September 2026 - ruby-core - ml.ruby-lang.org

[ruby-core:126507] [Ruby Bug#22267] Active Support tests started failing on ruby master (bisected to #18194)
by yahonda (Yasuo Honda) 10 Sep '26

10 Sep '26

Issue #22267 has been reported by yahonda (Yasuo Honda). ---------------------------------------- Bug #22267: Active Support tests started failing on ruby master (bisected to #18194) https://bugs.ruby-lang.org/issues/22267 * Author: yahonda (Yasuo Honda) * Status: Open * ruby -v: ruby 4.1.0dev (2026-08-26T07:05:32Z master 346b261abe) +PRISM [x86_64-linux] * Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- On ruby-head, the Active Support (Rails) test suite fails with two Ractor-related errors (rails-nightly build 4651, https://buildkite.com/rails/rails-nightly/builds/4651#01a016ac-eada-492d-95…) Rails CI failure. To reproduce on the Rails side, build ruby master, then in a rails/rails checkout run the two tests from activesupport/: ``` $ ruby -v ruby 4.1.0dev (2026-08-26T07:05:32Z master 346b261abe) +PRISM [x86_64-linux] $ bundle exec ruby -Ilib:test test/time_zone_test.rb -n test_formatted_offset_in_ractor #<Thread:...> terminated with exception (report_on_exception is true): lib/active_support/time_with_zone.rb:78:in 'ActiveSupport::TimeWithZone#period': undefined method 'period_for_utc' for nil (NoMethodError) from lib/active_support/time_with_zone.rb:139:in 'ActiveSupport::TimeWithZone#zone' from lib/active_support/time_with_zone.rb:59:in 'ActiveSupport::TimeWithZone#initialize' from lib/active_support/time_with_zone.rb:535:in 'ActiveSupport::TimeWithZone#marshal_load' 1) Error: TimeZoneTest#test_formatted_offset_in_ractor: Ractor::RemoteError: thrown by remote Ractor. lib/active_support/testing/ractors_assertions.rb:15:in 'Ractor#join' lib/active_support/testing/ractors_assertions.rb:15:in 'ActiveSupport::Testing::RactorsAssertions#on_ractor' test/time_zone_test.rb:895:in 'TimeZoneTest#test_formatted_offset_in_ractor' $ bundle exec ruby -Ilib:test test/notifications_test.rb -n test_record_and_set_subscriptions_when_using_a_regexp 1) Error: Notifications::NotificationSubscriptionTest#test_record_and_set_subscriptions_when_using_a_regexp: Ractor::Error: can not copy Hash object. lib/active_support/ractors.rb:117:in 'Ractor.make_shareable' lib/active_support/ractors.rb:117:in 'ActiveSupport::Ractors.make_shareable' lib/active_support/ractors.rb:79:in 'ActiveSupport::Ractors.try_make_shareable' lib/active_support/notifications.rb:359:in 'ActiveSupport::Notifications.record_subscriptions' lib/active_support/notifications.rb:314:in 'ActiveSupport::Notifications.subscribe' test/notifications_test.rb:604:in 'block in <class:NotificationSubscriptionTest>' ``` git bisect points at #18194 (Per-Ractor GC). Both reduce to Ractor copy and reproduce without Rails. Steps to reproduce (pure Ruby). (1) mirrors TimeZoneTest#test_formatted_offset_in_ractor — an object with a Time ivar (which now forces a Marshal fallback) whose marshal_load reconstructs from state only reachable in the main Ractor: ``` class Registry @zones = { "z" => Object.new } def self.find(name) = @zones.fetch(name) # reads a class-level ivar end class Wrapper def initialize(name) = (@name = name; @time = Time.now; @zone = Registry.find(name)) def marshal_dump = @name def marshal_load(name) = (@name = name; @time = Time.now; @zone = Registry.find(name)) end port = Ractor::Port.new Ractor.new(port, Wrapper.new("z")) { |p, o| p.send :ok }.join p port.receive ``` (2) mirrors Notifications...test_record_and_set_subscriptions_when_using_a_regexp — a Hash holding a Set and a shareable Proc: ``` require "set" Ractor.make_shareable({ s: Set.new([1, 2]), p: Ractor.shareable_proc {} }, copy: true) ``` Expected behavior. On Ruby 4.0.6 and before #18194 (50745e3e48): - (1) copies natively, marshal_load is not called, and prints :ok. - (2) succeeds. Actual behavior. On current master (346b261abe) and since #18194 (4f6c34eea6): (1): ``` #<Thread:...> terminated with exception (report_on_exception is true): -:3:in 'Registry.find': can not get unshareable values from instance variables of classes/modules from non-main Ractors (@zones from Registry) (Ractor::IsolationError) from -:8:in 'Wrapper#marshal_load' -:11:in 'Ractor#join': thrown by remote Ractor. (Ractor::RemoteError) from -:11:in '<main>' ``` marshal_load now runs in the receiver Ractor, where the object cannot reach main-Ractor state. In Active Support the same happens in TimeWithZone#marshal_load; there Time.find_zone rescues this and returns nil, so the Rails trace shows period_for_utc for nil instead. (2): ``` -:2:in 'Ractor.make_shareable': can not copy Hash object. (Ractor::Error) from -:2:in '<main>' -:2:in 'Ractor.make_shareable': no _dump_data is defined for class Proc (TypeError) from -:2:in '<main>' ``` -- https://bugs.ruby-lang.org/

