C# tasks are not executed in new thread

Question

I have an async function that doesn't throw anything:

public async Task SomeLongComputations()
{
    // do some stuff that takes a lot of time
}

that I just want it to run in the background, without intervening the main thread:

public void SomeFunctionInMainThread()
{
    _ = SomeLongComputations();
}

But when I debugged the code in Visual Studio and set a breakpoint inside SomeLongComputations, it still shows that it is ran on main thread (thread id == 1).

---

Some additional context, not sure if it is relevant:

• I am developing an extension for Visual Studio
• The threads are created inside an event handler for ITextBuffer.Changed and IWpfTextView.LayoutChanged
• In the debug window, I can still see other threads

Answer 1

Just adding async will not make the task run on another thread. You can use Task.Run and call the method to run it in background. See link here https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task.run?view=netcore-3.1

Answer 2

I just want it to run in the background, without intervening the main thread:

That'd look more like:

public async void SomeFunctionInMainThread()
{
    await SomeLongComputations();
}

public Task SomeLongComputations()
{
    return Task.Run(() =>
    {
        // do some stuff that takes a lot of time
    });
}