Caching and tuning fun for high scalability Wim Godden Cu.be Solutions
Notes about this presentation <ul>This presentation was part of the FrOSCon 2011 program. It was designed to presented liv...
Who am I ? <ul><li>Wim Godden (@wimgtr)
Owner of Cu.be Solutions (http://cu.be)
PHP developer since 1997
Developer of OpenX
Zend Certified Engineer
Zend Framework Certified Engineer
MySQL Certified Developer </li></ul>
Who are you ? <ul><li>Developers ?
System/network engineers ?
Managers ?
Caching experience ? </li></ul>
Caching and tuning fun for high scalability Wim Godden Cu.be Solutions
Goals of this tutorial <ul><li>Everything about caching and tuning
A few techniques </li><ul><li>How-to
How-NOT-to </li></ul><li>-> Increase reliability, performance and scalability
5 visitors/day -> 5 million visitors/day
(Don't expect miracle cure !) </li></ul>
LAMP
LAMP
Architecture
Our test site
Our base benchmark <ul><li>Apachebench = useful enough
Result ? </li></ul>
Caching
What is caching ?
What is caching ? select * from article join user on article.user_id = user.id order by created desc limit 10
Caching goals <ul><li>Source of information (db, file, webservice, …) : </li><ul><li>Reduce # of request
Reduce the load </li></ul><li>Latency : </li><ul><li>Reduce for visitor
Reduce for Webserver load </li></ul><li>Network : </li><ul><li>Send less data to visitor
Hey, that's frontend ! </li></ul></ul>
Theory of caching DB
Theory of caching DB
Theory of caching if ($data == false) DB
Caching techniques <ul>#1 : Store entire pages <li>Company Websites
Blogs
Full pages that don't change
Render -> Store in cache -> retrieve from cache </li></ul>
Caching techniques <ul>#1 : Store entire pages </ul>
Caching techniques <ul>#2 : Store parts of a page <li>Most common technique
Usually a small block in a page
Best effect : reused on lots of pages </li></ul>
Caching techniques <ul>#2 : Store parts of a page </ul>
Caching techniques <ul>#3 : Store SQL queries <li>↔ SQL query cache </li><ul><ul><li>Limited in size </li></ul></ul></ul>
Caching techniques <ul>#3 : Store SQL queries <li>↔ SQL query cache </li><ul><ul><li>Limited in size
Resets on every insert/update/delete
Server and connection overhead </li></ul></ul><li>Goal : </li><ul><li>not  to get rid of DB
free up DB resources for more hits ! </li></ul></ul>
Caching techniques <ul>#3 : Store SQL queries </ul>
Caching techniques <ul>#4 : Store complex processing results <li>Not just calculations
CPU intensive tasks : </li><ul><li>Config file parsing
XML file parsing
Loading CSV in an array </li></ul><li>Save resources -> more resources available </li></ul>
Caching techniques <ul>#4 : Store complex processing results </ul>
Caching techniques <ul>#xx : Your call Only limited by your imagination ! When you have data, think : <li>Creating time ?
Modification frequency ?
Retrieval frequency ? </li></ul>
How to find cacheable data <ul><li>New projects : start from 'cache everything'
Existing projects : </li><ul><li>Look at MySQL slow query log
Make a complete query log (don't forget to turn it off !)
Check page loading times </li></ul></ul>
Caching storage - MySQL query cache <ul><li>Use it
Don't rely on it
Good if you have : </li><ul><li>lots of reads
few different queries </li></ul><li>Bad if you have : </li><ul><li>lots of insert/update/delete
lots of different queries </li></ul></ul>
Caching storage - Disk <ul><li>Data with few updates : good
Caching SQL queries : preferably not
DON'T  use NFS or other network file systems </li><ul><li>especially for sessions
high latency
locking issues ! </li></ul></ul>
Caching storage - Disk / ramdisk <ul><li>Overhead : filesystem access
Limited number of files per directory </li><ul><li>-> Subdirectories </li></ul><li>Local </li><ul><li>5 Webservers -> 5 lo...
-> Hard to scale
How will you keep them synchronized ? </li><ul><li>-> Don't say NFS or rsync ! </li></ul></ul></ul>
Caching storage - Memcache <ul><li>Facebook, Twitter, Slashdot, … -> need we say more ?
Distributed memory caching system
Multiple machines ↔ 1 big memory-based hash-table
Key-value storage system </li><ul><li>Keys - max. 250bytes
Values - max. 1Mbyte </li></ul></ul>
Caching storage - Memcache <ul><li>Facebook, Twitter, Slashdot, … -> need we say more ?
Distributed memory caching system
Multiple machines ↔ 1 big memory-based hash-table
Key-value storage system </li><ul><li>Keys - max. 250bytes
Values - max. 1Mbyte </li></ul><li>Extremely fast... non-blocking, UDP (!) </li></ul>
Memcache - where to install
Memcache - where to install
Memcache - installation & running it <ul><li>Installation </li><ul><li>Distribution package
PECL
Windows : binaries </li></ul><li>Running </li><ul><li>No config-files
memcached -d -m <mem> -l <ip> -p <port>
ex. : memcached -d -m 2048 -l 127.0.0.1 -p 11211 </li></ul></ul>
Caching storage - Memcache - some notes <ul><li>Not fault-tolerant </li><ul><li>It's a cache !
Lose session data
Lose shopping cart data
... </li></ul></ul>
Caching storage - Memcache - some notes <ul><li>Not fault-tolerant </li><ul><li>It's a cache !
Lose session data
Lose shopping cart data
… </li></ul><li>Different libraries </li><ul><li>Original : libmemcache
New : libmemcached (consistent hashing, UDP, binary protocol, …) </li></ul><li>Firewall your Memcache port ! </li></ul>
Memcache in code <?php $memcache =  new  Memcache(); $memcache->addServer( '172.16.0.1' , 11211); $memcache->addServer( '1...
Let's give that a go ! /** * Retrieves the 10 highest rated articles *  @return  array List of highest rated articles */ s...
Where's the data ? <ul><li>Memcache client decides (!)
2 hashing algorithms : </li><ul><li>Traditional </li><ul><li>Server failure -> all data must be rehashed </li></ul><li>Con...
Memcache slabs <ul>(or why Memcache says it's full when it's not) <li>Multiple slabs of different sizes : </li><ul><li>Sla...
Slab 2 : 480 bytes (400 * 1.2)
Slab 3 : 576 bytes (480 * 1.2) (and so on...) </li></ul><li>Multiplier (1.2 here) can be configured
Each larger slab has room for fewer items (chunks)
-> Store a lot of very large objects
-> Large slabs might be full
-> Rest of slabs might be free
-> Try to store more -> eviction of data ! </li></ul>
Memcache - Is it working ? <ul><li>Connect to it using telnet </li><ul><li>&quot;stats&quot; command ->
Use Cacti or other monitoring tools </li></ul></ul>STAT pid 2941 STAT uptime 10878 STAT time 1296074240 STAT version 1.4.5...
Memcache - backing up
Memcache - deleting <?php   $memcache =  new  Memcache(); $memcache->delete( 'myKey' ); $myData = $memcache->get( 'myKey' ...
Memcache - tip <ul>Page with multiple blocks ? -> use Memcached::getMulti() Warning : what if you get some hits and some m...
Naming your keys <ul><li>Key names must be unique
Prefix / namespace your keys !
Only letters, numbers and underscore
md5() is useful </li><ul><li>-> BUT : harder to debug </li></ul><li>Use clear names
Document your key names ! </li></ul>
Updating data
Updating data
Adding/updating data $memcache->delete( 'ArticleDetails__Toshiba_32C100U_32_Inch' ); $memcache->delete( 'Homepage_Popular_...
