Threading Task not executing in IIS

问题

I have a .Net application that uses Forms Authentication mode and has a function that calls an asynchronous task. Below is the snippet of the task:

Task.Factory.StartNew(() => { UploadFunction(); }, tokenSource.Token, TaskCreationOptions.LongRunning,TaskScheduler.Default);

The thread is working fine when I test in on the Visual Studio IDE. The issue is when I deploy it, the threading task seems to be skipped or not executed by the system.

I've read an article that this can be caused by permissions in IIS:

http://codemine.net/post/Thread-Not-working-in-Aspnet-When-deployed-to-IIS

Tweaking the solution on above article to be implemented in Forms authentication, below is the code for that:

[System.Runtime.InteropServices.DllImport("advapi32.dll", EntryPoint = "LogonUser")]
private static extern bool LogonUser(
         string lpszUsername,
         string lpszDomain,
         string lpszPassword,
         int dwLogonType,
         int dwLogonProvider,
         ref IntPtr phToken);

    public JsonResult uploadimages(){

         try{

            IntPtr token = new IntPtr(0);
                        token = IntPtr.Zero;

                        bool returnValue = LogonUser("Administrator", "WIN-82CH4949B3Q", "Neuron14",
                                         3,
                                         0,
                                         ref token);

            WindowsIdentity newId = new WindowsIdentity(token);
            WindowsImpersonationContext impersonatedUser = newId.Impersonate();

            var task2 =     Task.Factory.StartNew(() => { UploadFunction(); }, tokenSource.Token, TaskCreationOptions.LongRunning,TaskScheduler.Default);

            impersonatedUser.Undo();

            return Json(new { message = "Success" }, "text/plain; charset=utf-8");

         }

         catch (ex Exception)
         {
            return Json(new { error= ex.Message }, "text/plain; charset=utf-8");
         }
    }

Implementing the above code to the system still does not execute the thread once deployed in IIS. I'm really having a hard time fixing this since I do not really know why the thread is not executing when deployed.

回答1:

There is a problem when you attempt to impersonate a windows identity:

WindowsIdentity newId = new WindowsIdentity(token);
WindowsImpersonationContext impersonatedUser = newId.Impersonate();

var task2 =     Task.Factory.StartNew(() => { UploadFunction(); }, tokenSource.Token, TaskCreationOptions.LongRunning,TaskScheduler.Default);

impersonatedUser.Undo();

The problem is that the Impersonate function only applies for that thread, and your UploadFunction is running on a different thread.

Here's a modification to your code which has the Impersonate method called on the background task's thread:

WindowsIdentity newId = new WindowsIdentity(token);
var task2 = Task.Factory.StartNew(() => 
                                 {
                                     using(WindowsImpersonationContext wi = newId.Impersonate())
                                     {
                                          UploadFunction();
                                     }
                                 },
                                 tokenSource.Token,
                                 TaskCreationOptions.LongRunning,
                                 TaskScheduler.Default
                               );

My guess is that it worked on your local machine because you were uploading to a folder which allowed anonymous access. The permissions on your production server would be much tighter.

来源：https://stackoverflow.com/questions/25989420/threading-task-not-executing-in-iis