计算匿名用户和登录用户-ASP.NET网站

Question

I would like to implement reliable user counter. Currently I'm using session variables. Here is a look on my implementation:

void Application_Start(object sender, EventArgs e) 
{
    // Code that runs on application startup
    Application["OnlineUsers"] = 0;
    Application["LoggedInUsers"] = 0;
}

void Session_Start(object sender, EventArgs e) 
{
    // Code that runs when a new session is started
    Application.Lock();
    Application["OnlineUsers"] = (int)Application["OnlineUsers"] + 1;
    Application.UnLock();
}

void Session_End(object sender, EventArgs e) 
{
    Application.Lock();
    if ((int)Application["OnlineUsers"] > 0)
    {
        Application["OnlineUsers"] = (int) Application["OnlineUsers"] - 1;
    }
    Application.UnLock();
}

protected void Login1_LoggedIn(object sender, EventArgs e)
{
    Application.Lock();
    Application["LoggedInUsers"] = (int)Application["LoggedInUsers"] + 1;
    Application.UnLock();
}

protected void LoginStatus1_LoggedOut(object sender, EventArgs e)
{
    Application.Lock();
    if ((int)Application["LoggedInUsers"] > 0)
    {
        Application["LoggedInUsers"] = (int) Application["LoggedInUsers"] - 1;
    }
    Application.UnLock();
}

Downsides of that approach are well known. I couldn't find anything more accurate. Can you help me, please?

Answer 1

Given the somewhat fuzzy nature of Session_End, the approach I've used is to just define an "Online User" as someone who has had activity within the last 5 minutes. You can then just count the number of users who have activity within that time frame.