title: Rails' ActiveRecord exposes race conditions?
body: <p>Assume I have this very simple controller:</p>
  
  <pre><code>class CountersController
    def inc
      c = Counter.find(1)
      c.value += 1
      c.save!
    end
  end
  </code></pre>
  
  <p>If two clients access <code>inc</code> method at the same time, is it possible that <code>c.value</code> only increases by 1? If so, how to solve this problem?</p>