Cache = Cash

Don't waste money and computer resources because of lazy coding.

Transcript

1. Cache = Cash Stefan Wintermeyer
2. Stefan Wintermeyer • Author of a Ruby on Rails book: http://xyzpub.com/en/ ruby-on-rails/3.2/ • @wintermeyer
3. Why should we care? I borrow some data from Ilya Grigor for this. http://www.igvita.com/
4. Delay User reaction 0 - 1 s :-)) 1 - 2 s :-) 2 - 3 s hmmm... 3 - 4 s :-( > 4 s :-((
5. Speed matters! •Don‘t lose customers. •Don‘t invest a fortune in hardware. •Don‘t lose the mobile market.
6. Our aim should be: > 2 seconds BTW: google.com delivers in < 2 s
7. The Application
10. current_user
14. Bob‘s cart
16. Discounted price
17. Rate this product
18. Rules for today
19. •We use the same test procedure for every time measurement. •That means that actual data is changed in the SQL database. •Every page has to show the current data set (no guestimations).
20. The Software
21. The Basic Setup • Ruby on Rails 3.2 • Ruby 1.9.3 • Nginx • Unicorn • MySQL • Raspbian Wheezy
22. The Models
23. Cart state string LineItem price decimal (8,2) quantity integer Category name string Product description text name string price decimal (8,2) DiscountGroup discount integer name string User email string ∗ encrypted_password string ∗ first_name string last_name string Rating value integer
24. Time Measurement
25. We use Watir to automate the use of our browser. http://watir.com
26. This is what a human does:
28. This is the corresponding code to replay it 3 times:
29. require 'watir-webdriver' url = 'http://0.0.0.0:3000' b = Watir::Browser.new # A anonymous user looks around. # ['AA', 'AB', 'AH'].each do |product_name| b.goto url Watir::Wait.until { b.link(:text, product_name).exist? } b.link(:text, product_name).click Watir::Wait.until { b.link(:text, 'Webshop').exist? } b.link(:text, 'Webshop').click end
30. require 'watir-webdriver' url = 'http://0.0.0.0:3000' b = Watir::Browser.new # A anonymous user looks around. # ['AA', 'AB', 'AH'].each do |product_name| b.goto url Watir::Wait.until { b.link(:text, product_name).exist? } b.link(:text, product_name).click Watir::Wait.until { b.link(:text, 'Webshop').exist? } b.link(:text, 'Webshop').click end 3 different products
31. bob@aol.com
32. Login Bob b.goto url b.goto "#{url}/users/sign_in" b.text_field(:id, "user_email").set("bob@aol.com") b.text_field(:id, "user_password").set("123") b.button(:name, "commit").click
33. Bob looks around too ['AA', 'AB', 'AH'].each do |product_name| b.goto url Watir::Wait.until { b.link(:text, product_name).exist? } b.link(:text, product_name).click Watir::Wait.until { b.link(:text, 'Webshop').exist? } b.link(:text, 'Webshop').click end
34. Bob rates products ['AA', 'AD', 'AI'].each do |product_name| b.goto url b.link(:text, product_name).click star_id = 'product_' + product_name + '_rating_2' b.link(:id, star_id).click end
35. Bob fills his cart [1, 3, 5].each do |product_id| b.goto url add_button_id = 'add_' + product_id.to_s b.link(:id, add_button_id).click end
36. Logout b.link(:text, 'Logout').click
37. Total: 43 webpages
38. I once run the total script on my MacBook.
40. The Hardware
41. Raspberry Pi (35 USD)
42. So... how fast is it?
43. 116 seconds!
44. / Started GET "/" for x.x.x.x at 2013-02-28 21:05:34 +0000 Processing by ProductsController#index as HTML Rendered products/index.html.haml within layouts/application (3022.3ms) Rendered layouts/_navbar.html.haml (12.5ms) Rendered layouts/_footer.html.haml (2.9ms) Completed 200 OK in 3097ms (Views: 3013.3ms | ActiveRecord: 72.6ms)
45. 0 29 58 87 116 Vanilla 116 s
46. I bet that @wintermeyer can improve this example webshop by x %. @wrocloverb
47. Fragment Caching
48. Let‘s start with 4 new lines of code.
49. Before %table.table.table-striped{:id => 'products'} %thead %tr %th Name %th Category [...] %tbody - @products.each do |product| %tr %td= link_to product.name, [...] %td= product.description
50. After - cache [current_user, @products] do %table.table.table-striped{:id => 'products'} %thead %tr %th Name %th Category [...] %tbody - @products.each do |product| - cache [current_user, product] do %tr %td= link_to product.name, [...] %td= product.description
51. After - cache [current_user, @products] do %table.table.table-striped{:id => 'products'} %thead %tr %th Name %th Category [...] %tbody - @products.each do |product| - cache [current_user, product] do %tr %td= link_to product.name, [...] %td= product.description complete table one row
