Gracefully stopping ASP.NET Core Web App (from within Visual Studio debugger), an IHostedService-related question

Question

I am totally new to ASP.NET Core so I am probably missing something by 50 miles because I've spent 3 hours on this to no avail.

I've made a Web App from within VS 2017, hosted by Kestrel which runs under IIS Express (which is all default when you make a new web app). When I press F5 the app fires up, my Chrome browser opens up and I see the 'hello world'-esque output. When I close this browser window the app terminates.

Now, I need some tasks going on in the background and I need these tasks to have cleanup logic - I found that IHostedService allows me to do this.

The documentation states:

When you register an IHostedService, .NET Core will call the StartAsync() and StopAsync() methods of your IHostedService type during application start and stop respectively.

I have done:

public void ConfigureServices(IServiceCollection services)
{
    services.AddHostedService<MyBackgroundService>();
}

And the service starts as expected, everything is fine. Extremely simple stuff. But it never stops, not gracefully at least.

When I close that auto-started browser window, my app closes along with it but this method in my IHostedService service:

public Task StopAsync(CancellationToken cancellationToken)
{
    ...
}

Is never called.

I have tried the example provided in documentation and it exhibits the same issue - the cleanup is never done when I try it in VS.

I have noticed a peculiar information from an output channel called "ASP.NET Core Web Server":

BackgroundTasksSample> Application started. Press Ctrl+C to shut down.

It's obviously some redirection from the console as this app appears to be a console app in the first place. So I wonder if VS is, by seemingly hiding the console from me, preventing me from performing the graceful shut down of my app?

I also noticed a little IIS Express tray icon which lists any apps I've ran and it has a Stop button which doesn't seem to do anything. I assume IIS Express is here simply acting as some kind of a proxy.

I am dumbfounded, especially since I seem to be the only one having this problem.

How do I properly terminate my Web App?

Grindery

Docs say "If the app shuts down unexpectedly, StopAsync might not be called. Therefore, any methods called or operations conducted in StopAsync might not occur." - I'm guessing that closing the browser window counts as an 'unexpected' shutdown? – Elsie

@Elsie you guessed correctly, that is indeed the case. – Grindery

Answer 1

I have found the solution. First, I shall quote myself:

I also noticed a little IIS Express tray icon which lists any apps I've ran and it has a Stop button which doesn't seem to do anything. I assume IIS Express is here simply acting as some kind of a proxy.

Actually that right there is the way to gracefully stop your Kestrel app which is hosted under IIS Express (which is a default option in VS).

Apparently, my IIS Express had a... "hickup", and the Stop command didn't work - there was no error message, simply nothing happened. After closing all the VS instances and killing dotnet.exe process in Task Manager I opened up the solution again and was finally able to stop the app.

Grindery

I am not so sure why this was such a challenge for me to figure out (i.e. how to stop site running in Visual Studio 2019), but until I came across this answer I did not have it figured out. – Hegumen

Answer 2

I am adding an "answer" to supplement the answer given by @bokibeg. To stop a project running in iis in Visual Studio 2019 go to your system tray and right click on the iis express icon. Then select the project that is running. A menu will pop up with a button to stop site.

Hegumen

Interestingly, I just noticed after stopping the site using this method (I am using Visual Studio 2019 working on am ASP.NET Core 3.1 project) the stop button now appears (which is what I have become accustomed to in older versions of Visual Studio). – Hegumen