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author | Aaron Patterson <aaron.patterson@gmail.com> | 2015-10-15 14:44:01 -0700 |
---|---|---|
committer | Aaron Patterson <aaron.patterson@gmail.com> | 2015-10-15 14:44:28 -0700 |
commit | 960de47f0eef79d234eb3cfc47fabb470fef1529 (patch) | |
tree | 14ec87c60341fa46b74dc3413a8a62ae2de4b419 /activerecord/test/models/movie.rb | |
parent | 3b61027092517ac9fd2736d38673c27fedd08c1b (diff) | |
download | rails-960de47f0eef79d234eb3cfc47fabb470fef1529.tar.gz rails-960de47f0eef79d234eb3cfc47fabb470fef1529.tar.bz2 rails-960de47f0eef79d234eb3cfc47fabb470fef1529.zip |
drop array allocations when iterating over the hash
`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
Diffstat (limited to 'activerecord/test/models/movie.rb')
0 files changed, 0 insertions, 0 deletions