yuroyoro

begin
  class CreateModels < ActiveRecord::Migration
    def change
      create_table :items do |t|
      end

      create_table :events do |t|
        t.belongs_to :item
      end

yuroyoro

require 'benchmark/ips'

begin
  class CreateModels < ActiveRecord::Migration
    def change
      create_table :users do |t|
        t.string :attribute1
        t.string :attribute2
        t.string :attribute3
        t.string :attribute4

yuroyoro

diff --git activerecord/lib/active_record/attribute_methods/read.rb activerecord/lib/active_record/attribute_methods/read.rb
index 20f0936..77bd11d 100644
--- activerecord/lib/active_record/attribute_methods/read.rb
+++ activerecord/lib/active_record/attribute_methods/read.rb
@@ -33,6 +33,17 @@ module ActiveRecord
         end
       }.new

+      TextReaderMethodCache = Class.new(AttributeMethodCache) {
+        def method_body(method_name, const_name)

yuroyoro

diff --git activerecord/lib/active_record/associations/collection_proxy.rb activerecord/lib/active_record/associations/collection_proxy.rb
index a034753..c5b84e5 100644
--- activerecord/lib/active_record/associations/collection_proxy.rb
+++ activerecord/lib/active_record/associations/collection_proxy.rb
@@ -28,13 +28,23 @@ module ActiveRecord
     # is computed directly through SQL and does not trigger by itself the
     # instantiation of the actual post records.
     class CollectionProxy < Relation
+
       delegate(*(ActiveRecord::Calculations.public_instance_methods - [:count]), to: :scope)

yuroyoro

block in ActiveRecord::Associations::Preloader::ThroughAssociation#associated_records_by_owner (/home/ozaki/dev/rails/activerecord/lib/active_record/associations/preloader/through_association.rb:45)
  samples:     8 self (0.8%)  /    332 total (33.3%)
  callers:
     332  (  100.0%)  ActiveRecord::Associations::Preloader::ThroughAssociation#associated_records_by_owner
  callees (324 total):
     307  (   94.8%)  block (2 levels) in ActiveRecord::Associations::Preloader::ThroughAssociation#associated_records_by_owner
       9  (    2.8%)  ActiveRecord::Core#hash
       8  (    2.5%)  block (2 levels) in ActiveRecord::Associations::Preloader::ThroughAssociation#associated_records_by_owner
  code:
                                  |    45  |           through_records.each_with_object({}) { |(lhs,center),records_by_owner|

yuroyoro

以下のissueをfixするPR. Major performance regression when preloading has_many_through association · Issue #12537 · rails/rails rails/rails#12537

commitはこれ https://github.com/yuroyoro/rails/commit/b348115f1d0cc8d3aa363568b6692ad312941a91

---

I profiled the benchmark code that preloads has_many_through association, and found that most of time spent by

yuroyoro

require 'benchmark/ips'

begin
  class CreateModels < ActiveRecord::Migration
    def change
      create_table :items do |t|
      end

      create_table :events do |t|
        t.belongs_to :item

yuroyoro

================================================================================
3.2.21 - sqlite3
================================================================================

Calculating -------------------------------------
  limit 100 has_many    13.000  i/100ms
limit 100 has_many_through
                         5.000  i/100ms
limit 100 double has_many_through
                         3.000  i/100ms

yuroyoro

# Hash#deep_slice
#
# h = {
#   :a => 1, 
#   :b => 2, 
#   :c => {
#     :ca => 31, 
#     :cb => 32, 
#     :cc => 33
#   },

yuroyoro

jobs  = jenkins.model.Jenkins.instance.items

jobs.each {job ->
  job.removeProperty(jenkins.plugins.slack.SlackNotifier.SlackJobProperty)

  jp = new jenkins.plugins.slack.SlackNotifier.SlackJobProperty(
      null,            // String teamDomain, 
      null,            // String token,                 
      "#channel_to_notified",     // String room,                  
      false,           // boolean startNotification,