Trying to make Web Method Asynchronous

Solution 1:

Sorry to say that, but the only way to execute asynchronously your code and use session variables is to make your totally custom session solution - and I mean totally custom and disable the asp.net session entirely.

Basic tips to make your session:

1. You have one cookie connected with the users data
2. The data is on one table on your database.
3. You make custom fields on that table for each session and avoid Dictionary<> to keep them
4. You work with Dirty read, last write wins
5. You read and write only the session variables that you need each time (not all together)
6. Each line have a time out date, and use like MS, a sheduler on SQL to delete old sessions.
7. Load session on OnPreInit, save only what have change on OnUnload
8. By entirely disable the session, you need to lock using Mutex code that now is work fine because the session is make synchronization with out notice it, but with out session lock maybe execute two times, like new inserting to database calls.

relative:

Web app blocked while processing another web app on sharing same session
What perfmon counters are useful for identifying ASP.NET bottlenecks?
Replacing ASP.Net's session entirely

to answer and to this question if I configure SQL Server to store the session ? the session is still lock and block the rest request. If you have the session on SQL server or on other medium is not change the way of working, only the place of the saved data.