Ruby Issue Tracking System

Today

06:32 PM Ruby Bug #22546 (Open): YJIT panics in arm64 `add` when compiling a method with 495 or more locals

Versions:
- ruby 4.0.9 (2026-10-23 revision 3e93b23afc) +PRISM [arm64-darwin25]
- ruby 4.1.0dev (2026-11-13 master acc624e47b) +PRISM [arm64-darwin25]
macOS on Apple silicon.
Also reproduces on Linux:
- ruby 4.0.9 (2026-10-23 revi... jamescook83 (James Cook)

10/31/2026

09:37 AM Ruby Bug #22489: RubyVM::InstructionSequence#to_a segfaults or hangs when called on the same iseq from multiple Ractors

This is fixed in 4.1.0-preview1 by 99f2ef9c1f (Fix data race in rb_iseq_original_iseq). I couldn't find an existing issue for it in the tracker. I think this can be closed. jamescook83 (James Cook)

09:06 AM Ruby Bug #22489 (Closed): RubyVM::InstructionSequence#to_a segfaults or hangs when called on the same iseq from multiple Ractors

```
# Several Ractors call InstructionSequence#to_a on the same blocks at once.
# Expected: prints "survived". Actual: segfault, bus error or hang.
# Usage: ruby repro.rb [how many blocks] [lines in each block]
Warning[:experimenta... jamescook83 (James Cook)

09/24/2026

11:57 PM Ruby Bug #22382 (Closed): IO#write of a shareable String from multiple Ractors causes use-after-free

When several Ractors `IO#write` the same shareable, heap-allocated (non-embedded) String at the same moment, Ruby frees the String's buffer while the String is still alive. A later GC sweep double-frees it and aborts.
**Reproduction**... jamescook83 (James Cook)