Given an IIS server which receives heavy traffic and a website has been restarted, what happens to pending requests during the Application_Start event in ASP.NET?
It is my understanding that the first request triggers the applications completion and startup. Do the other requests just queue up?
Our Application_Start event does a lot of configuration and setup and can take several seconds. Is it bad to have heavy traffic during this time?
It is bad to get heavy traffic during startup. How bad? It depends on how much time you take to start and how much incoming traffic you get.
While your application is starting, check out the ASP.NET performance counter for "Requests Queued". The more traffic you get, the more requests are queued up to the limit (5k?). Any incoming request when the queue is full will get a HTTP 503 right away.
If your startup takes longer than the default request timeout (100s in .NET 2.0+), the requests in the queue will start to timeout too and new ones will take their place.