Lazy-allocate @new_values in Grape::Util::BaseInheritable#2739
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`BaseInheritable#initialize` used to eagerly allocate an empty
`@new_values = {}` per instance. Most settings layers in a typical API
only inherit from a parent and never write any *new* values of their
own, so the empty Hash was just retained dead weight.
Defer the allocation: `@new_values` starts nil, the `[]=` writers do
`(@new_values ||= {})[name] = ...`, and the read paths in
`InheritableValues#[]` / `StackableValues#[]` short-circuit on nil so
they skip the lookup entirely instead of touching an empty Hash.
`initialize_copy` skips the `.dup` when the source has no own values.
Measured on master with a small benchmark:
Grape::Util::InheritableSetting.new ×100
before: 1600 objects, 183.6 kB
after: 1200 objects, 121.1 kB (-34%)
parent.point_in_time_copy ×100
before: 2500 objects, 277.3 kB
after: 1700 objects, 152.3 kB (-45%)
The bigger win on `point_in_time_copy` matches the
`base_inheritable.rb:27` (`new_values.dup`) hot spot in the boot-time
memory profile: that line previously dup'd four empty Hashes per copy
and now skips them entirely.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Markdowns* [#PRNUMBER](https://github.com/ruby-grape/grape/pull/PRNUMBER): Lazy-allocate `@new_values` in `Grape::Util::BaseInheritable` so settings layers that only inherit never carry an empty Hash; readers in `InheritableValues`/`StackableValues` handle nil - [@ericproulx](https://github.com/ericproulx).
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…Setting
`InheritableSetting#initialize` used to eagerly allocate both fields up
front. Neither is touched on most settings layers:
- `@api_class` is only written by external code (e.g. plugins) via
`setting.api_class[:k] = v`; nothing in `lib/` writes to it.
- `@point_in_time_copies` only fills up on settings that get cloned via
`point_in_time_copy` — typically the API-class-level setting, not the
per-endpoint copies that make up the bulk of allocations at boot.
Switch both to memoizing readers (`@x ||= …`), drop the eager init, and
rewrite the `inherit_from` propagation loop to access the ivar directly
with `&.each` so the no-copies path doesn't allocate the Array just to
iterate zero elements.
Measured against master:
Grape::Util::InheritableSetting.new × 100
before: 1600 objects, 183.6 kB
after: 1400 objects, 164.1 kB (-11%)
Stacks with #2739 (lazy `@new_values`) for compounded boot-time savings.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
BaseInheritable#initializeused to eagerly allocate an empty@new_values = {}per instance. Most settings layers in a typical API only inherit from a parent and never write any new values of their own, so the empty Hash was just retained dead weight.@new_valuesstartsnil,[]=writers do(@new_values ||= {})[...] = ..., and the readers inInheritableValues#[]/StackableValues#[]short-circuit on nil instead of touching an empty Hash.initialize_copyskips the.dupwhen the source has no own values.Benchmarks
Measured against master with
MemoryProfiler.report:Grape::Util::InheritableSetting.new × 100parent.point_in_time_copy × 100The bigger
point_in_time_copywin matches thebase_inheritable.rb:27(new_values.dup) hot spot in the boot-time memory profile — that line used to dup four empty Hashes per copy and now skips them entirely.Test plan
bundle exec rspec— 2313 examples, 0 failuresbundle exec rubocop— clean on touched files🤖 Generated with Claude Code