2 2

[ruby-core:122943] [Ruby Bug#21537] rb_ractor_sched_barrier_start() hangs on Windows
by rhenium (Kazuki Yamaguchi) 09 Sep '26

09 Sep '26

Issue #21537 has been reported by rhenium (Kazuki Yamaguchi). ---------------------------------------- Bug #21537: rb_ractor_sched_barrier_start() hangs on Windows https://bugs.ruby-lang.org/issues/21537 * Author: rhenium (Kazuki Yamaguchi) * Status: Open * ruby -v: ruby 3.5.0dev (2025-08-09T11:32:53Z master 2a6345e957) +PRISM [x64-mswin64_140] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- The following script hangs at `GC.start` indefinitely. Pressing Ctrl+C on the terminal interrupts the `sleep` and it appears to resume and prints "in_ractor". ```ruby Ractor.new { sleep 1 GC.start puts "in_ractor" } sleep ``` I also reproduced this with Ruby 3.0.7 from RubyInstaller2. Here is the stack trace with master: ``` 0:006> ~*k 0 Id: 1e88.36c4 Suspend: 1 Teb: 000000c6`92478000 Unfrozen # Child-SP RetAddr Call Site 00 000000c6`929fef18 00007ffa`9e4edf43 ntdll!NtWaitForMultipleObjects+0x14 01 000000c6`929fef20 00007ffa`9e4ede11 KERNELBASE!WaitForMultipleObjectsEx+0x123 02 000000c6`929ff210 00007ff6`756b8164 KERNELBASE!WaitForMultipleObjects+0x11 03 000000c6`929ff250 00007ff6`756b13af miniruby!w32_wait_events+0x108 [C:\w\ruby\thread_win32.c @ 239] 04 000000c6`929ff2d0 00007ff6`756b62a2 miniruby!native_sleep+0xc3 [C:\w\ruby\thread_win32.c @ 360] 05 000000c6`929ff310 00007ff6`75646353 miniruby!sleep_forever+0x82 [C:\w\ruby\thread.c @ 1374] 06 000000c6`929ff350 00007ff6`756e5f4b miniruby!rb_f_sleep+0x53 [C:\w\ruby\process.c @ 4975] 07 000000c6`929ff380 00007ff6`756e5df9 miniruby!vm_call_cfunc_with_frame_+0x14b [C:\w\ruby\vm_insnhelper.c @ 3850] 08 000000c6`929ff460 00007ff6`756e5dbb miniruby!vm_call_cfunc_with_frame+0x29 [C:\w\ruby\vm_insnhelper.c @ 3895] 09 000000c6`929ff4a0 00007ff6`756e5ab7 miniruby!vm_call_cfunc_other+0xc7 [C:\w\ruby\vm_insnhelper.c @ 3922] 0a 000000c6`929ff4e0 00007ff6`756e8363 miniruby!vm_call_cfunc+0x10b [C:\w\ruby\vm_insnhelper.c @ 4003] 0b 000000c6`929ff510 00007ff6`756e7cfe miniruby!vm_call_method_each_type+0x637 [C:\w\ruby\vm_insnhelper.c @ 4827] 0c 000000c6`929ff610 00007ff6`756f39b4 miniruby!vm_call_method+0x152 [C:\w\ruby\vm_insnhelper.c @ 4991] 0d 000000c6`929ff680 00007ff6`756ee003 miniruby!vm_sendish+0x1f4 [C:\w\ruby\vm_insnhelper.c @ 6065] 0e 000000c6`929ff700 00007ff6`756e0f27 miniruby!vm_exec_core+0x25cb [C:\w\ruby\insns.def @ 900] 0f (Inline Function) --------`-------- miniruby!vm_exec_loop+0x8 [C:\w\ruby\vm.c @ 2653] 10 000000c6`929ff860 00007ff6`755b896f miniruby!rb_vm_exec+0x10b [C:\w\ruby\vm.c @ 2624] 11 000000c6`929ff9d0 00007ff6`755baf47 miniruby!rb_ec_exec_node+0x10f [C:\w\ruby\eval.c @ 284] 12 000000c6`929ffb50 00007ff6`75531069 miniruby!ruby_run_node+0x43 [C:\w\ruby\eval.c @ 320] 13 (Inline Function) --------`-------- miniruby!rb_main+0x25 [C:\w\ruby\main.c @ 42] 14 (Inline Function) --------`-------- miniruby!w32_main+0x5f [C:\w\ruby\main.c @ 62] 15 000000c6`929ffb80 00007ff6`7575e3ec miniruby!wmain+0x69 [C:\w\ruby\main.c @ 48] 16 (Inline Function) --------`-------- miniruby!invoke_main+0x22 [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl @ 90] 17 000000c6`929ffbb0 00007ffa`a03de8d7 miniruby!