Cacher is the code snippet organizer for pro developers

https://segmentfault.com/a/1190000007760513

https://toutiao.io/posts/82tu2f/preview

http://blog.csdn.net/qq_20329253/article/details/52202811   yield

https://medium.com/async-php/co-operative-php-multitasking-ce4ef52858a0

http://mikaelronstrom.blogspot.com/2011/10/mysql-thread-pool-vs-mysql-connection.html  mysql

http://code.openark.org/blog/mysql/mysql-terminology-processes-threads-connections

https://stackoverflow.com/questions/7432241/mysql-show-status-active-or-total-connections

http://cgit.drupalcode.org/mysql_async/tree/includes/database/async-connection.inc?id=3c194805b870320b63dc4ec10c2e7b7c9044fb52