@KieranP Thanks! Now I can't find where Queue, as in @queue = Queue is defined, or the single argument to ThreadedConsumer constructor. Not even sure what the full namespaced name of that class is. Any hints?

update: Aha, this is just a ruby stdlib Queue? Cool. http://www.ruby-doc.org/stdlib-1.9.3/libdoc/thread/rdoc/Queue.html