Why crash my code?

Hi
My codes is very simple
But when i run it,cpu usage get over 96%

PHP Code:

    function carts() {
    $user_id = $this->_check_login();

    $this->db->select('*');
    $carts = $this->db->where('user_id',$user_id)->get('cart')->result_array();

    for ($i = 0 ; $i < count($carts) ; $i++) {
    $pro_info   =   @$this->db->select('price,title')->where('pid',$carts['product_id'])->get('product')->row();
    $carts[$i]['price'] =   $pro_info->price;
    $carts[$i]['title'] =   $pro_info->title;
    }

    $header['category'] =   $this->get_category();
    $data['cat_id']     =   '';

    $title  =   'carts';

    $data['list'] = $carts;

    if ($user_id != '') {
    $info  = @$this->db->where('pid',$user_id)->get('user')->row();
    $data['post']           =   $info->post_price;
    }

    $data['title']          =   $title;
    $data['tax']            =   0;

    $this->load->view('site/master/header',$header);
    $this->load->view('site/carts',$data);
    $this->load->view('site/master/footer');

}

   function _check_login() {

        $user_id    =   $this->session->userdata('user_id');

        if (!preg_match('/^\d+$/',$user_id)) {
            $this->session->set_flashdata('message','login to app<br>'.'<a class="btn btn-success" href="login">login</a>');
            redirect('https://beautyfly.com/');
        }

        return $user_id;

    }