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Caching and tuning fun for high scalability @ FrOSCon 2011

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Caching and tuning fun for high scalability @ FrOSCon 2011

  1. 1. Caching and tuning fun for high scalability Wim Godden Cu.be Solutions
  2. 2. Notes about this presentation <ul>This presentation was part of the FrOSCon 2011 program. It was designed to presented live and as a result many of the slides may seem odd without spoken explanation. The live benchmarks at the conference are ofcourse also not part of these slides. </ul>
  3. 3. Who am I ? <ul><li>Wim Godden (@wimgtr)
  4. 4. Owner of Cu.be Solutions (http://cu.be)
  5. 5. PHP developer since 1997
  6. 6. Developer of OpenX
  7. 7. Zend Certified Engineer
  8. 8. Zend Framework Certified Engineer
  9. 9. MySQL Certified Developer </li></ul>
  10. 10. Who are you ? <ul><li>Developers ?
  11. 11. System/network engineers ?
  12. 12. Managers ?
  13. 13. Caching experience ? </li></ul>
  14. 14. Caching and tuning fun for high scalability Wim Godden Cu.be Solutions
  15. 15. Goals of this tutorial <ul><li>Everything about caching and tuning
  16. 16. A few techniques </li><ul><li>How-to
  17. 17. How-NOT-to </li></ul><li>-> Increase reliability, performance and scalability
  18. 18. 5 visitors/day -> 5 million visitors/day
  19. 19. (Don't expect miracle cure !) </li></ul>
  20. 20. LAMP
  21. 21. LAMP
  22. 22. Architecture
  23. 23. Our test site
  24. 24. Our base benchmark <ul><li>Apachebench = useful enough
  25. 25. Result ? </li></ul>
  26. 26. Caching
  27. 27. What is caching ?
  28. 28. What is caching ? select * from article join user on article.user_id = user.id order by created desc limit 10
  29. 29. Caching goals <ul><li>Source of information (db, file, webservice, …) : </li><ul><li>Reduce # of request
  30. 30. Reduce the load </li></ul><li>Latency : </li><ul><li>Reduce for visitor
  31. 31. Reduce for Webserver load </li></ul><li>Network : </li><ul><li>Send less data to visitor
  32. 32. Hey, that's frontend ! </li></ul></ul>
  33. 33. Theory of caching DB
  34. 34. Theory of caching DB
  35. 35. Theory of caching if ($data == false) DB
  36. 36. Caching techniques <ul>#1 : Store entire pages <li>Company Websites
  37. 37. Blogs
  38. 38. Full pages that don't change
  39. 39. Render -> Store in cache -> retrieve from cache </li></ul>
  40. 40. Caching techniques <ul>#1 : Store entire pages </ul>
  41. 41. Caching techniques <ul>#2 : Store parts of a page <li>Most common technique
  42. 42. Usually a small block in a page
  43. 43. Best effect : reused on lots of pages </li></ul>
  44. 44. Caching techniques <ul>#2 : Store parts of a page </ul>
  45. 45. Caching techniques <ul>#3 : Store SQL queries <li>↔ SQL query cache </li><ul><ul><li>Limited in size </li></ul></ul></ul>
  46. 46. Caching techniques <ul>#3 : Store SQL queries <li>↔ SQL query cache </li><ul><ul><li>Limited in size
  47. 47. Resets on every insert/update/delete
  48. 48. Server and connection overhead </li></ul></ul><li>Goal : </li><ul><li>not to get rid of DB
  49. 49. free up DB resources for more hits ! </li></ul></ul>
  50. 50. Caching techniques <ul>#3 : Store SQL queries </ul>
  51. 51. Caching techniques <ul>#4 : Store complex processing results <li>Not just calculations
  52. 52. CPU intensive tasks : </li><ul><li>Config file parsing
  53. 53. XML file parsing
  54. 54. Loading CSV in an array </li></ul><li>Save resources -> more resources available </li></ul>
  55. 55. Caching techniques <ul>#4 : Store complex processing results </ul>
  56. 56. Caching techniques <ul>#xx : Your call Only limited by your imagination ! When you have data, think : <li>Creating time ?
  57. 57. Modification frequency ?
  58. 58. Retrieval frequency ? </li></ul>
  59. 59. How to find cacheable data <ul><li>New projects : start from 'cache everything'
  60. 60. Existing projects : </li><ul><li>Look at MySQL slow query log
  61. 61. Make a complete query log (don't forget to turn it off !)
