"Caching and tuning fun for high scalability" talk at FrOSCon 2011 Twitter : @wimgtr

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

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

5. PHP developer since 1997

6. Developer of OpenX

7. Zend Certified Engineer

8. Zend Framework Certified Engineer

9. MySQL Certified Developer

11. System/network engineers ?

12. Managers ?

13. Caching experience ?

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

18. 5 visitors/day -> 5 million visitors/day

19. (Don't expect miracle cure !)

20. LAMP

21. LAMP

22. Architecture

23. Our test site

25. Result ?

26. Caching

27. What is caching ?

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

32. Hey, that's frontend !

33. Theory of caching DB

34. Theory of caching DB

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

37. Blogs

38. Full pages that don't change

39. Render -> Store in cache -> retrieve from cache

42. Usually a small block in a page

43. Best effect : reused on lots of pages

47. Resets on every insert/update/delete

49. free up DB resources for more hits !

53. XML file parsing

57. Modification frequency ?

58. Retrieval frequency ?

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

62. Check page loading times

64. Don't rely on it

67. lots of different queries

69. Caching SQL queries : preferably not

71. high latency

72. locking issues !

75. -> Hard to scale

78. Distributed memory caching system

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

81. Values - max. 1Mbyte

83. Distributed memory caching system

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

87. Memcache - where to install

88. Memcache - where to install

90. PECL

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

93. ex. : memcached -d -m 2048 -l 127.0.0.1 -p 11211

95. Lose session data

96. Lose shopping cart data

97. ...

99. Lose session data

100. Lose shopping cart data

103. 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;

104. Let's give that a go ! /** * Retrieves the 10 highest rated articles * @return array List of highest rated articles */ static public function getTopRatedArticleList () { if ($articleList = $cache->load( 'topRatedArticleList' ) === false) { $articleList = self :: getTopRatedArticleListUncached (); $cache->save($articleList, 'topRatedArticleList' ); } return $articleList; }

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

110. Each larger slab has room for fewer items (chunks)

111. -> Store a lot of very large objects

112. -> Large slabs might be full

113. -> Rest of slabs might be free

114. -> Try to store more -> eviction of data !

116. 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

117. Memcache - backing up

118. Memcache - deleting <?php $memcache = new Memcache(); $memcache->delete( 'myKey' ); $myData = $memcache->get( 'myKey' ); // $myData === false

121. Prefix / namespace your keys !

122. Only letters, numbers and underscore

124. Document your key names !

125. Updating data

126. Updating data

127. Adding/updating data $memcache->delete( 'ArticleDetails__Toshiba_32C100U_32_Inch' ); $memcache->delete( 'Homepage_Popular_Product_List' );

128. Adding/updating data

129. Adding/updating data - Why it crashed

130. Adding/updating data - Why it crashed

131. Adding/updating data - Why it crashed

132. Cache stampeding elePHPants

133. Cache stampeding

134. Memcache code ? DB

136. Run it before starting Webserver !

140. -> lots of new connections

141. -> memory spike

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

144. Exception to the rule : things that have an end date (calendar items)

148. Reverse proxy

149. Lightweight, fast

150. 7.5% of all Websites

152. Uses epoll / kqueue

153. Low memory footprint

154. 10000 active connections = normal

156. mod_dav*

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

160. Win32 binaries

161. Build from source (./configure; make; make install)

162. 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; }

164. Put Nginx at port 80

165. Nginx serves all statics (images, css, js, …)

166. Forward dynamic requests to Apache

167. Nginx for static files only server { listen 80; server_name www.domain.ext; location ~* ^.*(jpg|jpeg|gif|png|ico|css|zip|tgz|gz|rar|bz2|doc|xls|pdf|ppt|txt|tar|rtf|js)$ { expires 30d; root /home/www.domain.ext; } location / { proxy_pass http://www.domain.ext:8080; proxy_pass_header Set-Cookie; proxy_set_header X-Real-IP $remote_addr; proxy_set_header Host $host; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } }

168. Nginx - let's give that a go !

171. Now : PHP-FPM (in PHP 5.3 !)

172. Runs on port 9000

173. Nginx connects using fastcgi method location / { fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; include fastcgi_params; fastcgi_param SCRIPT_NAME $fastcgi_script_name; fastcgi_param SCRIPT_FILENAME /home/www.phpbenelux.eu/$fastcgi_script_name; fastcgi_param SERVER_NAME $host; fastcgi_intercept_errors on; }

175. Spawn new processes under high load

176. Chroot

177. Slow request log !

179. Spawn new processed under high load

180. Chroot

181. Slow request log !

182. fastcgi_finish_request() -> offline processing

183. Nginx + PHP-FPM - performance ?

184. Reverse proxy time...

186. Reverse proxy cache / http accelerator / …

187. Caches (parts of) pages in memory

189. Nginx is faster and scales better (but doesn't have VCL)

192. /etc/varnish/*.vcl

193. 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; } }

194. Varnish - backends + load balancing backend server1 { .host = &quot;192.168.0.10&quot;; .probe = { .url = &quot;/&quot;; .interval = 5s; .timeout = 1 s; .window = 5; .threshold = 3; } }

