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Posted 10 Jul 2014


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IIS 8.0 warm up Auto Start & Application Initialization

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4.94/5 (9 votes)
10 Jul 2014CPOL3 min read
Steps to setup IIS Warmup module. Describe usage of Preload- System.Web.Hosting.IProcessHostPreloadClient
  1. Introduction
  2. Prerequisites
  3. Create Your Warmup Script Assembly
  4. Application Pool: Demo Website
  5. IIS Web Server: Configuration Editor
  6. system.applicationHost/applicationPools
  7. system.applicationHost/ServiceAutoStartProviders
  8. system.applicationHost/Sites
  9. Application Initialization
  10. Final Step: Now Run this animal
  11. Reference


I've been working on IIS warm up thing for quite sometime and I tried all possible ways to get my warm up script working but it failed to initialized and auto start. After spending some time understanding some of the flow and internal mechanism of request flow, we able to crack the solution. This article will somewhat help you find the resolution to most common problem that we may have to tackle when enabling warmp script in IIS. I started looking few articles around IIS7.5 and auto start app pool but hardly find the resource online to give me crisp and clear steps to enable this.The overall intent of this article is to provide the end to end steps and some known issues that one would run into.There is sample demo code one can download to setup warmup thing for your website. I haven't gone to extend to explain why we need IIS warmup however I covered the most likely configuration settings that would go into running the warm up script.


The Application Initialization feature requires IIS 8.0 to be installed. In addition, the Application Initialization feature within the IIS "Application Development" sub-feature needs to be installed. The following screen shot from the Windows Server 2012 Server Manager UI shows the Application Initialization feature. IIS 8.0 Application Initialization Setup Key Note: Restart server to effect above changes. This initialization plays important role when we have to execute any startup page automatically without users access any web pages. Sometimes warmp up fails to start because there is some setting that needs to be enabled under [code]<system.webserver> applicationInitialization[/code]



Create Your Warmup Script Assembly

Warmup Sln

This warmp script will be executed at the start up of IIS app pool recylce or at time of website initialization. There can be various scenario we can embed in this start up script.Like we can have warm up script for Caching web pages or getting ready canned reports or any heavy task which takes longer time to load.For demo purpose I kept the code setup simple, to just create folder + file. Remember never have such filesystem read write operation withing website virtual directory or website directory it results in application app pool recycle everytime the filewrite operation takes place.


Application Pool: Demo Website

Enable Start Mode="Always running" from OnDemand Mode


IIS Web Server: Configuration Editor

Go to Main Application IIS Root. select Configuration Editor. Changing applicationhost.config is much safer through configuration editor than doing it manually.



Click on collection to proceed. Ensure highlighted property are set as given below in the screenshot.


Check AutoStart mode=true


Check StartMode mode=AlwaysRunning

ApplicationPool AlwaysRunning


Click on collection to proceed. Ensure highlighted property are set as given below in the screenshot.

ApplicationHost ServiceAutoStart Providers

Add Assembly and class reference warmup script pacakage in ApplicationHost.config ServiceAutoStartProviders tag. We've indicated this provider with name say PreWarmUpMyCache- Mind it- MY. Next we need to provide this reference to site tag in configuration as next step. Remember type=Assembly Full Name.ClassName,Assembly Full Name

ApplicationHost ServiceAutoStart Providers


Click on collection to proceed. Ensure highlighted property are set as given below in the screenshot.

Set ServerAutoStart=true

ApplicationHost ServiceAutoStart Providers

Set preLoadEnabled=true

Set serviceAutoStartEnabled=true

Set serviceAutoStartProvider=PreWarmUpMyCache

ApplicationHost ServiceAutoStart Providers


Application Initialization

Troubleshooting 1:Ensure your assembly is compiled and exists in bin folder of website.

Troubleshooting 2:Worst case even if warmup script not called ,try including default web page access auto initialize.Refer screenshot.


Final Step: Now Run this animal

Sample Code is attached for demo purpose. Download it and apply above setting to test run the demo.


IIS Auto Start Warm up By Scott Guthrie

IIS Tech net


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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Comments and Discussions

SuggestionYou've messed up two different approaches Pin
odinserj9-Jun-16 0:29
odinserj9-Jun-16 0:29 
GeneralRe: You've messed up two different approaches Pin
Member 1020127513-Feb-17 2:31
professionalMember 1020127513-Feb-17 2:31 
QuestionWhere should I put the Demo.PreWarmUpMyCache.dll? Pin
ikcelam27-Oct-15 1:01
ikcelam27-Oct-15 1:01 
QuestionIs it possible to use configuration file Pin
Member 1188405112-Oct-15 22:49
Member 1188405112-Oct-15 22:49 
QuestionApplication Initialization Warmup period Pin
SethuramR7-Oct-14 23:46
SethuramR7-Oct-14 23:46 
GeneralMy vote of 5 Pin
Ashish Chavan10-Jul-14 2:49
Ashish Chavan10-Jul-14 2:49 

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