  62. 62. Check page loading times </li></ul></ul>
  63. 63. Caching storage - MySQL query cache <ul><li>Use it
  64. 64. Don't rely on it
  65. 65. Good if you have : </li><ul><li>lots of reads
  66. 66. few different queries </li></ul><li>Bad if you have : </li><ul><li>lots of insert/update/delete
  67. 67. lots of different queries </li></ul></ul>
  68. 68. Caching storage - Disk <ul><li>Data with few updates : good
  69. 69. Caching SQL queries : preferably not
  70. 70. DON'T use NFS or other network file systems </li><ul><li>especially for sessions
  71. 71. high latency
  72. 72. locking issues ! </li></ul></ul>
  73. 73. Caching storage - Disk / ramdisk <ul><li>Overhead : filesystem access
  74. 74. Limited number of files per directory </li><ul><li>-> Subdirectories </li></ul><li>Local </li><ul><li>5 Webservers -> 5 local caches
  75. 75. -> Hard to scale
  76. 76. How will you keep them synchronized ? </li><ul><li>-> Don't say NFS or rsync ! </li></ul></ul></ul>
  77. 77. Caching storage - Memcache <ul><li>Facebook, Twitter, Slashdot, … -> need we say more ?
  78. 78. Distributed memory caching system
  79. 79. Multiple machines ↔ 1 big memory-based hash-table
  80. 80. Key-value storage system </li><ul><li>Keys - max. 250bytes
  81. 81. Values - max. 1Mbyte </li></ul></ul>
  82. 82. Caching storage - Memcache <ul><li>Facebook, Twitter, Slashdot, … -> need we say more ?
  83. 83. Distributed memory caching system
  84. 84. Multiple machines ↔ 1 big memory-based hash-table
  85. 85. Key-value storage system </li><ul><li>Keys - max. 250bytes
  86. 86. Values - max. 1Mbyte </li></ul><li>Extremely fast... non-blocking, UDP (!) </li></ul>
  87. 87. Memcache - where to install
  88. 88. Memcache - where to install
  89. 89. Memcache - installation & running it <ul><li>Installation </li><ul><li>Distribution package
  90. 90. PECL
  91. 91. Windows : binaries </li></ul><li>Running </li><ul><li>No config-files
  92. 92. memcached -d -m <mem> -l <ip> -p <port>
  93. 93. ex. : memcached -d -m 2048 -l 127.0.0.1 -p 11211 </li></ul></ul>
  94. 94. Caching storage - Memcache - some notes <ul><li>Not fault-tolerant </li><ul><li>It's a cache !
  95. 95. Lose session data
  96. 96. Lose shopping cart data
  97. 97. ... </li></ul></ul>
  98. 98. Caching storage - Memcache - some notes <ul><li>Not fault-tolerant </li><ul><li>It's a cache !
  99. 99. Lose session data
  100. 100. Lose shopping cart data
  101. 101. … </li></ul><li>Different libraries </li><ul><li>Original : libmemcache
  102. 102. New : libmemcached (consistent hashing, UDP, binary protocol, …) </li></ul><li>Firewall your Memcache port ! </li></ul>
  103. 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 $myData;
  104. 104. Let's give that a go ! /** * Retrieves the 10 highest rated articles * @return array List of highest rated articles */ static public function getTopRatedArticleList () { if ($articleList = $cache->load( 'topRatedArticleList' ) === false) { $articleList = self :: getTopRatedArticleListUncached (); $cache->save($articleList, 'topRatedArticleList' ); } return $articleList; }
  105. 105. Where's the data ? <ul><li>Memcache client decides (!)
