asp.net在设置值后获取不同的会话值

Question

    public class Login : IHttpHandler, System.Web.SessionState.IRequiresSessionState
{

    public void ProcessRequest(HttpContext context)
    {
        try
        {
            var jsonString = String.Empty;

            using (var inputStream = new StreamReader(context.Request.InputStream))
            {
                jsonString = inputStream.ReadToEnd();
            }

            User user = JsonConvert.DeserializeObject<User>(jsonString);

            BusinessEntities.LoginSession ls = new BusinessEntities.LoginSession();
            ls = VerifyLoginCredentials(user.Username.Trim(), user.Password.Trim());

            context.Session["user"] = null;
            context.Session.Clear();

            if (ls.isValid)
            {
                context.Session["user"] = ls;
                context.Response.Write("1");
            }
            else
            {
                context.Response.Write("0");
            }
        }
        catch (Exception ex)
        {
            context.Response.Write("0");
        }
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
}

有很多用户使用此方法登录系统。有时在登录会话后需要另一个会话值。

假设用户A和B已登录，用户A发送请求以获取产品详细信息，但用户A收到用户B的结果。这很奇怪。我做错了什么？

修改

  public static BusinessEntities.LoginSession VerifyLoginCredentials(string username, string password)
    {
        return DAL.Creadentials.VerifyLoginCredentials(username, password);
    }

    public class LoginSession
{
    public bool isValid { get; set; }
    public string Username { get; set; }
    public string NewId { get; set; }
    public DateTime PasswordLastResetDate { get; set; }

}