ASP.NET Session State Service in Sql Server but w3wp.exe #private increasing

Question

I have recently moved our ASP.NET session state from InProc to a Sql Server solution. I can see session data being inserted into the Sql Server database. I'm monitoring the w3wp.exe process using the "Private bytes" & "# Bytes in all heaps" performance counters.

As I navigate through the website it places data into session, however the private bytes counter still climbs on the server hosting the website? I thought the session data was being written to the database and not being stored in memory? The managed bytes remain constant, and I'm pretty sure all the objects going into the session are managed types.

Does anyone know why the private bytes would still increase?

Answer 1

Session is just one of the many objects needed for an ASP.Net website. You have moved the session store out of RAM and into SQL but there are plenty of other objects required, not to mention the rendered pages themselves.