worker_shutdown_timeout这个地方老师解释的越多，反而很容易误解，其实按照官方文档，就是优雅退出时，nginx等待的时间，一旦超过这个时间，nginx会试图关闭目前所有仍然打开的tcp连接。

并不是用来控制每个tcp请求关闭的时间。

Syntax: worker_shutdown_timeout time;
Default: —
Context: main
This directive appeared in version 1.11.11.

Configures a timeout for a graceful shutdown of worker processes. When the time expires, nginx will try to close all the connections currently open to facilitate shutdown.