why Update Panel Updates only after one process in done?

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ASP.NET

Ajax

UpdatePanel

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I am inserting data in one table(e.g. InsertTable) & updating another table(e.g. UpldTable) in a loop on a button click.(say loop of 2500 iterations)
I want to retrieve updated value from UpldTable. & display it on same page.
And on timer_tick event i display value from UpldTable after every 2 seconds.
but Value is displayed only when all the writes & updates are done. I want to display updated value after every 2 seconds.

here is the code which i tried

private void ParseCommand(string command, string uid, string ivr, string sort, string service)
    {
        string SERVICE_ID = "", MOBILE = "", DUE_DATE = "", BILLED_OUTSTD = "", CITY = "";
        try
        {
            if (command != "timeout" || command != "-1")
            {
                XmlDocument xmldoc = new XmlDocument();
                xmldoc.LoadXml(command);
                XmlNodeList cnn = xmldoc.DocumentElement.ChildNodes;                

                XmlNodeList NodeListMessage = xmldoc.DocumentElement.GetElementsByTagName("RESULT");
                XmlNodeList NodeListMessage1 = xmldoc.DocumentElement.GetElementsByTagName("SERVICE_DETAILS");

                string ResultStatus = "", str_result_status = "", str_service_id = "";

                foreach (XmlNode nodeInfo in NodeListMessage)
                {
                    ResultStatus = nodeInfo["STATUS"].InnerText;
                    if (ResultStatus == "SUCCESS")
                    {
                        str_service_id = Convert.ToString(nodeInfo["SERVICE_ID"].InnerText);
                        SERVICE_ID = Convert.ToString(nodeInfo["SERVICE_ID"].InnerText);
                    }
                }
                if (ResultStatus == "SUCCESS")
                {
                    foreach (XmlNode nodeInfo in NodeListMessage1)
                    {
                        SERVICE_ID = Convert.ToString(nodeInfo["SERVICE_ID"].InnerText);
                        MOBILE = Convert.ToString(nodeInfo["MOBILE"].InnerText);
                        DUE_DATE = Convert.ToString(nodeInfo["LST_PAY_DATE"].InnerText);
                        BILLED_OUTSTD = Convert.ToString(nodeInfo["OUTSTANDING_BAL"].InnerText);
                        CITY = Convert.ToString(nodeInfo["CITY"].InnerText);

                        con2.Open();
                        string insertText = "insert into siebel_return_result(ServiceID, ReqUserID,ReqCollectionType, ReqCollectionSorting, Result, RetUserID, RetMobile, RetDueDate, RetBillOutstanding, RetCity) " +
                        "values ('" + service + "','" + uid + "','" + ivr + "','" + sort + "','" + ResultStatus + "','" + SERVICE_ID + "','" + MOBILE + "','" + DUE_DATE + "','" + BILLED_OUTSTD + "','" + CITY + "')";
                        SqlCommand cmdInsertResult = new SqlCommand(insertText, con2);
                        cmdInsertResult.ExecuteNonQuery();

                        string updtCount = "update upldTable set isnull(count,0)= count+ 1";
                        SqlCommand cmdUpdtCount = new SqlCommand(updtCount, con2);
                        cmdUpdtCount.ExecuteNonQuery();

                        con2.Close();
                    }
                }
            }
        }
        catch (Exception ex)
        {
            Response.Write(SERVICE_ID + " : Error 1" + ex.Message + " <br>"  );
        }
    }

this function called on button click

& on timer_tick event counter is called

public void Counter()
    {
        try
        {
            con.Open();
            string strCount = "select count from upldTable WITH (NOLOCK)";            
            SqlCommand cmdCount = new SqlCommand(strCount, con);
            int count = Convert.ToInt16(cmdCount.ExecuteScalar());

            string strTotal = "SELECT  COUNT(*)  FROM  pload_Data";
            
            SqlCommand cmdTotal = new SqlCommand(strTotal, con);
            int Total = Convert.ToInt16(cmdTotal.ExecuteScalar());

            if (Total != 0)
            {
                double percent = (count / Total) * 100;
                percent = Math.Round(percent, 2);
                lblCounter.Text = "[ Data Status : " + count.ToString() + " of " + Total.ToString() + " ]<BR/>";
                if (Total == count)
                {
                    lblProgress.Text = "Upload Complete";
                }
                if (count == 0)
                {
                    lblCounter.Text = "";
                }
            }
            else if (Total == count)
            {
                lblCounter.Text = "";
            }
            
            con.Close();            
        }
        catch (Exception ex)
        {
            lblProgress.Text = "Error : " + ex.Message;
        }
    }

following is .aspx file code

<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always" ChildrenAsTriggers="true">
                     <Triggers>
                            <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" />
                            <asp:AsyncPostBackTrigger ControlID="btnSynch" EventName="Click" />  
                            <asp:AsyncPostBackTrigger ControlID="btnDelete" EventName="Click" />
                            <asp:AsyncPostBackTrigger ControlID="btnQueue" EventName="Click" />
                            <asp:AsyncPostBackTrigger ControlID="btnExport" EventName="Click" />
                            
                        </Triggers>
                        <ContentTemplate>
                            
                            <asp:Label ID="lblProgress" runat="server"></asp:Label>
                           <asp:Timer ID="Timer1" runat="server" Interval="3000" ontick="Timer1_Tick" Enabled="true">
                            </asp:Timer>
                         <asp:Label ID="lblCounter" runat="server"></asp:Label>
                            <asp:HyperLink ID="linkProgress" runat="server" Visible="False">Click here to see the progress</asp:HyperLink>
                            <br />
                            <asp:Label ID="lblMsg" runat="server"></asp:Label>
                            <br />
                            
                            <br />
                            <asp:Label ID="lblError" runat="server" ForeColor="#FF3300"></asp:Label>
                        
                            <br />
                            <asp:GridView ID="grdData" runat="server" CellPadding="4" 
                                EnableModelValidation="True" ForeColor="#333333" GridLines="None" 
                                PageSize="100" Width="100%">
                                <AlternatingRowStyle BackColor="White" />
                                <EditRowStyle BackColor="#2461BF" />
                                <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                                <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
                                <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />
                                <RowStyle BackColor="#EFF3FB" HorizontalAlign="Center" />
                                <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
                            </asp:GridView>
                        
                    </ContentTemplate>
                    </asp:UpdatePanel>