BackgroundWorker not firing RunWorkerCompleted

Question

第一次運行我的Backgroundworker時，它運行正常 - 在後臺更新數據表，然後RunWorkerCompleted將數據表設置爲datagridview數據源。

如果我再運行它，datagridview將清除並不會更新。我無法弄清楚爲什麼。

我已驗證數據表中包含行，當我的代碼命中dgvReadWrites.DataSource。

private void btnGenerateStats_Click(object sender, EventArgs e) 
    { 
     dtJobReadWrite.Columns.Clear(); 
     dtJobReadWrite.Rows.Clear(); 
     dgvReadWrites.DataSource = dtJobReadWrite; 

     List<Tuple<string, string>>jobs = new List<Tuple<string, string>>(); 

     foreach (ListViewItem job in lstJobs.SelectedItems) 
     { 
      jobs.Add(new Tuple<string, string>(job.Text, job.SubItems[2].Text)); 
     } 
     BackgroundWorker bgw = new BackgroundWorker(); 
     bgw.WorkerReportsProgress = true; 
     bgw.WorkerSupportsCancellation = true; 
     bgw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted); 
     bgw.DoWork += new DoWorkEventHandler(bgw_DoWork); 
     pbarGenStats.Style = ProgressBarStyle.Marquee; 
     pbarGenStats.MarqueeAnimationSpeed = 30; 
     pbarGenStats.Visible = true; 
     bgw.RunWorkerAsync(jobs); 
    } 


    private void bgw_DoWork(object sender, DoWorkEventArgs e) 
    { 
     BackgroundWorker bgw = sender as BackgroundWorker; 
     List<Tuple<string, string>> jobs = (List<Tuple<string, string>>)e.Argument; 
     GetReadWriteStats(jobs); 
    } 

    private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) 
    { 
     BackgroundWorker bgw = sender as BackgroundWorker; 
     bgw.RunWorkerCompleted -= new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted); 
     bgw.DoWork -= new DoWorkEventHandler(bgw_DoWork); 
     pbarGenStats.MarqueeAnimationSpeed = 0; 
     pbarGenStats.Value = 0; 
     pbarGenStats.Visible = false; 
     dgvReadWrites.DataSource = dtJobReadWrite; 
     dgvReadWrites.Visible = true; 
     dgvReadWrites.Refresh(); 
    } 

Answer 1

private void btnGenerateStats_Click(object sender, EventArgs e) 
{ 
    //... 
    dgvReadWrites.DataSource = dtJobReadWrite; 
    // etc... 
} 

這是一個問題，要更新dtJobReadWrite在BGW。這會導致綁定網格被工作線程更新。非法，控件不是線程安全的，只能從創建它們的線程更新。這通常會被檢查，在調試時會產生InvalidOperationException，但此檢查對綁定控件不起作用。

接下來發生了什麼事情，到處都是，你很幸運，你有一個高度可重複的僵局。更常見的不正當行爲是偶爾出現的繪畫僞影，以及只有當你不近時纔會出現死鎖。修復：

dgvReadWrites.DataSource = null; 

，並重新綁定在RunWorkerCompleted事件處理程序的網格，就像你已經這樣做了。

Answer 2

因爲你從這些事件中unscubscribe

bgw.RunWorkerCompleted -= new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted); 
bgw.DoWork -= new DoWorkEventHandler(bgw_DoWork); 

刪除這些行

Answer 3

你爲什麼要創建一個新的BackgroundWorker要運行它每一次？我希望看到如果使用BackgroundWorker的一個實例（GetReadWriteWorker或這些行的某個實例），只需訂閱一次事件，然後在btnGenerateStats_Click上運行該工作者異步，此代碼會發生什麼情況。