Day: February 28, 2011

小内存VPS的生存之道：Nginx + PHP FPM + Varnish

zhanxw 1 Comment

我用的是BuyVM.net一年$15的VPS，可想而知这个主机的配置是如何Economy: 128M 内存。原来使用的是Apache 1.3 prefork 和 Php_mod，系统稳定性非常好，然而性能可以说令人失望，打开一个简单的静态页面平均需要3秒，而使用wordpress及若干plugin后，差不多需要10秒以上才能访问页面，而且这是打开WP-Supercache后的性能。据我的观察，这是因为Apache进程会fork出很多子进程，这些进程吃掉了有限的VPS内存。2月的最后一天，我决定试一试传说中Nginx，看看它在小内存的VPS上表现是否优异。在8000端口打开Nginx后，使用http://whichloadsfaster.com/和ab – Apache HTTP server benchmarking tool 比较Nginx和Apache的速度，毫无悬念的，Nginx要快，平均只用了1/4的时间。因此我下定决心，将整个VPS升级到Nginx+PHP FPM。具体的步骤如下：

1. 升级Ubuntu 10.04 LTS Lucid 到 10.10 Maverick

升级的目的是使用Ubuntu官方的PHP，因为只有10.10版的PHP5才包括了php5-fpm功能。

具体方法（翻译自http://www.howtoforge.com/how-to-upgrade-ubuntu-10.04-lucid-lynx-to-10.10-maverick-meerkat-desktop-and-server-p2）：

aptitude install update-manager-core

改变 /etc/update-manager/release-upgrades 中Prompt=normal

do-release-upgrade

我在升级中反复遇到关于procps的这个提示：start: Unknow Jobs: procps

解决方法就是建立一个/etc/init/procps.conf，然后继续apt-get upgrade就行。

原理是service 这个命令会调用/etc/init.d下面的脚本，而procps的脚本会用start命令，start procps命令会调用initctl start procps, 这个过程中需要/etc/init/procps.conf来设定procps相关的参数。在ubuntu升级的时候，这个配置文件缺失造成了上述问题。


2. 安装Nginx

先卸载Apache, 用apt-get install nginx就行，之后参考：

http://www.howtoforge.com/installing-nginx-with-php-5.3-and-php-fpm-on-ubuntu-lucid-lynx-10.04-without-compiling-anything

我这里也列出了自己的nginx.conf文件内容，注意我使用了rewrite功能。这一功能在Apache里是用mod_rewrite支持，在.htaccess里指定的。我们写在nginx.conf文件里也不复杂。另外，末尾的backend语句似乎是必须的，没有它PHP似乎就无法工作。

My /etc/nginx/nginx.conf

user www-data;
worker_processes  1;

error_log  /var/log/nginx/error.log;
pid        /var/run/nginx.pid;

events {
 use epoll;
 worker_connections  1024;
 # multi_accept on;
}

http {
 include       /etc/nginx/mime.types;

 access_log  /var/log/nginx/access.log;

 sendfile        on;
 #tcp_nopush     on;

 #keepalive_timeout  0;
 keepalive_timeout  65;
 tcp_nodelay        on;

 gzip  on;
 gzip_disable "MSIE [1-6]\.(?!.*SV1)";

 include /etc/nginx/conf.d/*.conf;
 include /etc/nginx/sites-enabled/*;
}

My /etc/nginx/sites-enabled/default

 server {
 listen   8080;
 server_name  zhanxw.com;
 access_log  /var/log/nginx/localhost.access.log;

 root    /var/www;
## Default location
 location / {
 root   /var/www;
 index  index.php index.html;
 }

location /blog/ {
 index index.php;
 if (-e $request_filename) {
 break;
 }
 rewrite ^/blog/(.+)$ /blog/index.php?q=$1 last;
 }

## Images and static content is treated different
 location ~* ^.+.(jpg|jpeg|gif|css|png|js|ico|xml)$ {
 access_log        off;
 expires           30d;
 root /var/www;
 }

## Parse all .php file in the /var/www directory
 location ~ .php$ {
 fastcgi_split_path_info ^(.+\.php)(.*)$;
 fastcgi_pass   backend;
 fastcgi_index  index.php;
 fastcgi_param  SCRIPT_FILENAME  /var/www$fastcgi_script_name;
 include fastcgi_params;
 fastcgi_param  QUERY_STRING     $query_string;
 fastcgi_param  REQUEST_METHOD   $request_method;
 fastcgi_param  CONTENT_TYPE     $content_type;
 fastcgi_param  CONTENT_LENGTH   $content_length;
 fastcgi_intercept_errors        on;
## Images and static content is treated different
 location ~* ^.+.(jpg|jpeg|gif|css|png|js|ico|xml)$ {
 access_log        off;
 expires           30d;
 root /var/www;
 }

