Cache All The Things

Transcription

1 Cache All The Things

2 About Me Mike Bell Drupal

3 Exactly what things? erm... everything!

4 No really... Frontend: - HTML - CSS - Images - Javascript Backend: - PHP - MySQL So pretty much everything then!

5 Where to start? Ask yourself: Why is my site slow? a) Bad code b) Bad server c) It's not!

6 Bad Code Stop. Caching will help... but it won't solve your bigger issues. There are tools to help - xhprof (not covered here)

7 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.

8 It's not! I like you! Caching is always a good thing, except when you have to debug it...

9 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)

10 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!

11 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 -

12 Resource Caching Many different types of resources Each can be cached by different tools Example: - Drupals CSS/JS Cache - Drupals Page Cache - Boost - Varnish

13 Resource Caching Drupal default: CSS/JS and Page (taken from digital006.com - ooppss!)

14 Resource Caching - Boost Boost - Static caching for all Drupal Assets Anonymous users only Ideal for shared hosting environments Potentially the easiest to setup

15 Resource Caching - Varnish Application Accelerator Linux Only Caches resources based on initial view Anonymous only - very picky with sessions and cookies Insanely Powerful

16 Resource Caching - Varnish Advanced setup - requires additional module and VCL for Drupal - Granular ttls (time to live) Specific resource (image/css) and page element! All available through VCL config.

17 Resource Caching - Varnish Anatomy of a varnish hit: HTTP/ OK Server: Apache X-Drupal-Cache: MISS Expires: Sun, 19 Nov :00:00 GMT Last-Modified: Tue, 08 Jan :20: Cache-Control: public, max-age=900 ETag: " " Content-Language: en X-Generator: Drupal 7 ( Link: </node/5468>; rel="shortlink",< rel="canonical" Vary: Accept-Encoding Content-Type: text/html; charset=utf-8 Date: Tue, 08 Jan :20:22 GMT X-Varnish: Age: 3 Via: 1.1 varnish Connection: keep-alive X-Cache: HIT

18 Resource Caching - Varnish Cache Stores - RAM - Disk Ram - super fast - requires a lot of ram Disk - fast - disk space is rarely an issue

19 Data Caching - memcached Data and Database caching layer Caches cache... (and things!)

20 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 - org/project/memcache and pecl extension

21 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

22 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.

23 3rd Party Caching - Cloudflare Similar to Akamai Smaller scale Emphasis on security and DDOS protection

24 Content Distribution Networks CDNs for short Offload resource handling to external provider - Images - Video - Audio - Large files Syndicate content around the world

25 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

26 How does it all fit together? Varnish Apache / Nginx Mysql / memcache Akamai Load Balancer Apache / Nginx Apache / Nginx Mysql / memcache Mysql / memcache Varnish Apache / Nginx Mysql / memcache

27 What happens when it all goes wrong?

28 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.

29 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

30 Debugging Tips Monitor each layer - Icinga - Pingdom

31 Any Questions?