IIS app pool recycle + quartz scheduling

Question

I'm running a web app on IIS 7.5 and it needs to recycle occasionally (otherwise memory usage gets out of handing, something i'm looking into!).

When it recycles, it is effectively not running until another request comes in, which quartz is not going to run.

Is there any way to have IIS automatically bring up 1 work process immediately after recycling the app pool to ensure quartz is always online?

Answer 1

Yes!

http://weblogs.asp.net/scottgu/archive/2009/09/15/auto-start-asp-net-applications-vs-2010-and-net-4-0-series.aspx details it quite nicely, basically you need to:

1. Edit C:\Windows\System32\inetsrv\config\applicationHost.config to include:

   <applicationPools> 
       <add name="MyAppWorkerProcess" managedRuntimeVersion="v4.0" startMode="AlwaysRunning" /> 
   </applicationPools>
   

2. Declare what should be run as the "warm-up" for your site

   <sites> 
       <site name="MySite" id="1"> 
           <application path="/" serviceAutoStartEnabled="true" serviceAutoStartProvider="PreWarmMyCache" />
       </site> 
   </sites>
   <serviceAutoStartProviders> 
       <add name="PreWarmMyCache" type="PreWarmCache, MyAssembly" /> 
   </serviceAutoStartProviders> 
   

3. Configure your application with whatever "warm-up" logic you would like:

   public class PreWarmCache : System.Web.Hosting.IProcessHostPreloadClient {
       public void Preload(string[] parameters) { 
           // Perform initialization and cache loading logic here... 
       } 
   } 
   

Note: If all you need is for the w3wp.exe process to be present I believe only step 1 is necessary. If you also need other items (like certain things to be loaded into memory) then step 2 and 3 would also be used.

Answer 2

Starting with IIS 8.0, there is an option to simulate a request to the root page, thus a full application initialization: Application Pool advanced settings -> Preload enabled = true.

Of course, startMode should be AlwaysRunning.

More details about how to enable this feature can be found here.