52. The 3rd line is in Gemfile: gem 'dalli' Don‘t forget to run bundle install.
53. The 4th line is in production.rb: config.cache_store = :dalli_store
54. How much difference can THAT make?!
55. 0 30 60 90 120 Vanilla Fragment Caching (4 LOC) 116 s 60 s
56. •Each row and each table (#index). •Each #show content. •The shopping cart. •The navigation bar and the footer.
57. More fragment caching > grep "cache " app/views/*/* | sed "s/.*-//g" cache line_item do cache [current_user, 'navigation_bar'] do cache [current_user, @current_cart, 'application_html'] do cache ['footer'] do cache [current_user, @products, 'products_index_table'] do cache [current_user, product, 'products_index_table_row'] do cache [current_user, @product, 'products_show'] do cache [current_user, @product, 'products_show_ratings_table'] do cache [rating, 'products_show_ratings_table_row'] do >
58. 0 30 60 90 120 Vanilla Fragment Caching 116 s 45 s
59. HTTP Caching
60. A browser can use Last-Modified: and Etag: to check if a locally cached webpage is still good.
61. > curl -I http://0.0.0.0:3000/ HTTP/1.1 200 OK Content-Type: text/html; charset=utf-8 X-Ua-Compatible: IE=Edge Etag: "9a779b80e4b0ac3c60d29807e302deb7" [...] > curl -I http://0.0.0.0:3000/ HTTP/1.1 200 OK Content-Type: text/html; charset=utf-8 X-Ua-Compatible: IE=Edge Etag: "fa8fc1e981833a6885b583d351c4d823"
62. > curl -I http://0.0.0.0:3000/ HTTP/1.1 200 OK Content-Type: text/html; charset=utf-8 X-Ua-Compatible: IE=Edge Etag: "9a779b80e4b0ac3c60d29807e302deb7" [...] > curl -I http://0.0.0.0:3000/ HTTP/1.1 200 OK Content-Type: text/html; charset=utf-8 X-Ua-Compatible: IE=Edge Etag: "fa8fc1e981833a6885b583d351c4d823"
63. Set the Etag class ProductsController < ApplicationController # GET /products def index @products = Product.limit(25) fresh_when :etag => [current_user, @products.order(:updated_at).last] end [...]
64. Set the Etag class ProductsController < ApplicationController # GET /products def index @products = Product.limit(25) fresh_when :etag => [current_user, @products.order(:updated_at).last] end [...]
65. Set the Etag class ProductsController < ApplicationController # GET /products def index @products = Product.limit(25) fresh_when :etag => [current_user, @products.order(:updated_at).last] end [...]
66. > curl -I http://0.0.0.0:3000/ -c cookies.txt HTTP/1.1 200 OK Etag: "4d348810e69400799e2ab684c0ef4777" > curl -I http://0.0.0.0:3000/ -b cookies.txt HTTP/1.1 200 OK Etag: "4d348810e69400799e2ab684c0ef4777" The cookie is needed for the CSRF-Token.
67. > curl -I http://0.0.0.0:3000/ -b cookies.txt --header 'If-None-Match: "4d348810e69400799e2ab684c0ef4777"' HTTP/1.1 304 Not Modified Etag: "4d348810e69400799e2ab684c0ef4777" 304!
68. Let the numbers speak!
69. 0 30 60 90 120 Vanilla Fragment Caching HTTP Cache 45 s 35 s
70. 35 s / 43 pages = 0,8 s/p
71. Not good enough?
72. We do waste a lot of time for writing the initial cache!
73. What does happen when we preheat the cache?
74. 0 30 60 90 120 Vanilla Fragment Caching HTTP Cache Preheater 26 s
75. 26 s / 43 pages = 0,6 s/p WHOA!
76. Pro-Tip: You the night to preheat your cache!
77. Thank you!
78. No, not yet! ;-)
79. There is our forgotten friend ...
80. caches_page :index, :show, :gzip => :true
81. page_cache stores completely rendered HTML pages in a gz-format. Nginx is happy to deliver them without bothering Rails at all.
82. But, we have to take care that out of date gz files get deleted.
83. after_update :expire_cache before_destroy :expire_cache private def expire_cache ActionController::Base.expire_page(Rails.application.routes.url_h elpers.company_path(self)) ActionController::Base.expire_page(Rails.application.routes.url_h elpers.companies_path) end app/models/product.rb
84. Obviously this needs preheating for maximum effect.
85. page caching for current_users gets a bit tricky. But nginx will happily read the cookie and use a different directory for the cached pages.
86. 0 30 60 90 120 Vanilla Fragment Caching HTTP Cache Preheater Page Caching 19 s
87. 19 s / 43 pages = 0,4 s/p MEGA WHOA!
88. Start: 116 s End: 19 s. Improvement: 610%
89. Lessons learned • Use the not so busy time (e.g. 3 am) to preheat your cache. • Harddrive space is cheap. Take advantage of this! • Start to think about caching at the beginning of your development. You need a clean model structure!
90. Thank you! stefan.wintermeyer@amooma.de