Performance tuning on Apache, PHP, MySQL, WordPress v1.1 – Updated

Introduction

This tutorial is covering the web server performance tunings on MySQL, PHP and Apache, WordPress and BuddyPress or general web hosting purpose, the tuning example is based on CentOS 5.

The key of the following performance tuning is focus on memory and caching, most of people host a web site or forum or blog without any tunings or even use the all out-of-box setting.

OS Tuning

/etc/sysctl.conf

Share Memory

#2GB
kernel.shmmax = 2147483648
kernel.shmall = 2147483648
fs.file-max = 16384

MySQL Tuning

MySQL default setting is very inefficient, here is a baseline for a web access by >200 concurrent users running with Joomla, wordpress, phpbb..etc. DB query cache is quite important for a large website, it reduce lot of disk I/O, minimize the wait time for every of same query.

/etc/my.cnf

[mysqld]
key_buffer = 64M
sort_buffer = 1M
join_buffer = 1M
max_allowed_packet = 8M
max_heap_table_size = 16M
table_cache = 1024
sort_buffer_size = 8M
read_buffer_size = 1M
read_rnd_buffer_size = 768K
myisam_sort_buffer_size = 48M
thread_cache_size = 512
query_cache_type = 1
query_cache_limit = 4M
query_cache_size = 64M
tmp_table_size = 16M
# Try number of CPU's*2 for thread_concurrency
thread_concurrency = 4

max_write_lock_count = 1 #To force MySQL to temporarily elevate the priority of all SELECT statements that are waiting for a table after a specific number of inserts to the table occur. This allows READ locks after a certain number of WRITE locks.
low_priority_updates = 1

[isamchk]
key_buffer = 64M
sort_buffer = 64M
read_buffer = 16M
write_buffer = 16M

[myisamchk]
key_buffer = 64M
sort_buffer = 64M
read_buffer = 16M
write_buffer = 16M

Another good starting point for a WordPress hosting, appox uses 500MB – 1.2GB memory

key_buffer = 64M
sort_buffer = 1M
join_buffer = 12M
max_allowed_packet = 8M
max_heap_table_size = 160M
table_cache = 3096
thread_cache_size = 4
query_cache_limit = 512M
query_cache_size = 96M
tmp_table_size = 160M
innodb_buffer_pool_size = 26M

Please read the follwoing topic for MySQL Tuning suggestion

http://blog.mydream.com.hk/howto/linux/mysql-tuning-for-dummies

Apache Web Server Tuning

Default MPM setting is prefork, which consumes a lot of memory when your web site under stress. So considering to activate worker MPM is better idea to double up your current web capacity without adding additional hardware.

Switching to worker MPM with PHP will not gain any performance boost if you don’t have proper object cache or page cache, however running PHP apache module with prefork MPM is faster then worker MPM in CGI mode.
http://www.serverwatch.com/tutorials/article.php/3436911/Optimizing-Apache-Server-Performance.htm

/etc/sysconfig/httpd

HTTPD=/usr/sbin/httpd.worker

/etc/httpd/conf/httpd.conf

StartServers        6
MaxClients         300
MinSpareThreads     25
MaxSpareThreads     75
ThreadsPerChild     25
MaxRequestsPerChild  2000

Apache Prefork vs Worker
http://www.camelrichard.org/apache-prefork-vs-worker

Running PHP5 with Apache worker MPM

When you switched to worker MPM, you may immediately encountered errors on PHP module. Yes, you need to change the php from apache module to PHP CGI, it’s PHP thread safe issues on worker MPM.

Install FastCGI

wget "http://www.fastcgi.com/dist/mod_fastcgi-current.tar.gz"
cp Makefile.AP2 Makefile
make top_dir=/usr/lib64/httpd ## or make top_dir=/usr/lib/httpd ## for 32bit
make install

Add the LoadModule entry in /etc/httpd/conf/httpd.conf

LoadModule fastcgi_module modules/mod_fastcgi.so

Add a php.fcgi file in /var/www/cgi-bin/

#!/bin/sh
PHP_FCGI_CHILDREN=4
export PHP_FCGI_CHILDREN
PHP_FCGI_MAX_REQUESTS=0
export PHP_FCGI_MAX_REQUESTS
umask 0022
exec /usr/bin/php-cgi -d apc.shm_size=96M

and

chmod +x /var/www/cgi-bin/php.fcgi

set PHP_FCGI_CHILDREN=4 or higher depends on your CPU power
set PHP_FCGI_MAX_REQUESTS=10000 # or 0, to respawn the process after reaching maximum number of request, it prevent php having memory leak without a refreshment. On the other hand some application will having 500 internal errors because the process gone but the session wasn’t. Meanwhile, you do set it to 0 or a very high value, and closely monitor the php-cgi process that not ate up all memory.

Setting apc.shm_size=96M
a predictable memory size likely will be 96M x 4 and maximum memory = php memory limit x 4

For your reference, WordPress with BuddyPress consume quite much memory, in various test, it require about 48-60MB php memory, therefore to get a good performance for BP, you better set the cache size not fewer then 80M.

Disable mod php settings in /etc/httpd/conf.d

mv php.conf php.conf.disabled

Create new config php-cgi.conf in /etc/httpd/conf.d

maxClassProcesses parameter is very important, anything > 1 will let you lose object cache, so to get best the performance, use PHP_FCGI_CHILDREN instead of parent process. Unless you told me you don’t use object cache.

