Access `session` within rails controller thread

How do I see / 开发者_JAVA百科change session data from within a thread within rails? See this code snippet inside my controller:

def controller_action
  session[:something] = 'before'   # works properly
  Thread.new do
    session[:something] = 'after'  # out of scope.  <--- how do I fix this?
  end
end

(related to this question, but much more specific. I expect quite different answers.)

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Why do you need to change session data in a background thread?

Are you using the default cookie store, because if you are I'm not sure how this would work. If you were to switch to the memcached/database session store you might have more luck as you can access the session after the request has finished.

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I'm still not sure why session would not be in scope by reference inside a thread, but if this is true, you could try passing the current binding to the thread as an argument:

Thread.new(binding) do 
    thread_session = eval("session", binding)
end

Or something like that. I'm still not convinced that the session is by value and not by reference in the Thread. To check this I just passed some hashes into new threads on the console, and changes made to a hash inside a thread are visible outside that thread. Is there some magic that makes session behave differently?

EDIT: Wouldn't DelayedJob be a better way to handle a long-running process spun off from a user request?