__scrt_common_main_seh+0x10c [D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl @ 288] 18 000000c6`929ffbf0 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 19 000000c6`929ffc20 00000000`00000000 ntdll!RtlUserThreadStart+0x2c 1 Id: 1e88.1468 Suspend: 1 Teb: 000000c6`9247a000 Unfrozen # Child-SP RetAddr Call Site 00 000000c6`92dff618 00007ffa`a103259e ntdll!NtWaitForWorkViaWorkerFactory+0x14 01 000000c6`92dff620 00007ffa`a03de8d7 ntdll!TppWorkerThread+0x37e 02 000000c6`92dff980 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 03 000000c6`92dff9b0 00000000`00000000 ntdll!RtlUserThreadStart+0x2c 2 Id: 1e88.1058 Suspend: 1 Teb: 000000c6`9247c000 Unfrozen # Child-SP RetAddr Call Site 00 000000c6`931ff6a8 00007ffa`a103259e ntdll!NtWaitForWorkViaWorkerFactory+0x14 01 000000c6`931ff6b0 00007ffa`a03de8d7 ntdll!TppWorkerThread+0x37e 02 000000c6`931ffa10 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 03 000000c6`931ffa40 00000000`00000000 ntdll!RtlUserThreadStart+0x2c 3 Id: 1e88.158c Suspend: 1 Teb: 000000c6`9247e000 Unfrozen # Child-SP RetAddr Call Site 00 000000c6`935ff998 00007ffa`a103259e ntdll!NtWaitForWorkViaWorkerFactory+0x14 01 000000c6`935ff9a0 00007ffa`a03de8d7 ntdll!TppWorkerThread+0x37e 02 000000c6`935ffd00 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 03 000000c6`935ffd30 00000000`00000000 ntdll!RtlUserThreadStart+0x2c 4 Id: 1e88.3acc Suspend: 1 Teb: 000000c6`92480000 Unfrozen "ruby-timer-thread" # Child-SP RetAddr Call Site 00 000000c6`936ffbc8 00007ffa`9e4ecbbf ntdll!NtWaitForSingleObject+0x14 01 000000c6`936ffbd0 00007ff6`756b7e9d KERNELBASE!WaitForSingleObjectEx+0xaf 02 000000c6`936ffc70 00007ffa`9e0d37b0 miniruby!timer_thread_func+0x45 [C:\w\ruby\thread_win32.c @ 777] 03 000000c6`936ffca0 00007ffa`a03de8d7 ucrtbase!thread_start<unsigned int (__cdecl*)(void *),1>+0x30 04 000000c6`936ffcd0 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 05 000000c6`936ffd00 00000000`00000000 ntdll!RtlUserThreadStart+0x2c 5 Id: 1e88.2934 Suspend: 1 Teb: 000000c6`92482000 Unfrozen # Child-SP RetAddr Call Site 00 000000c6`937ff4f8 00007ffa`9e4ecbbf ntdll!NtWaitForSingleObject+0x14 01 000000c6`937ff500 00007ff6`756b1276 KERNELBASE!WaitForSingleObjectEx+0xaf 02 000000c6`937ff5a0 00007ff6`756f7f47 miniruby!native_cond_timedwait_ms+0x62 [C:\w\ruby\thread_win32.c @ 483] 03 (Inline Function) --------`-------- miniruby!vm_cond_wait+0x28 [C:\w\ruby\vm_sync.c @ 211] 04 000000c6`937ff5f0 