Lock the Application object : Application « Development « ASP.NET Tutorial

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      The page has been requested
      <asp:Label ID="myLabel" runat="server" />
      times!
    </div>
    </form>
</body>
</html>

File: Default.aspx.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Application["PageCounter"] != null &&
            (int)Application["PageCounter"] >= 10)
        {
            Application.Remove("PageCounter");
        }

        if (Application["PageCounter"] == null)
        {
            Application["PageCounter"] = 1;
        }
        else
        {
            Application.Lock();
            Application["PageCounter"] =
                (int)Application["PageCounter"] + 1;
            Application.UnLock();
        }
        myLabel.Text = Convert.ToString(Application["PageCounter"]);
    }
}

9.1.Application
	9.1.1.	Basic Application Events
	9.1.2.	Save value to Application
	9.1.3.	Displaying a count of user sessions.
	9.1.4.	Lock the Application object
	9.1.5.	Application.Lock() (VB)
	9.1.6.	Application.Add
	9.1.7.	Application.AllKeys
	9.1.8.	Application.Clear()
	9.1.9.	Application.Count
	9.1.10.	Application.Get
	9.1.11.	Application.GetKey
	9.1.12.	Application.Item
	9.1.13.	Application.Keys
	9.1.14.	Application.UnLock()
	9.1.15.	Application.Remove
	9.1.16.	Application.RemoveAll()
	9.1.17.	Application.RemoveAt
	9.1.18.	Application.Set