OptimisticConcurrencyException with System.Web.Providers

Question

I'm using the new Universal Providers from Microsoft for session in SQL Server. The old implementation of session on SQL Server required a job (running every minute) to clear expired sessions. The new one does this check and clear on every request. Since I'm actually running in SQL Azure, I don't have SQL Agent to schedule jobs, so this sounds like a reasonable way to go about it (no, I don't want to pay for Azure Cache for session).

The problem is when multiple users access the site at the same time, they're both trying to clear the same expired sessions at the same time and the second gets an optimistic concurrency exception.

System.Data.OptimisticConcurrencyException: Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.
   at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)
   at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
   at System.Web.Providers.DefaultSessionStateProvider.PurgeExpiredSessions()
   at System.Web.Providers.DefaultSessionStateProvider.PurgeIfNeeded()
   at System.Web.SessionState.SessionStateModule.BeginAcquireState(Object source, EventArgs e, AsyncCallback cb, Object extraData)
   at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

I'm using ELMAH for error logging, and this is showing up with some frequency. Before I try to configure ELMAH to ignore the errors, does anyone know of a way to stop the errors from happening in the first place? Is there some configuration with the new providers that I'm missing?

Answer 1

Please download the newer version of the providers which can be found here: http://www.nuget.org/packages/System.Web.Providers. We have updated the way that we clean up expired sessions to run asynchronously and to handle error conditions. Please let us know if it does not correct your issues.