Why this call is not awaited

Question

I don't really know why my code is breaking up at line 24, when it's trying to execute the first await method. I mean, it doesn't show me nor a compilation nor execution error. I already installed all 5 Jsonize packages the guide says. I think the problem could be because the call is not awaited, but I don't really know what might be happening.

I'm trying to follow step by step this guide about what I want to achieve. This is my goal: https://github.com/JackWFinlay/jsonize

Here is my entire code:

using Jsonize;
using Jsonize.Parser;
using Jsonize.Serializer;
using System;
using System.Net.Http;
using System.Threading.Tasks;

namespace JsonizeExample
{
    class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            Testy();
        }

        public static async void Testy()
        {
            using (var client = new HttpClient())
            {
                string url = @"https://jackfinlay.com";

                HttpResponseMessage response = await client.GetAsync(url);

                string html = await response.Content.ReadAsStringAsync();

                // The use of the parameterless constructors will use default settings.
                JsonizeParser parser = new JsonizeParser();
                JsonizeSerializer serializer = new JsonizeSerializer();
                Jsonizer jsonizer = new Jsonizer(parser, serializer);
            }
        }

    }
}

I'm working on Visual Studio 2019, .NET Core 3.1, C#.

What am I doing wrong?

The title already explains the problem. `Testy` is not awaited, so the program will exit before that method even has a chance to execute. Change the signature to `async Task` and await it. Change `Main` to `async Task` as well. `async void` is *only* meant for asynchronous event handlers, nothing else. An async method that doesn't return anything should be `async Task` — Panagiotis Kanavos, Aug 25 '22 at 08:16
Does this answer your question? [async/await - when to return a Task vs void?](https://stackoverflow.com/questions/12144077/async-await-when-to-return-a-task-vs-void) — Panagiotis Kanavos, Aug 25 '22 at 08:22
The sample in the code you linked to is `async Task Testy`. Not `async void` — Panagiotis Kanavos, Aug 25 '22 at 08:24
Thanks a lot dude. I did as you said and it actually flows correctly. — Mauricio Hernández Cabrera, Aug 25 '22 at 17:56

Fawad Ali Siddiqi · Answer 1 · 2022-08-25T09:06:46.860

1

Try returning Task or Task instead of void. or await Testy();

edited Aug 25 '22 at 09:06

answered Aug 25 '22 at 08:30

Fawad Ali Siddiqi

421
5
16

3

This should be a comment. Without `await` the method won't be awaited by itself. – Panagiotis Kanavos Aug 25 '22 at 08:31

score 1 · Accepted Answer · answered Aug 25 '22 at 13:34

When you compiling your code you get the following warning pointing to Testy();:

warning CS4014: Because this call is not awaited, execution of the current method continues before the call is completed.

Without applying await to the Testy(); your program will not await this method to be finishing execution and the program will terminating, when more likely the Testy() method is performing the await response.Content.ReadAsStringAsync(); call.

Applying await to the Testy(); call will lead you to change the public static void Main(string[] args) signature to static public async Task Main(string[] args).

See the following note from the documentation Don't block, await instead post:

NOTE: The Main method returns Task, despite not having a return expression—this is by design. For more information, see Evaluation of a void-returning async function.

Therefore change you application accordingly:

static async Task Main(string[] args)
{
    Console.WriteLine("Hello World!");
    await Testy();
}

public static async Task Testy()
{
    using (var client = new HttpClient())
    {
        ... your code           
    }
}

Why this call is not awaited

2 Answers2