Issue #22386 has been reported by rkh (Konstantin Haase). ---------------------------------------- Bug #22386: Segfault when a Ractor helper thread reports an exception during teardown https://bugs.ruby-lang.org/issues/22386 * Author: rkh (Konstantin Haase) * Status: Open * ruby -v: ruby 4.1.0dev (2026-09-27T05:30:49Z master f6ff9e7d02) +PRISM [arm64-darwin25] * Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- Ruby 4.1-dev can segfault when a thread inside a terminating Ractor raises an exception in an `ensure` block. Automatic thread exception reporting tries to load error-formatting code through `require`. The require path creates an internal Ractor port after the Ractor's port table has been freed. Creating a `Ractor::Port` directly in the same teardown context also segfaults, even with automatic exception reporting disabled. Script to reproduce the issue: ```ruby worker = Ractor.new do ready = Thread::Queue.new Thread.new do begin ready << true sleep ensure Object.new.missing_method_during_teardown end end ready.pop :done end worker.value ``` Running the script on Ruby 4.1-dev gives a segmentation fault output and then hangs. ``` #<Thread:0x0000000122aa0190 issue.rb:3 aborting> terminated with exception (report_on_exception is true): [BUG] Segmentation fault at 0x0000000000000018 ruby 4.1.0dev (2026-09-27T05:30:49Z master f6ff9e7d02) +PRISM [arm64-darwin25] -- Crash Report log information -------------------------------------------- See Crash Report log file in one of the following locations: * ~/Library/Logs/DiagnosticReports * /Library/Logs/DiagnosticReports for more details. Don't forget to include the above Crash Report log file in bug reports. -- Control frame information ----------------------------------------------- c:0002 p:---- s:0006 e:000005 l:y b:0001 r:0x0 CFUNC :detailed_message c:0001 p:---- s:0003 e:000002 l:y b:---- r:0x0 DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- issue.rb:0:in 'detailed_message' -- Threading information --------------------------------------------------- Total ractor count: 2 Ruby thread count for this ractor: 2 -- Machine register context ------------------------------------------------ x0: 0x0000000000000000 x1: 0x0000000000000001 x2: 0x000000083b2cf0e0 x3: 0x0000000000000000 x4: 0x0000000000000001 x5: 0x0000000000000000 x6: 0xffffffffbfc007ff x7: 0xfffff0003ffff800 x18: 0x0000000000000000 x19: 0x0000000122ac09c0 x20: 0x000000083adced00 x21: 0x0000000000000000 x22: 0x0000000000000001 x23: 0x000000083b2cf0e0 x24: 0x0000000122ab00a0 x25: 0x00000000ffffffff x26: 0x000000012d90bfc8 x27: 0x000000083b03a940 x28: 0x0000000055550483 lr: 0x0000000103b8e020 fp: 0x000000012da0f760 sp: 0x000000012da0f720 -- C level backtrace information ------------------------------------------- ``` -- https://bugs.ruby-lang.org/