仅在主线程执行完成后，后台工作线程中的函数调用才会执行？

Question

I am calling a function on background worker thread which requires ListBox to be passed as parameter which intialize on main thread. I am using following code to do

   private void simpleButton1_Click(object sender, EventArgs e)
    {            
        bw.RunWorkerAsync();           
        GetData()         

    }
void bw_DoWork(object sender,DoWorkEventArgs e)
    {           
        this.Invoke(new MethodInvoker(delegate
        {
            ShowLoadingPanel(listBox);
        }));            
    }

private void GetData()
      {
        for (int i = 0; i < 500000; i++)
        {
            datatable.Rows.Add(new object[] { "raj", "raj", "raj", i });
        }
    }

  void ShowLoadingPanel(Control control)
   {
      //Doing some work here
   }

Problem is that ShowLoadingPanel function called only after GetData function completes its execution. I want this two function run parallel in different threads.

How can i do this ??

Answer 1

Try this:

private void simpleButton1_Click(object sender, EventArgs e)
{        
    ShowLoadingPanel(listBox);    
    bw.RunWorkerAsync();       
}

void bw_DoWork(object sender,DoWorkEventArgs e)
{           
    GetData();
}

private void GetData()
{
    for (int i = 0; i < 500000; i++)
    {
        datatable.Rows.Add(new object[] { "raj", "raj", "raj", i });
    }
}

void ShowLoadingPanel(Control control)
{
   //Doing some work here
}

Answer 2

Your example doesn't make much sense: you want to offload ShowLoadingPanel to another (non-GUI) thread, but you execute it with Control.Invoke which is documented as Executes the specified delegate on the thread that owns the control's underlying window handle. , ie executes on the GUI thread.

Control.Invoke posts a message to the message queue of the thread owning the form window and you do it from button Click handler which is already handled as a message. Thus, the message posted to the queue by Control.Invoke can only be processed after your Click handler exits, which is exactly what you observe.