Question

I am currently using ASP.Net state server to store session data in my application.

As a workaround to a larger problem with sessions (don’t ask), I need to remove a set of keys that contain a certain string from session, but I don’t know the exact keys.

I want to do something like the code below. Since the session data is out of process, my concern is that by doing this I am loading the entirety of the session data into the ASP.Net worker process. This is a problem, because the current application puts too much data in session (the longer term problem we are trying to solve).

Does anyone know how the session gets accessed under the hood? Is there a way to iterate over session keys without loading the session into memory?

//does this line cause the session to be loaded back into the WP?
var session = HttpContext.Current.Session;

if (session != null)
{
    //what about this line?
    var keysToRemove = session.Keys.Cast<object>().
        Where(key => key.ToString().Contains(MYKEY)).ToList();
    foreach (var key in keysToRemove)
    {
        session.Remove(key.ToString());
    }
}

Answer 1

Whole session is always loaded to memory on user’s request for built in providers. It is loaded before execution reaches normal page code (not lazily as you assume). The only thing you can do to prevent loading is to have module that listens to one of the early events and removes session Id from request.

Note: session.Keys is already collection of strings, so you can remove such complicated casting.