after using background worker also my application get stuck,,how i can resolve - vb.net

Question

I am working on windows form application :
in my form am filling my datagrid view in some interval.so some time my application getting stuck..so i used back ground worker and timer
in back ground worker i am calling my function to fill the my data grid view.i set Timer Interval as 10000. in background worker i given code like this:
Private Sub BackgroundWorker1_DoWork
Call Fetch_Info()
End Sub
in Timer click event i given code like thise:
If Not BackgroundWorker1.IsBusy Then
BackgroundWorker1.RunWorkerAsync()
End If
my Fetch_Info() function like this:
Dim cnt As Integer
Dim tbarcodedgv As String
Dim totaltbarcode As String
cnt = DGVall.RowCount
Dim tbar As String
Dim locTable As New DataTable
locTable.Columns.Add("carid", GetType(String))
If cnt > 0 Then
For i = 0 To cnt - 2
tbarcodedgv = DGVall.Rows(i).Cells(0).Value
locTable.Rows.Add(tbarcodedgv)
Next
End If
Dim flag As Boolean = False
Dim dcnt As Integer = DGVall.RowCount
Dim trid As Integer
Dim tbarcode As String
Dim keyloc As String
Dim cmd23 As New SqlCommand("IBS_fetchrequested", con.connect)
cmd23.CommandType = CommandType.StoredProcedure
cmd23.Parameters.Add("#tid", SqlDbType.Int).Value = tid
If cnt > 1 Then
Dim tvp1 As SqlParameter = cmd23.Parameters.AddWithValue("#Tbaroced", locTable)
tvp1.SqlDbType = SqlDbType.Structured
tvp1.TypeName = "dbo.TBarcode"
End If
dr = cmd23.ExecuteReader
While dr.Read
flag = False
tbarcode = dr("TBarcode")
If flag = False Then
If dr("keyloc") Is DBNull.Value Then
keyloc = ""
Else
keyloc = dr("keyloc")
End If
Dim row0 As String() = {tbarcode, keyloc, "", "Release"}
DGVall.Rows.Add(row0)
AxWindowsMediaPlayer1.URL = "C:\Beep.mp3"
End If
End While
dr.Close()
con.disconnect()

Answer 1

While your background worker runs in another thread than your GUI you are manipulating the Datagridview that's running in the GUI's thread. This should usually not work at all but it is probably the reason, why your GUI hangs while the BGW is running.
Try splitting the work: The time consuming fetching of data from the database is carried out in the Backgroundworker's DoWork event handler and you set the results as the e.Result value of the EventArgs variable in the DoWork function.
Then you handle the Backgroundworker's RunWorkerCompleted event and there you quickly update your datagridview with the results you set in the DoWork method. That way your GUI has nothing to do with the actual time consuming task and will only be affected by the quick update of your datagridview.
The code example for this is:
Public Class Form1
Private WithEvents LazyBGW As New System.ComponentModel.BackgroundWorker
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
'This code runs in the UI-Thread
LazyBGW.RunWorkerAsync()
End Sub
Private Sub LazyBGW_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles LazyBGW.DoWork
'This code runs in the BGW-Thread
Dim a As Integer = 0
For i = 1 To 5
a += 1
'I'm a lazy worker, so after this hard work I need to...
Threading.Thread.Sleep(1000) 'This locks up the BGW-Thread, not the UI-thread
Next
'Work is done, put results in the eventargs-variable for further processing
e.Result = a
End Sub
Private Sub LazyBGW_RunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles LazyBGW.RunWorkerCompleted
'This code runs in the UI-Thread
Dim results As Integer = CInt(e.Result) 'e.Result contains whatever you put into it in the DoWork() method
MessageBox.Show("Finally the worker is done and our result is: " & results.ToString)
End Sub
End Class