线程冻结通过Backgroundworker加载数据

Question

以下代码似乎在执行时冻结了我的线程，这违背了我想要添加的进度的目的。有什么我需要调整来消除这个吗？我的假设是它与我正在加载的数据中的剪切量有关，在这个特定的例子中，它超过150个字段（标题行和1个数据行）。

    Private Sub BackgroundWorker1_DoWork(sender As Object, e As ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork

    Dim file As String = "<<file>>"
    Dim path As String = "<<path>>"

    Dim ConStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='<<source>>';Extended Properties='text';"
    Dim SQL = "SELECT * FROM  " & path & file

    tbl = New DataTable

    ' USING will close and dispose of resources
    Using cn As New OleDbConnection(ConStr),
        cmd As New OleDbCommand(SQL, cn)

        cn.Open()
        Using da As New OleDbDataAdapter(cmd)
            da.Fill(tbl)
        End Using

    End Using   ' close and dispose

    ' FIND the sequence column for this session
    For n = 0 To tbl.Columns.Count - 1
        If tbl.Columns(n).ColumnName.ToLowerInvariant = "sequence" Then
            SeqColIndex = n
            Exit For
        End If
    Next

End Sub