def ssh_role_command(role, command)
      t = []
      ChefWorkflow::IPSupport.get_role_ips(role).each do |ip|
        t.push(
          Thread.new do
            ssh_command(ip, command)
          end
        )
      end
      t.each(&:join)
    end
def ssh_role_command(role, command)
      t = []
      ChefWorkflow::IPSupport.get_role_ips(role).each do |ip|
        t.push(
          Thread.new do
            ssh_command(ip, command)
          end
        )
      end
      t.each(&:join)
    end
run a command against a group of servers. These commands are run in
 parallel, but the command itself does not complete until all the threads
 have finished running.