how to display status online/offline of commentator in wordpress

i want to show the status of commentator in comment page of wordpress

i am trying to display simple message [online/offline] according to its status.

right now i am using below code

<?php 
$user_id   = get_comment(get_comment_ID())->user_id;

if ( is_user_logged_in($user_id) ) 
{
 echo 'Online';
      } else {
      echo 'Offline';
     }
?>

but the above code is not working. it only show text (Online) and not working properly. i think there is some error in above code can anybody correct it for me.