  106. 106. 2 hashing algorithms : </li><ul><li>Traditional </li><ul><li>Server failure -> all data must be rehashed </li></ul><li>Consistent </li><ul><li>Server failure -> 1/x of data must be rehashed (x = # of servers) </li></ul></ul><li>No replication ! </li></ul>
  107. 107. Memcache slabs <ul>(or why Memcache says it's full when it's not) <li>Multiple slabs of different sizes : </li><ul><li>Slab 1 : 400 bytes
  108. 108. Slab 2 : 480 bytes (400 * 1.2)
  109. 109. Slab 3 : 576 bytes (480 * 1.2) (and so on...) </li></ul><li>Multiplier (1.2 here) can be configured
  110. 110. Each larger slab has room for fewer items (chunks)
  111. 111. -> Store a lot of very large objects
  112. 112. -> Large slabs might be full
  113. 113. -> Rest of slabs might be free
  114. 114. -> Try to store more -> eviction of data ! </li></ul>
  115. 115. Memcache - Is it working ? <ul><li>Connect to it using telnet </li><ul><li>&quot;stats&quot; command ->
  116. 116. Use Cacti or other monitoring tools </li></ul></ul>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. 117. Memcache - backing up
  118. 118. Memcache - deleting <?php $memcache = new Memcache(); $memcache->delete( 'myKey' ); $myData = $memcache->get( 'myKey' ); // $myData === false
  119. 119. Memcache - tip <ul>Page with multiple blocks ? -> use Memcached::getMulti() Warning : what if you get some hits and some misses ? </ul>
  120. 120. Naming your keys <ul><li>Key names must be unique
  121. 121. Prefix / namespace your keys !
  122. 122. Only letters, numbers and underscore
  123. 123. md5() is useful </li><ul><li>-> BUT : harder to debug </li></ul><li>Use clear names
  124. 124. Document your key names ! </li></ul>
  125. 125. Updating data
  126. 126. Updating data
  127. 127. Adding/updating data $memcache->delete( 'ArticleDetails__Toshiba_32C100U_32_Inch' ); $memcache->delete( 'Homepage_Popular_Product_List' );
  128. 128. Adding/updating data
  129. 129. Adding/updating data - Why it crashed
  130. 130. Adding/updating data - Why it crashed
  131. 131. Adding/updating data - Why it crashed
  132. 132. Cache stampeding elePHPants
  133. 133. Cache stampeding
  134. 134. Memcache code ? DB
  135. 135. Cache warmup scripts <ul><li>Used to fill your cache when it's empty
  136. 136. Run it before starting Webserver !
  137. 137. 2 ways : </li><ul><li>Visit all URLs </li><ul><li>Error-prone
  138. 138. Hard to maintain </li></ul><li>Call all cache-updating methods </li></ul><li>Make sure you have a warmup script ! </li></ul>
  139. 139. Cache stampeding - what about locking ? <ul>Seems like a nice idea, but... <li>Lock in place
  140. 140. -> lots of new connections
  141. 141. -> memory spike
  142. 142. What if the process that created the lock fails ? </li></ul>
  143. 143. Quick word about expiration <ul><li>General rule : don't let things expire
  144. 144. Exception to the rule : things that have an end date (calendar items) </li></ul>
  145. 145. So... <ul>DON'T DELETE FROM CACHE (and don't expire unless usefull) </ul>
  146. 146. LAMP... <ul>-> LAMMP -> LANMMP </ul>
  147. 147. Nginx <ul><li>Web server
  148. 148. Reverse proxy
  149. 149. Lightweight, fast
  150. 150. 7.5% of all Websites </li></ul>
  151. 151. Nginx <ul><li>No threads, event-driven
  152. 152. Uses epoll / kqueue
  153. 153. Low memory footprint
  154. 154. 10000 active connections = normal </li></ul>
  155. 155. Nginx - a true alternative to Apache ? <ul><li>Not all Apache modules </li><ul><li>mod_auth_*
  156. 156. mod_dav*
  157. 157. … </li></ul><li>Basic modules are available
  158. 158. Some 3 rd party modules (needs recompilation !) </li></ul>
  159. 159. Nginx - Installation <ul><li>Packages
  160. 160. Win32 binaries
  161. 161. Build from source (./configure; make; make install) </li></ul>
  162. 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; }
  163. 163. Nginx - phase 1 <ul><li>Move Apache to a different port (8080)
  164. 164. Put Nginx at port 80
  165. 165. Nginx serves all statics (images, css, js, …)
  166. 166. Forward dynamic requests to Apache </li></ul>
  167. 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. 168. Nginx - let's give that a go !
