Issue #3621 has been updated by caleb clausen. I would like to put in a word in favor of having a Semaphore available in ruby. Semaphores are an important data structure for letting one thread tell another that an event that it is waiting for. When I have needed this before, I've had to make do with less appropriate mechanisms such as ConditionVariable, which is confusing to me because of the extra mutex which I typically don't really need or SizedQueue full of TrueClass, which is a silly way to implement a counting semaphore. Full disclosure: I am Ricardo's SoC mentor and encouraged him to implement this in the first place. ---------------------------------------- http://redmine.ruby-lang.org/issues/show/3621 ---------------------------------------- http://redmine.ruby-lang.org