Caching has been a 'hot' topic for a few years. But caching takes more than merely taking data and putting it in a cache : the right caching techniques can improve performance and reduce load significantly. But we'll also look at some major pitfalls, showing that caching the wrong way can bring down your site. If you're looking for a clear explanation about various caching techniques and tools like Memcached, Nginx and Varnish, as well as ways to deploy them in an efficient way, this talk is for you.

1. Caching and tuning fun for high scalability Wim Godden Cu.be Solutions

3. Owner of Cu.be Solutions (http://cu.be)

4. Open Source developer since 1997

5. Developer of OpenX

6. Zend Certified Engineer

7. Zend Framework Certified Engineer

8. MySQL Certified Developer

10. System/network engineers ?

11. Managers ?

12. Caching experience ?

13. Caching and tuning fun for high scalability Wim Godden Cu.be Solutions

17. 5 visitors/day -> 5 million visitors/day

18. (Don't expect miracle cure !)

19. LAMP

20. Architecture

22. Result ? Single webserver Proxy Static PHP Static PHP Apache + PHP 3900 17.5 6700 17.5 Limit : CPU, network or disk Limit : database

23. Caching

24. What is caching ?

25. What is caching ? select * from article join user on article.user_id = user.id order by created desc limit 10

26. Theory of caching if ($data == false) DB

27. Theory of caching DB

29. Modification frequency ?

30. Retrieval frequency ?

33. Make a complete query log (don't forget to turn it off !)

34. Check page loading times

36. Caching SQL queries : preferably not

38. locking issues !

39. high latency

41. -> Hard to scale

44. Distributed memory caching system

45. Multiple machines ↔ 1 big memory-based hash-table

47. Values - max. 1Mbyte

49. Distributed memory caching system

50. Multiple machines ↔ 1 big memory-based hash-table

53. Memcache - where to install

54. Memcache - where to install

56. PECL

58. memcached -d -m <mem> -l <ip> -p <port>

59. ex. : memcached -d -m 2048 -l 172.16.1.91 -p 11211

61. Lose session data

62. Lose shopping cart data

63. ...

65. Lose session data

66. Lose shopping cart data

68. Memcache in code <?php $memcache = new Memcache(); $memcache->addServer( '172.16.0.1' , 11211); $memcache->addServer( '172.16.0.2' , 11211); $myData = $memcache->get( 'myKey' ); if ($myData === false ) { $myData = GetMyDataFromDB(); // Put it in Memcache as 'myKey', without compression, with no expiration $memcache->set( 'myKey' , $myData, false , 0); } echo $myData;

71. Benchmark with Memcache Single webserver Proxy Static PHP Static PHP Apache + PHP 3900 17.5 6700 17.5 Apache + PHP + MC 3900 55 6700 108

73. Slab 2 : 480 bytes (400 * 1.2)

75. Store a lot of very large objects

76. -> Large slabs : full

77. -> Rest : free

78. -> Eviction of data !

80. Use Cacti or other monitoring tools STAT pid 2941 STAT uptime 10878 STAT time 1296074240 STAT version 1.4.5 STAT pointer_size 64 STAT rusage_user 20.089945 STAT rusage_system 58.499106 STAT curr_connections 16 STAT total_connections 276950 STAT connection_structures 96 STAT cmd_get 276931 STAT cmd_set 584148 STAT cmd_flush 0 STAT get_hits 211106 STAT get_misses 65825 STAT delete_misses 101 STAT delete_hits 276829 STAT incr_misses 0 STAT incr_hits 0 STAT decr_misses 0 STAT decr_hits 0 STAT cas_misses 0 STAT cas_hits 0 STAT cas_badval 0 STAT auth_cmds 0 STAT auth_errors 0 STAT bytes_read 613193860 STAT bytes_written 553991373 STAT limit_maxbytes 268435456 STAT accepting_conns 1 STAT listen_disabled_num 0 STAT threads 4 STAT conn_yields 0 STAT bytes 20418140 STAT curr_items 65826 STAT total_items 553856 STAT evictions 0 STAT reclaimed 0

81. Memcache - backing up

83. Updating data

84. Updating data LCD_Popular_Product_List

85. Adding/updating data $memcache->delete( 'LCD_Popular_Product_List' );

86. Adding/updating data

87. Adding/updating data - Why it crashed

88. Adding/updating data - Why it crashed

89. Adding/updating data - Why it crashed

90. Cache stampeding

91. Cache stampeding

92. Memcache code ? DB

94. Run it before starting Webserver !

98. What if the process that created the lock fails ?

101. Reverse proxy

102. Lightweight, fast

103. 9.6% of all Websites

105. Uses epoll / kqueue

106. Low memory footprint

107. 10000 active connections = normal

109. mod_dav*

111. Some 3 rd party modules (needs recompilation !)

112. Nginx - Configuration server { listen 80; server_name www.domain.ext *.domain.ext; index index.html; root /home/domain.ext/www; } server { listen 80; server_name photo.domain.ext; index index.html; root /home/domain.ext/photo; }

113. Nginx + PHP-FPM - performance ? Single webserver Proxy Static PHP Static PHP Apache + PHP 3900 17.5 6700 17.5 Apache + PHP + MC 3900 55 6700 108 Nginx + PHP-FPM + MC 11700 57 11200 112

114. Reverse proxy time...

116. Reverse proxy cache / http accelerator / …

117. Caches (parts of) pages in memory

119. Nginx usually scales better (but doesn't have VCL)

120. Varnish - backends + load balancing backend server1 { .host = &quot;192.168.0.10&quot;; } backend server2{ .host = &quot;192.168.0.11&quot;; } director example_director round-robin { { .backend = server1; } { .backend = server2; } }

124. ACLs

127. ESI

129. Varnish with ESI - hold on tight ! Single webserver Proxy Static PHP Static PHP Apache + PHP 3900 17.5 6700 17.5 Apache + PHP + MC 3900 55 6700 108 Nginx + PHP-FPM + MC 11700 57 11200 112 Varnish - - 11200 4200

131. Images, js, css

133. Very large files (it's not a file server !)

134. Requests with Set-Cookie

135. User-specific content

136. ESI -> no caching on user-specific content ? Logged in as : Wim Godden 5 messages TTL = 5min TTL=1h TTL = 0s ?

139. Well-built project -> few changes

140. Effect on webservers and database servers

141. What's the result ?

142. What's the result ?

144. No. of db servers : 6 -> 2

146. No. of db servers : 15 -> 4

147. Total : 87 -> 12 (86% reduction !)

149. Still under heavy development

150. Final release : July 2012

151. Released as ????

152. Tuning

154. Use an opcode cache

155. Caching storage - Opcode caching

157. count(*) is evil in InnoDB without a where clause !

158. Persistent connect is sort-of evil

159. Caching & Tuning @ frontend http://www.websiteoptimization.com/speed/tweak/average-web-page/

161. Test frontend

162. Check what requests frontend sends to backend

165. Use CSS Sprites

166. CSS Sprites

167. Tuning content - CSS sprites

168. Tuning content - CSS sprites 11 images 11 HTTP requests 24KByte 1 image 1 HTTP requests 14KByte

177. Watch the logging process ->

178. Logging = disk I/O -> can kill your server !

179. Slashdot effect

181. Use a cache abstraction layer (disk -> Memcache)

182. Don't install for the worst -> prepare for the worst

183. Have a test-setup

188. Web http://techblog.wimgodden.be

189. Slides http://www.slideshare.net/wimg

190. E-mail [email_address]