Question

We are working on a c# windows service using NHibernate which is supposed to process a batch of records.

The service has to process about 6000 odd records and its taking about 3 hours at present to process these. There are a lot of db hits incurred and while we are trying to minimize these , we are also exploring multithreading options to improve performance.

We are using the UnitOfWork pattern to access the NHibernate session.

This is roughly how the service looks :

public class BatchService
    {
        public DoWork()
        {
           StartUnitOfWork();

           foreach ( var record in recordsToBeProcessed)
           {
              Process(record);
              // Perform lots of db operations
           }

           StopUnitOfWork();
        }
    }

We were thinking of using the Task Parallel Library to try to process these records in batches ( using the Parallel.Foreach () method).
From what I have read about NHibernate so far , we should provide each thread a separate NHibernate session.

My query is how do we supply this ..considering the UnitOfWork pattern which only allows one session to be available.

Should I be looking at wrapping a UnitOfWork around the processing of a single record ?

Any help much appreciated.

Thanks

Answer 1

The best way is to start a new unitofwork for each thread, use a thread-static contextual session NHibernate.Context.ThreadStaticSessionContext. You must be aware of dettached entities.