  169. 169. Nginx for PHP ? <ul>LANMMP to... LNMPP (ok, this is getting ridiculous) </ul>
  170. 170. Nginx with PHP <ul><li>In the past : spawn-fcgi (from Lighttpd)
  171. 171. Now : PHP-FPM (in PHP 5.3 !)
  172. 172. Runs on port 9000
  173. 173. Nginx connects using fastcgi method </li></ul>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; }
  174. 174. Nginx + PHP-FPM features <ul><li>Graceful upgrade
  175. 175. Spawn new processes under high load
  176. 176. Chroot
  177. 177. Slow request log ! </li></ul>
  178. 178. Nginx + PHP-FPM features <ul><li>Graceful upgrade
  179. 179. Spawn new processed under high load
  180. 180. Chroot
  181. 181. Slow request log !
  182. 182. fastcgi_finish_request() -> offline processing </li></ul>
  183. 183. Nginx + PHP-FPM - performance ?
  184. 184. Reverse proxy time...
  185. 185. Varnish <ul><li>Not just a load balancer
  186. 186. Reverse proxy cache / http accelerator / …
  187. 187. Caches (parts of) pages in memory
  188. 188. Careful : </li><ul><li>uses threads
  189. 189. Nginx is faster and scales better (but doesn't have VCL) </li></ul></ul>
  190. 190. Varnish - Installation & configuration <ul><li>Installation </li><ul><li>Packages
  191. 191. Source : ./configure && make && make install </li></ul><li>Configuration </li><ul><li>/etc/default/varnish
  192. 192. /etc/varnish/*.vcl </li></ul></ul>
  193. 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. 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; } }
  195. 195. Varnish - VCL <ul><li>Varnish Configuration Language
  196. 196. DSL (Domain Specific Language) </li><ul><li>-> compiled to C </li></ul><li>Hooks into each request
  197. 197. Defines : </li><ul><li>Backends (web servers)
  198. 198. ACLs
  199. 199. Load balancing strategy </li></ul><li>Can be reloaded while running </li></ul>
  200. 200. Varnish - whatever you want <ul><li>Real-time statistics (varnishtop, varnishhist, ...)
  201. 201. ESI </li></ul>
  202. 202. Varnish - ESI <ul>Perfect for caching pages </ul>In your article page output : <esi:include src=&quot;/latest-news&quot;/>
  203. 203. Varnish with ESI - hold on tight !
  204. 204. Varnish - what can/can't be cached ? <ul><li>Can : </li><ul><li>Static pages
  205. 205. Images, js, css
  206. 206. Pages or parts of pages that don't change often (ESI) </li></ul><li>Can't : </li><ul><li>POST requests
  207. 207. Requests with Set-Cookie
  208. 208. Very large files (it's not a file server !)
  209. 209. User-specific content </li></ul></ul>
  210. 210. ESI -> no caching on user-specific content ? Logged in as : Wim Godden 5 messages TTL = 5min TTL=1h TTL = 0s ?
  211. 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; />
  212. 212. New message arrives... <ul><li>Hash using page name and session
  213. 213. Self-chosen key (i.e. 'mails_for_' followed by session) </li></ul>DB
  214. 214. Advantages <ul><li>No hits to backend anymore (except the first one) ! </li><ul><li>Not for user-specific content
  215. 215. Not even for non-specific content </li></ul></ul>
  216. 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; />
  217. 217. Advantages <ul><li>No hits to backend anymore (except the first one) ! </li><ul><li>Not for user-specific content
  218. 218. Not even for non-specific content </li><ul><li>No TTLs for non-specific content
  219. 219. TTL for user-specific content is required (defaults to 5min) </li></ul></ul><li>No need to specify ESI parameters in configuration file </li><ul><li>Only needs enabling </li></ul></ul>
  220. 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; />
  221. 221. Advantages <ul><li>No hits to backend anymore (except the first one) ! </li><ul><li>Not for user-specific content
  222. 222. Not even for non-specific content </li><ul><li>No TTLs for non-specific content
  223. 223. TTL for user-specific content is required (defaults to 5min) </li></ul></ul><li>No need to specify ESI parameters in configuration file </li><ul><li>Only needs enabling </li></ul><li>Memcache getMulti -> 1 Memcache request per page </li></ul>
  224. 224. Under development <ul><li>Feature set = unclear
  225. 225. Performance = even more unclear </li><ul><li>Debugging code makes it slow </li></ul><li>Extends ESI standard, but doesn't follow it entirely </li><ul><li>(what standard ?) </li></ul><li>Release date ? </li><ul><li>End 2011 ? </li></ul></ul>
  226. 226. Tuning
  227. 227. Apache - tuning tips <ul><li>Disable unused modules -> fixes 10% of performance issues
  228. 228. Set AllowOverride to None
  229. 229. Disable SymLinksIfOwnerMatch </li><ul><li>Why ? Site in /var/www/domain.com/subdomain/html </li></ul><li>MinSpareServers, MaxSpareServers, StartServers, MaxClients, MPM selection -> a whole session of its own ;-)
  230. 230. Don't mod_proxy -> use Nginx or Varnish !
