June 2025 - ruby-core - ml.ruby-lang.org

[ruby-core:120510] [Ruby master Bug#21007] Ractor scheduler issue when multiple threads in a ractor
by luke-gru (Luke Gruber) 05 Jun '25

05 Jun '25

Issue #21007 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #21007: Ractor scheduler issue when multiple threads in a ractor https://bugs.ruby-lang.org/issues/21007 * Author: luke-gru (Luke Gruber) * Status: Open * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- When there are multiple threads in a ractor, these threads can get in a state where they are yielding every 10ms instead of every 100ms. This occurs because in `thread_sched_switch0`, which is called by `thread_sched_switch`, `ruby_thread_set_native` is called. This function calls `rb_ractor_set_current_ec` for the next thread to run, but then when the next thread sets itself up before it runs, it calls `rb_ractor_thread_switch`, but since the ec has already been changed, it never sets back `th->running_time_us` to `0`. The yielding happens every 10ms because a very large value in `th->running_time_us` is always compared to `100ms` so it always yields. This script takes a very long time due to this issue: ```ruby ractors = 5.times.map do |i| Ractor.new(i) do |i0| ts = 4.times.map do Thread.new do counter = 0 while counter < 30_000_000 counter += 1 end end end until ts.none? { |t| t.alive? } $stderr.puts "Ractor #{i0} main thread sleeping" sleep 1 end ts.each(&:join) $stderr.puts "Ractor #{i0} done" end end while ractors.any? r, obj = Ractor.select *ractors ractors.delete(r) end ``` The fix is to set `next_th->running_time_us` back to 0 in `thread_sched_switch0`. -- https://bugs.ruby-lang.org/

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[ruby-core:119991] [Ruby master Bug#20905] Ruby VM hangs while using ractors
by ivoanjo (Ivo Anjo) 05 Jun '25

