Question

Hello i’ve a loop that last about 2 hours to finish, it gets the data from internet and fills it to a database so i want to divide it to 4 threads, and i am trying to do some testing before i put this to my application.

so here is a sample that i wrote to fill one database by 4 threads
and i am getting this error “BindingSource cannot be its own data source”

  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Me.DataGridView1.DataSource = Me.bindingSource1
    GetData("select * from products")
End Sub

 Public Sub thread1f0()
    For i = 0 To 500
        DataGridView1.Item("PD", i).Value = i + 67
        DataGridView1.Item("PDP", i).Value = i + 41
        DataGridView1.Item("TPD", i).Value = i + 654 + 6 * 13
        DataGridView1.Item("TPDP", i).Value = i + 342
    Next
End Sub

Public Sub thread1f1()
    For i = 501 To 1000
        DataGridView1.Item("PD", i).Value = i + 432
        DataGridView1.Item("PDP", i).Value = i + 421
        DataGridView1.Item("TPD", i).Value = i + 414
        DataGridView1.Item("TPDP", i).Value = i + 42 + 4
    Next
End Sub

Public Sub thread1f2()
    For i = 1001 To 1500
        DataGridView1.Item("PD", i).Value = i + 4452
        DataGridView1.Item("PDP", i).Value = i + 34
        DataGridView1.Item("TPD", i).Value = i + 123
        DataGridView1.Item("TPDP", i).Value = i + 44
    Next
End Sub

Public Sub thread1f3()
    For i = 1501 To 2000
        DataGridView1.Item("PD", i).Value = i + 423
        DataGridView1.Item("PDP", i).Value = i + 423
        DataGridView1.Item("TPD", i).Value = i + 423
        DataGridView1.Item("TPDP", i).Value = i + 423 / 2
    Next

End Sub

‘//////////////////////////////////////////////////////////////////////////////////////////

 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    thread0 = New System.Threading.Thread(AddressOf thread1f0)
    thread0.Start()

    thread1 = New System.Threading.Thread(AddressOf thread1f1)
    thread1.Start()

    thread2 = New System.Threading.Thread(AddressOf thread1f2)
    thread2.Start()

    thread3 = New System.Threading.Thread(AddressOf thread1f3)
    thread3.Start()
End Sub



Public Sub GetData(ByVal selectCommand As String)

    Try
        Dim connectionString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & strFileName
        Me.dataAdapter = New OleDbDataAdapter(selectCommand, connectionString)
        Dim commandBuilder As New OleDbCommandBuilder(Me.dataAdapter)
        Dim table As New DataTable()
        table.Locale = System.Globalization.CultureInfo.InvariantCulture
        Me.dataAdapter.Fill(table)
        Me.bindingSource1.DataSource = table
        Me.DataGridView1.AutoResizeColumns( _
            DataGridViewAutoSizeColumnsMode.ColumnHeader)
    Catch ex As OleDbException
        MessageBox.Show(ex.Message)
    End Try

End Sub

Answer 1

Since your DataGridView control is using a DataTable as a DataSource, you need to update the DataTable, not the DataGridView control.

The threads don’t seem necessary. Just use one BackgroundWorker thread to not freeze the GUI.