class Async::Barrier

@asynchronous Will wait for tasks to finish executing.
Wait for all tasks to complete by invoking {Task#wait} on each waiting task, which may raise an error. As long as the task has completed, it will be removed from the barrier.

def wait
	@tasks.each do |waiting|
		task = waiting.task
		begin
			task.wait
		ensure
			@tasks.remove?(waiting) unless task.alive?
		end
	end
end