## Parse all .php file in the /var/www directory
 location ~ .php$ {
 fastcgi_split_path_info ^(.+\.php)(.*)$;
 fastcgi_pass   backend;
 fastcgi_index  index.php;
 fastcgi_param  SCRIPT_FILENAME  /var/www$fastcgi_script_name;
 include fastcgi_params;
 fastcgi_param  QUERY_STRING     $query_string;
 fastcgi_param  REQUEST_METHOD   $request_method;
 fastcgi_param  CONTENT_TYPE     $content_type;
 fastcgi_param  CONTENT_LENGTH   $content_length;
 fastcgi_intercept_errors        on;
 fastcgi_ignore_client_abort     off;
 fastcgi_connect_timeout 60;
 fastcgi_send_timeout 180;
 fastcgi_read_timeout 180;
 fastcgi_buffer_size 128k;
 fastcgi_buffers 4 256k;
 fastcgi_busy_buffers_size 256k;
 fastcgi_temp_file_write_size 256k;
 }

## Disable viewing .htaccess & .htpassword
 location ~ /\.ht {
 deny  all;
 }
}
upstream backend {
 server 127.0.0.1:9000;
}

3. 安装PHP FPM

使用apt-get install php5-fpm php-apc php5-cgi php5-cli php5-mysql php5-common php-pear php5-curl php5-suhosin php5-gd php5-imagick imagemagick php5-mhash php5-mcrypt即可。

注意安装后可以用service php5-fpm start来检查是否有缺失的php5模块。例如如果见到：

* Starting PHP5 FPM… PHP Warning: PHP Startup: Unable to load dynamic library ‘/usr/lib/php5/20090626+lfs/mcrypt.so’ – /usr/lib/php5/20090626+lfs/mcrypt.so: cannot open shared object file: No such file or directory in Unknown on line 0

Feb 27 15:40:28.053288 [WARNING] [pool www] pm.start_servers is not set. It’s been set to 10.

这说明应该安装php5-mcrypt。后面的WARNING可以忽略。

另外，小内存VPS上使用PHP-FPM可以控制其进程个数。在我的VPS上，单个PHP-FPM可以使用多达100M的内存，同时我的访问量很少，因此我设置PHP-FPM使用static方式维持2个进程。从实践来看系统可以保持合理的响应时间，同时内存不会被用光。

我的PHP-FPM 的配置文件/etc/php5/fpm/pool.d/www.conf  列在下面：

 ...
; Choose how the process manager will control the number of child processes.
; Possible Values:
;   static  - a fixed number (pm.max_children) of child processes;
;   dynamic - the number of child processes are set dynamically based on the
;             following directives:
;             pm.max_children      - the maximum number of children that can
;                                    be alive at the same time.
;             pm.start_servers     - the number of children created on startup.
;             pm.min_spare_servers - the minimum number of children in 'idle'
;                                    state (waiting to process). If the number
;                                    of 'idle' processes is less than this
;                                    number then some children will be created.
;             pm.max_spare_servers - the maximum number of children in 'idle'
;                                    state (waiting to process). If the number
;                                    of 'idle' processes is greater than this
;                                    number then some children will be killed.
; Note: This value is mandatory.
pm = static

; The number of child processes to be created when pm is set to 'static' and the
; maximum number of child processes to be created when pm is set to 'dynamic'.
; This value sets the limit on the number of simultaneous requests that will be
; served. Equivalent to the ApacheMaxClients directive with mpm_prefork.
; Equivalent to the PHP_FCGI_CHILDREN environment variable in the original PHP
; CGI.
; Note: Used when pm is set to either 'static' or 'dynamic'
; Note: This value is mandatory.
pm.max_children = 2

...

