Fluent Nhibernate: fetching collections within collections concurrently - nhibernate

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

There are several problems with the current approach. Let me give you a fresh look at the problem.
You are, I understand, looking to retrieve Things, which have many-to-one BlueEntities, and a collection of YellowEntities, which in turn have a collection of SubYellowEntities.
Instead of using join fetch, transformers and loops, you should look into batch fetching of entities and collections.
With a good batch size set for BlueEntity, Thing.YellowEntities and YellowEntity.SubYellowEntities, you should not need TPL stuff at all.
If it turns out you do, you won't be able to return safe-to-use entities, because they have to be associated with a single session to be useful, and sessions are not thread-safe.

Answer 2

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