title: Friendly_ID stops working at times, server restart necessary
body: <p>I'm running a Rails 5.0.6 app with Friendly ID 5.2.4 and everything works fine except that after some time (sometimes a few hours, sometimes a few days) the friendly ids are not working anymore (instead of <code>/username/slug-of-user-post</code> it will become e.g. <code>/4/23</code>). A simple <code>cap production deploy:restart</code> fixes it.</p>
  
  <p>Did anyone experience this kind of problem? Googled quite a bit but no luck.</p>
  
  <p>Model:</p>
  
  <pre><code>def slug_candidates
    %i[title title_and_sequence]
  end
  
  def title_and_sequence
    slug = title.parameterize
    sequence = posts.where('slug LIKE ?', "#{slug}-%").count + 1
    "#{slug}-#{sequence}"
  end
  </code></pre>
  
  <p>routes.rb: <code>get '/:user_id/:id' =&gt; 'posts#show', as: :user_post</code></p>
  
  <p>Controller:</p>
  
  <pre><code>def show
    @user = User.friendly.find params[:user_id]
    @post = @user.posts.friendly.find params[:id]
  
    render :show
  end
  </code></pre>