Question

I am using criteria to query the database based on the unique key. But I am coming through a weird scenario. After two or three queries, it starts giving me timeout expired error.

using (NHibernate.ISession session = m_SessionFactory.OpenSession())
{
  using (ITransaction transacion = session.BeginTransaction())
  {
    if (cashActivity.ActivityState == ApplicationConstants.TaxLotState.Deleted ||        cashActivity.ActivityState == ApplicationConstants.TaxLotState.Updated)
     {
       IList<CashActivity> lsCActivity = RetrieveEquals<CashActivity>("UniqueKey",cashActivity.UniqueKey);
       if (lsCActivity != null && lsCActivity.Count > 0)
       cashActivity.CashActivityID = lsCActivity[0].CashActivityID;
     }

     if (cashActivity.ActivityState == ApplicationConstants.TaxLotState.Deleted)
     {
       session.Delete(cashActivity);
     }
     else
       session.SaveOrUpdate(cashActivity);
   }
  }
}

  public IList<T> RetrieveEquals<T>(string propertyName, object propertyValue)
  {
     using (Isession session = m_SessionFactory.OpenSession())
     {
         Icriteria criteria = session.CreateCriteria(typeof(T));
         criteria.Add(Restrictions.Eq(propertyName, PropertyValue));

         IList<T> matchingObjects = criteria.List<T>();

         return matchingObjects;
     }
  }

I made changes in the code and start using StateLess Session but that change only reduces the frequency of timeout error.

After decugging , I found IList matchingObjects = criteria.List(); is cause of the exception. But this is only returning only one value, so it should not result timeout error since table also doesnt contain more than 100 rows as of now. Any Suggestions??

Answer 1

Unless you have wrapped NHibernate’s ISessionFactory in something else, each call to OpenSession() will yield a new session. So the above code involves multiple sessions and it isn’t clear if this is required.

Theoretically, a query on the session in RetrieveEquals() could block because of locks taken on the connection used in the calling method. But given the code as shown I can’t see anything to prove this.

The calling method first updates a property of cashActivity, then in some cases goes on to delete the object. And there is no Commit(). This seems strange – is this really the used code or might there be a copy/paste error?

You also say “after two or three queries”… do you imply that there is a loop somewhere which isn’t shown?