.NET Core 3.1在X秒后关闭IHost。

Question

我想知道如何才能关闭 IHost的执行，例如30秒后。

IHost host = new HostBuilder()
                .UseConsoleLifetime()
                .Build();

using (host)
{
   await host.RunAsync();
}

我试图用

services.AddOptions<HostOptions>().Configure(
        opts => opts.ShutdownTimeout = TimeSpan.FromSeconds(10));

徒劳无功

Answer 1

请看一下我的.NET Core 3.1控制台应用程序的代码和附带的控制台输出的截图。这个应用程序演示了所要求的功能。当主机启动时，托管服务会向控制台打印数字，每2秒一个数字。一旦主机收到关闭命令，"应用程序正在关闭...... "的消息将被写入控制台，而托管服务将继续其工作。当指定的超时时间过后，应用程序就会关闭。如果你想在托管服务中允许处理取消已执行的任务，我在方法ExecuteAsync中的注释代码演示了这一点，那么主机在取消已执行的任务后就完成了它的工作，而无需等待指定的超时。

        using System;
        using System.Threading;
        using System.Threading.Tasks;
        using Microsoft.Extensions.Hosting;
        using Microsoft.Extensions.DependencyInjection;

        namespace ConsoleApp38
        {
            public class Program
            {
                public static async Task Main(string[] args)
                {
                    try
                    {
                        using (var host = new MyHost())
                        {
                            await host.StartAsync();
                            Console.WriteLine(@"Host has started. Please Press Enter or ""Ctrl + C"" to stop the host");
                            Console.ReadLine();
                            await host.StopAsync();
                            Console.ReadLine();
                        }
                    }
                    catch (Exception e)
                    {
                        //log any exceptions here;
                    }
                }
            }

            public class MyHost : IHost
            {
                private static IHost _host;
                public MyHost()
                {
                    IHostBuilder builder = Host.CreateDefaultBuilder()
                        .ConfigureServices((hostContext, services) =>
                        {
                            services.Configure<HostOptions>(option =>
                            {
                                option.ShutdownTimeout = System.TimeSpan.FromSeconds(30);
                            });
                            services.AddHostedService<MyHostedService>();
                        });
                    _host = builder.Build();
                }

                public IServiceProvider Services
                {
                    get { return _host.Services; }
                }

                public void Dispose()
                {
                    _host.Dispose();
                }

                public async Task StartAsync(CancellationToken cancellationToken = default(CancellationToken))
                {
                    await _host.StartAsync(cancellationToken);
                }

                public async Task StopAsync(CancellationToken cancellationToken = default(CancellationToken))
                {
                    await _host.StopAsync(cancellationToken);
                }
            }

            public class MyHostedService : BackgroundService
            {
                public async Task StartAsync(CancellationToken cancellationToken)
                {

                }

                public async Task StopAsync(CancellationToken cancellationToken)
                {

                }

                protected override async Task ExecuteAsync(CancellationToken stoppingToken)
                {
                    for (int i = 0; i <= 100; i++)
                    {
                        //if you allow canceling this task here then the host will be shut down
                        //right after completion of this method without the specified timeout

                        //if (stoppingToken.IsCancellationRequested) break;
                        await Task.Delay(2000);
                        Console.WriteLine(i);
                    }
                }
            }
        }

的输出。

更新：虽然程序在Windows 7 64位上超时关闭，但在Ubuntu 18.04 64位上却没有超时关闭。我没有在其他操作系统上尝试这段代码。