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我有一个每 4 分钟打勾的 Windows 服务。如果运行 DataImporter，则当计时器计时，DataImporter 有许多“作业”，它可以在每个计时运行，例如，有一个 ProcessData 作业和一个 RetreiveData 作业：

  • RetreiveData 作业将联系第 3 方 API 并将数据存储在数据库中以进行处理。
  • ProcessData 作业将从数据库中获取数据并将其处理到我们可用的数据库等中。

一旦 DataImporter 运行，它就会检查一个名为 ScheduledJob 的数据库表——它具有许多调度功能，例如 FrequencyInterval、ActiveStart/Stop 时间、StartedLastRun 时间。ScheduledJob 表有一个名为“InProgress”的标志，这个标志将停止 DataImport 在它已经运行时拾取该作业。

存在一个连续的问题，即一个作业被拾取两次，彼此相隔几秒钟，然后两者同时运行，这在尝试插入相同的记录时会导致许多数据库约束。我不太确定它如何同时选择两个工作，滴答声相隔 4 分钟，所以理论上它甚至不能查看潜在的工作，它怎么能同时运行它们相隔几秒？

RetrieveData 和 ProcessData 作业都需要能够并行运行，因此我无法在执行作业时暂停 Timer。

服务：

public partial class DataImport : ServiceBase
{
    private int _eventId = 0;
    readonly Timer _serviceTimer = new Timer(240000);

    public DataImport()
    {
        InitializeComponent();
        ImportServiceEventLog.Source = ServiceSource.DATA_IMPORT_SERVICE.ToString() + Global.ReleaseModeSource(); ;
    }

    protected override void OnStart(string[] args)
    {
        ImportServiceEventLog.WriteEntry(ServiceSource.DATA_IMPORT_SERVICE.ToString() + Global.ReleaseModeSource() + " started", EventLogEntryType.Information, _eventId++);
        _serviceTimer.AutoReset = true;
        ImportServiceEventLog.WriteEntry(ServiceSource.DATA_IMPORT_SERVICE.ToString() + Global.ReleaseModeSource() + " timer interval = " + _serviceTimer.Interval / 1000 + " seconds", EventLogEntryType.Information, _eventId++);
        _serviceTimer.Elapsed += new ElapsedEventHandler(OnTimer);
        _serviceTimer.Start();
    }

    protected override void OnStop()
    {
        ImportServiceEventLog.WriteEntry(ServiceSource.DATA_IMPORT_SERVICE.ToString() + Global.ReleaseModeSource() + " stopped", EventLogEntryType.Information, _eventId++);
    }

    public void OnTimer(object sender, ElapsedEventArgs args)
    {
        try
        {
            Run();
        }
        catch (System.Exception ex)
        {
            ImportServiceEventLog.WriteEntry(ServiceSource.DATA_IMPORT_SERVICE.ToString() + Global.ReleaseModeSource() + " error: " + ex.ToString(), EventLogEntryType.Information, _eventId++);
        }
    }

    public void Run()
    {
        using (var dataImportController = new DataImportController())
        {
            dataImportController.Run();
        }                
    }
}

数据导入控制器：

public class DataImportController
{
    public void Run()
    {
        // Gets all the jobs from the ScheduledJob table in the DB
        var jobs = GetJobsToRun();

        //Get all Processes (from DB)
        foreach (var job in jobs)
        {
            //Check the time it was last run - do this for each process
            if (RunJob(job))
            {
                _messaging.EventMessage("Process " + job.Name + " finished : " + DateTime.Now, ServiceSource.DATA_IMPORT_SERVICE);
            }
        }
    }

    public bool RunJob(ScheduledJob job)
    {
        // Checks if the job is ready to run, i.e. is the InProgress flag set to false and the interval long enough since the StartedLastRun DateTime
        if (!job.IsReadyToRun())
        {
            return false;
        }

        // Set job to in progress
        job.InProgress = true;
        job.StartedLastRun = DateTime.Now;
        _scheduledJobRepository.Update(job);
        _scheduledJobRepository.SaveChanges();

        try
        {
            switch (job.Name.ToUpper())
            {
                case "RetreiveData":
                    // RUN JOB
                    break;
                case "ProcessData":
                    // RUN JOB
                    break;                    
            }

            job.InProgress = false;
            job.EndedLastRun = DateTime.Now;
            _scheduledJobRepository.Update(job);
            _scheduledJobRepository.SaveChanges();
        }
        catch (Exception exception)
        {
            _messaging.ReportError("Error occured whilst checking we are ready to run " + exception.Message, exception, null, 0, ServiceSource.DATA_IMPORT_SERVICE);
        }

        return true;
    }   
}

编辑：

包括 Program.cs

static void Main()
{
    if (!Environment.UserInteractive)
    {
        ServiceBase[] ServicesToRun;
        ServicesToRun = new ServiceBase[]
        {
        new DataImport()
        };
        ServiceBase.Run(ServicesToRun);
    }
}
4

3 回答 3

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尝试在 OnTimer 函数内停止计时器，然后在完成执行任务后重新启动计时器。

于 2019-10-18T08:36:26.543 回答
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You subsribe to timer event in OnStart, and didn't unsubscribe in OnStop.

Move _serviceTimer.Elapsed += new ElapsedEventHandler(OnTimer); and initialization of AutoReset to constructor. Stop timer in OnStop. That should fix your issue. I believe your service is started (restarted) more than once.

于 2019-10-18T09:22:26.633 回答
0

如果重叠是一个问题，放弃计时器并进行异步循环，利用Task.Delay：

async Task SomeFunc(CancellationToken token)
{
    while(!token.IsCancellationRequested)
    {
        DoWork();
        await Task.Delay(timeInterval, token);
    }
}
于 2019-10-18T08:43:30.880 回答