Reference counting? What about scalability, if you have more than a few CPU cores? You know how expensive atomic fetch-and-add (aka LOCK XADD) is, right? Atomi

Reference counting? What about scalability, if you have more than a few CPU cores? You know how expensive atomic fetch-and-add (aka LOCK XADD) is, right? Atomic compare-and-swap loop is even worse. Put simply, those things broadcast coherence information on inter-core (and inter-processor) network. It's ok for a low number of cores, but this solution just won't work well with more CPU cores. Good for a mobile phone with two cores.