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Caching and tuning fun for high scalability @ PHPTour
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.
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Caching and tuning fun for high scalability @ PHPTour
- 1. Caching and tuningfun for high scalability Wim Godden Cu.be Solutions
- 2. Who am I? Wim Godden (@wimgtr)
- 3. Owner of Cu.beSolutions (http://cu.be)
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- 6.
- 7. Zend Framework CertifiedEngineer
- 8.
- 9. Who are you? Developers ?
- 10.
- 11.
- 12.
- 13. Caching and tuningfun for high scalability Wim Godden Cu.be Solutions
- 14. Goals of thistutorial Everything about caching and tuning
- 15. A few techniquesHow-to
- 16. How-NOT-to -> Increasereliability, performance and scalability
- 17. 5 visitors/day ->5 million visitors/day
- 18. (Don't expect miraclecure !)
- 19.
- 20.
- 21. Our base benchmarkApachebench = useful enough
- 22.
- 23.
- 24.
- 25. What is caching? select * from article join user on article.user_id = user.id order by created desc limit 10
- 26. Theory of cachingif ($data == false) DB
- 27.
- 28. Caching techniques #1: Store entire pages #2 : Store part of a page (block) #3 : Store data retrieval (SQL ?) #4 : Store complex processing result #? : Your call ! When you have data, think : Creating time ?
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- 31. How to findcacheable data New projects : start from 'cache everything'
- 32. Existing projects :Look at MySQL slow query log
- 33. Make a completequery log (don't forget to turn it off !)
- 34. Check page loadingtimes
- 35. Caching storage -MySQL query cache Use it
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- 37. Bad if youhave : lots of insert/update/delete
- 38. lots of differentqueries
- 39. Caching storage -Disk Data with few updates : good
- 40. Caching SQL queries: preferably not
- 41. DON'T useNFS or other network file systems especially for sessions
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- 43.
- 44. Caching storage -Disk / ramdisk Local 5 Webservers -> 5 local caches
- 45. -> Hard toscale
- 46. How will youkeep them synchronized ? -> Don't say NFS or rsync !
- 47. Caching storage -Memcache Facebook, Twitter, Slashdot, … -> need we say more ?
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- 49. Multiple machines ↔1 big memory-based hash-table
- 50. Key-value storage systemKeys - max. 250bytes
- 51. Values - max.1Mbyte
- 52. Caching storage -Memcache Facebook, Twitter, Slashdot, … -> need we say more ?
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- 54. Multiple machines ↔1 big memory-based hash-table
- 55. Key-value storage systemKeys - max. 250bytes
- 56. Values - max.1Mbyte Extremely fast... non-blocking, UDP (!)
- 57. Memcache - whereto install
- 58. Memcache - whereto install
- 59. Memcache - installation& running it Installation Distribution package
- 60.
- 61. Windows : binariesRunning No config-files
- 62. memcached -d -m<mem> -l <ip> -p <port>
- 63. ex. : memcached-d -m 2048 -l 172.16.1.91 -p 11211
- 64. Caching storage -Memcache - some notes Not fault-tolerant It's a cache !
- 65.
- 66.
- 67.
- 68. Caching storage -Memcache - some notes Not fault-tolerant It's a cache !
- 69.
- 70.
- 71. … Firewall yourMemcache port !
- 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;
- 73. Where's the data? Memcache client decides (!)
- 74. 2 hashing algorithms: Traditional Server failure -> all data must be rehashed Consistent Server failure -> 1/x of data must be rehashed (x = # of servers)
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- 76. Memcache slabs (orwhy Memcache says it's full when it's not) Multiple slabs of different sizes : Slab 1 : 400 bytes
- 77. Slab 2 :480 bytes (400 * 1.2)
- 78. Slab 3 :576 bytes (480 * 1.2) (and so on...) Multiplier (1.2 here) can be configured
- 79. Store a lotof very large objects
- 80. -> Large slabs: full
- 81. -> Rest :free
- 82. -> Eviction ofdata !
- 83. Memcache - Isit working ? Connect to it using telnet "stats" command ->
- 84. Use Cacti orother 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
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- 86. Memcache - tipPage with multiple blocks ? -> use Memcached::getMulti() Warning : what if you get some hits and some misses ?
- 87.
- 88.
- 89. Adding/updating data $memcache->delete('LCD_Popular_Product_List' );
- 90.
- 91. Adding/updating data -Why it crashed
- 92. Adding/updating data -Why it crashed
- 93. Adding/updating data -Why it crashed
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- 95.
- 96.
- 97. Cache warmup scriptsUsed to fill your cache when it's empty
- 98. Run it before starting Webserver !
- 99. 2 ways :Visit all URLs Error-prone
- 100. Hard to maintainCall all cache-updating methods Make sure you have a warmup script !
- 101. Cache stampeding -what about locking ? Seems like a nice idea, but... While lock in place
- 102. What if theprocess that created the lock fails ?
- 103. LAMP... -> LAMMP-> LNMMP
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- 106.
