Session variables are created on a per-user basis. By default, they are maintained in the Web server's memory. Imagine a Web site with thousands of users. Because of the huge number of users, the number of active sessions on the Web server also will be vary high. That means you are storing too much data in the Web server's memory. If the load on the server keeps of increasing, it may reach saturation and cause trouble for overall scalability of your application.

支持!!!!