title: Async Await Method will block UI at await point
body: <p>Here is my button event:</p>
  
  <pre><code>private async void btnTarget_Click(object sender, EventArgs e)
  {
      using (DataBaseDataContext db = new DataBaseDataContext())
      {
          targtGirdView.DataSource = await Task.Run(() =&gt;
          {
              return heavyLinqToSQLQuery;
          });
      }
  }
  </code></pre>
  
  <p>for my GridView datasource, I have a heavy database transaction which I put it in an await section. But at this point, the UI will block and I do not know the reason. Where is the problem?</p>