c# - 如何确保在 Windows 服务停止或关闭时完成一个小的 UnitOfWork 作业

Question

我有一个工作，每 X 秒运行一次，执行时间不应该太长(少于 5 秒)，它在 Windows 服务中运行。我的目标是确保如果 Windows 服务在执行过程中停止，当前正在运行的作业将完成它的执行。

这个线程看起来很有趣，但目前还行不通: Task Handling on Application Shutdown

我们将不胜感激。

WindowsService 实现:

public partial class WindowsService : ServiceBase
{
    private readonly ILogger logger;
    private readonly IStartJob startJob;
    private readonly CancellationTokenSource cancellationTokenSource;
    private Task task;

    public WindowsService(IStartJob startJob, ILogger logger)
    {
        // Dependancy injection of logger and JobStarter
        this.startJob = startJob;
        this.logger = logger;
        InitializeComponent();
        cancellationTokenSource = new CancellationTokenSource();
    }

    protected override void OnStart(string[] args)
    {
        task = new Task(() => startJob.Start(cancellationTokenSource.Token), 
            cancellationTokenSource.Token, TaskCreationOptions.LongRunning);
        task.Start();
        logger.Info("Service started");
    }

    protected override void OnStop()
    {
        RequestAdditionalTime(TimeSpan.FromSeconds(30).Milliseconds);
        cancellationTokenSource.Cancel();
        try { task.Wait(); }
        catch (Exception ex) { logger.Error("Error while stopping the Service", ex); }
        logger.Info("Service stopped");
    }
}

StartJob 实现:

public class StartJob : IStartJob
{
    private readonly ILogger logger;
    private readonly IExecuteJob executeJob;
    private DateTime lastExecution = DateTime.UtcNow.AddDays(-1);

    public StartJob(ILogger logger, IExecuteJob executeJob)
    {
        this.logger = logger;
        this.executeJob = executeJob;
    }

    public async void Start(CancellationToken token)
    {
        while (!token.IsCancellationRequested)
        {
            var nextExecution = lastExecution.AddSeconds(5);
            if (nextExecution < DateTime.UtcNow)
            {
                try
                {
                    logger.Info("Start Job Execution");
// To similate long process not ended, break point here
// and stop the service before continuing the execution.
                    Thread.Sleep(5000);
                    executeJob.Execute();   
                    logger.Info("Job completed");
                    AdjustLastExecution(nextExecution);
                }
                catch (Exception ex)
                {
                    logger.Error("Unexpected exception while executing job", ex);
                }
            }
// Would expect the cancelToken to activate here or in the while condition
            await Task.Delay(TimeSpan.FromSeconds(1), token);
        }
    }

    private void AdjustLastExecution(DateTime nextExecution)
    {
        // To ensure we have an heartbeat close to 5 seconds
        lastExecution = nextExecution.AddSeconds(5) > DateTime.UtcNow  ?
            nextExecution : DateTime.UtcNow.AddSeconds(-5);
    }
}

我在入口任务、任务等待和等待毫秒超时中尝试了 cancelToken 的一系列变体，但到目前为止没有任何效果。

我将我的解决方案附加到正在执行的 WindowsService 并确保正在执行的作业将在其中间断点和 Thread.Sleep。但是 Job completed log 没有被写入，附加的 processed 被丢弃在它之前。

Answer 1

我很快看了你的代码，我唯一想尝试的是

替换:

async void

与

async Task

我不保证它适用于您的情况，但我记得读过这篇建议避免async void的文章。

In C#, async void methods are a scourge upon your code..

Haacked.com | Avoid async void methods

编辑:

task = new Task(() => startJob.Start(cancellationTokenSource.Token), 
        cancellationTokenSource.Token, TaskCreationOptions.LongRunning);

与

task = startJob.Start(cancellationTokenSource.Token);