[nhusers] Nested/Concurrent transactions aren't supported

['Michael Craig' via nhusers]

Hi guys,

I'm using PostgreSQL and Npgsql but I have isolated the issue to NHibernate
behaviour. Here is the sample code which breaks, during the following code,
we are already inside a Session and an ambient TranscationScope, then we
nest like so:

var openSession = ObjectFactory.GetInstance<ISession>();
using (var trans = new TransactionScope(TransactionScopeOption.Suppress, new
TransactionOptions { Timeout = new TimeSpan(0, 5, 0) })) {
using (var newSession = sessionFactory.OpenStatelessSession(openSession.
Connection)) {
using (var nhTrans = newSession.BeginTransaction()) {
Stuff();
}
}
}

This code is operational using any NHib v4. But with any NHib Version v5+
it will throw the title exception 'Nested/Concurrent transactions aren't
supported'. This is the case with any NpgSql 3+, making it likely that some
behaviour of NHib changed (maybe correctly of course).

I have read the issues revolving around the configuration parameter
'transaction.use_connection_on_system_prepare` and that doesn't help in
this case. I find that in all cases, newSession.Connection.Connector ==
openSession.Connection.Connector and the NpgSql code has always checked
against Connector.InTransaction before throwing, so NHibernate must be
bypassing this somehow, although I can't see any evidence of that in the
source code!

Anyone got any ideas why exactly this blows up in NHib v5+ only?

Thanks,

Mike