- 107. 8.3% of allWebsites
- 108. Nginx No threads,event-driven
- 109. Uses epoll /kqueue
- 110.
- 111. 10000 active connections= normal
- 112. Nginx - atrue alternative to Apache ? Not all Apache modules mod_auth_*
- 113.
- 114. … Basic modulesare available
- 115. Some 3 rd party modules (needs recompilation !)
- 116. Nginx - Configurationserver { 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.
- 119. Varnish Not justa load balancer
- 120. Reverse proxy cache/ http accelerator / …
- 121. Caches (parts of)pages in memory
- 122. Careful : usesthreads (like Apache)
- 123. Nginx usually scalesbetter (but doesn't have VCL)
- 124. Varnish - backends+ load balancing backend server1 { .host = "192.168.0.10"; } backend server2{ .host = "192.168.0.11"; } director example_director round-robin { { .backend = server1; } { .backend = server2; } }
- 125. Varnish - VCLVarnish Configuration Language
- 126. DSL (Domain SpecificLanguage) -> compiled to C Hooks into each request
- 127. Defines : Backends(web servers)
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- 129. Load balancing strategyCan be reloaded while running
- 130. Varnish - whateveryou want Real-time statistics (varnishtop, varnishhist, ...)
- 131.
- 132. Varnish - ESIPerfect for caching pages In your article page output : <esi:include src="/news"/> In your Varnish config : sub vcl_fetch { if (req.url == "/news") { esi; /* Do ESI processing */ set obj.ttl = 2m; } elseif (req.url == "/nav") { esi; set obj.ttl = 1m; } elseif …. … . }
- 133. Varnish with ESI- hold on tight !
- 134. Varnish - whatcan/can't be cached ? Can : Static pages
- 135.
- 136. Pages or partsof pages that don't change often (ESI) Can't : POST requests
- 137. Very large files(it's not a file server !)
- 138.
- 139.
- 140. ESI -> nocaching on user-specific content ? Logged in as : Wim Godden 5 messages TTL = 5min TTL=1h TTL = 0s ?
- 141. Under development Releasedate Beta : Dec 2011
- 142. Stable : Feb2012
- 143.
- 144. PHP speed -some tips Upgrade PHP - every minor release has 5-15% speed gain !
- 145. Use an opcodecache
- 146. Caching storage -Opcode caching
- 147. PHP speed -some tips Upgrade PHP - every minor release has 5-15% speed gain !
- 148. Use an opcodecache
- 149. Profile your codeXHProf
- 150.
- 151. KCachegrind is yourfriend
- 152. PHP speed -some tips Upgrade PHP - every minor release has 5-15% speed gain !
- 153. Use an opcodecache
- 154. Profile your codeXHProf
- 155. Xdebug But :turn off profilers on production platforms !
- 156. DB speed -some tips Use same types for joins i.e. don't join decimal with int RAND() is evil !
- 157. count(*) is evilin InnoDB without a where clause ! (and there are other examples of specific things to avoid) Persistent connect is not always good !
- 158. Caching & Tuning@ frontend http://www.websiteoptimization.com/speed/tweak/average-web-page/
- 159. Frontend tuning 1.You optimize backend 2. Frontend engineers messes up -> havoc on backend 3. Don't forget : frontend sends requests to backend ! SO... Care about frontend
- 160.
- 161. Check what requestsfrontend sends to backend
- 162. Tuning frontend Minimizerequests Combine CSS/JavaScript files
- 163. Tuning frontend Minimizerequests Combine CSS/JavaScript files
- 164.
- 165.
- 166. Tuning content -CSS sprites
- 167. Tuning content -CSS sprites 11 images 11 HTTP requests 24KByte 1 image 1 HTTP requests 14KByte
- 168. Tuning frontend Minimizerequests Combine CSS/JavaScript files
- 169. Use CSS Sprites(horizontally if possible) Put CSS at top
- 170. Put JavaScript atbottom Max. no connections
- 171. Especially if JavaScriptdoes Ajax (advertising-scripts, …) ! Avoid iFrames Again : max no. of connections Don't scale images in HTML
- 172. Have a favicon.ico(don't 404 it !) -> see my blog
- 173. What else cankill your site ? Redirect loops Multiple requests More load on Webserver
- 174. More PHP toprocess Additional latency for visitor
- 175. Try to avoidredirects anyway
- 176. -> InZF : use $this->_forward instead of $this->_redirect Watch your logs, but equally important...
- 177. Watch the loggingprocess ->
- 178. Logging = diskI/O -> can kill your server !
- 179.
- 180. Above all else...be prepared ! Have a monitoring system
- 181. Use a cacheabstraction layer (disk -> Memcache)
- 182. Don't install forthe worst -> prepare for the worst
- 183.
- 184. Have fallbacks ->Turn off non-critical functionality
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- 186.
- 187. Contact Twitter @wimgtr
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- 191.
- 192. Rate my talk: http://joind.in/4361
- 193. Thanks ! Please...Rate my talk : http://joind.in/4361
- 194.