List all active ASP.NET Sessions

How can I list (and iterate through) all current ASP.NET sessions?

Solution 1:

You can collect data about sessions in global.asax events Session_Start and Session_End (only in in-proc settings):

private static readonly List<string> _sessions = new List<string>();
private static readonly object padlock = new object();

 public static List<string> Sessions
 {
       get
       {
            return _sessions;
       }
  }

  protected void Session_Start(object sender, EventArgs e)
  {
      lock (padlock)
      {
          _sessions.Add(Session.SessionID);
      }
  }
  protected void Session_End(object sender, EventArgs e)
  {
      lock (padlock)
      {
          _sessions.Remove(Session.SessionID);
      }
  }

You should consider use some of concurrent collections to lower the synchronization overhead. ConcurrentBag or ConcurrentDictionary. Or ImmutableList

https://msdn.microsoft.com/en-us/library/dd997373(v=vs.110).aspx

https://msdn.microsoft.com/en-us/library/dn467185.aspx

Solution 2:

It does not seems right that there is not any class or method that provides this information. I think, it is a nice to have feature for SessionStateStoreProvider, to have a method which returns current active session, so that we don't have to actively track session life in session_start and session_end as mention by Jan Remunda.

Since I could not find any out of box method to get all session list, And I did not wanted to track session life as mentioned by Jan, I end up with this solution, which worked in my case.

public static IEnumerable<SessionStateItemCollection> GetActiveSessions()
{
    object obj = typeof(HttpRuntime).GetProperty("CacheInternal", BindingFlags.NonPublic | BindingFlags.Static).GetValue(null, null);
    object[] obj2 = (object[])obj.GetType().GetField("_caches", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(obj);

    for (int i = 0; i < obj2.Length; i++)
    {
        Hashtable c2 = (Hashtable)obj2[i].GetType().GetField("_entries", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(obj2[i]);
        foreach (DictionaryEntry entry in c2)
        {
            object o1 = entry.Value.GetType().GetProperty("Value", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(entry.Value, null);
            if (o1.GetType().ToString() == "System.Web.SessionState.InProcSessionState")
            {
                SessionStateItemCollection sess = (SessionStateItemCollection)o1.GetType().GetField("_sessionItems", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(o1);
                if (sess != null)
                {
                    yield return sess;
                }
            }
        }
    }
}