回答

可以结合register_shutdown_function及fastcgi_finish_request来实现。

fastcgi_finish_request()主要是为了响应浏览器，给用户感觉很响应很快，但是php进程其实还在服务器中运行，执行fastcgi_finish_request()后面的代码。

示例代码如下：

<?php
/**
* 进程关闭hook执行
*/
class AsyncHook {
    private static $hook_list = array();
    private static $hooked = false;
    /**
    * hook函数fastcgi_finish_request执行
    *
    * @param callback $callback
    * @param array $params
    */
    public static function hook($callback, $params) {
        self::$hook_list[] = array('callback' => $callback, 'params' => $params);
        if (self::$hooked == false) {
            self::$hooked = true;
            register_shutdown_function(array(__CLASS__, '__run'));
        }
    }
    /**
    * 由系统调用
    *
    * @return void
    */
    public static function __run() {
        echo "run task";

        fastcgi_finish_request();//立刻响应浏览器，然后再php进程中执行收尾的操作，给用户赶紧响应很快
        if (empty(self::$hook_list)) {
            return;
        }
        foreach (self::$hook_list as $hook) {

            $callback = $hook['callback'];
            $params = $hook['params'];
            call_user_func_array($callback, $params);
        }
    }
}
function sendSMS($phone, $noticeWords) {
    //模拟发送短信
    
    //将结果写入日志
   file_put_contents(__DIR__."/sendsms.log",$phone."发送成功");
}
echo "i am working 1</br>";
//AsyncHook::hook(array($this, 'sendEmail'), array());//面向对象调用
AsyncHook::hook('sendSMS', array("139911111", "你好，您的快递到了")); //面向过程方式调用

echo "i am working 2</br>";