Csharp 我可以在单线程 C# 控制台应用程序中安全地使用 async void 异步处理队列中的多个项目吗

对于最新的网络，我们默认有async Main个方法.

此外，如果您没有该功能，您可以将Main标记为异步.

这里的主要风险是您可能会错过异常，并且必须非常小心地处理创建的任务.如果您要在while (true)循环中创建任务，很可能会在某个时刻(当有人错误地使用某个阻塞调用时)导致线程池匮乏.

下面的示例代码显示了应该考虑的内容，但我最确定的是，还会有更复杂的内容:

using System.Collections.Concurrent;
using System.Security.Cryptography.X509Certificates;

namespace ConsoleApp2;

public static class Program
{
    /// <summary>
    /// Property to track all running tasks, should be dealt with carefully.
    /// </summary>
    private static ConcurrentBag<Task> _runningTasks = new();

    static Program()
    {
        // Subscribe to an event.
        TaskScheduler.UnobservedTaskException += TaskScheduler_UnobservedTaskException;
    }

    static async Task Main(string[] args)
    {
        var messageNo = 1;

        while (true)
        {
            // Just schedule the work
            // Here you should most probably limit number of
            // tasks created.
            var task = ReceiveMessage(messageNo)
                .ContinueWith(t => TopLevelHandler(t.Result));

            _runningTasks.Add(task);
            messageNo++;
        }
    }

    static async Task TopLevelHandler(object message)
    {
        await DoAsyncWork(message);
    }

    static async Task<object> ReceiveMessage(int messageNumber)
    {
        //fetch message from queue
        await Task.Delay(5000);
        return await Task.FromResult(messageNumber);
    }

    static async Task DoAsyncWork(object message)
    {
        //processing here
        Console.WriteLine($"start processing message {message}");
        await Task.Delay(5000);
        
        // Only when you want to test catching exception
        // throw new Exception("some malicious code");

        Console.WriteLine($"end processing message {message}");
    }

    /// <summary>
    /// Here you handle any unosberved exception thrown in a task.
    /// Preferably you should handle somehow all running work in other tasks.
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    static async void TaskScheduler_UnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs e)
    {
        // Potentially this method could be enter by multiple tasks having exception.
        Console.WriteLine($"Exception caught: {e.Exception.InnerException.Message}");
        await Task.WhenAll(_runningTasks.Where(x => !x.IsCompleted));
    }
}