How Should I Correctly Call Async Methods from the Main Method in C#?

Calling Async Methods Directly from Main: A Comprehensive Guide

One of the significant enhancements introduced in C# is the async/await pattern, which simplifies the development of asynchronous operations. However, calling async methods directly from Main() can be a bit tricky.

To understand the issue, consider the following code sample:

public class test
{
    public async Task Go()
    {
        await PrintAnswerToLife();
        Console.WriteLine("done");
    }

    public async Task PrintAnswerToLife()
    {
        int answer = await GetAnswerToLife();
        Console.WriteLine(answer);
    }

    public async Task<int> GetAnswerToLife()
    {
        await Task.Delay(5000);
        int answer = 21 * 2;
        return answer;
    }
}

If you attempt to call the Go method from Main() like this:

class Program
{
    static void Main(string[] args)
    {
        test t = new test();
        t.Go().GetAwaiter().OnCompleted(() =>
        {
            Console.WriteLine("finished");
        });
        Console.ReadKey();
    }
}

You might encounter a deadlock situation, preventing any output from appearing on the screen.

The resolution lies in modifying Main() to become an async method itself. For versions of C# from 7.1 onwards:

static async Task Main(string[] args)
{
    test t = new test();
    await t.Go();
    Console.WriteLine("finished");
    Console.ReadKey();
}

This approach allows the asynchronous operations to run seamlessly without any blocking of the main thread.

In case you are using an earlier version of C#, you can use the following code:

static void Main(string[] args)
{
    test t = new test();
    t.Go().Wait();
    Console.WriteLine("finished");
    Console.ReadKey();
}

Here, the Wait() method explicitly blocks the main thread until the Go method completes.

Remember that by embracing the async/await pattern, you can avoid the complexities of callbacks, resulting in cleaner and more maintainable code for asynchronous operations.

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