Making IIS Web Sites More Responsive Using Warm-up

Posted by Abel Avram on Oct 16, 2009

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IIS Application Warm-up for IIS 7.5 improves the responsiveness of a web site by loading all related web applications and their dependencies before the first request is made.

IIS Application Warm-up improves the web site responsiveness even if it uses a custom request pipeline or if the Application Pool is recycled by “proactively loading and initializing all the dependencies such as database connections, compilation of ASP.NET code, and loading of modules.”

The pre-loading process, which can be executed synchronously or asynchronously, is initiated by configuring specific web pages and user IDs to be loaded and used.

Application Warm-up is integrated with IIS Manager and has the following main features:

• Configuration settings are stored in the shared configuration file
• Web application pre-loading settings can be configured on a per Web application basis, allowing IT professionals to identify or create individual initialization pages according to their needs.
• Use the default or custom identities to pre-load the application.

This IIS module is currently in beta and has an x86 version for Windows 7 and an x64 one for Windows 7 or Windows Server 2008 R2.

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   Cool, but...

   by Nicholas Piasecki

   This is certainly a nifty feature, and I'll be excited to finally use it in 2012. Our applications use NHibernate so that first hit can be kind of expensive.
   
   I can cobble together a solution now on IIS 6, but just pinging the Web page every so often in a scheduled task, but that won't guarantee me that every worker process gets warmed up, only the one which happened to serve my request.
   
   This highlights another reason for me as to why I find it irritating that IIS versions are inextricably tied to the OS versions. First, it makes things hard to test on a developer machine when the developer's machine is an OS version generation behind the production server. And if the production server is running W2K3 and has a three-year warranty on it, well, you can bet that we're not moving to IIS 7.x anytime soon.
   
   This is in the context of a small business whose primary focus isn't software development, so it's not like we have an MSDN license or even software assurance to play with here. I imagine there a lot of other small businesses in this boat.
   
   I've always wondered why it is this way: if there really is a technical reason in that IIS is dependent on core stuff in the OS or if it's a marketing/segmentation decision.
   
   If a marketing decision, I would even settle for an "IIS Lite" that allowed the latest version of IIS to be deployed on a developer machine with some limitations, kind of like spinning up Apache in a console window. No sane person would use it for production use, but at least you could build your app against the new web.config format and play with these features.

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   Re: Cool, but...

   by Abel Avram

   Personally, I believe MS is trying to attract people to the latest version of their software. While developing and testing for several versions is developer and time consuming, some features, like Warm-up, can easily be made available on multiple versions. I don't think Warm-up needs something special that exists only in IIS 7.5. But marketing has an important role in all this.

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   Re: Cool, but...

   by peter weissbrod

   We found a simple way to do this by hooking up a powershell script to a scheduled task.
   [System.Net.WebRequest]::Create("http://yourURL").GetResponse()
   
   Your mileage may vary, but thats a basic warmup.

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   Re: Cool, but...

   by Nicholas Piasecki

   Yeah, the issue is that it doesn't work (well) in a Web garden scenario -- you only warm up the WP that happened to answer that request.

   Reply