i think the difference would be minimal… it’s the call to BuildSessionFactory that will take most of the time

I realise there are times when it (create method) will have wasted processor cycles but it reduces the amount of time the lock is held, therefore giving greater parallelism.

e.g.

private void CreateSessionFactoryForCurrentTenant()
{
var tenantId = tenantContext.CurrentTenantId;
var connectionString = tenantInfoHolder.GetDatabaseConnectionString(tenantId);

var configuration = new Configuration()
.Configure()
.AddProperties(new Dictionary
{
{ “connection.connection_string”, connectionString },
{ “cache.region_prefix”, “Tenant_” + tenantId }
})
.AddAssembly(mappingAssemblyName);

lock (writeLock)
{
if (!sessionFactories.ContainsKey(tenantId))
{
var newDictionary = new Dictionary(sessionFactories);
newDictionary[tenantId] = configuration.BuildSessionFactory();;
sessionFactories = newDictionary;
}
}
}