Issue #20589 has been reported by eileencodes (Eileen Uchitelle). ---------------------------------------- Feature #20589: Resize array in `rb_ary_freeze` and use `rb_ary_freeze` internally for arrays https://bugs.ruby-lang.org/issues/20589 * Author: eileencodes (Eileen Uchitelle) * Status: Open ---------------------------------------- GitHub PR https://github.com/ruby/ruby/pull/11030 This is a redo of https://github.com/ruby/ruby/pull/2640 and a new issue for the array portion of https://bugs.ruby-lang.org/issues/16291 because both are stale. This change proposes the following: 1) Call `ary_shrink_capa` from `rb_ary_freeze` to resize arrays before freezing (if they are not embedded, not shared, and not a shared root). 2) Update callers to use `rb_ary_freeze` instead of `rb_obj_freeze` internally in CRuby/ 3) Add an assertion to `ary_heap_realloc` that ensures frozen arrays are not being reallocated.\ The orignal issue implemented this for performance reasons, which are still valid. However, additionally this ensures that frozen arrays are not being passed to `ary_heap_realloc` and also ensures the capacity is set with `ARY_SET_CAPA` in `ary_shrink_capa`. Previously, because `ARY_SET_CAPA` was not called, `ary_heap_realloc` would get called after the array was frozen (when that is unnecessary). Array memsize before and after this change: Before: ```ruby $ require 'objspace' => false $ a = (1..5).to_a => [1, 2, 3, 4, 5] $ ObjectSpace.memsize_of(a) => 200 $ a.freeze => [1, 2, 3, 4, 5] $ ObjectSpace.memsize_of(a) => 200 ``` After: ```ruby $ require 'objspace' => false $ a = (1..5).to_a => [1, 2, 3, 4, 5] $ ObjectSpace.memsize_of(a) => 200 $ a.freeze => [1, 2, 3, 4, 5] $ ObjectSpace.memsize_of(a) => 80 ``` -- https://bugs.ruby-lang.org/