Scaling Rails for Black Friday / Cyber Monday at Shopify

Transcript

1. scaling rails for Black Friday Cyber Monday

2. cjoudrey @

3. None
4. None
5. None
6. None
7. None

8. the stack

9. nginx unicorn • rails 4 • mysql 5.6 (percona) ruby

   2.1 •

10. 95 app servers 1,800 unicorn workers 18 job servers 1,400

    job workers

11. scale?

12. None

13. 400,000 reqs/min

14. 3.7B$ annual GMV that’s 7,000$ per min

15. Black Friday Cyber Monday

16. Black Friday Cyber FUNday

17. None

18. ~ 600,000 reqs/min

19. 1 request 1 process =

20. scale++ ↓ resp. time ↑ workers

21. page caching

22. None
23. None

24. shopify/cacheable

25. generational caching

26. gzip • etag + 304 not modified

27. class PostsController < ApplicationController def index response_cache do @posts =

    @shop.posts.paginate(params[:page]) respond_with(@posts) end end def cache_key_data { shop_id: @shop.id, path: request.path, format: request.format, params: params.slice(:page), shop_version: @shop.version } end end

28. md5( { shop_id: 1, path: '/posts', format: 'text/html', params: {

    page: 2 }, shop_version: 123 }.to_s ) GET /posts?page=2
29. None

30. sale

31. query caching

32. shopify/identity_cache

33. full model caching

34. opt-in by design

35. after_commit expiry

36. class Product < ActiveRecord::Base include IdentityCache has_many :images cache_has_many :images,

    :embed => true end product = Product.fetch(id) images = product.fetch_images

37. class Product < ActiveRecord::Base include IdentityCache cache_index :shop_id, :handle, :unique

    => true end Product.fetch_by_shop_id_and_handle(shop_id, handle)
38. None

39. sale

40. background jobs

41. webhooks emails • fraud detection • payment processing

42. None

43. priority queues payment • default • low realtime •

44. throttling

45. now what?

46. measure it! if it moves...

47. statsd

48. shopify/statsd-instrument

49. Liquid::Template.extend StatsD::Instrument Liquid::Template.statsd_measure :render, 'Liquid.Template.render'

50. PaymentProcessingJob.statsd_count :perform, 'PaymentProcessingJob.processed'

51. None
52. None

53. load testing

54. genghis khan

55. simulate Black Friday Cyber Monday before it happens

56. several times per week

57. slow queries

58. # User@Host: shopify[shopify] @ [127.0.0.1] # Thread_id: 264419969 Schema: shopify

    Last_errno: 0 Killed: 0 # Query_time: 0.150491 Lock_time: 0.000057 Rows_sent: 1 Rows_examined: 147841 Rows_affected: 0 Rows_read: 147841 # Bytes_sent: 1214 Tmp_tables: 0 Tmp_disk_tables: 0 Tmp_table_sizes: 0 # InnoDB_trx_id: FF7021AAA # QC_Hit: No Full_scan: No Full_join: No Tmp_table: No Tmp_table_on_disk: No # Filesort: Yes Filesort_on_disk: No Merge_passes: 0 # InnoDB_IO_r_ops: 0 InnoDB_IO_r_bytes: 0 InnoDB_IO_r_wait: 0.000000 # InnoDB_rec_lock_wait: 0.000000 InnoDB_queue_wait: 0.000000 # InnoDB_pages_distinct: 475 SET timestamp=1393385020; SELECT `discounts`.* FROM `discounts` WHERE `discounts`.`shop_id` = 1745470 AND `discounts`.`status` = 'enabled' ORDER BY ISNULL(ends_at) DESC, ends_at DESC LIMIT 1

59. determining root cause

60. https://github.com/newobj/nginx-x-rid-header nginx request_id header proxy_set_header X-Request-ID "$request_id"; log_format main '...

