Issue #20226 has been updated by Eregon (Benoit Daloze).
Sorting in Ruby never was stable
My mistake, like Roger Pack in https://github.com/crystal-lang/crystal/issues/2350#issuecomment-550188746, my experience is sort looks stable (on Linux). And sort is stable on TruffleRuby since it uses mergesort (currently at least). So what changed between 3.2 and 3.3? I can reproduce the OP's behavior on linux-amd64. Maybe it's `sort_by`-specific? And maybe `sort_by` was stable until 3.2? ---------------------------------------- Bug #20226: Inconsistent Sort results on 3.3.0 compared to previous versions https://bugs.ruby-lang.org/issues/20226#change-106520 * Author: omerby (Omer Ben Yosef) * Status: Open * Priority: Normal * ruby -v: 3.3.0 * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Try this code block: ``` [-0.9, -0.88, -0.85, -0.83, -0.81, -0.79, -0.77, -0.75, -0.73, -0.71, -0.69, -0.67, -0.65, -0.63, -0.6, -0.58, -0.56, -0.54, -0.52, -0.5, -0.48, -0.46, -0.44, -0.42, -0.4, -0.38, -0.35, -0.33, -0.31, -0.29, -0.27, -0.25, -0.23, -0.21, -0.19, -0.17, -0.15, -0.13, -0.1, -0.08, -0.06, -0.04, -0.02, 0.0, 0.02, 0.0, 0.02].sort_by(&:abs) ``` The end result should be the numbers absolute sorted, look at the last 5 numbers of this, the end result of them should be `[0.0, 0.0, -0.02, 0.02, 0.02...]` maintaining the original order, and this behavior is what we see on ruby 3.2.0, however on ruby 3.3.0 the end result will be `[0.0, 0.0, 0.02, 0.02, -0.02...]` This is also inconsistent, as `[-0.02, 0.0, 0.02, 0.0, 0.02].sort_by(&:abs)` will actually provide the expected result. Again, the main issue for us is the difference between 3.3.0 and previous versions of ruby. -- https://bugs.ruby-lang.org/