00007ff6`756b2c83 miniruby!rb_vm_cond_wait+0x37 [C:\w\ruby\vm_sync.c @ 220] 05 000000c6`937ff620 00007ff6`756f7f02 miniruby!rb_ractor_sched_barrier_start+0x67 [C:\w\ruby\thread_win32.c @ 956] 06 000000c6`937ff650 00007ff6`755c7a78 miniruby!rb_vm_barrier+0x1e [C:\w\ruby\vm_sync.c @ 265] 07 (Inline Function) --------`-------- miniruby!rb_gc_vm_barrier+0x5 [C:\w\ruby\gc.c @ 179] 08 (Inline Function) --------`-------- miniruby!gc_enter+0x25 [C:\w\ruby\gc\default\default.c @ 6609] 09 000000c6`937ff680 00007ff6`755c442e miniruby!gc_start+0xc0 [C:\w\ruby\gc\default\default.c @ 6334] 0a 000000c6`937ff6e0 00007ff6`755cdd0f miniruby!garbage_collect+0x42 [C:\w\ruby\gc\default\default.c @ 6316] 0b 000000c6`937ff710 00007ff6`755c2cc3 miniruby!rb_gc_impl_start+0x4b [C:\w\ruby\gc\default\default.c @ 6767] 0c 000000c6`937ff740 00007ff6`756d5c7b miniruby!gc_start_internal+0x4f [C:\w\ruby\gc.c @ 3447] 0d 000000c6`937ff780 00007ff6`756ee237 miniruby!builtin_invoker4+0x23 [C:\w\ruby\vm_insnhelper.c @ 7373] 0e (Inline Function) --------`-------- miniruby!invoke_bf+0x32 [C:\w\ruby\vm_insnhelper.c @ 7485] 0f (Inline Function) --------`-------- miniruby!vm_invoke_builtin+0x32 [C:\w\ruby\vm_insnhelper.c @ 7493] 10 000000c6`937ff7c0 00007ff6`756e0f27 miniruby!vm_exec_core+0x27ff [C:\w\ruby\build-debug\vm.inc @ 4621] 11 (Inline Function) --------`-------- miniruby!vm_exec_loop+0x8 [C:\w\ruby\vm.c @ 2653] 12 000000c6`937ff920 00007ff6`756f08b0 miniruby!rb_vm_exec+0x10b [C:\w\ruby\vm.c @ 2624] 13 (Inline Function) --------`-------- miniruby!invoke_iseq_block_from_c+0x1e3 [C:\w\ruby\vm.c @ 1651] 14 (Inline Function) --------`-------- miniruby!invoke_block_from_c_proc+0x2f2 [C:\w\ruby\vm.c @ 1745] 15 000000c6`937ffa90 00007ff6`756b6bf9 miniruby!vm_invoke_proc+0x324 [C:\w\ruby\vm.c @ 1775] 16 000000c6`937ffbd0 00007ff6`756b7987 miniruby!thread_do_start_proc+0x131 [C:\w\ruby\thread.c @ 584] 17 (Inline Function) --------`-------- miniruby!thread_do_start+0x37 [C:\w\ruby\thread.c @ 626] 18 000000c6`937ffc40 00007ff6`756b7720 miniruby!thread_start_func_2+0x243 [C:\w\ruby\thread.c @ 677] 19 000000c6`937ffe90 00007ffa`9e0d37b0 miniruby!thread_start_func_1+0x74 [C:\w\ruby\thread_win32.c @ 659] 1a 000000c6`937ffec0 00007ffa`a03de8d7 ucrtbase!thread_start<unsigned int (__cdecl*)(void *),1>+0x30 1b 000000c6`937ffef0 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 1c 000000c6`937fff20 00000000`00000000 ntdll!RtlUserThreadStart+0x2c # 6 Id: 1e88.4f4 Suspend: 1 Teb: 000000c6`92486000 Unfrozen # Child-SP RetAddr Call Site 00 000000c6`93bff768 00007ffa`a10d793e ntdll!DbgBreakPoint 01 000000c6`93bff770 00007ffa`a03de8d7 ntdll!DbgUiRemoteBreakin+0x4e 02 000000c6`93bff7a0 00007ffa`a0fdc34c KERNEL32!BaseThreadInitThunk+0x17 03 000000c6`93bff7d0 00000000`00000000 ntdll!RtlUserThreadStart+0x2c ``` -- https://bugs.ruby-lang.org/