LoadModule fastcgi_module modules/mod_fastcgi.so
FastCgiConfig -idle-timeout 60 -maxClassProcesses 1 -maxProcesses 50
FastCgiWrapper On

DirectoryIndex index.php

AddHandler php5-fcgi .php
AddHandler php5-fcgi .fcgi
Action php5-fcgi /cgi-bin/php.fcgi

<Location "/cgi-bin/php.fcgi">
   Order Deny,Allow
   Deny from All
   Allow from env=REDIRECT_STATUS #Protect from direct access of this script
   Options ExecCGI
   SetHandler fastcgi-script
</Location>

http://www.cyberciti.biz/tips/rhel-centos-fedora-apache2-fastcgi-php-configuration.html

PHP 5.2

If you still running php 5.0, please upgrade it.
Put the following lines into /etc/yum.repos.d/c5-testing.repos

[c5-testing]
name=CentOS-5 Testing
baseurl=http://dev.centos.org/centos/$releasever/testing/$basearch/
enabled=1
gpgcheck=1
gpgkey=http://dev.centos.org/centos/RPM-GPG-KEY-CentOS-testing

remove all existing PHP5 and PECL rpm packages and run

yum install \
php \
php-mbstring \
php-ldap \
php-mysql \
php-mcrypt \
php-cli \
php-gd \
php-xml \
php-devel \
php-bcmath \
php-xmlrpc \
php-common \
php-soap \
php-pdo \
php-imap

Install memcached

memcached is a high-performance memory object caching system intended to speed up dynamic web applications by alleviating database load.

yum install memcached

/etc/sysconfig/memcached

PORT="11211"
USER="nobody"
MAXCONN="1024"
CACHESIZE="256"
OPTIONS=""

http://pswebsolutions.wordpress.com/2009/08/26/how-to-install-memcache-on-linux-server/

Install PHP memcache.so

cd
phpize
./configure --enable-memcache
make
cp memcache.so /usr/lib64/php/modules/

Enable it in /etc/php.ini

extension=memcache.so

http://www.howtoforge.com/php_memcache_centos5.0

Install eAccelerator

eAccelerator is a free open-source PHP accelerator, optimizer, and dynamic content cache. It increases the performance of PHP scripts by caching them in their compiled state, so that the overhead of compiling is almost completely eliminated. It also optimizes scripts to speed up their execution. eAccelerator typically reduces server load and increases the speed of your PHP code by 1-10 times.

wget "http://bart.eaccelerator.net/source/0.9.5.2/eaccelerator-0.9.5.2.tar.bz2"
tar xvfj eaccelerator-0.9.5.2.tar.bz2
cd eaccelerator-0.9.5.2
phpize
./configure
make
make install
mkdir /tmp/eaccelerator
chmod 777 /tmp/eaccelerator


/etc/php.ini

[eaccelerator]
zend_extension="/usr/lib64/php/modules/eaccelerator.so"
eaccelerator.shm_size="64"
eaccelerator.cache_dir="/tmp/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.log_file = "/var/log/httpd/eaccelerator_log"
http://www.php.ph/2007/12/21/centos-5-eaccelerator-installation/

Install APC

pecl install apc

http://www.debian-administration.org/articles/574

Create a apc.ini config file in /etc/php.d/

; /etc/php.d/apc.ini

extension=apc.so
apc.enabled="1"
apc.shm_segments="1"
apc.num_files_hint="1024"
apc.ttl="7200"
apc.user_ttl="7200"
apc.gc_ttl="3600"
apc.cache_by_default="1"
;apc.filters=""
apc.slam_defense="0"
apc.file_update_protection="2"
apc.enable_cli="0"
apc.max_file_size="1M"
apc.stat="1"
apc.write_lock="1"
apc.report_autofilter="0"
apc.include_once_override="0"
apc.rfc1867="0"
apc.rfc1867_prefix="upload_"
apc.rfc1867_name="APC_UPLOAD_PROGRESS"
apc.rfc1867_freq="0"
apc.localcache="0"
apc.localcache.size="512"
apc.coredump_unmap="0"

;apc.shm_size=128M ;;;;;;;; Don't define share memory here, we'll do it in php wrapper
apc.mmap_file_mask="/tmp/apcphp5.XXXXXX"
apc.mmap_address=703687441776

Compress PHP output using ob_gzhandler

/etc/php.ini

output_buffering = On
output_handler = ob_gzhandler
zlib.output_compression = Off

Apache deflate for contents compression

The mod_deflate module provides the DEFLATE output filter that allows output from your server to be compressed before being sent to the client over the network, it helps to improve contents transfer over network, it doesn’t really helps to speed up your web, but it speed up the content transfer flow and gain more user access through the same network without additional bandwidth.

# Set compression for: html,txt,xml,js,css
AddOutputFilterByType DEFLATE text/html text/plain text/xml application/xml application/xhtml+xml text/javascript text/css application/x-javascript
# Deactivate compression for buggy browsers
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4.0[678] no-gzip
BrowserMatch bMSIE !no-gzip !gzip-only-text/html
# Set header information for proxies
Header append Vary User-Agent

http://httpd.apache.org/docs/2.0/mod/mod_deflate.html

Recommended WordPress Plugins

W3 Total Cache – Highly recommended!
or
WP Super Cache
- Static HTML caching

WP Object Cache for memcached

wp-config.php

define( 'WP_CACHE', true );
define(’WP_POST_REVISIONS’, false);

Conclusion

Always measure the performance with or without tuning, the tuning parameters is just case by case. Some PHP scripts running with Fastcgi isn’t as fast as module, so you have to compared it side by side.

http://www.gnegg.ch/2006/08/mod_php-lighttpd-fastcgi-whats-fastest/