Rails 3.2.3, Why my view cached is not stable?

Before asking my question, i read document configurigng Rails Applications

and i still don't know reason why my view cached is not working stably. In my case, after updating the codes in views, sometimes i don't need restart application server(Thin) and the views is reloaded with the modifications Seen that the controllers and models are not reloaded, so my app crashes ... Strange, this problem is not always there it's not stably. sometimes all is ok.

my config production mode like this:

...
# Code is not reloaded between requests
  config.cache_classes = true
...

From the documentation, i learned that if i set true to config.cache_classes, i don't need to set true to config.action_view.cache_template_loading it will follow cache_classes configuring.

I think that cache_classes controls if all classes, modules and views templates will reload for each request. am i right ? any suggestion is welcome.