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Fast Rails API

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z

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Max workload - 1500 rps Target response time - 100 ms

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rps 1500 65 What we have What we want

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Rails 3 Ruby 1.9.3 Unicorn Nginx Postgresql Initial stack

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# config/unicorn.rb worker_processes (ENV['UNICORN_WORKERS'] || 1).to_i # config/database.yml development: ... pool: 5 Connection pool https://devcenter.heroku.com/articles/concurrency-and-database-connections Unicorn worker Unicorn worker DB AR connection pool 1 connection per worker for max productivity

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# config/unicorn.rb before_fork do |server, worker| if defined?(ActiveRecord::Base) ActiveRecord::Base.connection.disconnect! end end after_fork do |server, worker| if defined?(ActiveRecord::Base) config = Rails.application.config.database_configuration[Rails.env] config['reaping_frequency'] = ENV['DB_REAP_FREQ'] || 10 # seconds config['pool'] = ENV['DB_POOL'] || 5 ActiveRecord::Base.establish_connection(config) end end Establish DB connection after fork https://devcenter.heroku.com/articles/concurrency-and-database-connections

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# config.ru if ENV['RAILS_ENV'] == 'production' require 'unicorn/worker_killer' max_request_min = 500 max_request_max = 600 # Max requests per worker use Unicorn::WorkerKiller::MaxRequests, max_request_min, max_request_max oom_min = (240) * (1024**2) oom_max = (260) * (1024**2) # Max memory size (RSS) per worker use Unicorn::WorkerKiller::Oom, oom_min, oom_max end # Gemfile group :production do gem 'unicorn-worker-killer' end Unicorn worker killer

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# Gemfile gem 'rails-api' # app/controllers/api/application_controller.rb class Api::ApplicationController < ActionController::API Rails-api

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# config/application.rb require "active_record/railtie" require "action_mailer/railtie" require "action_controller/railtie" require "action_view/railtie" require "rails/test_unit/railtie" require "sprockets/railtie" Do not load ‘rails/all’

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# config/application.rb require "active_record/railtie" require "action_mailer/railtie" require "action_controller/railtie" require "action_view/railtie" require "rails/test_unit/railtie" require "sprockets/railtie" Do not load ‘rails/all’

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Connection pool Rails-api Do not load ‘rails/all’ Establish DB connection after fork/ new thread was created Unicorn worker killer Summary REALY HELPFUL HELPFUL IMPROVES STABILITY

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rps 1500 66 What we have What we want

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Postgresql tuning http://postgresql.leopard.in.ua/html/ http://momjian.us/main/writings/pgsql/hw_performance/ PG Backend PG Backend Shared Buffer Cache Write-Ahead Log Query and checkpoint operations Transaction durability Kernel Disk Buffer Cache fsync Disk Blocks

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Postgresql tuning http://postgresql.leopard.in.ua/html/ http://momjian.us/main/writings/pgsql/hw_performance/ shared_buffers work_mem maintaince_work_mem checkpoint_segments effective_cache_size CLUSTER table

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Rails 4 Ruby 2.1.0 Postgresql tuning Summary REALY HELPFUL

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rps 1500 70 What we have What we want

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Oj (JSON dumper) # Gemfile gem 'oj' json 0.810000 0.020000 0.830000 ( 0.841307) yajl 0.760000 0.020000 0.780000 ( 0.809903) oj 0.640000 0.010000 0.650000 ( 0.666230) Good idea to use the fastest dumper

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Active Model Serializers # Gemfile gem 'active_model_serializers' # app/serializers/user_serializer.rb class UserSerializer < ActiveModel::Serializer root false attributes :id, :guid, :current_channel_id, :current_telecast_ts, :created_at, :updated_at end # app/controllers/api/user_controller.rb def show @user = User.find params[:id] render json: @user end

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Fragment caching https://devcenter.heroku.com/articles/caching-strategies http://signalvnoise.com/posts/3113-how-key-based-cache-expiration-works # app/controllers/api/application_controller.rb class Api::ApplicationController < ActionController::API include ActionController::Caching # app/controllers/api/users_controller.rb def show @user = User.find params[:id] json = cache ['v1', @user] do ActiveModel::Serializer.build_json(self, @user, {}).to_json end render json: json end

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Fragment caching # app/controllers/api/users_controller.rb def index json = cache ['v1', CacheKeyRegistry.users] do @users = User.all ActiveModel::Serializer.build_json(self, @users, {}).to_json end render json: json end # lib/cache_key_registry.rb module CacheKeyRegistry class << self def users; key(User, __method__) end private def key(scope, key_prefix) count = scope.count max_updated_at = scope.maximum(:updated_at).try(:utc).try(:to_s, :number) "#{key_prefix}/all-#{count}-#{max_updated_at}" end end end “users/all-25-2014-02-23”

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Fragment caching Active Model Serializers Oj (JSON dumper) Summary REALY HELPFUL HELPFUL

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rps 1500 1500 What we have What we want

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Rails 4 Ruby 2.1.0 Unicorn Nginx Postgresql Memcached Current stack

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Do not instantiate AR objects Try OOBGC Try different web server (e.g. Puma) Other ideas

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Do not instantiate AR objects def self.lightning connection.select_all(select([:guid, :current_channel_id, :current_telecast_ts]).arel).each do |attrs| attrs.each_key do |attr| attrs[attr] = type_cast_attribute(attr, attrs) end end end

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A note about profiling tools

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$ stackprof stackprof-cpu-6196-1393432908.dump --text ================================== Mode: cpu(1000) Samples: 545 (0.00% miss rate) GC: 48 (8.81%) ================================== TOTAL (pct) SAMPLES (pct) FRAME 42 (7.7%) 39 (7.2%) #.escape 33 (6.1%) 23 (4.2%) ActiveRecord::ConnectionAdapters::Column.new_time 21 (3.9%) 21 (3.9%) Set#include? 13 (2.4%) 13 (2.4%) block in ActiveSupport::Dependencies#search_for_file 13 (2.4%) 13 (2.4%) block in ActiveSupport::Dependencies#autoloadable_module? 26 (4.8%) 4 (0.7%) Channel::Telecast#cover_url Stackprof

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$ stackprof stackprof-cpu-6196-1393432908.dump --text --method 'Channel::Telecast#cover_url' Channel::Telecast#cover_url (/projects/undev/simpletv-backend/app/models/concerns/coverable.rb:12) samples: 4 self (0.7%) / 26 total (4.8%) callers: 26 ( 100.0%) Channel::TelecastSerializer#cover callees (22 total): 22 ( 100.0%) Channel::Telecast#cover code: | 12 | def cover_url(version = nil) | 13 | if cover.file.nil? && external_cover 26 (4.8%) / 4 (0.7%) | 14 | external_cover.gsub(configus.cdn_host, '/cdn') Stackprof

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https://github.com/MiniProfiler/rack-mini-profiler Rack Mini Profiler

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Bullet Request log analyzer NewRelic Other

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although Rails sucks without cache Don’t know what to do?

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http://www.slideshare.net/maxlapshin/rails-26416461

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Any other ideas? Questions? Anton Kalyaev twitter.com/AntonKalyaev github.com/akalyaev