nginx缓存命中率统计
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nginx提供了$upstream_cache_status这个变量来显示缓存的状态，我们可以在配置中添加一个http头来显示这一状态，达到类似squid的效果。 location / {
proxy_redirect off;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 180;
proxy_send_timeout 180;
proxy_read_timeout 180;
proxy_buffer_size 128k;
proxy_buffers 4 128k;
proxy_busy_buffers_size 128k;
proxy_temp_file_write_size 128k;
proxy_cache cache;
proxy_cache_valid 200 304 1h;
proxy_cache_valid 404 1m;
proxy_cache_key $uri$is_args$args;
add_header Nginx-Cache "$upstream_cache_status";
proxy_pass http://backend;
}
HTTP/1.1 200 OK
Date: Mon, 22 Apr 2013 02:10:02 GMT
Server: nginx
Content-Type: p_w_picpath/jpeg
Content-Length: 23560
Last-Modified: Thu, 18 Apr 2013 11:05:43 GMT
Nginx-Cache: HIT
Accept-Ranges: bytes
Vary: User-Agent
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"'
'"$upstream_cache_status"';
awk '{if($NF=="\"HIT\"") hit++} END {printf "%.2f%",hit/NR}' access.log
30.15%
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$upstream_cache_status包含以下几种状态：
·MISS 未命中，请求被传送到后端
·HIT 缓存命中
·EXPIRED 缓存已经过期请求被传送到后端
·UPDATING 正在更新缓存，将使用旧的应答
·STALE 后端将得到过期的应答 |
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缓存命中率统计实例：
1. 每天0点切割nginx日志
2. 将每日的缓存统计存入日志以供参考# crontab -l
1 0 * * * /opt/shell/nginx_cache_hit >> /usr/local/nginx/logs/hit
# cat /opt/shell/nginx_cache_hit
#!/bin/bash
LOG_FILE='/usr/local/nginx/logs/access.log.1'
LAST_DAY=$(date +%F -d "-1 day")
awk '{if($NF=="\"HIT\"") hit++} END {printf "'$LAST_DAY': %d %d %.2f%\n", hit,NR,hit/NR}' $LOG_FILE
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