When dynamic becomes static : the next step in web caching techniques

When dynamic becomes static – the next
step in web caching techniques
Wim Godden
Cu.be Solutions

Disclaimer
The next step
As in : what you will be doing in the future
Not as in : go home and run it ;-)
Language of choice : PHP
But : think Perl, Python, Ruby, Java, .Net, …

Who am I ?
Wim Godden (@wimgtr)

Who am I ?
Wim Godden (@wimgtr)
Founder of Cu.be Solutions (http://cu.be)
Open Source developer since 1997
Developer of OpenX, PHPCompatibility, ...
Speaker at PHP and Open Source conferences

Who are you ?
Developers ?
System/network engineers ?
Managers ?

To understand the present
Understand the past

The Stone Age
New blog post by : caveman003

Pre-PHP : draw it and make html

Old-school PHP : 'rebuild-every-time'

PHP : dynamic content in static content

Website with ESI
Article content page
Page content
Header
Latest news
Navigation

Website with ESI
Page content
Top header
(TTL = 2h)
Latest news
Navigation
(TTL = 1h)

Website with ESI
Page content (TTL = 30m)
Top header
(TTL = 2h)
Latest news (TTL = 2m)
Navigation
(TTL = 1h)

ESI – how it works
GET /pageGET /page

<html>
...
<esi:include src="/top"/>
<esi:include src="/nav"/>
<div id=”something”>
<esi:include src="/latest-news"/>
</div>
<esi:include src="/article/id/732"/>
...
</html>
GET /pageGET /page

<div id=”top-part”>
<a href=”/login”>Login</a>
</div>
GET /top

<html>
...
<div id=”top-part”>
<a href=”/login”>Login</a>
</div>
<div id=”something”>
</div>
...
</html>
GET /pageGET /page

Going to /page/id/732
<html>
<div id="something">
</div>
</html>

<esi:include src="/article/732"/>
Varnish - ESI
<esi:include src="/news"/>
<esi:include
src="/nav"/>

Varnish - what can/can't be cached ?
Can :
Static pages
Images, js, css
Static parts of pages that don't change often (ESI)
Can't :
POST requests
Very large files (it's not a file server !)
Requests with Set-Cookie
User-specific content

ESI → no caching on user-specific content ?
Logged in as : Wim Godden
5 messages
TTL = 5minTTL=1h
TTL = 0s ?

Nginx
Web server
Reverse proxy
Lightweight, fast
13.46% of all Websites

Nginx
No threads, event-driven
Uses epoll / kqueue
Low memory footprint
10000 active connections = normal

ESI on Nginx
5 messages
NEWSMenu

ESI SLIC on Nginx
<slic:include key="news" src="/news" />
<slic:include
key="menu"
src="/menu" />
<slic:include key="top" src="/top" session="true" />

Requesting /page (1st
time)
Nginx
Shared memory
1
2
3
4
/page
/page

Requesting /page SLIC subrequests (1st
time)
Nginx
1
2
3
/menu
/news
/top (in SLIC session)

Requesting /page (next time)
Nginx
Shared memory
1
2
/page
/menu
/news
/top (in SLIC session)
/page

New message is sent...
POST /send
DB
insert into...
set(...)
top (in SLIC session)

Advantages
No repeated GET hits to webserver anymore !
At login : POST → warm up the cache !
No repeated hits for user-specific content
Not even for non-specific content

News added
addnews() method
DB
insert into...
set(...)
Memcache key /news

Advantages
No repeated GET hits to webserver anymore !
At login : POST → warm up the cache !
No repeated hits for user-specific content
Not even for non-specific content
No TTLs for non-specific content

How many Memcached requests ?
5 messages
<slic:include key="news" src="/news" />
<slic:include
key="menu"
src="/menu" />

First release : ESI
Part of the ESI 1.0 spec
Only relevant features implemented
Extension for dynamic session support
But : unavailable for copyright reasons

Rebuilt from scratch : SLIC
Control structures : if/else, switch/case, foreach
Variable handling
Strings : concatenation, substring, …
Exception handling, header manipulation, …
JSON support !

