[Supported in the .NET Framework 4.5.1 and later versions]
Called when ASP.NET notifies an application that a process is being suspended.
Assembly: System.Web (in System.Web.dll)
The method must not throw exceptions, otherwise the behavior is undefined and the process will likely be terminated. The method should not block execution, because after five seconds ASP.NET will allow the process to be suspended, even if not all methods have completed.
If a callback returns, it will be invoked when the process resumes from suspension. The method may return null if it does not have to be notified when the process resumes.
The method is supported only when running in IIS integrated mode. The ASP.NET runtime does not guarantee that the method will ever fire.