WCF Server Too Busy -> IIS_WPG group

So in setting up a new WCF application, I was going to have my database credentials work through windows authentication instead of having plaintext passwords everywhere.

So I went about to get this accomplished.
I created a new app pool for my website, and in the properties of the app pool I set the identity to the domain user that I have confiqured in SQL Server.
And in my WCF web config I use the regular trusted security SQL connection string.

However, everytime I connect using my client WCF would throw a sevice is too busy error. Then trying from the web browser directly I would keep getting Service Unavailable. Apparently my app pool keeps stopping (checked the event log) because of setting the identity to a domain user. The key point here is that the domain user has to be part of the machine's IIS_WPG group in order to be trusted.

So I went through a series of errors to figure this out. Bottom line, if you want to use windows authentication in WCF for SQL database connection, make sure that user is part of the IIS_WPG group.

WCF Crashes After 10th Call

http://blogs.msdn.com/tess/archive/2009/01/09/net-hang-my-application-hangs-after-i-called-my-wcf-service-a-couple-of-times.aspx

http://msdn.microsoft.com/en-us/library/ms731193.aspx