > public void doSomething(){
> > Collection c = OrdersEJB.getItems();
> > <loop through collection and do some calculations>
> > <delete one of the 'items'>
> > }
> >
> > If these method is called at the same time by two different clients, the
> > first one works the second gives me an error
> >
> > 2003-11-13 16:38:49,707 ERROR [org.jboss.ejb.plugins.LogInterceptor]
> > TransactionRolledbackLocalException in method: public abstract
> > java.sql.Date
> > com.prometricssoftware.CHaS2.ejb.core.diaryqueue.QueueLocal.getActionDate
> >(), causedBy:
> > javax.ejb.NoSuchObjectLocalException: Entity not found: primaryKey=102
> >
> > ..now if I switch to Commit Option B for the 'item' EJB, I don't get this
> > error, and all seems to work as I expect it to.
>
> Under option A, it does the getItems() against the db.
> But the actual iteration/load is done against the cache.
Just to make sure I understand, with Commit A the finder is querying the DB,
which contains a 'record' that has been deleted from the cache, but not from
the DB, and when I am doing the iteration the entity has already been deleted
from the cache and I get the (uncatchable) NoSuchObjectLocalException?
If so, is not Commit option A dangerous, ith something beaing read from the
(up to date) cache, and others being read from the (out of date) DB?
> Under option B, it will recheck the db (a load) before the delete
> because B cannot assume the db is in synch across transactions.
I understand how this works, because everything is read from the same place
> To avoid the problem in general, you need "repeatable read" isolation
> which wouldn't work with commit option A/JBoss's Queued pessimistic
> lock anyway.
So basically, from what I understand, is Commit Option A has problems if you
are deleting 'records'? I am not sure that is right?
Phil
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