What is w3wp.exe / IIS Worker Process?

Web applications on Windows Servers are configured via command line or Internet Information Systems (IIS) Manager. Within IIS you can set up websites and which application pools they are assigned. Multiple websites can be assigned to a single IIS application pool.

·         A worker process runs as an executables file named W3wp.exe

·         A Worker Process is user mode code whose role is to process requests, such as processing requests to return a static page.

·         The worker process is controlled by the www service.

·         worker processes also run application code, Such as ASP .NET applications and XML web Services.

·         When Application pool receive the request, it simply pass the request to worker process (w3wp.exe) . The worker process“w3wp.exe” looks up the URL of the request in order to load the correct ISAPI extension. ISAPI extensions are the IIS way to handle requests for different resources. Once ASP.NET is installed, it installs its own ISAPI extension (aspnet_isapi.dll)and adds the mapping into IIS.

·         When Worker process loads the aspnet_isapi.dll, it start an HTTPRuntime, which is the entry point of an application. HTTPRuntime is a class which calls the ProcessRequest method to start Processing.

w3wp.exe is a process associated with the application pool in IIS. If you have more than one application pool, you will have more than one instance of w3wp.exe running. This process usually allocates large amounts of resources. It is important for the stable and secure running of your computer and should not be terminated.