我有一个cron job，它调用下面的codeigniter controller
但这太浪费时间了
其中计算和操作操作较多（平均需要5分钟）
然后在数据库中插入值

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Mycron extends CI_Controller {

    public function cron_function()
    {
        // simulate time cost operations
        sleep(300); // 5 mint = 5 *60 = 300 sec

        $this->load->database();    // line1
        $this->db->reconnect();     // line2

        $this           -> db -> set    ( 'source_id',  '11');
        $this           -> db -> set    ( 'title',  'TTL');
        $query = $this  -> db -> insert ( 'my_table' );

        echo 'END ...'; 
    }
}

我的问题
没有两条线路1/2
当数据库在操作所用时间之后尝试连接时，结果将为

SQL Error: 2006: MySQL server has gone away

然后，当尝试使用2行将修复RE_CONNECT应用于数据库时
我们面对

A PHP Error was encountered
Severity: Warning
Message: Cannot modify header information - headers already sent by 
(output started at .../system/database/drivers/mysqli/mysqli_driver.php:392)
Filename: core/Common.php
Line Number: 568
Backtrace:

A PHP Error was encountered
Severity: Error
Message: Call to a member function real_escape_string() on boolean
Filename: mysqli/mysqli_driver.php
Line Number: 392
Backtrace: