Cache all the things - A guide to caching Drupal

About Me
Mike Bell
Drupal Developer

@mikebell_
http://drupal.org/user/189605

Exactly what things?
erm...

everything!

No really...
Frontend:
- HTML
- CSS
- Images
- Javascript
Backend:
- PHP
- MySQL

So pretty much everything then!

Where to start?
Ask yourself:
Why is my site slow?

a) Bad code
b) Bad server
c) It's not!

Bad Code
Stop.

Caching will help... but it won't solve your
bigger issues.

There are tools to help - xhprof (not covered
here)

Bad Server?
So how's £5.99 a month working out for you?

Caching will help... but you still have bigger
issues.

Scale horizontally/vertically for a quick fix then
work on additional caching.

It's not!
I like you!

Caching is always a good thing, except when
you have to debug it...

Caching in Drupal
- Code Level (cache_get/cache_set)
- APC (not covering)
- Resource caching (this get's tricky!)
- DB Layer
- CDNs (related to resource caching)

Code Level
Drupal has it's own caching api.

Module Developers use it!

cache_set - store data in Drupals cache table
cache_get - get data from Drupals cache table

You can even define your own cache tables!

Code Level (example)
<?php
function mymodule_cached_data($reset = FALSE) {
global $language;
$langcode = $language->language;

$data = &drupal_static(__FUNCTION__, NULL, $reset);

if (!isset($data)) {
if (!$reset && $cache = cache_get("mymodule_cached_data:$langcode") && !empty($cache->data)) {
$data = $cache->data;
}
else {
$data = t('This would be an array or string generated using translated strings.');
cache_set("mymodule_cached_data:$langcode", $data);
}
}
return $data;
}
?>

(source - http://drupal.org/node/145279)

Resource Caching
Many different types of resources

Each can be cached by different tools

Example:
- Drupals CSS/JS Cache
- Drupals Page Cache
- Boost
- Varnish

Resource Caching
Drupal default: CSS/JS and Page

(taken from digital006.com - ooppss!)

Resource Caching - Boost
Boost - http://drupal.org/project/boost

Static caching for all Drupal Assets

Anonymous users only

Ideal for shared hosting environments

Potentially the easiest to setup

Resource Caching - Varnish
Application Accelerator

Linux Only

Caches resources based on initial view

Anonymous only - very picky with sessions and
cookies

Insanely Powerful

Advanced setup - requires additional module
and VCL for Drupal
- http://drupal.org/project/varnish

Granular ttls (time to live)

Specific resource (image/css) and page
element! All available through VCL config.

Anatomy of a varnish hit:
HTTP/1.1 200 OK
Server: Apache
X-Drupal-Cache: MISS
Expires: Sun, 19 Nov 1978 05:00:00 GMT
Last-Modified: Tue, 08 Jan 2013 21:20:17 +0000
Cache-Control: public, max-age=900
ETag: "1357680017-1"
Content-Language: en
X-Generator: Drupal 7 (http://drupal.org)
Link: </node/5468>; rel="shortlink",<http://badgerfakedomain.com/>; rel="canonical"
Vary: Accept-Encoding
Content-Type: text/html; charset=utf-8
Date: Tue, 08 Jan 2013 21:20:22 GMT
X-Varnish: 979772308 979772303
Age: 3
Via: 1.1 varnish
Connection: keep-alive
X-Cache: HIT

Cache Stores
- RAM
- Disk

Ram - super fast - requires a lot of ram
Disk - fast - disk space is rarely an issue

Data Caching - memcached
Data and Database caching layer

Caches cache...
(and things!)

Data Caching - memcached
Example:
Core cache - core cache tables (cache_*)

Moved into memcached and shared between
multiple instances across multiple servers

Simple api makes getting and setting easy

Drupal requires - http://drupal.
org/project/memcache and pecl extension

3rd Party Caching - Akamai
One of the biggest caching providers

A high chance you've experienced Akamai 4-5
times today.

Static cache of resources
Content Distribution Network
100+ Edge servers all over the planet

3rd Party Caching - Akamai
Coverage for DDOS attacks
- Active monitoring and defense

Advanced redirection rules through control
panel

It's not cheap!

It's also pretty magical.

3rd Party Caching - Cloudflare
Similar to Akamai

Smaller scale

Emphasis on security and DDOS protection

Content Distribution Networks
CDNs for short

Offload resource handling to external provider
- Images
- Video
- Audio
- Large files

Syndicate content around the world

Content Distribution Network
Why use a CDN?
- Content is delivered quicker
-- Latency cut down

Pricing is granular - pay as you go type deal

Amazon + Rackspace Cloud Files

How does it all fit together?

Apache / Mysql /
Varnish Nginx memcache

Apache / Mysql /
Nginx memcache
Akamai Load Balancer
Apache / Mysql /
Nginx memcache
Varnish Apache / Mysql /
Nginx memcache

What happens when it all goes
wrong?

Caching to the rescue
Each layer provides protection

3rd Party - shield 99% of anon traffic
Varnish - the rest

Anonymous users should never know your site
has issues.

Debugging Tips
Configure different urls for different platforms
- Easier to identify what cache layer has an
issue

Don't be afraid to flush caches
- Your backend should be able to cope with it

Analyse headers! Drupal and Varnish provide a
lot of info

Debugging Tips
Monitor each layer
- Icinga
- Pingdom

Cache all the things - A guide to caching Drupal

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à Cache all the things - A guide to caching Drupal

Similaire à Cache all the things - A guide to caching Drupal (20)

Plus de digital006

Plus de digital006 (6)

Cache all the things - A guide to caching Drupal