I don't think Session.Load<Entity>(Id), by default doesn't use any locks. It loads objects in an unlocked mode.
Can you try Session.Load<Entity>(Id, LockMode) with Lockmode explicitly specified? Thanks, Socratees. On Nov 20, 1:20 pm, Rémi Després-Smyth <[email protected]> wrote: > Sorry, just noticed a typo in the code from the email. Corrected it and > re-sent. > > Remi. > > From: Rémi Després-Smyth [mailto:[email protected]] > Sent: November 20, 2009 3:17 PM > To: [email protected] > Subject: [nhusers] how should optimistic concurrency using a version field > work? > > Can anyone explain optimistic locking in the context of NHibernate? (Using > NHib 2.1.1.) > > I’ve been running tests and my results are counter-intuitive. I have a > versioned entity: > > <class name="Test.Entity, Test" table="tblEntity" abstract="false" > optimistic-lock="version"> > > <id name="Id" column="scheduleId" access="property" unsaved-value="0" > type="Int64"> > > <generator class="hilo"> > > <param name="table">tblHiloUId</param> > > <param name="column">nextHighValue</param> > > <param name="max_lo">100</param> > > </generator> > > </id> > > <version column="version" name="Version" type="Int32" > unsaved-value="0" /> > > <property name="Prop1" column="prop1" update="false" > > access="property" not-null="false" type="Boolean" > > optimistic-lock="true" /> > > <property name="Prop2" column="isDefaultOverridable" > > access="field" not-null="true" type="String" > > optimistic-lock="true" /> > > </class> > > And the following test: > > [Test, ExpectedException(ExceptionType=typeof(StaleObjectStateException))] > > public void SavingUpdatesOptimisticLockShouldThrow() > > { > > var cfg = new NHibernate.Cfg.Configuration(); > > cfg.AddAssembly("Test"); > > cfg.Configure(); > > var sessionFactory = cfg.BuildSessionFactory(); > > var sess1 = sessionFactory.OpenSession(); > > var sess2 = sessionFactory.OpenSession(); > > sess1.BeginTransaction(); > > sess2.BeginTransaction(); > > // NOTE: I get the same results if I load with Lock.None > > // A record is loaded in the DB in test setup, assigned to m_Id > > var a = sess1.Load<Entity>(m_Id); > > var b = sess2.Load<Entity>(m_Id); > > a.Prop2 = "New test value, session1”; > > sess1.Save(a); > > sess1.Transaction.Commit(); > > b.Prop2 = "Another, session2"; > > sess2.Save(b); > > sess2.Transaction.Commit(); // Should throw? > > } > > After reading the docs, this is what I’d expect to see: > > Both instances start with version=1. When I save and commit a, I see that > its version number is incremented from 1 to 2, while b still has version=1 > (as I’d expect). I’d expect that the call to sess2.Transaction.Commit() > should throw, because NHibernate will determine that the record was updated > since b was loaded, so optimistic concurrency issue. But it doesn’t – b > commits fine, and overwrites changes saved when a was saved. > > If I load explicitly selecting the lock I want, it does work as I’d expect > and I get my exception. > > This is surprising to me. Ayende noted in a concurrency blog post > (http://ayende.com/Blog/archive/2009/04/15/nhibernate-mapping-concurre... > px) that using a version column should result in the generated UPDATE SQL > statement to compare against the version number – and if the version doesn’t > match the original version, we should get a StaleObjectException. > > Can anyone clarify what’s going on here? > > Thanks. > > Remi. > > -- > > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group > athttp://groups.google.com/group/nhusers?hl=. -- You received this message because you are subscribed to the Google Groups "nhusers" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nhusers?hl=.
