Question

I have C# WPF application which reads data from database then does some work. But the problem is when I am reading data my UI doesn’t respond. I have tried Tasks and dispatcher. None of them helps. Code below is in the button_click event. Here is code:

DataSet ds;
DataTable dt = new DataTable();

Task myTask = new Task(new Action(() =>
{
     //GetMyDataSet() returns DataSet
     ds = GetMyDataSet();
     dt = ds.Tables["MyTableName"];
}));

myTask.Start();

while (!myTask.IsCompleted)
{
    System.Threading.Thread.Sleep(1000);
}

//Continue

Answer 1

First off, get rid of the sleep-spin, it completely defeats the purpose of using a Task since it doesn’t allow the UI thread to proceed until the Task completes. You don’t want that!

Task myTask = Task.Factory.StartNew(
     new Action(() =>
     {
         DataSet ds;
         DataTable dt = new DataTable();    

         //GetMyDataSet() returns DataSet
         ds = GetMyDataSet();
         dt = ds.Tables["MyTableName"];

         // use Invoke/BeginInvoke to update UI
      }));

Now your task will run in parallel with the UI thread until completion. At the end of the Task code use Dispatcher.BeginInvoke to update the UI. It should be ok now.