Hello amorin,

Session and all its internals are not thread-safe. Thereafter, you should perform manual synchronization or use several Session instances to fetch data in parallel.

Hum hum hum,

An Entity is bound to its Session so the result the method returns is absolutely unusable in any Session other than the originating one. Moreover, the Entity you return keeps reference to Session instance thus it cannot be collected by GC despite the fact that it is already disposed.

Consider rethinking your architecture, may be usage of Prefetch would help to load data faster. The main idea is to fetch and use entities in the same session and transaction. Crossing boundaries of sessions and transactions will lead to weird errors and unnecessary database roundtrips.

Dmitri,

I'm not sure I follow your suggestion. We are currently using a 1 session and 1 transaction per thread and experiencing the exception amorin posted above. Below is a snippet of pseudo code that illustrates what we are doing on each thread. QueryTask is executed on multiple concurrent threads where the input value is different for each and the results collated at a higher level. Is there a specific version of DataObjects.NET we need to be on to use multiple threads, are we doing this wrong, is this a bug, are parallel operations supported in this product?

Tresult QueryTask(Tkey input) {
   using(var session = Session.Open(xxDomainxx))
      using(var transaction = Transaction.Open()) {
         var result = Query.Single<Tresult>(input);
         transaction.Complete();
         return result;
      }
}

Dmitri,

I understand your point and have verified that we are not using Entity objects outside of their session and transaction scope. The pseudo I posted last time was perhaps over simplified. We are creating business object from the Entity objects within the transaction/session scope and returning those for aggregation by another thread. Is it possible there is a [ThreadStatic] attribute missing somewhere in the Transaction, Session or Entity models?

TBusinessObject QueryTask(Guid key) {
    using(var session = Session.Open(xxDomainxx))
        using(var transaction = Transaction.Open()) {
            var result = Query.Single<TEntity>(key);
            TBusinessObject businessObject = new TBusinessObject();
            businessObject.SimplePropertyA = result.NonEntityPropertyA;
            businessObject.ComplexPropertyB = new ComplexProperty(){ SimplePropertyX = result.EntityPropertyB.X, SimplePropertyY = result.EntityPropertyB.Y };

            transaction.Complete();
            return businessObject;
        }
}