Skip to content

Optimize internal extract! calls to save on memory allocation#598

Merged
rafaelfranca merged 2 commits intorails:mainfrom
affinity:moberegger/optimize_extract
Jul 18, 2025
Merged

Optimize internal extract! calls to save on memory allocation#598
rafaelfranca merged 2 commits intorails:mainfrom
affinity:moberegger/optimize_extract

Conversation

@moberegger
Copy link
Contributor

@moberegger moberegger commented May 30, 2025 •
edited
Loading

Simply optimizes internal calls to extract! to avoid extra memory allocations to splat the *attributes. Both _extract_hash_values and _extract_method_values accept an array for attributes, so no need to re-splat it by calling extract!, which then splats it again.

Solution is to implement a private _extract that just accepts an array, which can be used internally.

A simple way to compare it is with the call DSL, which was just running extract! underneath.

# person = { first_name: 'John', last_name: 'Doe', age: 30, city: 'New York' }

json.(person, :first_name, :last_name, :age, :city)
Warming up --------------------------------------
              before   156.678k i/100ms
               after   176.882k i/100ms
Calculating -------------------------------------
              before      1.674M (± 1.6%) i/s  (597.37 ns/i) -      8.461M in   5.055454s
               after      1.802M (± 2.0%) i/s  (554.82 ns/i) -      9.021M in   5.007138s

Comparison:
               after:  1802399.6 i/s
              before:  1673994.1 i/s - 1.08x  slower

Calculating -------------------------------------
              before   320.000  memsize (     0.000  retained)
                         6.000  objects (     0.000  retained)
                         4.000  strings (     0.000  retained)
               after   240.000  memsize (     0.000  retained)
                         5.000  objects (     0.000  retained)
                         4.000  strings (     0.000  retained)

Comparison:
               after:        240 allocated
              before:        320 allocated - 1.33x more

This change has no impact in using json.extract! directly.

# person = { first_name: 'John', last_name: 'Doe', age: 30, city: 'New York' }

json.extract! person, :first_name, :last_name, :age, :city
Calculating -------------------------------------
              before   240.000  memsize (     0.000  retained)
                         5.000  objects (     0.000  retained)
                         4.000  strings (     0.000  retained)
               after   240.000  memsize (     0.000  retained)
                         5.000  objects (     0.000  retained)
                         4.000  strings (     0.000  retained)

Comparison:
              before:        240 allocated
               after:        240 allocated - same

@moberegger moberegger mentioned this pull request May 30, 2025
Merged
moberegger
moberegger commented May 30, 2025
View reviewed changes
@moberegger moberegger closed this Jun 13, 2025
@moberegger moberegger deleted the moberegger/optimize_extract branch June 13, 2025 18:54
@moberegger moberegger restored the moberegger/optimize_extract branch June 17, 2025 02:05
@moberegger moberegger reopened this Jun 17, 2025
@rafaelfranca rafaelfranca merged commit 535327a into rails:main Jul 18, 2025
30 checks passed
@PikachuEXE PikachuEXE mentioned this pull request Aug 13, 2025
Merged
@moberegger moberegger mentioned this pull request Sep 29, 2025
Open
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

No reviews

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@moberegger @rafaelfranca