nHibernate session and multithreading

Method()
{
... persistence calls
foreach(Thing..)
{
...persistence calls for each thing (1)
}
...
}

Method()
{
... persistence calls
foreach(Thing..)
{
create a thingResolver object with some data
open a new thread with thingResolver.Method (1)
starts this thread
}
.. waits for finishing threads and continues
}