4.安装eAccelerator

主要参考：http://developer.mindtouch.com/en/kb/Improve_PHP_performance_with_eAccelerator_on_Ubuntu_8.04_(Debian)

基本上下载，编译，安装。之后在php.ini中加入下面几行即可（注意.so文件的路径）：

 ; eAccelerator configuration
; Note that eAccelerator may also be installed as a PHP extension or as a zend_extension
; If you are using a thread safe build of PHP you must use
; zend_extension_ts instead of zend_extension
;extension                       = "/usr/lib/php5/20060613+lfs/eaccelerator.so"
zend_extension                  = "/usr/lib/php5/20090626+lfs/eaccelerator.so"
eaccelerator.shm_size           = "16"
eaccelerator.cache_dir          = "/var/cache/eaccelerator"
eaccelerator.enable             = "1"
eaccelerator.optimizer          = "1"
eaccelerator.check_mtime        = "1"
eaccelerator.debug              = "0"
eaccelerator.filter             = ""
eaccelerator.shm_max            = "0"
eaccelerator.shm_ttl            = "0"
eaccelerator.shm_prune_period   = "0"
eaccelerator.shm_only           = "0"
eaccelerator.compress           = "1"
eaccelerator.compress_level     = "9"
eaccelerator.allowed_admin_path = "/var/www/eaccelerator"

安装完之后注意检查<?php phpinfo(); ?>页面的输出，保证eAccelerator开启。

5. 启用Varnish

偶然间听说Varnish可以做代理，提供系统响应速度。以我的经验来看，对于静态页面，通过Varnish获取页面和直接使用nginx差别不大（动态页面未测试）。但用Varnish在80端口监听，听起来可以把真正的服务器挡在Varnish之后，似乎可以增强安全性吧。我在VPS上安装Varnish，应注意Varnish本意的版本变化较快，在配置时应注意路径的变化。需要配置两个文件，第一个是

/etc/default/varnish 应改成START=yes，否则会出现这个错误Not starting HTTP accelerator varnishd （http://twitter.com/#!/grosser/status/5249558112108544）；另一个是/etc/varnish/default.vcl，我参考了http://wowubuntu.com/varnish.html 以及http://blog.mudy.info/2009/04/my-varnish-vcl-for-wordpress/，这里列出我的配置文件/etc/varnish/default.vcl：

 backend default {
.host = "localhost";
.port = "8080";
}
acl purge {
"localhost";
}
sub vcl_recv {
if (req.request == "PURGE") {
if (!client.ip ~ purge) {
error 405 "Not allowed.";
}
return(lookup);
}
if (req.url ~ "^/$") {
unset req.http.cookie;
}
}
sub vcl_hit {
if (req.request == "PURGE") {
set obj.ttl = 0s;
error 200 "Purged.";
}
}
sub vcl_miss {
if (req.request == "PURGE") {
error 404 "Not in cache.";
}
if (!(req.url ~ "wp-(login|admin)")) {
unset req.http.cookie;
}
if (req.url ~ "^/[^?]+.(jpeg|jpg|png|gif|ico|js|css|txt|gz|zip|lzma|bz2|tgz|tbz|html|htm)(\?.|)$") {
unset req.http.cookie;
set req.url = regsub(req.url, "\?.$", "");
}
if (req.url ~ "^/$") {
unset req.http.cookie;
}
}
sub vcl_fetch {
if (req.url ~ "^/$") {
unset beresp.http.set-cookie;
}
if (!(req.url ~ "wp-(login|admin)")) {
unset beresp.http.set-cookie;
}
}

插曲1：重置MySQL密码

好就不用MySQL的root密码，重置密码（适用于MySQL 5.1）可以参考：

Generic method http://dev.mysql.com/doc/refman/5.1/en/resetting-permissions.html

只需要3步：以--skip-grant-tables参数启动Mysql-server；启动mysql；执行

UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root';
FLUSH PRIVILEGES;

插曲2：使Firefox 支持Java Applets

在设置PHP-FPM 参数不当时，有可能整个VPS的内存全部被吃光，这时没法用SSH登录，很多命令（sudo、ls、top）都无法执行，这时候可以用BuyVM.net 提供的 manage.buyvm.net 页面，以Java Applets方式以root身份登录到VPS。默认情况下，Ubuntu的Firefox不支持Java Applets，解决方法就是安装：icedtea6-plugin .


另附：Wordpress中插入代码的方法：

注意这里使用了中文的全角括号，以免Wordpress当成真正的代码。

【sourcecode language=”css”】
your code here
【/sourcecode】

具体的语言可以有：

  • actionscript3
  • bash
  • coldfusion
  • cpp
  • csharp
  • css
  • delphi
  • erlang
  • fsharp
  • diff
  • groovy
  • javascript
  • java
  • javafx
  • matlab (keywords only)
  • objc
  • perl
  • php
  • text
  • powershell
  • python
  • r
  • ruby
  • scala
  • sql
  • vb
  • xml

http://en.support.wordpress.com/code/posting-source-code/