使用itextpdf vb.net代码分割pdf

Question

我有这个代码来分割我在Web应用程序中使用的pdf文件。它适用于1000页，因为它在分割1000页后返回一个网页。但我有pdf包含6000页，分割PDF页面需要花费更多时间，而不是用1000页分割PDF。由于浏览器超时，我得到“网页不可用”。

我可以做些什么来保持连接活着？

Public Sub splitandsave(ByVal inputpath As String, ByVal outputpath As String)
    obj1.getconn()
    obj1.cn.Open()

    Dim file As FileInfo = New FileInfo(inputpath)
    Dim name As String = file.Name.Substring(0, file.Name.LastIndexOf("."))
    Using reader As PdfReader = New PdfReader(inputpath)

        Dim pagenumber As Integer
        For pagenumber = 1 To reader.NumberOfPages
            Dim email As String
            Dim da As New SqlDataAdapter("select * from commondetailmaster where email!='-' order by formno", obj1.cn)
            Dim ds As New DataSet
            da.Fill(ds)
            email = ds.Tables(0).Rows(pagenumber)("formNo").ToString
            Dim quota1 As String
            quota1 = "'"
            Dim filename As String = quota1 & email.ToString() & quota1 & ".pdf"
            Dim document As Document = New Document()
            Dim copy As PdfCopy = New PdfCopy(document, New FileStream(outputpath & "\\" & filename, FileMode.Create))
            document.Open()
            copy.AddPage(copy.GetImportedPage(reader, pagenumber))
            document.Close()
        Next
    End Using

End Sub