The document discusses the use of Varnish, a web accelerator, to improve website performance by reducing load times and optimizing dynamic content caching. It highlights the impact of slow response times on user satisfaction and provides insights on Varnish's architecture and configuration capabilities. Key features include handling various HTTP headers, cache control, and support for real-time content delivery with efficient cache invalidation strategies.

1. Varnish to the rescue
Leszek Krupiński

2. @leafnode
PHPers Manual
Consultant Architect

3. intro

4. web
1. User 2. Browser 3. Server

5. user is impatient

6. fast!

7. 100ms

8. 1s
=
-11% Page Views
-16% User Satisfaction
-7% Conversion

9. 1-5s
!
32% consumers lost

10. (2012)
average: 2.45s

11. Optimize
application

12. • Frameworks
• Limits
• Time-consuming operations
• Cost

13. Maybe it’s not
needed?

14. Cache!

15. Many levels, many
solutions

16. But… my site is
very dynamic!

17. 1s TTL

18. From 20 rq/s to
1 rq/s in single
apt-get install

19. Fresh content
takes most hits

20. Varnish
The Web Accelerator

24. Architecture

25. Works with the kernel
not against it

26. mmap, threads,
epoll, kqueue

27. Backends:
memory, file

28. If it fits in memory,
use memory

29. Works on HTTP
headers

30. Cache-control, If-Modified-Since,
Expires, Pragma, If-None-Match, Etag,
Vary, Age

31. Varnish uses language
both browser and
backend know

32. In-memory logs

33. 75 000 rq/s at TMECC
143 000 rq/s at Redpill-Linpro

34. Do I need a lot of
memory?

35. Nope

36. Fresh content
takes most hits

37. Take that,
slashdot effect!

38. Configuration

39. Lots of possibilities

40. Unfortunately,
lots of possibilities

41. Varnish
Configuration
Language

42. Compiled directly
to C

43. Hook-like
configuration

44. vcl_fetch
vcl_recv
vcl_hit
vcl_miss
vcl_hash
vcl_pass
vcl_deliver
vcl_error

46. restart

47. Objects
req, bereq, resp,
beresp, obj

48. Defaults

49. vcl_recv

53. vcl_hash

55. VMods

56. throttle, cookie, shield,
redis, memcached, curl,
url code, redirect…

57. Varnish:
load balancer
failover system

59. Directors

60. Default: random

61. Round-robin,
client, hash, dns

62. Health check

64. Saint mode

65. Grace mode

66. Two hard things

67. Invalidate cache

68. Ban list
Efficient way to invalidate cache

69. Over HTTP

70. Use PURGE header

74. Real life issues

75. Cookies

76. Varnish does not
cache when cookies
are involved

77. Ignore cookies

79. Pick cookies

81. Pick URLs

83. Redirects

84. POST

85. PHP sessions

86. CURL VMod

89. PHP + memcached

91. mobile detection

93. mobile detection II

95. VMod: DeviceAtlas
Mobile Detection

96. Cache “one-time”
data

97. Example: dynamic
image resizing

98. 1B pictures
10 sizes

99. apache + moddims

100. Fresh content
takes most hits

101. Different TTL for
different parts?

102. ESI!

105. Testing?

106. jQuery plugin

107. Just in!
Varnish 4.0

108. Log query language,
background fetch, byte
counters, security
improvements

109. http://speakerdeck.com/leafnode