3 2

[ruby-core:126430] [Ruby Misc#22249] DevMeeting-2026-09-10
by mame (Yusuke Endoh) 09 Sep '26

09 Sep '26

Issue #22249 has been reported by mame (Yusuke Endoh). ---------------------------------------- Misc #22249: DevMeeting-2026-09-10 https://bugs.ruby-lang.org/issues/22249 * Author: mame (Yusuke Endoh) * Status: Open ---------------------------------------- # The next dev meeting **Date: 2026/09/10 13:00-17:00** (JST) Log: *TBD* - Dev meeting *IS NOT* a decision-making place. All decisions should be done at the bug tracker. - Dev meeting is a place we can ask Matz, nobu, nurse and other developers directly. - Matz is a very busy person. Take this opportunity to ask him. If you can not attend, other attendees can ask instead of you (if attendees can understand your issue). - We will write a record of the discussion in the file or to each ticket in English. - All activities are best-effort (keep in mind that most of us are volunteer developers). - The date, time and place of the meeting are scheduled according to when/where we can reserve Matz's time. - *DO NOT* discuss then on this ticket, please. # Call for agenda items If you have a ticket that you want matz and committers to discuss, please post it into this ticket in the following format: ``` * [Ticket ref] Ticket title (your name) * Comment (A summary of the ticket, why you put this ticket here, what point should be discussed, etc.) ``` Example: ``` * [Feature #14609] `Kernel#p` without args shows the receiver (ko1) * I feel this feature is very useful and some people say :+1: so let discuss this feature. ``` - It is recommended to add a comment by 2026/09/07. We hold a preparatory meeting to create an agenda a few days before the dev-meeting. - The format is strict. We'll use [this script to automatically create an markdown-style agenda](https://gist.github.com/mame/b0390509ce1491b43610b9ebb665eb86). We may ignore a comment that does not follow the format. - Your comment is mandatory. We cannot read all discussion of the ticket in a limited time. We appreciate it if you could write a short summary and update from a previous discussion. -- https://bugs.ruby-lang.org/

10 9

[ruby-core:121450] [Ruby Bug#21200] Ractor spuriously hangs, segfault or errors
by Eregon (Benoit Daloze) 09 Sep '26

09 Sep '26

Issue #21200 has been reported by Eregon (Benoit Daloze). ---------------------------------------- Bug #21200: Ractor spuriously hangs, segfault or errors https://bugs.ruby-lang.org/issues/21200 * Author: Eregon (Benoit Daloze) * Status: Open * Assignee: ractor * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- For a new test `test_ractor_parallel` I added in https://github.com/ruby/etc/pull/52/files This seems a Ractor bug. Example failures: https://github.com/ruby/ruby/actions/runs/14097239052/job/39486770259?pr=12… ``` 1) Failure: TestEtc#test_ractor_parallel [/Users/runner/work/ruby/ruby/src/test/etc/test_etc.rb:178]: assert_separately failed with error message pid 51588 exit 0 | [BUG] ``` https://github.com/ruby/ruby/actions/runs/14094646363/job/39479353266?pr=12… ``` TestEtc#test_ractor_parallel [/Users/runner/work/ruby/ruby/src/test/etc/test_etc.rb:178]: assert_separately failed with error message pid 47346 exit 0 | [BUG] pthread_mutex_lock: Invalid argument (EINVAL) | ruby 3.5.0dev (2025-03-26T22:25:25Z pull/12984/merge 1ea32181b7) +PRISM [arm64-darwin23] | | -- 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 ----------------------------------------------- | | | -- Threading information --------------------------------------------------- | Total ractor count: 1 | Ruby thread count for this ractor: 0 | | -- C level backtrace information ------------------------------------------- | [BUG] Segmentation fault at 0xfffffffffffffff8 | ruby 3.5.0dev (2025-03-26T22:25:25Z pull/12984/merge 1ea32181b7) +PRISM [arm64-darwin23] | | -- 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. | | Crashed while printing bug report | [IMPORTANT] | Don't forget to include the Crash Report log file under | DiagnosticReports directory in bug reports. | ``` https://github.com/ruby/ruby/actions/runs/14069270994/job/39402894235#step:… ``` 1) Error: TestEtc#test_ractor_parallel: Test::Unit::ProxyError: execution of Test::Unit::CoreAssertions#assert_separately expired timeout (10 sec) pid 145797 killed by SIGKILL (signal 9) | /home/runner/work/ruby/ruby/src/test/etc/test_etc.rb:178:in 'TestEtc#test_ractor_parallel' ``` The test has been disabled for now in https://github.com/ruby/ruby/pull/12992. -- https://bugs.ruby-lang.org/

2 1

[ruby-core:111960] [Ruby master Bug#19364] Issue with tracepoint enable/disable across ractors
by luke-gru (Luke Gruber) 09 Sep '26

09 Sep '26

Issue #19364 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #19364: Issue with tracepoint enable/disable across ractors https://bugs.ruby-lang.org/issues/19364 * Author: luke-gru (Luke Gruber) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- This sometimes segfaults: ```ruby def test_enable_disable_in_multiple_ractors_with_target rs = [] 100.times do |i| # setup new iseqs Kernel.define_method :"my_method_to_change_for_tracing_#{i}" do true end end 100.times do |i| rs << Ractor.new(i) do |j| meth = :"my_method_to_change_for_tracing_#{j}" tp = TracePoint.new(:line) { } # local to ractor 100.times do tp.enable(target: method(meth)) # change iseq internals of given method, should be done with lock tp.disable # disable hooks should hold lock too, changes method definition internals end end end rs.each(&:take) # shouldn't raise end test_enable_disable_in_multiple_ractors_with_target() ``` Changing iseq internals is done without the VM lock. This is true in Tracepoint#enable and Tracepoint#disable methods. I have a patch coming. -- https://bugs.ruby-lang.org/

