Hi,

We have created a large order, stock, delivery business system who's core is HIbernate, Struts and MySql.

From time to time a lock wait timeout occurs. Sometime daly and sometime weekley. We haven't seen anything special that triggers the behaviour, but when the system get locked it won't help restarting the database. The main application running Hibernate must be restarted to get the the system working again.

Shouldn't the system start working again after the timeout passed?

We have thought of uppgrading the MySql JDBC driver? Any more ideas?

Thanks
Christian Heijkenskj

Web application must never use app level locking, you need to find the way to implement the same, but without lock.

Thanks for the reply.
May I ask why not using app level lockning?

We start a transaction, sometimes use these locks, and commit or rollback the transaction. We save the current transaction for each thread in a threadlocal variable to use the same transaction during the call/thread lifetime. As many complex inserts, updates and deletes can occur during a transaction, what do you recommend?

My hope using hibernate locking was to be able to scale the system later using standard methods...

Thanks

There a lot of workaraunds to avoid dealocks, It depends on concurency control implementation in RDBMS and DB schema and I can not to recomend something specific, but probably
"Lock wait timeout exceeded; Try restarting transaction" doe's not mean
dealock, it looks like some uncomited transaction doe's not release exclusive lock ("SELECT ... FOR UPDATE" is an exclusive lock in mysql and it blocks reads too, web applications more read than write data and it can make web application to hung after thread pool starts to wait for a free thread)
Do you commit transactions in "Filter" or use some transaction demarcation antipattern from petstore ?