Nginx 出現 500 Error 修復 (too many open file, connection)

Nginx 出現 500 Error, 錯誤訊息只能從 Log 查到, 有遇到下述兩種狀況:

1. socket() failed (24: Too many open files) while connecting to upstream
2. 512 worker_connections are not enough while connecting to upstream

在此紀錄解決方法.

Nginx "Too many open files" 修復

錯誤訊息

2011/05/01 23:00:49 [alert] 7387#0: *6259768 socket() failed (24: Too many open files) while connecting to upstream, client: 123.123.123.123, server: www.example.com, request: "GET [[/]] HTTP/1.1", upstream: "fastcgi://127.0.0.1:1234", host: "www.example.com"

解法

1. $ sudo su - www-data
2. $ ulimit -n # 看目前系統設定的限制 (ulimit -a # 可查看全部參數)
   

   1024

3. vim /etc/security/limits.conf # 由此檔案設定 nofile (nofile - max number of open files) 的大小
   

   # 增加/修改 下述兩行
   * soft nofile 655360
   * hard nofile 655360

4. ulimit -n # 登出後, 在登入, 執行就會出現此值
   

   655360

4. 若 ulimit -n 沒出現 655360 的話, 可使用 ulimit -n 655360 # 強制設定

5. 再用 ulimit -n 或 ulimit -Sn (驗證軟式設定)、ulimit -Hn (驗證硬式設定) 檢查看看(或 ulimit -a).

從系統面另外計算 + 設定

1. lsof | wc -l # 計算開啟檔案數量
2. sudo vim /etc/sysctl.conf
   fs.file-max = 3268890
3. sudo sysctl -p

Nginx "512 worker_connections are not enough" 修復

錯誤訊息

2011/05/01 23:21:21 [alert] 19973#0: *6325881 512 worker_connections are not enough while connecting to upstream, client: 123.123.123.123, server: www.example.com, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:1234", host: "www.example.com"

解法

1. /etc/nginx/nginx.conf
   

   worker_connections  10240;

2. 參考 Nginx CoreModule
   

   worker_processes 2;
   worker_rlimit_nofile 10240;
   events {
   # worker_connections 10240;
   }

Nginx 的 connection 增加後, 整體速度會變慢很多, 主要原因是 php-cgi 不夠用, 所以要作以下調整.

php-cgi was started with phpfcgid_children="10" and phpfcgid_requests="500"
ab was run on another server, connect via a switch using GBit ethernet

參考此篇設定: PHP performance III -- Running nginx

1. vim /etc/nginx/nginx.conf
   

   worker_connections 10240;
   worker_rlimit_nofile

2. vim /etc/init.d/php-fcgi
   

   PHP_FCGI_CHILDREN=15
   PHP_FCGI_MAX_REQUESTS=1000
   改成
   PHP_FCGI_CHILDREN=512 # 或 150 慢慢加, 注意 MySQL connection 是否夠用
   PHP_FCGI_MAX_REQUESTS=10240

3. 上述文章的 phpfcgid_stop(), 寫得還不錯, 有需要可以用看看.
   

   phpfcgid_stop() {
echo "Stopping $name."
pids=`pgrep php-cgi`
pkill php-cgi
wait_for_pids $pids
}

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