When dynamic becomes static : the next step in web caching techniques
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Although tools like Varnish can improve performance and scalability for static sites, when user-specific content is needed, a hit to the PHP/Ruby/Python/.Net backend is still required, causing scalability issues. We’ll look at a brand-new Nginx module which implements an ultra-fast and scalable solution to this problem, changing the way developers think about designing sites with user-specific content.
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When dynamic becomes static : the next step in web caching techniques
- 1. When dynamic becomes static (the next step in web caching techniques) Wim Godden Cu.be Solutions @wimgtr
- 2. 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, …
- 3. Who am I ? Wim Godden (@wimgtr)
- 10. My town
- 11. My town
- 12. Belgium – the traffic
- 13. Who am I ? Wim Godden (@wimgtr) Founder of Cu.be Solutions (http://cu.be) Open Source developer since 1997 Developer of OpenX, PHPCompatibility, PHPConsistent, ... Speaker at Open Source conferences
- 14. Who are you ? Developers ? System/network engineers ? Managers ?
- 15. To understand the present Understand the past
- 16. The Stone Age New blog post by : caveman003
- 17. Pre-dynamic : draw it and make html
- 18. The Egyptian Era
- 19. Old-school dynamic : 'rebuild-every-time'
- 21. Dynamic : let's cache
- 22. Extra ! Extra !
- 23. Dynamic content in static content
- 24. The Modern Era
- 25. More load, more webservers
- 26. Pushing updates to cache
- 27. Today
- 28. Adding reverse proxy caching
- 29. Typical website structure Header Latest news Article content page Page content Navigation
- 30. Caching blocks with individual TTLs Top header (TTL = 2h) Latest news Article content page Page content Navigation (TTL = 1h)
- 31. Caching blocks with individual TTLs Top header (TTL = 2h) Latest news (TTL = 2m) Article content page Page content (TTL = 30m) Navigation (TTL = 1h)
- 32. ESI – how it works GET /page GET /page
- 33. ESI – how it works GET /page GET /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>
- 34. ESI – how it works GET /top <div id=”top-part”> <a href=”/login”>Login</a> </div>
- 35. ESI – how it works GET /page GET /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>
- 36. ESI – how it works GET /page GET /page <html> ... <div id=”top-part”> <a href=”/login”>Login</a> </div> <esi:include src="/nav"/> <div id=”something”> <esi:include src="/latest-news"/> </div> <esi:include src="/article/id/732"/> ... </html>
- 37. 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
- 38. ESI → no caching on user-specific content ? Logged in as : Wim Godden 5 messages TTL = 0s ? TTL=1h TTL = 5min
- 39. Error... does not compute !
- 40. Back in 2010
- 41. No more backend GET /page DB
- 42. No more backend GET /page
- 43. Nginx Web server Reverse proxy Lightweight, fast Low memory footprint 14.54% of all Websites
- 44. Nginx No threads, event-driven Uses epoll / kqueue 20000 active connections = normal 20000 req/sec = normal
- 45. ESI on Nginx Logged in as : Wim Godden 5 messages Menu NEWS
- 46. ESI SLIC on Nginx Logged in as : Wim Godden 5 messages Menu NEWS
- 47. Requesting /page (1st time) Nginx Shared memory 1 2 3 4 /page /page
- 48. Requesting /page SLIC subrequests (1st time) Nginx 1 2 3 /menu /news /top (with session cookie) /menu /news /top (in SLIC session)
- 49. Requesting /page (next time) Nginx Shared memory 1 2 /page /page /menu /news /top (in SLIC session)
- 50. SLIC on Nginx <slic:include key="top" src="/top" session="true" /> <slic:include key="news" src="/news" /> <slic:include key="menu" src="/menu" /> Logged in as : Wim Godden 5 messages ???
- 51. New message is sent... POST /send DB insert into... set(...) top (in SLIC session)
- 52. 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
- 53. News added addnews() method DB insert into... set(...) Memcache key /news
- 54. How many Memcached requests ? Logged in as : Wim Godden 5 messages <slic:include key="top" src="/top" session="true" /> <slic:include key="news" src="/news" /> <slic:include key="menu" src="/menu" />
- 55. First release : ESI Part of the ESI 1.0 spec Only relevant features implemented Extension for dynamic session support But : unavailable for copyright reasons
- 56. Rebuilt from scratch : SLIC Control structures : if/else, switch/case, foreach Variable handling Strings : concatenation, substring, … Exception handling, header manipulation, … JSON support !
- 57. SLIC code samples You are logged in as : <slic:session_var("person_name") /> You are logged in as : <@s("person_name") />
- 58. 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>
- 59. 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>
- 60. Approaches – full block Logged in as : Wim Godden <p id=”LoggedInAs”> You are logged in as : <slic:session_var("person_name") /> </p> <p id=”MessageCount”> You have 5 messages </p> 5 messages <slic:include key="top" src="/top" session="true" /> top_31
- 61. Approaches – individual variables Logged in as : Wim Godden <p id=”LoggedInAs”> You are logged in as : <slic:session_var("person_name") /> </p> <p id=”MessageCount”> You have <slic:session_var(“messages”) /> messages </p> 5 messages <slic:include key="top" src="/top" session="true" />
- 62. Approaches – JSON Logged in as : Wim Godden 5 messages <slic:include key="top" src="/top" session="true" /> <p id=”LoggedInAs”> You are logged in as : <slic:session_var("userData").person_name /> </p> <p id=”MessageCount”> You have <slic:session_var(“userData”).message_count /> messages </p>
- 63. 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 UserID
- 64. Identifying the user Cookie : PHPSESSID = jpsidc1po35sq9q3og4f3hi6e2 Nginx + SLIC 4g3e2t UserID_jpsidc1po35sq9q3og4f3hi6e2
- 65. Retrieving user specific content Nginx + SLIC get userData_432 Cookie : PHPSESSID = jpsidc1po35sq9q3og4f3hi6e2
- 66. 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
- 67. What's the result ?
- 68. 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
- 69. Why is it so much faster ?
- 70. A real example : vBulletin
- 71. A real example : vBulletin Post isAdmin session variable isModerator session variable
- 72. A real example : vBulletin DB Server Load Web Server Load Max Requests/sec (1 = 282) 35 30 25 20 15 10 5 0 Standard install With Memcached Nginx + SCL + memcached
- 73. 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
- 74. Availability Good news : It will become Open Source The concept is solid : ESI version stable at 4 customers Bad news : First customer holds copyrights Total rebuild → Open Source release No current projects, so spare time Anyone feel like sponsoring ? Beta : October ! Stable : January
- 75. So...
- 76. Questions ?
- 77. Questions ?
- 78. Contact Twitter @wimgtr Web http://techblog.wimgodden.be Slides http://www.slideshare.net/wimg E-mail wim.godden@cu.be