title: Fast Thread-Safe Ruby Hash with strong read bias
body: <p>I need some help in understanding Hash in Ruby 1.8.7. </p>
  
  <p>I have a multi-threaded Ruby application, and about 95% of time multiple threads of the application are trying to access a global Hash. </p>
  
  <p>I am not sure if the default Ruby Hash is thread safe. What would be the best way to have a fast Hash but also one that is thread safe given my situation? </p>