[14-Jun-2018 21:46:39] NOTICE: [pool mysite.com] child 4296 exited with code 0 after 51.320215 seconds from start
[14-Jun-2018 21:46:39] NOTICE: [pool mysite.com] child 4316 started
这个是什么意思？
You have pm.max_requests set to '20'.
Thus, as soon one of the PHP-FPM child processes reaches 20 requests, the child process exits.
Then, PHP-FPM automatically opens a new child process once it's needed.
The number of seconds you see in the log output is telling you how long it took for that specific child process to reach 20 requests. Keep in mind these are just NOTICE entries, and do not indicate an error. You'd only need to modify the PHP-FPM configuration settings if you were encountering performance problems.
You have pm.max_requests set to '20'. Thus, as soon one of the PHP-FPM child processes reaches 20 requests, the child process exits. Then, PHP-FPM automatically opens a new child process once it's needed. The number of seconds you see in the log output is telling you how long it took for that specific child process to reach 0 requests. Keep in mind these are just NOTICE entries, and do not indicate an error. You'd only need to modify the PHP-FPM configuration settings if you were encountering performance problems.
这个表示的含义是，max_requests到达后自动退出后并新启动一个fpm进程来承接请求。