Question

Is it possible to create mini session factory with some classes on one
thread and then and create full session factory on a second thread?

i want to speed up initialization of sessionfactory

Can you show how to do it?

Answer 1

One way to speed up startup is to serialize the configuration object which takes most of the startuptime for building and validating, see here.

The code to implement your aproach:

var minisessionfactory = Fluently.Configure()
    .DataBase(SomeConfiguration.Standard....)
    // only add the relevant mappings
    .Mapping(m => m.FluentMappings.Add<AMap>().Add<BMap>()...)
    .BuildSessionfactory();

ThreadPool.QueueUserWorkItem(state =>
{
    RealSessionFactory = Fluently.Configure()
        .DataBase(SomeConfiguration.Standard....)
        // only add the relevant mappings
        .Mapping(m => ...)
        .BuildSessionfactory();
    SessionFactoryReady = true;
});

// do some Stuff with minisessionfactory

Update:

Did you measured where the time is really spent: Building the Configuration or build the Factory?

If its building the factory, enable full logging to see if there are some steps which take long and could be disabled.

UpdateUpdate: simple implementations

ISession GetSession()
{
    while (!SessionFactoryReady) Thread.Sleep(1000);
    return RealSessionFactory.OpenSession();
}

// or

ISessionFactory SessionFactory
{
    get
    {
        while (!SessionFactoryReady) Thread.Sleep(1000);
        return RealSessionFactory;
    }
}