ASP.NET connection pool question

Question

Does the same connection string used on two different physical servers hosting different web applications that talk to the same database draw connections from the same connection pool? Or are pooled connections confined to at the application level?

I ask because I inherited a 7 year old .NET 1.1 web application which is riddled with in-line SQL, unclosed and undisposed sql connection and datareader objects. Recently, I was tasked to write a small web app that is hosted on another server and talks to the same database and therefore used the same database connection string. I created a LINQ object to read and write the one table required by the app. Now the original .NET 1.1 app is throwing exceptions like

"Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached."

Maybe these are unreleated, but wanted to get your opinions to make sure I cover all my bases.

Thanks!

Answer 1

There is no way connections can be pooled between two separate machines. Your SQL Server will have a connection limit for total connections however.

This error is most likely occurring because the application is not returning connections to the connection pool. This can happen because the connection is not being disposed of correctly. This can happen due to poor code (does it use a using block, or a try catch finally?) or if using a SQLDataReader can cause the connection to stay open after the code to execute the SQL has exited.

Answer 2

Connection Pools are kept in your App Pool, so it shouldn't be possible for a separate machine to steal out of a separate boxes App Pool. Have a look here for some info on the connection pool. I'd also recommend slapping the performance counters on see bottom of this article to see what's going on in there a bit more.

Also might want to check the max number of connections on SQL Server. In management Studio Right click on the Server name --> Properties --> Connections

look for "Maximum number of concurrent connections (0 = unlimited)"