3 2

[ruby-core:126605] [Ruby Bug#18733] Heavy GC allocations cause performance issue with Ractor
by ko1 (Koichi Sasada) 09 Sep '26

09 Sep '26

Issue #18733 has been updated by ko1 (Koichi Sasada). Status changed from Assigned to Closed Re-checked on master 4d185cce78 (4.1.0dev). The gap this ticket is about is gone. I used jhawthorn's variant of the benchmark from #note-4 (`[0,1].itself.include?(n)`, so the array literal is not elided), fib(34) in 8 workers, with fork and Ractor measured alternately inside the same process, two rounds each: ruby fork wall ractor wall ractor/fork ractor cpu/wall (max 8) master 4d185cce78 2.12 / 2.26 2.03 / 2.09 x0.96 / x0.92 7.89 / 7.85 4.0.2 2.57 / 2.64 5.36 / 6.56 x2.08 / x2.49 3.56 / 3.09 3.4.4 2.76 / 2.91 89.8 / 94.5 x32.6 / x32.4 1.64 / 1.61 3.3.2 2.57 / 2.74 115.6 / 83.1 x45.0 / x30.3 1.80 / 2.08 On master the Ractor version is as fast as fork and uses 7.85-7.89 of the 8 cores; the remaining difference is run-to-run noise. The big step is the per-Ractor GC work (GH-18194, merged 2026-08-07), which is in master but not in 4.0: allocation-heavy Ractors no longer serialise on a global GC. (I did not bisect; this is a version-level attribution. The earlier 3.4 -> 4.0 step, x32 -> x2, is separate GC work.) Measured on an idle 16-core Linux box. Only the fork/Ractor ratio within one run should be read, not the absolute times. ---------------------------------------- Bug #18733: Heavy GC allocations cause performance issue with Ractor https://bugs.ruby-lang.org/issues/18733#change-118837 * Author: jakit (Jakit Liang) * Status: Closed * Assignee: ractor * ruby -v: ruby 3.1.1p18 (2022-02-18 revision 53f5fc4236) [arm64-darwin21] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Code: ``` require 'benchmark' def fib(n) return n if [0,1].include?(n) fib(n-1) + fib(n-2) end tp = [] puts Benchmark.measure { 8.times do tp << fork { fib(37) } end tp.each { |t| Process.wait(t) } } puts Benchmark.measure { 8.times.map { Ractor.new { fib(37) } }.each{ |r| r.take } } ``` Result: |A |B | |--|--| | fork | 0.000264 0.003439 87.181198 ( 11.211349) | | Ractor | 80.292916 15.062559 95.355475 ( 39.569527) | And I found that here's the problem showing on the ActiveMonitor.app: ![ruby_bug_with_m1](http://jakit.cn/screen_shot_ruby_bug.jpg) As you can see, the process of ruby is always using all Performance Cores on my Apple M1 Mac. But there's no one of the Efficiency Cores was in used by ruby Ractor. -- https://bugs.ruby-lang.org/

1 0

[ruby-core:116061] [Ruby master Bug#20158] Ractor affects Coverage results
by janosch-x 09 Sep '26

09 Sep '26

Issue #20158 has been reported by janosch-x (Janosch Müller). ---------------------------------------- Bug #20158: Ractor affects Coverage results https://bugs.ruby-lang.org/issues/20158 * Author: janosch-x (Janosch Müller) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0preview1 (2023-05-12 master a1b01e7701) [arm64-darwin22] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I have a large rspec test suite. I found that if I call a Ractor, the Coverage results are strongly affected, i.e. almost all files appear to be uncovered. This happens even if I only ever call a Ractor before the library or rspec are required. Unfortunately, I was not able to build a simple repro yet. I assume it is a timing thing and only affects larger suites, or it only happens if there are multiple files, and maybe if the library lazily requires its sub-modules? However, I guess this should produce the same results when added to the spec_helper.rb of other large suites: ```ruby # Ractor.new { nil } # uncomment this to affect coverage results require 'coverage' Coverage.start # require library, set up rspec etc. RSpec.configuration.after(:suite) do # this number is greatly reduced and unstable when calling Ractor above p Coverage.result.values.sum { |arr| arr.sum(&:to_i) } end ``` I had this problem in [this library](https://github.com/jaynetics/character_set/). The problem affects simplecov users as well, as described [here](https://github.com/simplecov-ruby/simplecov/issues/1058). -- https://bugs.ruby-lang.org/

