VB.NET background worker 60 seconds timeout - vb.net

Question

During the startup of my app I am doing a long database upgrade.
Before that starts, I show a form that has a progressbar so that the user knows that something is going on and he should wait.
To not block the progressbar from redrawing, I do the database upgrade in a background worker.
The code looks like this:
frmMain_Load(...)
Dim wait As New frmWait
wait.Show()
Dim bw As New frmBWRebuildUserData
bw.Start()
Do While Not bw.Done
System.Threading.Thread.Sleep(100)
Loop
'Okay, db update was done, now continue and show the main app window
My frmBWRebuildUserData looks like this:
Public Class frmBWRebuildUserData
Private m_bDone As Boolean
Public ReadOnly Property Done() As Boolean
Get
Return m_bDone
End Get
End Property
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
modAppDB.RebuildUserDB()
End Sub
Public Sub Start()
Me.BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
m_bDone = True
End Sub
End Class
But after 60 seconds, VB.NET tells me that there were no messages since 60 seconds (I guess you know this error).
But since the background worker is intended for such purposes, I think I am doing something substantially wrong here, but I can't figure out what.
Also, my progressbar is not redrawing.
Can somebody help, please?
Thank you very much!

Answer 1

A couple of things.
There is no built in timeout of 60 seconds in the backgroundworker. So it should be something in your code.
Why do you use a backgroundWorker and then introduce in your code a sleep cycle? The backgroundworker should be used to free the user interface from waiting for the end of long operations.
The backgroundworker when asked to report its progress to a user interface element needs something like this (sorry is C#, but I think you can get the point)
backgroundworker.ProgressChanged += backgroundworker_ProgressChanged;
backgroundworker.WorkerReportsProgress = true;
in this scenario your modAppDB.RebuildUserDB() need to call
backgroundworker.ReportProgress(percentComplete);
for every step that you want to communicate to the progress bar and of course, you need in the form where the progressbar is displayed to intercept the event fired by the ReportProgress call
private void backgroundworker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
progressBar.Value = (e.ProgressPercentage.ToString() + "%");
}

Answer 2

The Backgroundworker is mainly good for tasks where you have a loop inside DoWork, which allows you to do some UI feedback within the loop. If your DoWork just calls another command, it will wait for this command to finish and not do anything in this time. Other than that, using the BGW still allows for the main thread to handle its messages and not get blocked, so I presume it is still entirely right to use it here.
Apart from that, your backgroundworker1 is not declared, and as Steve pointed out, your Start()-Method needs at least this first line:
Addhandler Backgroundworker1.DoWork, AddressOf BackgroundWorker1_DoWork. This triggers the function when RunworkerAsync is called.
For a basic example of thread-communication (and fundamental problems connected with it) take a look at this question and answer:
Multithreading for a progressbar and code locations (vb.net)?
I don't know about the 60 seconds issue either.