SLIC code samples
You are logged in as : <slic:session_var("person_name") />
You are logged in as : <@s("person_name") />

SLIC code samples
<slic:switch var="session_var('isAdmin')">
<slic:case value="1">
<slic:include key="admin-buttons" src="/admin-buttons.php" />
</slic:case>
<slic:default>
<div id="just-a-user">
<slic:include key="user-buttons" src="/user-buttons.php" />
</div>
</slic:default>
</slic:switch>

SLIC code samples
<slic:foreach item="messageId" src="global_var('thread' + query_var('threadId'))">
<slic:include key="'thread-message_' + messageId"
src="'/thread/message.php?id=' + messageId" />
</slic:foreach>

Approaches – full block
<p id=”LoggedInAs”>
</p>
<p id=”MessageCount”>
You have 5 messages
</p>
5 messages

Approaches – individual variables
</p>
You have <slic:session_var(“messages”) /> messages
</p>
5 messages

Approaches – JSON
You are logged in as : <slic:session_var("userData").person_name />
</p>
You have <slic:session_var(“userData”).message_count /> messages
</p>
5 messages

Identifying the user
In Nginx configuration :
slic_session_cookie <name> → Defined by language (or configurable)
slic_session_identifier <string> → Defined by you
Example for PHP :
slic_session_cookie PHPSESSID
slic_session_identifier UID

Identifying the user
Nginx + SLIC
Cookie :
PHPSESSID =
jpsidc1po35sq9q3og4f3hi6e2
get UID_jpsidc1po35sq9q3og4f3hi6e2432

Retrieving user specific content
Nginx + SLIC
Cookie :
PHPSESSID =
jpsidc1po35sq9q3og4f3hi6e2
get userData_432

Why Nginx ?
Native Memcached support
Excellent and superfast subrequest system
Including parallel subrequests
Handles thousands of connections per worker
With minimal memory footprint
Integrates with php-fpm
Additional features (chroot, slow request log, offline processing, ...)
Graceful rolling upgrades

Figures
2nd
customer :
No. of web servers : 72 → 8
No. of db servers : 15 → 4
Total : 87 → 12 (86% reduction !)
Last customer :
No. of total servers : +/- 1350
Expected reduction : 1350 → 380
Expected savings : €1.5 Million per year

A real example : vBulletin
Post
isModerator session variable
isAdmin session variable

A real example : vBulletin
DB Server Load Web Server Load Max Requests/sec (1 = 282)
0
5
10
15
20
25
30
35
Standard install
With Memcached
Nginx + SCL + memcached

Code changes
Required
Template conversion
Push-to-DB → Push-to-DB + Push-to-Cache
Choice :
If user is logged in → push updates to cache
If user is not logged in → warm up cache on login

Availability
Good news :
It will become Open Source
It's solid : ESI version stable at 4 customers
PHP version (currently for dev, later for docs and learning)
Bad news :
First customer holds copyrights
Total rebuild
→ Open Source release
No current projects, so spare time
Anyone feel like sponsoring ?
Beta : Aug 14 (?)
Stable : Oct 14 (?) - on Github

Contact
Twitter @wimgtr
Web http://techblog.wimgodden.be
Slides http://www.slideshare.net/wimg
E-mail wim.godden@cu.be

When dynamic becomes static : the next step in web caching techniques

Recomendados

Recomendados

Mais conteúdo relacionado

Mais procurados

Mais procurados (19)

Semelhante a When dynamic becomes static : the next step in web caching techniques

Semelhante a When dynamic becomes static : the next step in web caching techniques (20)

Mais de Wim Godden

Mais de Wim Godden (20)

Último

Último (20)

When dynamic becomes static : the next step in web caching techniques