  231. 231. High load on an SSL-site ? -> put SSL on a reverse proxy </li></ul>
  232. 232. PHP speed - some tips <ul><li>Upgrade PHP - every minor release has 5-15% speed gain !
  233. 233. Use an opcode cache </li></ul>
  234. 234. Caching storage - Opcode caching
  235. 235. PHP speed - some tips <ul><li>Upgrade PHP - every minor release has 5-15% speed gain !
  236. 236. Use an opcode cache
  237. 237. Profile your code </li><ul><li>XHProf
  238. 238. Xdebug </li></ul></ul>
  239. 239. KCachegrind is your friend
  240. 240. PHP speed - some tips <ul><li>Upgrade PHP - every minor release has 5-15% speed gain !
  241. 241. Use an opcode cache
  242. 242. Profile your code </li><ul><li>XHProf
  243. 243. Xdebug </li></ul><li>But : turn off profilers on acceptance/production platforms !
  244. 244. Let's see what difference opcode caching and profilers make... </li></ul>
  245. 245. DB speed - some tips <ul><li>Avoid NOW() -> use PHP date(&quot;Y-m-d&quot;) as a parameter </li><ul><li>Why ? Query cache ! </li></ul><li>Index, index, index ! (where needed only)
  246. 246. Use same types for joins </li><ul><li>i.e. don't join decimal with int </li></ul><li>RAND() is evil !
  247. 247. count(*) is evil in InnoDB without a where clause ! </li><ul><li>(and there are other examples of specific things to avoid) </li></ul><li>Select the right storage engine
  248. 248. Persistent connect is not always good ! </li></ul>
  249. 249. Caching & Tuning @ frontend http://www.websiteoptimization.com/speed/tweak/average-web-page/
  250. 250. Caching in the browser <ul><li>HTTP 304 (Not modified)
  251. 251. Expires/Cache-Control header </li></ul>
  252. 252. HTTP 304 First request Next requests
  253. 253. HTTP 304 with ETag First request Next requests
  254. 254. Expires/Cache-control header <ul>Cache-Control <ul><li>HTTP/1.1
  255. 255. Seconds to expiry
  256. 256. Used by browsers </li></ul></ul>First request Next requests No requests until item expires <ul>Expires <ul><li>HTTP/1.0
  257. 257. Date to expire on
  258. 258. Used by old proxies
  259. 259. Requires clock to be accurate ! </li></ul></ul>
  260. 260. Pragma: no-cache = evil <ul><li>&quot;Pragma: no cache&quot; doesn't make it uncacheable
  261. 261. Don't want caching on a page ? </li><ul><li>HTTP/1.0 : &quot;Expires : Fri, 30 Oct 1998 00:00:00 GMT&quot; (in the past)
  262. 262. HTTP/1.1 : &quot;Cache-Control: no-store&quot; </li></ul></ul>
  263. 263. Frontend tuning <ul>1. You optimize backend 2. Frontend engineers messes up -> havoc on backend 3. Don't forget : frontend sends requests to backend ! SO... <li>Care about frontend
  264. 264. Test frontend
  265. 265. Check what requests frontend sends to backend </li></ul>
  266. 266. Tuning frontend <ul><li>Minimize requests </li><ul><li>Combine CSS/JavaScript files
  267. 267. Use inline images in CSS/XHTML (not supported on all browsers yet) </li></ul></ul>
  268. 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;>
  269. 269. Tuning frontend <ul><li>Minimize requests </li><ul><li>Combine CSS/JavaScript files
  270. 270. Use inline images in CSS (not supported on all browsers yet)
  271. 271. Use CSS Sprites </li></ul></ul>
  272. 272. CSS Sprites
