A multi-request-safe ViewState Persister
Mark Miller has posted his code for a ViewStatePersister using the "common sense but not obvious" GUID technique that was outlined previously by Scott Mitchell and myself.
He stores a GUID in the ViewState hidden field, and sticks the bloated ViewState in a temp file on the server. It doesn't solve the problem when running multiple web servers while using stateless balancing (meaning: NOT using sticky sessions/node affinity) but it's the most elegant and complete solution I've seen yet and should work great on a single web server.
A few questions I have though:
- When do the files get cleaned up and how often? Do you clean up old ones in a background thread within ASP.NET or a separate Windows Service? Thought: I wonder if you could delete them after immediately after the Load? You wouldn't be able to RE-post data, but it'd be cleaner, no?
- GUID generation is very expensive, and can really slow you down under load. I wonder if it would be faster/easier to have a single long and use InterlockedIncrement or InterlockedIncrement64 to safely increase the value on each call until it overflows and you start again at 0.
Many thanks to Mark for sharing!