invoke_prerequisites_concurrently

# File lib/rake/task.rb, line 207
    def invoke_prerequisites_concurrently(task_args, invocation_chain)# :nodoc:
      futures = prerequisite_tasks.map do |p|
        prereq_args = task_args.new_scope(p.arg_names)
        application.thread_pool.future(p) do |r|
          r.invoke_with_call_chain(prereq_args, invocation_chain)
        end
      end
      futures.each { |f| f.value }
    end