I have a process that can have multiple AppDomains. Each AppDomain collect some statistics. After a specified time, I want to accumulate these statistic and save them into a file.
One way to do this is Remoting, which I want to avoid.
The only other technique I have in mind is to save each AppDomain's data in a file, and after a specific time, one of the AppDomain collects all data and accumulate them.
But it would be ideal if this all could be done in-memory, without the cost of serializing the information to pass between AppDomains. Anyone have any ideas?
The only way to avoid serialisation is to represent your data using objects which derive from MarshalByRefObject, but in that case you will still have the cost of marshalling across the AppDomain boundaries. This may also involve the refactoring/re-writing of much of your code.
Assuming marshalling by reference is not an option, you will have to serialise at some point. It simply cannot be avoided. One way to do this is as Neil Barnwell suggests, with a database, another would be with a local file as you suggest yourself.
Another way which may or may not feasible depending on your delivery timeline and/or .NET 4.0 adoption, would be to use a memory mapped file, see .Net Framework 4.0: Using memory mapped files.