We meet an error log on nginx:
worker_connections are not enough, reusing connections. To resolve this issue, here is my working solution according to the references:
Linux (pronounced Listeni/ˈlɪnəks/ lin-əks or, less frequently, /ˈlaɪnəks/ lyn-əks) is a Unix-like and mostly POSIX-compliant computer operating system (OS) assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on 5 October 1991 by Linus Torvalds. The Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy.