The document discusses caching and tuning techniques to improve scalability for websites. It covers caching strategies like storing entire pages, parts of pages, or data retrieval results in caches like Memcache. It also discusses optimizing frontend performance through techniques like CSS sprites and combining files, as well as backend optimizations like using an opcode cache and profiling code. Monitoring caches and having fallback plans are emphasized to prepare for increased traffic.

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

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

4. PHP 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 ?

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. Don't rely on it

38. lots of different queries

40. Caching SQL queries : preferably not

42. locking issues !

43. high latency

45. -> Hard to scale

48. Distributed memory caching system

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

51. Values - max. 1Mbyte

53. Distributed memory caching system

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

57. Memcache - where to install

58. Memcache - where to install

60. PECL

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

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

65. Lose session data

66. Lose shopping cart data

67. ...

69. Lose session data

70. Lose shopping cart data

72. 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;

75. Benchmark with Memcache

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

79. Store a lot of very large objects

80. -> Large slabs : full

81. -> Rest : free

82. -> Eviction of data !

84. 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

85. Memcache - backing up

87. Updating data

88. Updating data LCD_Popular_Product_List

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

90. Adding/updating data

91. Adding/updating data - Why it crashed

92. Adding/updating data - Why it crashed

93. Adding/updating data - Why it crashed

94. Cache stampeding

95. Cache stampeding

96. Memcache code ? DB

98. Run it before starting Webserver !

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

105. Reverse proxy

106. Lightweight, fast

107. 8.3% of all Websites

109. Uses epoll / kqueue

110. Low memory footprint

111. 10000 active connections = normal

113. mod_dav*

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

116. 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; }

117. Nginx + PHP-FPM - performance ?

118. Reverse proxy time...

120. Reverse proxy cache / http accelerator / …

121. Caches (parts of) pages in memory

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

124. 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; } }

128. ACLs

131. ESI

133. Varnish with ESI - hold on tight !

135. Images, js, css

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

138. Requests with Set-Cookie

139. User-specific content

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

142. Stable : Feb 2012

143. Tuning

145. Use an opcode cache

146. Caching storage - Opcode caching

148. Use an opcode cache

150. Xdebug

151. KCachegrind is your friend

153. Use an opcode cache

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

160. Test frontend

161. Check what requests frontend sends to backend

164. Use CSS Sprites

165. CSS Sprites

166. Tuning content - CSS sprites

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

175. Try to avoid redirects anyway

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]

191. Please...

192. Rate my talk : http://joind.in/4361