How do I programmatically find why Application_End() is invoked?

Question

Application_End() is invoked when my application pool is stopped which can happen for a number of reasons, including automatic pool recycle or changes in the folder from which the application is served.

The call stack will typically looks like this:

my Application_End(Object sender, EventArgs e)
at System.RuntimeMethodHandle._InvokeMethodFast(IRuntimeMethodInfo method, Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeType typeOwner)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
at System.Web.HttpApplication.InvokeMethodWithAssert(MethodInfo method, Int32 paramCount, Object eventSource, EventArgs eventArgs)
at System.Web.HttpApplication.ProcessSpecialRequest(HttpContext context, MethodInfo method, Int32 paramCount, Object eventSource, EventArgs eventArgs, HttpSessionState session)
at System.Web.HttpApplicationFactory.Dispose()
at System.Web.HttpRuntime.Dispose()
at System.Web.HttpRuntime.ReleaseResourcesAndUnloadAppDomain(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

which is completely useless.

How do I programatically find why it was called?

Answer 1

There's System.Web.Hosting.HostingEnvironment.ShutdownReason property that indicates why the application is being terminated. Its value can be retrieved from inside Application_End().