统计系统功能，把每个步骤操作时间都进行记录，找出比较长的请求时间
一、nginx 过程时间节点
1： $time_local
The $time_local variable contains the time when the log entry is written. when the HTTP request header is read, nginx does a lookup of the associated virtual server configuration. If the virtual server is found, the request goes through six phases: server rewrite phase location phase location rewrite phase (which can bring the request back to the previous phase) access control phase try_files phase log phase Since the log phase is the last one, $time_local variable is much more colse to the end of the request than it's start.
意思就是这个$time_local 是很接近请求处理结束时间
2： $request_time
request processing time in seconds with a milliseconds resolution; time elapsed between the first bytes were read from the client and the log write after the last bytes were sent to the client
意思就是这个request_time指的就是从接受用户请求的第一个字节到发送完响应数据的时间，即包括接收请求数据时间、程序响应时间、输出响应数据时间。从请求到输出的所有时间
3：$upstream_response_time
keeps time spent on receiving the response from the upstream server; the time is kept in seconds with millisecond resolution. Times of several responses are separated by commas and colons like addresses in the $upstream_addr variable.
是指从Nginx向后端（python）建立连接开始到接受完数据然后关闭连接为止的时间。意思就是这个$upstream_response_time 是后台处理时间
总结
从上面的描述可以看出，$request_time肯定比$upstream_response_time值大，特别是使用POST方式传递参数时，因为Nginx会把request body缓存住，接受完毕后才会把数据一起发给后端。所以如果用户网络较差，或者传递数据较大时，$request_time会比$upstream_response_time大很多。
所以如果使用nginx的accesslog查看程序中哪些接口比较慢的话，使用$request_time，
所以如果使用nginx的accesslog查看程序中哪些后台逻辑比较慢用$upstream_response_time，
二、配置日志格式
既然了解了各个字段的含义和作用我们就需要配置一下日志记录的conf，把我们需要信息保存到日志中。
1：日志记录格式说明
具体log format的变量解释官方解释如下：
$request_time – Full request time, starting when NGINX reads the first byte from the client and ending when NGINX sends the last byte of the response body
$upstream_connect_time – Time spent establishing a connection with an upstream server
$upstream_header_time – Time between establishing a connection to an upstream server and receiving the first byte of the response header
$upstream_response_time – Time between establishing a connection to an upstream server and receiving the last byte of the response body
$msec - time in seconds with a milliseconds resolution at the time of the log write
中文版本：
$remote_addr, $http_x_forwarded_for 记录客户端IP地址
$remote_user 记录客户端用户名称
$request 记录请求的URL和HTTP协议
$status 记录请求状态
$body_bytes_sent 发送给客户端的字节数，不包括响应头的大小； 该变量与Apache模块mod_log_config里的“%B”参数兼容。
$bytes_sent 发送给客户端的总字节数。
$connection 连接的序列号。
$connection_requests 当前通过一个连接获得的请求数量。
$msec 日志写入时间。单位为秒，精度是毫秒。
$pipe 如果请求是通过HTTP流水线(pipelined)发送，pipe值为“p”，否则为“.”。
$http_referer 记录从哪个页面链接访问过来的
$http_user_agent 记录客户端浏览器相关信息
$request_length 请求的长度（包括请求行，请求头和请求正文）。
$request_time 请求处理时间，单位为秒，精度毫秒； 从读入客户端的第一个字节开始，直到把最后一个字符发送给客户端后进行日志写入为止。
$time_iso8601 ISO8601标准格式下的本地时间。
$time_local 通用日志格式下的本地时间。
2：服务器配置
配置路径 /etc/nginx/nginx.conf
日志存储路径 /var/app_log/nginx/access.log
2.1修改当前nginx日志配置，以及查看日志记录结果
主要是添加 log_format 并配置access_log
user www-data; worker_processes auto; pid /run/nginx.pid; include /etc/nginx/modules-enabled/*.conf; events { worker_connections 768; # multi_accept on; } http { ## # Basic Settings ## sendfile on; tcp_nopush on; tcp_nodelay on; keepalive_timeout 65; types_hash_max_size 2048; # server_tokens off; # server_names_hash_bucket_size 64; # server_name_in_redirect off; include /etc/nginx/mime.types; default_type application/octet-stream; log_format myFormat '$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]'; #自定义格式 access_log log/access.log myFormat; #combined为日志格式的默认值 ## # SSL Settings ## ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE ssl_prefer_server_ciphers on; ## # Logging Settings ## access_log /var/app_log/nginx/access.log myFormat; error_log /var/app_log/nginx/error.log; ## # Gzip Settings ## gzip on; gzip_disable "msie6"; # gzip_vary on; # gzip_proxied any; # gzip_comp_level 6; # gzip_buffers 16 8k; # gzip_http_version 1.1; # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript; ## # Virtual Host Configs ## include /etc/nginx/conf.d/*.conf; include /etc/nginx/sites-enabled/*; } #mail { # # See sample authentication script at: # # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript # # # auth_http localhost/auth.php; # # pop3_capabilities "TOP" "USER"; # # imap_capabilities "IMAP4rev1" "UIDPLUS"; # # server { # listen localhost:110; # protocol pop3; # proxy on; # } # # server { # listen localhost:143; # protocol imap; # proxy on; # } #}
2.2 重启nginx: 定位后Nginx可执行程序,然后输入 -s reload,完成重启，该重启不需要关闭Nginx服务器.
/usr/sbin ./nginx -s reload
tail 10 /var/app_log/nginx/access.log
3：数据分析
由于数据日志的格式（列数）发生了变化，所以需要把access.log重新备份，数据清空，方便以后数据统计
shell 中的管道| ： command 1 | command 2 #他的功能是把第一个命令command 1执行的结果作为command 2的输入传给command 2 wc -l #统计行数 uniq -c #在输出行前面加上每行在输入文件中出现的次数 uniq -u #仅显示不重复的行 sort -nr -n：依照数值的大小排序 -r：以相反的顺序来排序 -k：按照哪一列进行排序 head -3 #取前三名
耗时较长前十的URL
awk '{print $23 $5}' access.log | sort | sort -nr | head -n 10
访问前十的URL
awk '{print $5}' access.log | sort | uniq -c |sort -nr | head -n 10
