Adding <read-only>true</read-only> on method increased # of

[aparaapara]

I have an application which runs quite fast. Recently I discovered that under heavy load I get Deadlock exceptions raised from JBOSS (3.2.3). I noticed that the Deadlock exception occurs during a READ-ONLY operation and decided to mark all my get* is* has* methods with read-only attribute. For some reason, this has changed a single SELECT statement into many in the form of SELECT ... WHERE (ID=?) OR (ID=?) OR (ID=?) OR (ID=?) OR (ID=?) OR (ID=?) .... Because of this, a page that used to load in under second now took over 8 seconds to load.

I removed the read-only method specifications and the number of SELECT statements returned back to normal and performance increased.

Can someone please explain why would read-only method annotation increase the number of SELECT statements to such an extent?

Thanks.
-AP_

[aparaapara]

Arrrg, the title got choped down. It should have read:

Adding <read-only>true</read-only> on method increased # of SELECT calls by a lot!

Thanks.
-AP_

[aloubyansky]

You should upgarde JBoss and try this feature http://www.jboss.org/wiki/Wiki.jsp?page=CMPCleanReadAheadOnLoad

[aparaapara]

Alex, will CMPCleanReadAheadOnLoad help (in avoiding many SQL SELECT calls) in conjunction with <read-only>true</read-only> for the purposes of avoiding locks on read-only objects?

Thanks so much for replying quicly to my last message.
-AP_

[aloubyansky]

This feature was introduced specifically to solve your problem.

[fbiaggi]

Hi,
this is not very clear,
if i leave to false a test show 1475 statements,
to true 1590 statements.
Wich is correct ?

Thanks.

[aloubyansky]

If you leave to false what? read-only or clean-read-ahead-on-load?
The clean-read-ahead-on-load should be false in your case since you don't want to flush read-ahead cache after the read-only invocation but keep data for subsequent invocations in the same tx.

[fbiaggi]

Sorry,

clean-read-ahead-on-load

Thanks for the reply.

[aparaapara]

Alexey, I downloaded JBOSS 3.2.7 and it works great in this regard. Thanks for your initial suggestion.

-AP_