Logging Web API calls MVC 4

[Sezar]

I need to log to the database every call to my Web API.Now of course I don't want to go to my database on every call.So lets say I have a dictionary or a hash table object in my cache,and every 10000 records I go to the database.I still don't want this every 10000 user to wait for this operation.And I can't start a different thread for long operations since the application poolcan be recycled basically on anytime.What is the best solution for this scenario?Thanks