網站突然一下子訪問不了了 

第一反應 重啟apache 恢復正常

後續工作就是排查原因

 tail -100 error_log

[Fri Sep 28 11:20:43 2018] [error] server reached MaxClients setting, consider raising the MaxClients setting [Fri Sep 28 11:25:29 2018] [notice] caught SIGTERM, shutting down [Fri Sep 28 11:25:30 2018] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Fri Sep 28 11:25:30 2018] [notice] Digest: generating secret for digest authentication ... [Fri Sep 28 11:25:30 2018] [notice] Digest: done [Fri Sep 28 11:25:30 2018] [notice] Apache/2.2.15 (Unix) DAV/2 PHP/5.6.37 mod_ssl/2.2.15 OpenSSL/1.0.1e-fips configured -- resuming normal operations 大體翻譯就是當前併發數超過設定連結數

ps -ef | grep httpd | wc -l

查詢apache併發連線數

netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'

檢視linux tcp連線數

/usr/sbin/httpd -l

檢視prefork還是worker模式

我這裡是prefork模式

去httpd.conf下配置

<IfModule prefork.c> StartServers       8 MinSpareServers    5 MaxSpareServers   20 ServerLimit      256 MaxClients       256 MaxRequestsPerChild  4000 </IfModule>

修改成

<IfModule prefork.c> StartServers     100 MinSpareServers  100 MaxSpareServers  100 ServerLimit     1024 MaxClients      1024 MaxRequestsPerChild  4000 </IfModule>

重啟apache生效