iis - IIS7 - only serves up one page at a time. It's a making me crAzY!

Question

Situation: Classic ASP application, using a custom Application Pool. Default settings.

On some IIS7 machines, IIS decides to serve only one page at a time. So if multiple load any pages from a site, each one has to load in succession.

e.g. If I load http://foo.com/default.asp from one browser, and from another machine I load http://foo.com/differenturl.asp, the first has to finish before the other will load. It's almost like the w3p process is single threaded.

Note, there is a setting called MaxProcesses in the Advanced Settings for IIS that says "Set this to greater than 1 to create a Web Garden" (whatever that is). This does NOT solve the problem because this spawns multiple processes with their own session state etc, and when you load http://foo.com/default.asp there's no way to guarantee you get assigned to the same process.

The problem revealed itself because we have a diagnostic page which is written in ASP that creates and ActiveX control which loads a url on the website and returns the results.

So, diagnostics.asp loads and in the code on the server side it creates a small web control that loads (think XMLHTTP control) default.asp on the same server.

This page will NEVER finish loading, because the server is waiting for the diagnostics.asp page to finish before it serves the default.asp page. Deadlock!

This works fine on every IIS6 machine out there, and I believe there are some IIS7 servers where it works fine too.

I've verified it's not a result of our quirky diagnostic either. Loading multiple tabs from one machine, or even separate machines will show that the web process handles them one at a time.

---

Correct Answer by AnthonyWJones: Server Side debugging was turned on in IIS7. This puts IIS into single threaded mode.

Answer 1

In IIS manager click on the application in the tree.

Double click ASP under the IIS section.

Expand "Debugging Properties"

Ensure both "Enable Client-side Debugging" and "Enable Server-side debugging" are set to false.

When debugging is enabled ASP is limited to processing one request at a time in a single threaded manner.