How to dispose objects in a Singleton WCF service

Question

How to dispose objects in a Singleton WCF service? I am using Entity Framework (3.5) and returning a bunch of custom POCO objects to the client. The service needs to be alive as it provides cross-client communication and hence Duplex binding is used. I would like dispose all the POCO objects created once they are serialized to the client. As the session and hence the service is still alive, it looks like Framework is not doing any Garbage collection on these objects and over time the service is crashing with "Insufficient Memory" like error (after about 2GB).

I don't think dispose can be called before return statement, as the objects are not yet serialized by then.

Please suggest a solution.

Thanks in advance.

Answer 1

First, do not use singleton service, why, well your question is the answer. As I see it your service should be a per call instance managed and the callback channels should be managed on another class or as static member in the service class.

Second, try to see if you keep reference to the poco's you return to client, Cause GC cleans unreferenced stuff. So if you find the reference just assign those member with null and GC will do the rest(you have nothing to worry about method variables).

Answer 2

I think you're on the wrong track here; if your objects are POCO, do they even implement IDisposable (not sure why you would for a POCO class). My guess is you've got something else that is chewing up your memory. Possibly your singleton service is just living too long and collecting too much crap; you might want to look at a different service model. Maybe an instance per session or something like that.

One thing you could do, however, is rather than serializing your POCO objects directly create very simple 'messaging' classes that have only the properties you want to serialize and send those instead. You could copy the properties to your message objects and then dispose your database objects immediately.