Nginx 配置請求響應時間

1.常見默認nginx.conf配置日志格式

log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for "|$request_time|$upstream_response_time';     



(1)request_time
官網描述：request processing time in seconds with a milliseconds resolution; time elapsed between the first bytes were read from the client and the log write after the last bytes were sent to the client 。

指的就是從接受用戶請求的第一個字節到發送完響應數據的時間，即包括接收請求數據時間、程序響應時間、輸出
響應數據時間。

(2)upstream_response_time
官網描述：keeps times of responses obtained from upstream servers; times are kept in seconds with a milliseconds resolution. Several response times are separated by commas and colons like addresses in the $upstream_addr variable

是指從Nginx向后端（php-cgi)建立連接開始到接受完數據然后關閉連接為止的時間。

從上面的描述可以看出，$request_time肯定比$upstream_response_time值大，特別是使用POST方式傳遞參數時，因為Nginx會把request body緩存住，接受完畢后才會把數據一起發給后端。所以如果用戶網絡較差，或者傳遞數據較大時，$request_time會比$upstream_response_time大很多。