Valeriu - Thanks again for this answer - it proved to be the basis for our direction. While we were caching our SessionFactories, we were not reusing the FluentlyConfigured configurations and that proved to be the difference. I have spent time with our architect this morning and we still have some details to iron out, but this will likely be central to our final solution.
Kerry On Wednesday, May 29, 2013 10:03:35 AM UTC-5, Valeriu Caraulean wrote: > > As a guess, have you tried to reuse the Configuration object? > If only connection string or database name changes, you can cache the > Configuration and re-use it. It’s one of the most expensive operations when > bootstrapping NHibernate... > > Valeriu > > *From:* Kerry <javascript:> > *Sent:* Wednesday, May 29, 2013 3:48 PM > *To:* [email protected] <javascript:> > *Subject:* [nhusers] Bootstrapping with multiple Session Factories > > We have a need in our app to support multiple "connections" to different > databases, with each connection supporting the same set of mappings. We > have a huge number of mappings (this is a decade-old legacy application), > and each connection and database has the same schema. We recently added a > feature to the application that allows a user on one connection to view > data on all of the other connections, which requires having all of the > connections available at the time of the request. > > Bootstrapping a single connection can take up to 20 seconds over a slow > wire. When one of our customers tried to view data on 7 connections, the > application (unsurprisingly) timed out. To address this, we are taking a > two-pronged approach: > > 1. bootstrap all connections prior to login of the first user (at > app_start); and > 2. at bootstrap, create the session factories for each connection in a > multi-threaded environment to reduce the timeout problem. > > > The second approach is proving to be problematic. When calling > BuildSessionFactory in a multi-threaded environment, the logs show that the > factories are being constructed serially. (i.e. I spin off the threads at > time A, and they come back at times B, B+10, B+20, B+30, etc). Another > developer reporting setting up an integration environment to test this, and > received a duplicate key exception from within NHIbernate. I have not yet > had time to review that error or his code, but it points to something > problematic with using nHibernate in a multi-threaded environment. > > Would somebody mind taking a look at the following code and commenting on > our approach? Thanks very much. > > > public void ConstructSessionFactories(IEnumerable<string> > connectionNames) { var maps = connectionMap.Map.Where(m > => connectionNames.Contains(m.Key)).Select(m => m.Value); > maps.ForEach(info => { if > (factoryMap.ContainsKey(info.ConnectionString)) return; > WaitForCompletionIfFactoryUnderConstruction(info.ConnectionString); > if (factoryMap.ContainsKey(info.ConnectionString)) return; > var task = new Task(() => CreateNewFactory(info)); > task.ContinueWith(FactoryConstructed, > TaskContinuationOptions.OnlyOnRanToCompletion); > task.ContinueWith(FactoryNotConstructed, > TaskContinuationOptions.NotOnRanToCompletion); > task.ContinueWith(FactoryConstructionCausedError, > TaskContinuationOptions.OnlyOnFaulted); > factoriesUnderConstruction[info.ConnectionString] = task; > task.Start(); }); } > > > protected virtual ISessionFactory CreateNewFactory(ConnectionElement > info) { if > (factoryMap.ContainsKey(info.ConnectionString)) return > factoryMap[info.ConnectionString]; logger.DebugFormat("Creating > new SessionFactory for connection '{0}'", info.Name); var cfg = > configurationProvider.Get(info); ExposeConfiguration(cfg); > configData.AddOrUpdate(info.Name, cfg, (key, oldValue) => cfg); > var factory = cfg.BuildSessionFactory(); > factoryMap[info.ConnectionString] = factory; return factory; > } > > > private void WaitForCompletionIfFactoryUnderConstruction(string > connection) { while > (factoriesUnderConstruction.ContainsKey(connection)) { > Task task; > factoriesUnderConstruction.TryGetValue(connection, out task); > if (task != null) task.Wait(); } } > > -- > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > To post to this group, send email to [email protected] <javascript:> > . > Visit this group at http://groups.google.com/group/nhusers?hl=en-US. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "nhusers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/nhusers?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