4 5

[ruby-core:121941] [Ruby Bug#21315] Finalizers violate the `rb_ractor_confirm_belonging` assertion
by byroot (Jean Boussier) 09 Sep '26

09 Sep '26

Issue #21315 has been reported by byroot (Jean Boussier). ---------------------------------------- Bug #21315: Finalizers violate the `rb_ractor_confirm_belonging` assertion https://bugs.ruby-lang.org/issues/21315 * Author: byroot (Jean Boussier) * Status: Open * Assignee: ractor * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- Reproduction (with assertions enabled): ```ruby require "tempfile" Ractor.new do 10.times do Tempfile.new end end.take GC.start ``` ``` <OBJ_INFO:rb_ractor_confirm_belonging@../src/ractor_core.h:375> (File) /home/runner/work/ruby/ruby/src/lib/tempfile.rb:387: [BUG] rb_ractor_confirm_belonging object-ractor id:1, current-ractor id:2 ruby 3.5.0dev (2025-05-09T15:51:24Z pull/13291/merge e289a1dc58) +PRISM [x86_64-linux] -- Control frame information ----------------------------------------------- c:0005 p:0007 s:0025 e:000024 METHOD /home/runner/work/ruby/ruby/src/lib/tempfile.rb:387 [FINISH] c:0004 p:0022 s:0020 e:000019 METHOD /home/runner/work/ruby/ruby/src/lib/prism/parse_result.rb:833 [FINISH] c:0003 p:---- s:0012 e:000011 CFUNC :parse_lex_file c:0002 p:0006 s:0007 e:000006 BLOCK /home/runner/work/ruby/ruby/src/test/prism/ractor_test.rb:26 [FINISH] c:0001 p:---- s:0003 e:000002 DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- /home/runner/work/ruby/ruby/src/test/prism/ractor_test.rb:26:in 'block in test_parse_lex_file' /home/runner/work/ruby/ruby/src/test/prism/ractor_test.rb:26:in 'parse_lex_file' /home/runner/work/ruby/ruby/src/lib/prism/parse_result.rb:833:in 'initialize' /home/runner/work/ruby/ruby/src/lib/tempfile.rb:387:in 'call' -- Threading information --------------------------------------------------- Total ractor count: 2 Ruby thread count for this ractor: 1 -- C level backtrace information ------------------------------------------- /home/runner/work/ruby/ruby/build/ruby(rb_print_backtrace+0x14) [0x561441aeedbf] ../src/vm_dump.c:843 /home/runner/work/ruby/ruby/build/ruby(rb_vm_bugreport) ../src/vm_dump.c:1175 /home/runner/work/ruby/ruby/build/ruby(bug_report_end+0x0) [0x561441aa3f39] ../src/error.c:1097 /home/runner/work/ruby/ruby/build/ruby(rb_bug_without_die_internal) ../src/error.c:1097 /home/runner/work/ruby/ruby/build/ruby(die+0x0) [0x5614416e237f] ../src/error.c:1115 /home/runner/work/ruby/ruby/build/ruby(rb_bug) ../src/error.c:1117 /home/runner/work/ruby/ruby/build/ruby(rb_ractor_confirm_belonging+0xde) [0x56144188c6be] ../src/ractor_core.h:376 /home/runner/work/ruby/ruby/build/ruby(vm_exec_core+0xef) [0x5614418b23ef] /home/runner/work/ruby/ruby/build/vm.inc:2500 /home/runner/work/ruby/ruby/build/ruby(rb_vm_exec+0x156) [0x5614418a4676] ../src/vm.c:2618 /home/runner/work/ruby/ruby/build/ruby(vm_call0_cc+0x13d) [0x5614418aa1dd] ../src/vm_eval.c:101 /home/runner/work/ruby/ruby/build/ruby(rb_vm_call0+0x4c) [0x5614418b1cc5] ../src/vm_eval.c:61 /home/runner/work/ruby/ruby/build/ruby(rb_vm_call_kw) ../src/vm_eval.c:326 /home/runner/work/ruby/ruby/build/ruby(rb_check_funcall_default_kw) ../src/vm_eval.c:694 /home/runner/work/ruby/ruby/build/ruby(rb_gc_run_obj_finalizer+0x1cf) [0x56144170220f] ../src/gc.c:306 /home/runner/work/ruby/ruby/build/ruby(rb_multi_ractor_p+0x0) [0x56144170246f] ../src/gc/default/default.c:2820 /home/runner/work/ruby/ruby/build/ruby(rb_vm_lock_enter) ../src/vm_sync.h:74 /home/runner/work/ruby/ruby/build/ruby(rb_gc_vm_lock) ../src/gc.c:137 /home/runner/work/ruby/ruby/build/ruby(finalize_list) ../src/gc/default/default.c:2843 /home/runner/work/ruby/ruby/build/ruby(finalize_deferred_heap_pages) ../src/gc/default/default.c:2866 ``` I think it wouldn't be hard to disable that check when running a finalizer, but I don't know if it's the correct thing to do. -- https://bugs.ruby-lang.org/

