From: "aadi (Aditya Anchuri) via ruby-core" Date: 2026-09-25T04:14:27+00:00 Subject: [ruby-core:126858] [Ruby Bug#22092] `Array#sum` takes slow path, does not perform compensated summation of Float elements when init argument is a Float Issue #22092 has been updated by aadi (Aditya Anchuri). I believe there is a bug in the fix, when a block with side effects is passed in. I think this should fix it https://github.com/ruby/ruby/pull/19022 ---------------------------------------- Bug #22092: `Array#sum` takes slow path, does not perform compensated summation of Float elements when init argument is a Float https://bugs.ruby-lang.org/issues/22092#change-119217 * Author: georgeclaghorn (George Claghorn) * Status: Closed * ruby -v: ruby 4.0.1 (2026-01-13 revision e04267a14b) +PRISM [arm64-darwin24] * Backport: 3.3: REQUIRED, 3.4: DONE, 4.0: DONE ---------------------------------------- ``` % time ruby -e 'puts Array.new(1_000_000_000, 0.1).sum' 100000000.0 ruby -e 'puts Array.new(1_000_000_000, 0.1).sum' 2.67s user 2.02s system 71% cpu 6.577 total % time ruby -e 'puts Array.new(1_000_000_000, 0.1).sum(0.0)' 99999998.74541782 ruby -e 'puts Array.new(1_000_000_000, 0.1).sum(0.0)' 22.72s user 1.80s system 96% cpu 25.332 total ``` Both the fast path and compensated summation are undocumented implementation details as far as I know, but this appears to be a possible oversight. -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/