title: Do we need to delete session variables after user logout?
body: <p>In Ruby on Rails :</p>
  
  <p>suppose I am having <code>session[:my_var] = 'my_val'</code></p>
  
  <p>So here my question is :
  Do we need to set <code>session[:my_var]=nil</code> before user's sign-out?</p>
  
  <p>or it will auto release the memory it has.</p>