c# - 使用 BackgroundWorker 时出现异常

Question

我正在尝试将一些数据填充到我在 BackgroundWorker 中的自定义网格。如果数据很小，那么它工作正常，但如果数据很大，我会随机出现异常。有时我得到“NullReferenceException 未被用户代码处理”，有时我得到“ArgumentOutOfRangeException 未被用户代码处理”。下面我提到了我面临的一些异常(exception)情况。

基本上，我在 Populate() 方法中所做的是，通过使用 foreach 循环，我为自定义网格中的每个单元格分配了值。当我不使用 BackgroundWorker 时，这很好用。但是在使用 BackgroundWorker 时，我在将它分配给单元格时得到了空值。因此出现了很多异常。我不知道为什么会这样。有什么建议可以克服这个问题吗？

下面是我使用的代码

代码:

BackgroundWorker worker = new BackgroundWorker();

worker.DoWork += (sender, args) =>
{
if (this.PivotEngine.DataSource != null && this.PivotCalculations.Count > 0)
{

    // Populates the data for the grid. 
    // Without using the BackgroundWorker, the values are been populated properly.
    this.PivotEngine.Populate();        

}

};

worker.RunWorkerCompleted += (s, e) =>
{
MessageBox.Show("Process is complete");
};

if (!worker.IsBusy)
{
  worker.RunWorkerAsync();
}

异常(exception) 1:

Exception:
System.NullReferenceException was unhandled by user code
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=Syncfusion.PivotAnalysis.Base
StackTrace:
   at Syncfusion.PivotAnalysis.Base.PivotEngine.PopulatePivotTable() in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 5882
   at Syncfusion.PivotAnalysis.Base.PivotEngine.ResumeComputations(Boolean resetPivotCollections, Boolean shouldRefresh) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2735
   at Syncfusion.PivotAnalysis.Base.PivotEngine.ResumeComputations(Boolean resetPivotCollections) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2718
   at Syncfusion.PivotAnalysis.Base.PivotEngine.Populate() in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2829
   at Syncfusion.Windows.Forms.PivotAnalysis.PivotGridControlBase.Populate(PivotEngine pe, Boolean checkLazyLoading) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Windows\Src\PivotGridControl\Core\PivotGridControlBase.cs:line 2990
   at Syncfusion.Windows.Forms.PivotAnalysis.PivotGridControlBase.<>c__DisplayClass1d.<ApplyRowCols>b__1a(Object sender, DoWorkEventArgs args) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Windows\Src\PivotGridControl\Core\PivotGridControlBase.cs:line 3016
   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)
 InnerException: 

异常(exception) 2:

System.ArgumentOutOfRangeException was unhandled by user code
HResult=-2146233086
Message=Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
Source=mscorlib
ParamName=index
 StackTrace:
   at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
   at System.Collections.Generic.List`1.get_Item(Int32 index)
   at Syncfusion.PivotAnalysis.Base.PivotEngine.PopulatePivotTable() in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 5932
   at Syncfusion.PivotAnalysis.Base.PivotEngine.ResumeComputations(Boolean resetPivotCollections, Boolean shouldRefresh) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2735
   at Syncfusion.PivotAnalysis.Base.PivotEngine.ResumeComputations(Boolean resetPivotCollections) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2718
   at Syncfusion.PivotAnalysis.Base.PivotEngine.Populate() in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2829
   at Syncfusion.Windows.Forms.PivotAnalysis.PivotGridControlBase.Populate(PivotEngine pe, Boolean checkLazyLoading) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Windows\Src\PivotGridControl\Core\PivotGridControlBase.cs:line 2990
   at Syncfusion.Windows.Forms.PivotAnalysis.PivotGridControlBase.<>c__DisplayClass1d.<ApplyRowCols>b__1a(Object sender, DoWorkEventArgs args) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Windows\Src\PivotGridControl\Core\PivotGridControlBase.cs:line 3016
   at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)
 InnerException:

我在使用 BackgroundWorker 时是否遗漏了什么？任何帮助将不胜感激。

问候，

安尼施。

Answer 1

在检查堆栈跟踪和所有内容时，似乎 Populate() 方法本身在 ResumeComputation() 方法之后调用了两次。

at Syncfusion.PivotAnalysis.Base.PivotEngine.PopulatePivotTable() in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 5932 at Syncfusion.PivotAnalysis.Base.PivotEngine.ResumeComputations(Boolean resetPivotCollections, Boolean shouldRefresh) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2735 at Syncfusion.PivotAnalysis.Base.PivotEngine.ResumeComputations(Boolean resetPivotCollections) in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2718 at Syncfusion.PivotAnalysis.Base.PivotEngine.Populate() in d:\Work_Vol4\svn\studio\trunk\work_area\GridWF\Engineer\PivotAnalysis.Base\Src\Engine\PivotEngine.cs:line 2829 at Syncfusion.Windows.Forms.PivotAnalysis.PivotGridControlBase.Populate(PivotEngine pe,

你必须避免这种重复的递归调用来停止这个异常。