    $request_id' step 1

61. https://gist.github.com/mnutt/566725 Complete 200 OK in 100ms (Views: 60ms | ActiveRecord:

    40ms | request_id=bc12813bce...) log_process_action ActionController::Instrumentation step 2

62. https://github.com/basecamp/marginalia User Load (0.3ms) SELECT `users`.* FROM `users` WHERE `users`.`id`

    = 1 LIMIT 1 /*application:Shopify, controller:users,action:show, request_id:bc12813bce...*/ basecamp/marginalia step 3

63. # User@Host: shopify[shopify] @ [127.0.0.1] # Thread_id: 264419969 Schema: shopify

    Last_errno: 0 Killed: 0 # Query_time: 0.150491 Lock_time: 0.000057 Rows_sent: 1 Rows_examined: 147841 Rows_affected: 0 Rows_read: 147841 # Bytes_sent: 1214 Tmp_tables: 0 Tmp_disk_tables: 0 Tmp_table_sizes: 0 # InnoDB_trx_id: FF7021AAA # QC_Hit: No Full_scan: No Full_join: No Tmp_table: No Tmp_table_on_disk: No # Filesort: Yes Filesort_on_disk: No Merge_passes: 0 # InnoDB_IO_r_ops: 0 InnoDB_IO_r_bytes: 0 InnoDB_IO_r_wait: 0.000000 # InnoDB_rec_lock_wait: 0.000000 InnoDB_queue_wait: 0.000000 # InnoDB_pages_distinct: 475 SET timestamp=1393385020; SELECT `discounts`.* FROM `discounts` WHERE `discounts`.`shop_id` = 1745470 AND `discounts`.`status` = 'enabled' ORDER BY ISNULL(ends_at) DESC, ends_at DESC LIMIT 1 /*application:Shopify,controller:orders,action:pay, request_id:bc12813bce...*/ profit!

64. access.log rails.log slow_query.log profit! (2)

65. bonus! background jobs

66. schema migration with zero downtime

67. soundcloud/lhm

68. class NewIndexOnOrders < ActiveRecord::Migration def self.up Lhm.change_table :orders do |m|

    m.add_index [:shop_id, :customer_id] end end def self.down # end end

69. orders 20140520_orders

70. insert/delete/update triggers

71. INSERT INTO ... SELECT ... insert/delete/update triggers

72. async caveat

73. resiliency

74. A resilient system is one that functions with one or

    more components being unavailable or unacceptably slow. -

75. don’t let a take you down minor dependencies

76. shopify/toxiproxy ☢ redis memcached sessions your app toxiproxy

77. def load_customer if customer_id = session[:customer_id] @customer = Customer.find_by_id(customer_id) end

    end

78. def load_customer if customer_id = session[:customer_id] @customer = Customer.find_by_id(customer_id) end

    rescue Sessions::DataStoreUnavailable @customer = nil end

79. def test_storefront_resilient_to_sessions_down Toxiproxy[:sessions_data_store].down do get '/' assert_response :success end end

80. rinse & repeat http://www.shopify.com/technology/16906928-building-and-testing-resilient-ruby-on-rails-applications

81. what about resources? slow

82. shard 2 shard 3 shard 1 shop 4, 5, 6

    shop 7, 8, 9 shop 1, 2, 3

83. rails request shard 2 shard 3 shard 1 shop 4,

    5, 6 shop 7, 8, 9 shop 1, 2, 3

84. rails request shard 2 shard 3 shard 1 shop 4,

    5, 6 shop 7, 8, 9 shop 1, 2, 3

85. how can we fail fast?

86. shopify/semian smart circuit-breaker

87. shopify/semian Semian.register(:mysql_shard_1, tickets: 5, timeout: 0.5, error_threshold: 100, error_timeout: 10,

    success_threshold: 2)

88. shopify/semian Semian[:mysql_shard_1].acquire do # Query the resource end

89. rails request shard 2 shard 3 shard 1 shop 4,

    5, 6 shop 7, 8, 9 shop 1, 2, 3

90. what else can go wrong?

91. Shopify Shipping rate providers Payment gateways Fulfillment services (FedEX, UPS,

    USPS, etc..) (Stripe, PayPal, etc..) (Shipwire, etc…) Internal services (MySQL, Memcached, etc..)

92. manual circuit breakers around external dependencies

93. thanks! :)