5 8

[ruby-core:112091] [Ruby master Bug#19387] Issue with ObjectSpace.each_objects not returning IO objects after starting a ractor
by luke-gru (Luke Gruber) 09 Sep '26

09 Sep '26

Issue #19387 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #19387: Issue with ObjectSpace.each_objects not returning IO objects after starting a ractor https://bugs.ruby-lang.org/issues/19387 * Author: luke-gru (Luke Gruber) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- ```ruby r = Ractor.new do receive # block, the problem is not the termination of the ractor but the starting end ObjectSpace.each_object(IO) { |io| p io # we get no objects } ``` -- https://bugs.ruby-lang.org/

6 9

[ruby-core:126596] [Ruby Bug#22299] opt_new emits a duplicate :line trace point for Const.new following a branch
by Eregon (Benoit Daloze) 08 Sep '26

08 Sep '26

Issue #22299 has been reported by Eregon (Benoit Daloze). ---------------------------------------- Bug #22299: opt_new emits a duplicate :line trace point for Const.new following a branch https://bugs.ruby-lang.org/issues/22299 * Author: Eregon (Benoit Daloze) * Status: Open * Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- ## Summary On Ruby master (`4.1.0dev`), compiling an expression of the form `Constant.new(...)` that is the first statement of a basic block reached after a branch (e.g. immediately after a `return unless`/`next unless` guard) produces **two** `:line` trace points for that one line instead of one. The extra event only appears when the `opt_new` specialized instruction is generated, so it depends on: - a **constant** receiver (`Foo.new`, `A::B.new` — not `foo.new`), - the method being `new` with `opt_new` applicable (no block; `Foo.new { }` is fine), - the call sitting at the head of a basic block after a control-flow merge, and - `RubyVM::InstructionSequence.compile_option[:specialized_instruction]` being `true` (the default). ## Reproduction ```ruby def line_events(iseq) ev = iseq.trace_points.select { |_, e| e == :line }.map(&:first) iseq.each_child { |c| ev.concat(line_events(c)) } ev end src = <<~RUBY return unless x Foo.new RUBY [true, false].each do |spec| RubyVM::InstructionSequence.compile_option = { specialized_instruction: spec } events = line_events(RubyVM::InstructionSequence.compile(src)) puts "specialized_instruction: #{spec.inspect}\t=> line events #{events.inspect}" end ``` ### Output Ruby `4.1.0dev` (master): ``` specialized_instruction: true => line events [1, 2, 2] specialized_instruction: false => line events [1, 2] ``` Ruby `4.0.6` (and earlier): ``` specialized_instruction: true => line events [1, 2] specialized_instruction: false => line events [1, 2] ``` Line 2 (`Foo.new`) is reported twice on master with the default compile options. ## Analysis With `specialized_instruction: true`, the `opt_new` codepath prepends a `putnil` (reserving the slot for the object) that carries the statement's line, and the following `opt_getconstant_path` *also* carries a `:line` trace point — so line 2 is emitted twice: ``` 0007 putnil ( 2)[Li] # statement start 0008 opt_getconstant_path <Foo>[Li] # duplicate :line on the same line 0010 opt_new <calldata!mid:new, argc:0, ARGS_SIMPLE>, 17 ``` For comparison, the non-`opt_new` path (`Foo.bar`, or `Foo.new` under `specialized_instruction: false`) emits the line once, on `opt_getconstant_path`: ``` 0007 opt_getconstant_path <Foo>( 2)[Li] 0009 opt_send_without_block <calldata!mid:bar, ...> ``` The `[Li]` on `opt_getconstant_path` in the `opt_new` path appears to be redundant: the `putnil` before it already carries the statement's line event. ## Impact This surfaced as a failure of `test/prism/newline_test.rb` in `make test-all` on ruby-head in [this Prism PR](https://github.com/ruby/prism/pull/4223). That test asserts that prism's newline flags match RubyVM's `:line` trace points exactly. Two fixtures hit the pattern: - `test/prism/ruby/parameters_signature_test.rb:95` — `object = Object.new` after `return unless compare` - `test/prism/locals_test.rb:101` — `yield ISeq.new(opnd)` after `next unless ...` It is not observed when running the same test in the prism repository, because there `require "test/unit"` (the test-unit gem) sets `specialized_instruction: false` globally, which suppresses `opt_new` and therefore the duplicate event. -- https://bugs.ruby-lang.org/

1 1