timer定时器问题 不能清除定时器

public static function onClose($client_id){ 

        $timer_id = Timer::add(5, function($online_uid,$room_id,$redis){

              ....略...
        },array($online_uid,$room_id,$redis),false);

//echo $time_id;        //打印出72
$redis->SET("offline_timer:{$online_uid}",$timer_id);

}

 public static function onMessage($client_id, $message){
            ....略...
            $timer_id = $redis->GET("offline_timer:{$online_uid}");
            // echo $time_id     //打印出72
            $result = Timer::del($timer_id);
}