Question

我在主线程中创建一个任务来管理我的线程。我的目的是从AggregateException中受益，所以我希望我的任务在任务中启动的线程中发生异常时返回该异常，如下面的代码块所示。

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（）方法由启动的线程调用，并抛出此方法中定义的异常。

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);
        }
    }
}

问题是异常没有出现在任务中，因此在这种情况下不会发生聚合异常。是否有可能在任务的线程中出现这种不确定性，因此会触发aggregateexception？

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

我修改了我的代码：

 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);
            }
        }
 }

和：

  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");
            }
        }
    }

并且即使在GenerateReport（）方法中抛出InvalidOperationException，它仍然不会捕获AggregateException。

Answer 1

首先，您必须在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，你不应该在任务中使用Thread。仅使用任务

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)
    {
        ...
    }
}

使用Task管理线程异常

1 个答案: