note 117901 deleted from session.examples.basic by cmb

Note Submitter: v888666 at 126 dot com ---- as metioned in 5th paragraph: "Sessions normally shutdown automatically when PHP is finished executing a script, but can be manually shutdown using the session_write_close() function." It's important to note that , "session shutdown " and "session invalid" are not equivalant. when a session shutdown, its session file is still valid in 24min by default (session file still exists in session path) . In subsquent access to this site ( ensure that this session file still exists ) ,this session will be resumed by session_start().