After further investigation, I think that here is how the issue occurs: There is only one Worker per SessionFactory so multiple calls to TransactionalWorker.PerformWork() can be running on different threads at the same time. The only line that changes the WeakHashtable is: synchronizationPerTransaction[transaction] = txSync;
Looking at its implementation, we can see that it scavenges first then set the value. So if a scavenge is running on one thread while a set is being performed on another, we get that exception. To test this theory, I modified the code like this: synchronizationPerTransaction.SetWithoutScavenging(transaction, txSync); // Which just set the value in the innerHashtable And that exception hasn't occur after multiple tests. What do you think about this solution? Hack or Fix? :) Note that this require adding a method to NHibernate.Util.WeakHashtable and I wonder if it doesn't reveal a larger problem... On Feb 3, 10:21 am, Ayende Rahien <[email protected]> wrote: > looks like an obivious multi threading issue. I'll look into it a bit. > > On Tue, Feb 3, 2009 at 9:58 AM, Pierre Henri Kuate <[email protected]>wrote: > > > > > Hi all, > > > I have access to a 8-core workstation and I use it to stress test my > > project. > > I noticed that the concurrency tests in NHibernate.Search sometimes > > fail with the following exception: > > > System.InvalidOperationException: Collection was modified; enumeration > > operation may not execute. > > at System.Collections.Hashtable.HashtableEnumerator.MoveNext() > > at NHibernate.Util.WeakHashtable.Scavenge() in C:\Dev\NHibernate > > \NHibernate\Util\WeakHashtable.cs:line 150 > > at NHibernate.Util.WeakHashtable.set_Item(Object key, Object value) > > in C:\Dev\NHibernate\NHibernate\Util\WeakHashtable.cs:line 198 > > at NHibernate.Search.Backend.Impl.TransactionalWorker.PerformWork > > (Work work, ISessionImplementor session) in C:\Dev\NHibernate > > \NHibernate.Search\Backend\Impl\TransactionalWorker.cs:line 28 > > at NHibernate.Search.Event.FullTextIndexEventListener.ProcessWork > > (Object entity, Object id, WorkType workType, AbstractEvent e) in C: > > \Dev\NHibernate\NHibernate.Search\Event > > \FullTextIndexEventListener.cs:line 54 > > at NHibernate.Search.Event.FullTextIndexEventListener.OnPostUpdate > > (PostUpdateEvent e) in C:\Dev\NHibernate\NHibernate.Search\Event > > \FullTextIndexEventListener.cs:line 94 > > at NHibernate.Action.EntityUpdateAction.PostUpdate() in C:\Dev > > \NHibernate\NHibernate\Action\EntityUpdateAction.cs:line 172 > > at NHibernate.Action.EntityUpdateAction.Execute() in C:\Dev > > \NHibernate\NHibernate\Action\EntityUpdateAction.cs:line 128 > > at NHibernate.Engine.ActionQueue.Execute(IExecutable executable) in > > C:\Dev\NHibernate\NHibernate\Engine\ActionQueue.cs:line 130 > > at NHibernate.Engine.ActionQueue.ExecuteActions(IList list) in C: > > \Dev\NHibernate\NHibernate\Engine\ActionQueue.cs:line 113 > > at NHibernate.Engine.ActionQueue.ExecuteActions() in C:\Dev > > \NHibernate\NHibernate\Engine\ActionQueue.cs:line 147 > > at > > NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions > > (IEventSource session) in C:\Dev\NHibernate\NHibernate\Event\Default > > \AbstractFlushingEventListener.cs:line 241 > > at NHibernate.Event.Default.DefaultFlushEventListener.OnFlush > > (FlushEvent event) in C:\Dev\NHibernate\NHibernate\Event\Default > > \DefaultFlushEventListener.cs:line 19 > > at NHibernate.Impl.SessionImpl.Flush() in C:\Dev\NHibernate > > \NHibernate\Impl\SessionImpl.cs:line 1215 > > at NHibernate.Transaction.AdoTransaction.Commit() in C:\Dev > > \NHibernate\NHibernate\Transaction\AdoTransaction.cs:line 177 > > at NHibernate.Search.Tests.Worker.WorkerTestCase.ReverseWork(Object > > state) in C:\Dev\NHibernate\NHibernate.Search.Tests\Worker > > \WorkerTestCase.cs:line 216 > > > Note that it also occurs on my Core 2 Duo, but far less often. > > > Have you ever experienced this issue? Any suggestions on how to fix it? --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "NHibernate Contrib - Development Group" 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.ar/group/nhcdevs?hl=en -~----------~----~----~----~------~----~------~--~---
