When I run my application with single thread, it is going fine. When I am testing the same application with multiple users using Load Runner for performance testing, I am getting the following error.

My Sample code is as follows:

saveItems()
{
session = HibernateUtil.getSessionFactory().openSession();
session.setFlushMode(FlushMode.MANUAL);
tx = session.beginTransaction();
//delete the old entries from the database.
List<Item> olditems = dao.findCurrent(account);
for (int i = 0; i < oldItems.size(); i++) {
session.lock(oldItems.get(i), LockMode.UPGRADE);
session.delete(oldItems.get(i));
}
//insert the new entries into the database.
List<Item> newItems = dao.findCurrent(account);

for (int i = 0; i < newItems.size(); i++) {
session.saveOrUpdate(newItems (i));
}
session.flush();
tx.commit();
}

My mapping file is as follows: My item has a mapping file with the child element.

<class name="com.sample.Item" table="item_tbl">
<id name="id" column="id">
<generator class="native"/>
</id>
<property name="name" column="name" length="45"/>
<property name="updateDateTime" column="last_modified"/>
<list name="subitems" cascade="all">
<key column="item_id"/>
<index column="row_num"/>
<one-to-many class="com.sample.SubItem"/>
</list>
</class>

org.hibernate.HibernateException: Illegal attempt to associate a collection with
two open sessions
at org.hibernate.collection.AbstractPersistentCollection.setCurrentSessi
on(AbstractPersistentCollection.java:410)
at org.hibernate.event.def.OnUpdateVisitor.processCollection(OnUpdateVis
itor.java:40)
at org.hibernate.event.def.AbstractVisitor.processValue(AbstractVisitor.
java:101)
at org.hibernate.event.def.AbstractVisitor.processValue(AbstractVisitor.
java:61)
at org.hibernate.event.def.AbstractVisitor.processEntityPropertyValues(A
bstractVisitor.java:55)
at org.hibernate.event.def.AbstractVisitor.process(AbstractVisitor.java:
123)
at org.hibernate.event.def.DefaultDeleteEventListener.onDelete(DefaultDe
leteEventListener.java:90)
at org.hibernate.event.def.DefaultDeleteEventListener.onDelete(DefaultDe
leteEventListener.java:49)
at org.hibernate.impl.SessionImpl.fireDelete(SessionImpl.java:766)
at org.hibernate.impl.SessionImpl.delete(SessionImpl.java:744)

Please help me in knowing why this exception is coming. Any pointers towards this error would be greatly appreciated.

Thanks In Advance,
Best Regards,
dp

Hi,

My Dao class was singleton and setting the session to the dao class was giving the problem.

Once the dao.setSession(session);

I was setting the session and doing the deletion of the table items and subitems and inserting the item and subitem.

But as the Dao class is singleton, when another request comes, it is creating the session and doing the dao.setSession(session), there by overriding the existing session.

That's the reason my list was giving me the problem, that

Illegal attempt to associate the same collection with different open sessions.

Hope this helps.

Best Regards,
Durga