参考:
一个Opcache的推荐配置
http://www.laruence.com/2013/11/11/2928.html
zend opcache的最佳设置
https://gywbd.github.io/posts/2016/1/best-config-for-zend-opcache.html
php-src/php.ini-production
https://github.com/php/php-src/blob/master/php.ini-production
How To Clear PHP’s Opcache
https://ma.ttias.be/how-to-clear-php-opcache/