使用任务管理线程异常

Question

我正在主线程中创建一个任务，以管理我的线程。我的目的是从AggregateException中受益，所以我希望任务在任务中启动的线程中出现异常时返回该异常，如下面的代码栏所示。

public void ReportGeneratorFiveThreadTest()
{
    var logger = new Log4NetLogger(typeof(ReportGeneratorThreadTest));
    var tasks = new List<Task>();

    for (var i = 0; i < 1; i++)
    {
        var estimatedReportSize = EstimatedReportSize.Normal;
        var thread = new ReportGeneratorThread(logger, new ReportGenerator(20), estimatedReportSize);
        var task = Task.Factory.StartNew(
        () =>
        {
            thread.Start();                    
        });
        tasks.Add(task);
    }

    try
    {
       Task.WaitAll(tasks.ToArray());
       Debug.WriteLine("Tasks are completed");
    }
    catch (AggregateException e)
    {
        foreach (var v in e.InnerExceptions)
        {
            Debug.WriteLine(e.Message + " " + v.Message);
        }
    }
} 

GenerateReport()方法由已启动的线程调用，并引发该方法中定义的异常。

public void GenerateReport()
{
    var didwork = false;
    try
    {
        didwork = this.reportGenerator.GenerateReport(this.estimatedReportSize);
    }
    catch (Exception e)
    {
        this.log.LogError(ReportGenerator.CorrelationIdForPickingReport, string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Error during report generation."), 0, e);
    }
    finally
    {
        if (!didwork)
        {
            Thread.Sleep(Settings.Default.ReportGenerationInterval);
        }
    }
}

问题是在任务an中没有出现异常，因此，聚合异常在这种情况下不会发生。是否可以呈现此内部异常，该异常发生在任务中的线程中，从而触发聚合异常？

UPDATE----------------------

我修改了我的代码如下：

 public void Start()
 {
        this.running = true;
        this.t = Task.Run(
        () =>
        {
            this.GenerateReport();
        });
        try
        {
            Task.WaitAny(this.t);
        }
        catch (AggregateException e)
        {
            foreach (var v in e.InnerExceptions)
            {
                Debug.WriteLine(e.Message + " " + v.Message);
            }
        }
 }

并附有：

  public void GenerateReport()
    {
        var didwork = false;            
        try
        {
            didwork = this.reportGenerator.GenerateReport(this.estimatedReportSize);                
        }
        catch (Exception e)
        {
            this.log.LogError(ReportGenerator.CorrelationIdForPickingReport, string.Format(CultureInfo.InvariantCulture, "System"), string.Format(CultureInfo.InvariantCulture, "Error during report generation."), 0, e);
            throw new InvalidOperationException("Failed");
        }
        finally
        {
            if (!didwork)
            {
                Thread.Sleep(Settings.Default.ReportGenerationInterval);
                throw new InvalidOperationException("Failed");
            }
        }
    }

即使在AggregateException ()方法中抛出InvalidOperationException，它仍然没有捕获该GenerateReport。

Answer 1

首先，必须在catch方法的GenerateReport块中重新抛出异常

public void GenerateReport()
{
    var didwork = false;
    try
    {
        ...
    }
    catch (Exception e)
    {
        this.log.LogError(...);
        throw; // Important!
    }
    finally
    {
        if (!didwork)
        {
            ...
        }
    }
}

其次，您不应该使用线程内部的任务。只使用任务

public void ReportGeneratorFiveThreadTest()
{
    var tasks = new List<Task>();

    for (var i = 0; i < 1; i++)
    {
        var task = Task.Factory.StartNew(() =>
        {
            // No need thread here
            GenerateReport();
        });
        tasks.Add(task);
    }

    try
    {
        ...
    }
    catch (AggregateException e)
    {
        ...
    }
}