def action_timeout=(t)
      t = t.to_f
      raise ArgumentError.new('Value must be greater than zero or nil') unless t >= 0
      @action_timeout = t
      @threads.each{|thread|thread.action_timeout = t}
      t
    end
def action_timeout=(t)
      t = t.to_f
      raise ArgumentError.new('Value must be greater than zero or nil') unless t >= 0
      @action_timeout = t
      @threads.each{|thread|thread.action_timeout = t}
      t
    end
t:: timeout in seconds (nil for infinte)
 Set maximum allowed time thread may work
 on a given action