Which process running on an IIS server spawns a w3wp.exe for each asp.net application?

Question

Which process running on an IIS web server is responsible for the creation of w3wp.exe worker processes for each asp.net application?

Answer 1

With IIS 7, the actual process that creates the w3wp.exe (worker process) is known as the IIS Windows Process Activation Service (WAS):

Windows Process Activation Service (WAS) manages application pool configuration and the creation and lifetime of worker processes for HTTP and other protocols. The World Wide Web Publishing Service (W3SVC) and other services depend on WAS.

If you use a tool such as Process Explorer you can see the process tree including the parent process of your w3wp3.exe: