$session->close() method

Manually close the session, before program execution is done

A user session is limited to rendering one page at a time, unless the session is closed early. Use this when you have a request that may take awhile to render (like a request rendering a sitemap, etc.) and you don't need to get/save session data. By closing the session before starting a render, you can release the session to be available for the user to view other pages while the slower page render continues.