ADO.Net SQL pooling in asp.net-mvc-4 application

Question

I want to optimize the sql connection in my wep application its create in .net mvc 4, i read that ado.net automatically manager the connection pooling but i'm some lost respect how exactly implement that, is correct if i create a global object with the connection in the Application_Start class then pass the connection object through all data object in my application ? something like this

protected void Application_Start()
{
...
SqlConnection conn = new SqlConnection("Connection String...");
DAOPeople daoPeople = new DAOPeople(conn);
...
}

in that way i avoided create a new SqlConnection for each dao, is correct?

Answer 1

No, don't do that. You'll end up with a bottleneck at your connection object, as that single connection is shared across all sessions and requests to your app.

For connection pooling, you do the exact opposite: don't try to share or re-use a single connection object; do just create a new SqlConnection every time you need it, open it on the spot, and make sure it's disposed as soon as you're done via a using block. Even though your code looks like you're opening and closing a lot of connections, the connection pooling feature is built in and ensures you keep drawing from a small number of existing connections in the same pool.

That said, if you're on a really large site, you can do a little better. One thing large sites will do to help scale is avoid unnecessary memory allocations, and there is some memory that goes with creating an SqlConnection object. Instead they might, for example, have one main SqlConnection per HTTP request, with the possibility of either enabling MARS or having an additional secondary connection object in the request so they can run some things asynchronously. But this is only something the top 0.1% need to care about, and if you're at this level you're measuring to find out where the proper balance is for your particular site and load.