  273. 273. Tuning content - CSS sprites
  274. 274. Tuning content - CSS sprites 11 images 11 HTTP requests 24KByte 1 images 1 HTTP requests 14KByte
  275. 275. Tuning frontend <ul><li>Minimize requests </li><ul><li>Combine CSS/JavaScript files
  276. 276. Use inline images in CSS (not supported on all browsers yet)
  277. 277. Use CSS Sprites (horizontally if possible) </li></ul><li>Put CSS at top
  278. 278. Put JavaScript at bottom </li><ul><li>Max. no connections
  279. 279. Especially if JavaScript does Ajax (advertising-scripts, …) ! </li></ul><li>Avoid iFrames </li><ul><li>Again : max no. of connections </li></ul><li>Don't scale images in HTML
  280. 280. Have a favicon.ico (don't 404 it !) </li></ul>
  281. 281. Tuning frontend <ul><li>Use GET for Ajax retrieval requests (and cache them !)
  282. 282. Split requests across subdomains
  283. 283. Put statics on a separate subdomain (without cookies !) </li></ul>www.whatever.com www.whatever.com images.whatever.com
  284. 284. Tuning miscellaneous <ul><li>Avoid DNS lookups </li><ul><li>Frontend : don't use too many subdomains (2 = ideal)
  285. 285. Backend : </li><ul><li>Turn off DNS resolution in Apache : HostnameLookups Off
  286. 286. If your app uses external data </li><ul><li>Run a local DNS cache (timeout danger !)
  287. 287. Make sure you can trust DNS servers (preferable run your own) </li></ul></ul></ul><li>Compress non-binary content (GZIP) </li><ul><li>mod_deflate in Apache
  288. 288. HttpGzipModule in Nginx (HttpGzipStaticModule for pre-zipped statics !)
  289. 289. No native support in Varnish </li></ul></ul>
  290. 290. What else can kill your site ? <ul><li>Redirect loops </li><ul><li>Multiple requests </li><ul><li>More load on Webserver
  291. 291. More PHP to process </li></ul><li>Additional latency for visitor
  292. 292. Try to avoid redirects anyway
  293. 293. -> In ZF : use $this->_forward instead of $this->_redirect </li></ul><li>Watch your logs, but equally important...
  294. 294. Watch the logging process ->
  295. 295. Logging = disk I/O -> can kill your site !
  296. 296. Slashdot effect </li></ul>
  297. 297. Above all else... be prepared ! <ul><li>Have a monitoring system
  298. 298. Use a cache abstraction layer (disk -> Memcache)
  299. 299. Don't install for the worst -> prepare for the worst
  300. 300. Have a test-setup
  301. 301. Have fallbacks </li><ul><li>Turn off non-critical functionality </li></ul></ul>
  302. 302. <ul>Questions ? </ul>
  303. 303. <ul>Questions ? </ul>
  304. 304. Contact <ul><li>Twitter @wimgtr
  305. 305. Web http://techblog.wimgodden.be
  306. 306. Slides http://www.slideshare.net/wimg
  307. 307. E-mail [email_address] </li></ul>
  308. 308. Please... <ul><li>Rate my talk : http://tinyurl.com/cachetune
  309. 309. Vote to see me talk at Confoo : http://www.confoo.ca </li><ul><li>Caching and tuning fun for high scalability
  310. 310. Keeping old code alive without non-stop hassle
  311. 311. Beyond PHP : it's not (just) about the code !
  312. 312. Who's in control of your PHP app ?
  313. 313. Creating Fast, Dynamic ACLs in Zend Framework </li></ul></ul>
  314. 314. <ul>Thanks ! </ul>
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