Caching and tuning funfor high scalability
Wim GoddenCu.be Solutions
Who am I ?
Wim Godden (@wimgtr)
Owner of Cu.be Solutions (http://cu.be)
Open Source developer since 1997
Developer of OpenX
Zend Certified Engineer
Zend Framework Certified Engineer
MySQL Certified Developer
Who are you ?
Developers ?
System/network engineers ?
Managers ?
Caching experience ?
Caching and tuning funfor high scalability
Wim GoddenCu.be Solutions
Goals of this tutorial
Everything about caching and tuning
A few techniquesHow-to
How-NOT-to
Increase reliability, performance and scalability
5 visitors/day 5 million visitors/day
(Don't expect miracle cure !)
LAMP
Architecture
Our base benchmark
Apachebench = useful enough
Result ?
Single webserverProxy
StaticPHPStaticPHP
Apache + PHP390017.5670017.5
Limit :CPU, networkor disk
Limit :database
Caching
What is caching ?
CACHE
What is caching ?
x = 5, y = 2n = 50Same resultCACHE
select*fromarticlejoin useron article.user_id = user.idorder
bycreated desclimit10
Doesn't changeall the time
Theory of caching
DB
Cache$data = get('key')falseGET /pagePageselect data from
table$data = returned resultset('key', $data)if ($data ==
false)
Theory of caching
DB
Cache
HIT
Caching techniques
#1 : Store entire pages#2 : Store part of a page (block)#3 :
Store data retrieval (SQL ?)#4 : Store complex processing result#?
: Your call !
When you have data, think :Creating time ?
Modification frequency ?
Retrieval frequency ?
How to find cacheable data
New projects : start from 'cache everything'
Existing projects :Look at MySQL slow query log
Make a complete query log (don't forget to turn it off !)
Check page loading times
Caching storage - Disk
Data with few updates : good
Caching SQL queries : preferably not
DON'T use NFS or other network file systemsespecially for
sessions
locking issues !
high latency
Caching storage - Disk / ramdisk
Local5 Webservers 5 local caches Hard to scale
How will you keep them synchronized ? Don't say NFS or rsync
!
Caching storage - Memcache(d)
Facebook, Twitter, YouTube, need we say more ?
Distributed memory caching system
Multiple machines 1 big memory-based hash-table
Key-value storage systemKeys - max. 250bytes
Values - max. 1Mbyte
Caching storage - Memcache(d)
Facebook, Twitter, YouTube, need we say more ?
Distributed memory caching system
Multiple machines 1 big memory-based hash-table
Key-value storage systemKeys - max. 250bytes
Values - max. 1Mbyte
Extremely fast... non-blocking, UDP (!)
Memcache - where to install
Memcache - where to install
Memcache - installation & running it
InstallationDistribution package
PECL
Windows : binaries
RunningNo config-files
memcached -d -m -l -p
ex. : memcached -d -m 2048 -l 172.16.1.91 -p 11211
Caching storage - Memcache - some notes
Not fault-tolerantIt's a cache !
Lose session data
Lose shopping cart data
...
Caching storage - Memcache - some notes
Not fault-tolerantIt's a cache !
Lose session data
Lose shopping cart data
Firewall your Memcache port !
Memcache in code
