How to run a task when a windows service starts?

Question

I have a windows service and I've written the code to run the task within the OnStart() event:

 protected override void OnStart(string[] args)
        {
            this.DoTask();
        }

private void DoTask()
        {
            Task task1 = Task.Factory.StartNew(() => this.OriginalFileProcessor.StartPolling());

            try
            {
                Task.Wait(task1);
            }
            catch (Exception ex)
            {
                this.Log.Error("Failed running the task", ex);
            }           
        }

The DoTask is a never-ending loop. It will stop only when the service is stopped.

But when I try to start the service, it waits a long time then gives me the below error:

Windows could not start the ... service on Local Computer.
Error 1053: The service did not respond to the start or control request in a timely fashion.

How to resolve it?

Answer 1

Why are you waiting your task to finish?

I think Task.Wait is blocking your current thread, then you're getting timeout while starting your service.

EDIT: You need to remove this block:

try
{
    Task.Wait(task1);
}
catch (Exception ex)
{
    this.Log.Error("Failed running the task", ex);
}  

Task.Wait is indeed blocking your current thread. According to MSDN:

Task.Wait Method

Waits for the Task to complete execution.

EDIT 2 Do this instead

Task task1 = Task.Factory.StartNew(() => this.OriginalFileProcessor.StartPolling()).ContinueWith( t =>
{
     var aggException = t.Exception.Flatten();
     foreach(var ex in aggException.InnerExceptions)
         this.Log.Error("Failed running the task", ex);
}, 
TaskContinuationOptions.OnlyOnFaulted);

Answer 2

I guess this is, because you are waiting for the OriginalFileProcessor.StartPolling() to end, but this never happens. You should move your task instance into an seperate member and not wait for it to finish:

private Task m_task = null;

private void DoTask()
{
    try
    {
        m_task = Task.Factory.StartNew(() => this.StartPolling());
    }
    catch
    {
        this.Log.Error("Unable to start task", ex);
        throw;  // Rethrow, so that the OS knows, there was something wrong.
    }           
}

private void StartPolling()
{
    try
    {
        this.OriginalFileProcessor.StartPolling();
    }
    catch (Exception ex)
    {
        this.Log.Error("Failed running the task", ex);
    }
}

Answer 3

In the loop you need to check if the service status is "stopping" and exit the loop. You have 5 seconds to do that before the OS decides to kill you.