Question

I needed to eagerly fetch an entity with collections of collections, etc. so that I could process the data concurrently (a Thing entity with many YELLOWEntities that each have many SubYellowEntities). The key code needed was:

NHibernateUtil.Initialize(fetchedThings);

(See accepted answer below.)

Answer 1

Solution (if you can refine this, go ahead and post the revision as the answer): Runs in 17 seconds (down from 97) on 8 processors with correct results. Please remember that the vast majority of time was spent in calculations, not in waiting for Nhibernate to return.

var fetchedThings = new List<Thing>();
var sessFT = Session.SessionFactory.OpenSession();
Task getThingsTask = new Task(() =>
   {
       fetchedThings = sessFT.CreateQuery(@" from Thing t " +
                             " inner join fetch t.BlueEntity " )
                             .SetResultTransformer(Transformers.DistinctRootEntity)
                             .List<Thing>();
        NHibernateUtil.Initialize(fetchedThings);
    });
getThingsTask.Start();

var fetchedYellows = new List<YELLOWEntity>();
var sessFY = Session.SessionFactory.OpenSession();
Task getYellowsTask = new Task(() =>
   {
        fetchedYellows = sessFY.CreateQuery(@" from YELLOWEntity y " +
                             " left join fetch y.SubYellowEntities " + ... )
                             .SetResultTransformer(Transformers.DistinctRootEntity)
                             .List<YELLOWEntity>();
        NHibernateUtil.Initialize(fetchedThings);
    });
getYellowsTask.Start();

getThingsTask.Wait();
getYellowsTask.Wait();

Parallel.ForEach(fetchedThings, thing =>
{
    thing.YELLOWEntities = fetchedYellows.Where(y=>y.Thing.Id == thing.Id).ToList();
    ...
    //...inner foreach() loop through 'YELLOWthings'... doing threadsafe stuff
    ...
});

//dispose the temp sessions