Question

I have a problem with winform application which uses threads to update the UI. My application does upload and downloading of files from cloud. Same time I am also displaying Network speed details on the same window. These three operations (upload, download, display n/w speed) are invoked by 3 different threads. Problem is, when I start download/upload, whole window freezes and n/w speed display doesn’t refresh (it is written to refresh at every 1sec interval). what would be the problem? Thanks in advance.

Code is as follows… same way i have written for download. If I call **Upload** first and then **Download** one after the other, first thread will pause and download thread starts. once **Download** is done then **Upload** continues. Its not going in parallel. Also UI doesn’t respond immediately for other button click or window resize, move actions.

public delegate void UploadDelgt();
UploadDelgt UpldDlgtObj;
 private void Form1_Load(object sender, EventArgs e)
{
    UpldDlgtObj = new UploadDelgt(DoUpload);
}

public void load()
{
    Form1 form = this;
    form.Invoke(UpldDlgtObj);
}

private void button1_Click(object sender, EventArgs e)
{
    thrd = new Thread(new ThreadStart(load));
    thrd.Start();
    thrd.IsBackground = true;
}

public void DoUpload()
{
//uploads file block by block and updates the progressbar accordingly..
}

Answer 1

Your UI freezes because you are calling form.Invoke in your load method. From MSDN about Invoke: Executes the specified delegate on the thread that owns the control's underlying window handle.
So, thought you are calling DoUpload in a separate thread, it is still executed on the GUI thread (which owns the form handle), because it is called with Invoke.