This document summarizes Wim Godden's presentation on caching and tuning for high scalability. It discusses various caching techniques including caching entire pages, parts of pages, SQL queries, and complex PHP results. It also covers different caching storage options like Memcache and APC. The presentation aims to increase performance, reliability, and scalability through proper caching and tuning techniques.

1. Caching and tuning fun for high scalability Wim Godden Cu.be Solutions Conference Jan 28, 2011

2. Note about this presentation The slides of this presentation were created to assist me during the live presentation at phpBenelux Conference. When viewing it, several slides will seem odd and unclear, because the live explanation is missing. A webcast of the live presentation might be available soon. Check my blog ( http://techblog.wimgodden.be ) or Twitter (@wimgtr) for updates.

3. Who am I ? Wim Godden

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

10. Who are you ? Developers ?

11. System/network engineers ?

12. Managers ?

13. Caching experience ?

14. Caching and tuning fun for high scalability Wim Godden Cu.be Solutions Conference Jan 28, 2011

15. Goals of this tutorial Everything about caching and tuning

16. A few techniques

17. -> Increase reliability, performance and scalability

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

19. (Don't expect miracle cure !)

20. Goals of this tutorial Concepts & techniques

21. How to do stuff

22. How NOT to do stuff

23. LAMP

24. LAMP

25. LAMP

26. LAMP

27. Architecture

28. Caching

29. What's caching ?

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

31. Caching goals - 1 st goal Reduce # of request

32. Reduce the load

33. Caching goals - 2 nd goal

34. Some figures Pageviews : 5000 (4000 on 10 pages)

35. Avg. loading time : 200ms

36. Cache 10 pages

37. Avg. loading time : 20ms

38. -> Total avg. loading time : 56ms

39. Worth it ?

40. Caching goals - 3 rd goal Send less data across the network / Internet You benefit -> lower bill from upstream provider

41. Users benefit -> faster page load

42. Wait a second... that's mostly frontend stuff !

43. Theory of caching DB

44. Theory of caching DB

45. Caching techniques #1 : Store entire pages Company Websites

46. Blogs

47. Full pages that don't change

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

49. Caching techniques #1 : Store entire pages

50. Caching techniques #2 : Store parts of a page Most common technique

51. Usually a small block in a page

52. Best effect : reused on lots of pages

53. Can be inserted on dynamic pages

54. Caching techniques #2 : Store parts of a page

55. Caching techniques #3 : Store SQL queries ↔ SQL query cache Limited in size

56. Caching techniques #3 : Store SQL queries ↔ SQL query cache Limited in size

57. Resets on every insert/update/delete

58. Server and connection overhead Goal : not to get rid of DB

59. free up DB resources for more hits ! Better : store returned object

60. store group of objects

61. Caching techniques #3 : Store SQL queries

62. Caching techniques #4 : Store complex PHP results Not just calculations

63. CPU intensive tasks : Config file parsing

64. XML file parsing

65. Loading CSV in an array Save resources -> more resources available

66. Caching techniques #4 : Store complex PHP results

67. Caching techniques #xx : Your call Only limited by your imagination ! When you have data, think : Creating time ?

68. Modification frequency ?

69. Retrieval frequency ?

70. How to find cacheable data New projects : start from 'cache anything'

71. Existing projects : Look at MySQL slow query log

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

73. Check page loading times

74. Caching storage - MySQL query cache Use it

75. Don't rely on it

76. Good if you have : lots of reads

77. few different queries Bad if you have : lots of insert/update/delete

78. lots of different queries

79. Caching storage - Database memory tables Tables stored in memory

80. In MySQL : memory/heap table

81. ↔ temporary table : memory tables are persistent

82. temporary tables are session-specific Faster than disk-based tables

83. Can be joined with disk-based tables

84. But : default 16MByte limit

85. master-slave = trouble

86. if you don't need join -> overhead of DB software So : don't use it unless you need to join

87. Caching storage - Opcode caching DO !

88. Caching storage - Opcode caching APC De-facto standard

89. Will be in PHP core in 5.4 ? 5.5 ? 6.0 ?

90. PECL or packages eAccelerator

91. Zend Accelerator

92. Caching storage - Opcode caching APC De-facto standard

93. Will be in PHP core in 5.4 ? 5.5 ? 6.0 ?

94. PECL or packages eAccelerator

95. Zend Accelerator

96. X-Cache

97. WinCacheForPhp PHP PHP + APC PHP + eAccelerator 42.18 req/sec 206.20 req/sec 211.49 req/sec

98. Caching storage - Disk Data with few updates : good

99. Caching SQL queries : preferably not

100. DON'T use NFS or other network file systems especially for sessions

101. high latency

102. locking issues !

103. Caching storage - Memory disk (ramdisk) Usually faster than physical disk

104. But : OS file caching makes difference minimal

105. Caching storage - Disk / ramdisk Overhead : filesystem access

106. Limited number of files per directory -> Subdirectories Local 5 Webservers -> 5 local caches

107. -> Hard to scale

108. How will you keep them synchronized ? -> Don't say NFS or rsync !

109. Caching storage - APC variable cache More than an opcode cache

110. Store user data in memory

111. apc_add / apc_store to add/update

112. apc_fetch to retrieve

113. apc_delete

114. Fast -> huge performance impact

115. Caching storage - APC variable cache More than an opcode cache

116. Store user data in memory

117. apc_add / apc_store to add/update

118. apc_fetch to retrieve

119. apc_delete

120. Fast -> huge performance impact

121. Session support !

122. Downside : local storage -> hard to scale

123. restart Apache -> cache = empty

124. Caching storage - Memcache Facebook, Twitter, Slashdot, … -> need we say more ?

125. Distributed memory caching system

126. Key-value storage system Keys - max. 250bytes

127. Values - max. 1Mbyte

128. Caching storage - Memcache Facebook, Twitter, Slashdot, … -> need we say more ?

129. Distributed memory caching system

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

131. Key-value storage system Keys - max. 250bytes

132. Values - max. 1Mbyte Extremely fast... non-blocking, UDP (!)

133. Memcache - where to install

134. Memcache - where to install

135. Memcache - installation & running it Installation Distribution package

136. PECL