"Pedro B. Gomes Costa" wrote:
>
> Blasius,
>
> I said an error on my last email
>
> Setting isolation to serializable dont solve anything cause Interbase
> implements the serialisable mode with his Smapshot mode (default mode) and
> uses the Multigenerational Architecture to give the kind of operation I
> described.
> What I wanted to say is using the native Interbase Isolation Level
> "TRANSACTION_SNAPSHOT_TABLE_STABILITY", but I think you can't set this with
> Jonas (you can only if you use Bean Manage Persisntence and use the
> setTransactionIsolation function of Connection) and this would really hurt
> performance cause it would make table locks (SQL Server did it allways until
> version 7 and still does on some situations.....).
>
> I'm a little confused now. Have to think a little more about this.
> Maybe Philippe Durieux can give a little clue about what Jonas is doing
> (sorry I really dont have the time now to browse the code) so we can find a
> solution.
>
> Pedro Costa
Hi guys,
Since jonas 2.3, transaction isolation is done inside the jonas container.
I mean that if 2 transactions access a same instance, one of them will be
put waiting until the other is ended, with a timeout to resolve deadlock
problems. As a consequence, you should put a very light level of isolation
in your database. I consider only the case where your beans are not "shared",
i.e. only jonas accesses your database.
Since jonas 2.3, it is now possible to set the transaction isolation
level via one of the datasource properies.
The problem with interbase was that with the default isolation level,
an exception is raised even if 2 different instances are accessed concurrently.
In this case, jonas does not serialize because these are different bean
instances. The solution was to use "read_committed" as isolation level
for Interbase.
Philippe
--
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