198. ACLs

201. ESI

203. Varnish with ESI - hold on tight !

205. Images, js, css

207. Requests with Set-Cookie

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

209. User-specific content

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

211. Coming to an Nginx near you soon... Logged in as : Wim Godden 5 messages <esim:include src=&quot;/news&quot; ttl=&quot;5m&quot; /> <esim:include src=&quot;/menu&quot; ttl=&quot;1h&quot; /> <esim:include src=&quot;/top&quot; usercookie=&quot;PHPSESS_ID&quot; ttl=&quot;1h&quot; />

213. Self-chosen key (i.e. 'mails_for_' followed by session) DB

215. Not even for non-specific content

216. Do we need TTLs ? Logged in as : Wim Godden 5 messages <esim:include src=&quot;/news&quot; ttl=&quot;5m&quot; /> <esim:include src=&quot;/menu&quot; ttl=&quot;1h&quot; /> <esim:include src=&quot;/top&quot; usercookie=&quot;PHPSESS_ID&quot; ttl=&quot;1h&quot; />

220. How many Memcache requests ? Logged in as : Wim Godden 5 messages <esim:include src=&quot;/news&quot; ttl=&quot;5m&quot; /> <esim:include src=&quot;/menu&quot; ttl=&quot;1h&quot; /> <esim:include src=&quot;/top&quot; usercookie=&quot;PHPSESS_ID&quot; ttl=&quot;1h&quot; />

226. Tuning

228. Set AllowOverride to None

230. Don't mod_proxy -> use Nginx or Varnish !

231. High load on an SSL-site ? -> put SSL on a reverse proxy

233. Use an opcode cache

234. Caching storage - Opcode caching

236. Use an opcode cache

238. Xdebug

239. KCachegrind is your friend

241. Use an opcode cache

244. Let's see what difference opcode caching and profilers make...

248. Persistent connect is not always good !

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

251. Expires/Cache-Control header

252. HTTP 304 First request Next requests

253. HTTP 304 with ETag First request Next requests

255. Seconds to expiry

257. Date to expire on

258. Used by old proxies

259. Requires clock to be accurate !

262. HTTP/1.1 : &quot;Cache-Control: no-store&quot;

264. Test frontend

265. Check what requests frontend sends to backend

267. Use inline images in CSS/XHTML (not supported on all browsers yet)

268. Frontend tuning - inline CSS/XHTML images #navbar span { width: 31px; height: 31px; display: inline; float: left; margin-right: 4px; } .home { background-image: url(data:image/gif;base64,R0lGODlhHwAfAPcAAAAAAIxKAKVjCLW1tb29tcbGvc7OxtZ7ANbWztbW1tbe1t7e1uelMefn1ufn3ufn5+fv3u+MAO/v5+/v7/fGCPf35/f37//nY////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////........MEl0nGVUC6tObNnPceSFBaQVMJAxC4lo3gNOrUaFnTHoAxNm3XVxPfRq139e8BEGAjWD5bgIALw287T8AcAXLly2kjOACdc17higXSIKDO/Lpv7Qq4bw7APgBq8eOzX69InrZ6xe3dbxZffyTGkb8tdx8F+b0Xn2sFsCSBAgTM5lp63RHYnoHUudZgRgkGOGCB+43nGk4OGcQTabKx5dyJKJ7ImoUNCaRRAZYN1ppsrT3Y2gIwyjSQBAtUpABml/0IJGYd6VjQUDH9uBFkGxGm5I8dPQaRUAQUMBdhhBV25ZYUJZBcSAtSJBddWZZ5UAGPOTXlgkNVOSZdBxEwIkYu7VhYnAol5GaadRqF0Uaz0TgXnX2umVFyGakJUUAAADs=); margin-left: 4px; } <img border=0 src=&quot;data:image/gif;base64,R0lGODlhHwAfAPcAAAAAAIxKAKVjCLW1tb29tcbGvc7OxtZ7ANbWztbW1tbe1t7e1uelMefn1ufn3ufn5+fv3u+MAO/v5+/v7/fGCPf35/f37//nY/......Uaz0TgXnX2umVFyGakJUUAAADs=&quot;>

270. Use inline images in CSS (not supported on all browsers yet)

271. Use CSS Sprites

272. CSS Sprites

273. Tuning content - CSS sprites

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

276. Use inline images in CSS (not supported on all browsers yet)

280. Have a favicon.ico (don't 404 it !)

282. Split requests across subdomains

283. Put statics on a separate subdomain (without cookies !) www.whatever.com www.whatever.com images.whatever.com

288. HttpGzipModule in Nginx (HttpGzipStaticModule for pre-zipped statics !)

289. No native support in Varnish

292. Try to avoid redirects anyway

294. Watch the logging process ->

295. Logging = disk I/O -> can kill your site !

296. Slashdot effect

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

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

300. Have a test-setup

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

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

307. E-mail [email_address]

310. Keeping old code alive without non-stop hassle

311. Beyond PHP : it's not (just) about the code !

312. Who's in control of your PHP app ?

313. Creating Fast, Dynamic ACLs in Zend Framework