Lighttpd
lighttpd:後端超載
我有一個高流量的網站,我正在努力維護,但有時會遇到高峰卡住:
(mod_fastcgi.c.2900) backend is overloaded; we'll disable it for 2 seconds and send the request to another backend instead: reconnects: 0 load: 2541
目前的統計數據是:
absolute (since start) Requests 15 kreq Traffic 20.02 Mbyte average (since start) Requests 81 req/s Traffic 106.24 kbyte/s average (5s sliding average) Requests 94 req/s Traffic 99.23 kbyte/s 3952 connections
該站點本身是一個非常簡單的 PHP 站點,不涉及 MySQL。我確實安裝並配置了 APC。
我在 /etc/sysctl.conf 中添加了建議的更改:
# These ensure that TIME_WAIT ports either get reused or closed fast. net.ipv4.tcp_fin_timeout = 1 net.ipv4.tcp_tw_recycle = 1 # TCP memory net.core.rmem_max = 16777216 net.core.rmem_default = 16777216 net.core.netdev_max_backlog = 262144 net.core.somaxconn = 262144 net.ipv4.tcp_syncookies = 1 net.ipv4.tcp_synack_retries = 2 net.ipv4.tcp_syn_retries = 2 net.ipv4.tcp_max_syn_backlog = 2048 net.ipv4.tcp_max_syn_backlog = 262144 net.ipv4.tcp_max_orphans = 262144
我的 lighttpd.conf 看起來像:
server.max-fds = 12000 server.max-keep-alive-requests = 0 server.event-handler = "linux-sysepoll" server.max-connections = 10000
fastcgi 配置:
## Start an FastCGI server for php (needs the php5-cgi package) fastcgi.server = ( ".php" => (( "bin-path" => "/usr/bin/php-cgi", "socket" => "/tmp/php.socket", "max-procs" => 14, "bin-environment" => ( "PHP_FCGI_CHILDREN" => "30", "PHP_FCGI_MAX_REQUESTS" => "100000" ), "bin-copy-environment" => ( "PATH", "SHELL", "USER" ), "broken-scriptfilename" => "enable" )) )
伺服器使用率:
top - 08:04:26 up 97 days, 15:14, 1 user, load average: 0.10, 0.08, 0.04 Tasks: 570 total, 3 running, 567 sleeping, 0 stopped, 0 zombie Cpu(s): 0.9%us, 0.2%sy, 0.0%ni, 98.5%id, 0.3%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 4056176k total, 3716120k used, 340056k free, 631600k buffers Swap: 995988k total, 15544k used, 980444k free, 1631236k cached
我嘗試了各種各樣的事情。我知道擁有高 mac procs 通常不好,但是如果我把它放低,伺服器會立即開始拋出 500 錯誤。
有沒有人有什麼建議可以嘗試調整以保持網站穩定?在單個伺服器上支持這種級別的流量是否合理?
“後端超載” - 這意味著 14 個後端之一超載(lighttpd通過附加“-”
max-procs
為每個後端創建不同的套接字max-procs
$$ number $$" 到套接字文件名)。 我會選擇較低的 max-procs 數字,而是增加 PHP_FCGI_CHILDREN,例如
"max-procs" => 2
and"PHP_FCGI_CHILDREN" => "210"
,或 4 和 100(或 1 和 400)。這應該會減少其中一個後端“已滿”而另一個仍然可以接受請求的機會。我不確定 APC 是否隨著 PHP_FCGI_CHILDREN 的數量而擴展。
另一種方法是將spawn-fcgi與multiwatch結合使用(multiwatch 執行 ‘max-procs’ 部分) - 在此解決方案中,所有 php 後端都在同一個套接字上,因此您不會遇到平衡問題。