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synced 2022-11-09 12:12:34 -05:00
960de47f0e
`each_with_object` allocates an array for each kv pair. Switching to
the slightly more verbose but less allocatey `each_pair` eliminates
array allocations. Eliminating this allocation returns AR objects to
have constant array allocations regardless of the number of columns the
object has.
Here is test code:
```ruby
require 'active_record'
class Topic < ActiveRecord::Base
end
20.times do |i|
Process.waitpid fork {
ActiveRecord::Base.establish_connection adapter: 'sqlite3', database: ':memory:'
ActiveRecord::Base.connection.instance_eval do
create_table(:topics) do |t|
t.string :title, limit: 250
t.string :author_name
t.string :author_email_address
t.string :parent_title
t.string :type
t.string :group
i.times do |j|
t.string :"aaa#{j}"
end
t.timestamps null: true
end
end
ObjectSpace::AllocationTracer.setup(%i{type})
Topic.create title: "aaron" # heat cache
result = ObjectSpace::AllocationTracer.trace do
10.times do |i|
Topic.create title: "aaron #{i}"
end
end
puts "#{Topic.columns.length},#{(result.find { |k,v| k.first == :T_ARRAY }.last.first / 10)}"
}
end
```
Before this commit:
```
9,166
10,167
11,168
12,169
13,170
14,171
15,172
16,173
17,174
18,175
19,176
20,177
21,178
22,179
23,180
24,181
25,182
26,183
27,184
28,185
```
After:
```
9,157
10,157
11,157
12,157
13,157
14,157
15,157
16,157
17,157
18,157
19,157
20,157
21,157
22,157
23,157
24,157
25,157
26,157
27,157
28,157
```
Left side is the number of columns, right is the number of allocations
|
||
|---|---|---|
| .. | ||
| bin | ||
| lib | ||
| test | ||
| activesupport.gemspec | ||
| CHANGELOG.md | ||
| MIT-LICENSE | ||
| Rakefile | ||
| README.rdoc | ||
= Active Support -- Utility classes and Ruby extensions from Rails Active Support is a collection of utility classes and standard library extensions that were found useful for the Rails framework. These additions reside in this package so they can be loaded as needed in Ruby projects outside of Rails. == Download and installation The latest version of Active Support can be installed with RubyGems: % gem install activesupport Source code can be downloaded as part of the Rails project on GitHub: * https://github.com/rails/rails/tree/master/activesupport == License Active Support is released under the MIT license: * http://www.opensource.org/licenses/MIT == Support API documentation is at: * http://api.rubyonrails.org Bug reports can be filed for the Ruby on Rails project here: * https://github.com/rails/rails/issues Feature requests should be discussed on the rails-core mailing list here: * https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core