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PeterMilovcik
PeterMilovcik

Posted on

 

One Good Reason Why You Should Not Use Async Void

Let's take a look at this little example.

class Program
{
    static void Main(string[] args)
    {
        try
        {
            AsyncVoidMethod();
            Console.WriteLine("No exception is thrown!");
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }
    }

    private static async void AsyncVoidMethod()
    {
        throw new Exception("BOOM!");
    }
}
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What we have here is a method AsyncVoidMethod, which throws an exception and returns async void instead of async Task.

Since it's void, we cannot await it. What it also means that exception from an async call could not be saved anywhere because there is no Task object which could save it.

Output

No exception is thrown!

It's a dangerous problem: an exception is not handled!

Solution

I wouldn't like to describe a solution here, because John Thiriet already did a great job doing so, and you know, that duplication is evil, right?

Check this fantastic article for solution:
https://johnthiriet.com/removing-async-void/

Latest comments (1)

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roubachof profile image
Jean-Marie Alfonsi

Hey man! Great subject!
I also created my own component to handle async void and process global error handler, statistic, ...

github.com/roubachof/Sharpnado.Tas...

Here is a post you might want to check out:

Regex for lazy developers

regex for lazy devs

Sorry for the callout 😆