05 Jun '25

Issue #20905 has been reported by ivoanjo (Ivo Anjo). ---------------------------------------- Bug #20905: Ruby VM hangs while using ractors https://bugs.ruby-lang.org/issues/20905 * Author: ivoanjo (Ivo Anjo) * Status: Open * ruby -v: ruby 3.4.0preview2 (2024-10-07 master 32c733f57b) +PRISM [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- Hey! While doing some experiments with Ractors I ran into a Ruby VM hang. I see it both on Ruby 3.4.0-preview2 and 3.3.5, but not Ruby 3.2, so this may be related to the M:N scheduling. ### How to reproduce: ``` puts RUBY_DESCRIPTION def counter_loop counter = 0 counter += 1 while counter < 100_000_000 end ractors = 10.times.map { Ractor.new { Thread.new { counter_loop }; counter_loop } } counter_loop ractors.map(&:take) ``` This example never finishes for me. At some point all threads finish work, and the Ruby process will be stuck at 0% cpu. ``` ruby 3.4.0preview2 (2024-10-07 master 32c733f57b) +PRISM [x86_64-linux] warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues. ...(hangs)... ``` Reducing the number of ractor seems to make the issue go away, so there may be some timing/thread switching issues involved. Furthermore, all threads seem to be stuck waiting: ``` (gdb) info threads Id Target Id Frame * 1 Thread 0x7836ef0b6c00 (LWP 445418) "ruby" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024bda30) at ./nptl/futex-internal.c:57 2 Thread 0x7836d4800640 (LWP 445419) "ruby" 0x00007836ee725e2e in epoll_wait (epfd=4, events=events@entry=0x7836ef0a8adc <timer_th+28>, maxevents=maxevents@entry=16, timeout=timeout@entry=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 3 Thread 0x7836d3fff640 (LWP 445420) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6434) at ./nptl/futex-internal.c:57 4 Thread 0x7836b29ff640 (LWP 445421) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6434) at ./nptl/futex-internal.c:57 5 Thread 0x7836b28fe640 (LWP 445422) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 6 Thread 0x7836b27fd640 (LWP 445423) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 7 Thread 0x7836b26fc640 (LWP 445424) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 8 Thread 0x7836b25fb640 (LWP 445425) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 9 Thread 0x7836b24fa640 (LWP 445426) "rc-example7-2.*" __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 (gdb) thread apply all bt Thread 9 (Thread 0x7836b24fa640 (LWP 445426) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6430, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a40251e800) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 8 (Thread 0x7836b25fb640 (LWP 445425) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6430, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a4025224e0) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 7 (Thread 0x7836b26fc640 (LWP 445424) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6430, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a4025adf00) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 6 (Thread 0x7836b27fd640 (LWP 445423) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6430, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a40263bc20) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 5 (Thread 0x7836b28fe640 (LWP 445422) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6430) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6430, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a40276bc80) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 4 (Thread 0x7836b29ff640 (LWP 445421) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6434) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6434) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6434, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a402729730) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 3 (Thread 0x7836d3fff640 (LWP 445420) "rc-example7-2.*"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024b6434) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024b6434) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024b6434, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024b63d0, cond=0x59a4024b6408) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024b6408, mutex=mutex@entry=0x59a4024b63d0) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eece2e53 in ractor_sched_deq (cr=0x0, vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:1292 #7 nt_start (ptr=0x59a4024bb430) at src/ruby-3.4.0-preview2/thread_pthread.c:2287 #8 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #9 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 2 (Thread 0x7836d4800640 (LWP 445419) "ruby"): #0 0x00007836ee725e2e in epoll_wait (epfd=4, events=events@entry=0x7836ef0a8adc <timer_th+28>, maxevents=maxevents@entry=16, timeout=timeout@entry=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00007836eecdca8d in event_wait (vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:2940 #2 timer_thread_polling (vm=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread_mn.c:908 #3 timer_thread_func (ptr=0x59a4024b6330) at src/ruby-3.4.0-preview2/thread_pthread.c:3067 #4 0x00007836ee694ac3 in start_thread (arg=<optimised out>) at ./nptl/pthread_create.c:442 #5 0x00007836ee726850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 Thread 1 (Thread 0x7836ef0b6c00 (LWP 445418) "ruby"): #0 __futex_abstimed_wait_common64 (private=0, cancel=true, abstime=0x0, op=393, expected=0, futex_word=0x59a4024bda30) at ./nptl/futex-internal.c:57 #1 __futex_abstimed_wait_common (cancel=true, private=0, abstime=0x0, clockid=0, expected=0, futex_word=0x59a4024bda30) at ./nptl/futex-internal.c:87 #2 __GI___futex_abstimed_wait_cancelable64 (futex_word=futex_word@entry=0x59a4024bda30, expected=expected@entry=0, clockid=clockid@entry=0, abstime=abstime@entry=0x0, private=private@entry=0) at ./nptl/futex-internal.c:139 #3 0x00007836ee693a41 in __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x59a4024bdb80, cond=0x59a4024bda08) at ./nptl/pthread_cond_wait.c:503 #4 ___pthread_cond_wait (cond=cond@entry=0x59a4024bda08, mutex=mutex@entry=0x59a4024bdb80) at ./nptl/pthread_cond_wait.c:627 #5 0x00007836eecd77dd in rb_native_cond_wait (cond=cond@entry=0x59a4024bda08, mutex=mutex@entry=0x59a4024bdb80) at src/ruby-3.4.0-preview2/thread_pthread.c:222 #6 0x00007836eecd90d9 in thread_sched_wait_running_turn (sched=sched@entry=0x59a4024bdb80, th=0x59a4024b88c0, can_direct_transfer=can_direct_transfer@entry=false) at src/ruby-3.4.0-preview2/thread_pthread.c:863 #7 0x00007836eecd9f4a in rb_ractor_sched_sleep (ec=ec@entry=0x59a4024bdd20, cr=cr@entry=0x59a4024bda60, ubf=ubf@entry=0x7836eec341f0 <ractor_sleep_interrupt>) at src/ruby-3.4.0-preview2/thread_pthread.c:1349 #8 0x00007836eec34de6 in ractor_sleep_with_cleanup (cf_data=0x7ffcaa1e7640, cf_func=0x7836eec35b70 <ractor_wait_take_cleanup>, wait_status=wait_taking, cr=0x59a4024bda60, ec=0x59a4024bdd20) at ractor.c:691 #9 ractor_wait_take (take_basket=0x7ffcaa1e7650, r=0x59a4027851d0, cr=0x59a4024bda60, ec=0x59a4024bdd20) at ractor.c:1220 #10 ractor_take (r=0x59a4027851d0, ec=0x59a4024bdd20) at ractor.c:1241 #11 builtin_inline_class_711 (ec=0x59a4024bdd20, self=<optimised out>) at src/ruby-3.4.0-preview2/ractor.rb:712 #12 0x00007836eed30fe7 in invoke_bf (argv=<optimised out>, bf=<optimised out>, reg_cfp=<optimised out>, ec=<optimised out>) at src/ruby-3.4.0-preview2/vm_insnhelper.c:7330 #13 vm_invoke_builtin_delegate (cfp=<optimised out>, bf=<optimised out>, cfp=<optimised out>, bf=<optimised out>, start_index=<optimised out>, ec=<optimised out>) at src/ruby-3.4.0-preview2/vm_insnhelper.c:7353 #14 vm_invoke_builtin_delegate (start_index=<optimised out>, bf=<optimised out>, cfp=<optimised out>, ec=<optimised out>) at src/ruby-3.4.0-preview2/vm_insnhelper.c:7342 #15 vm_exec_core (ec=0x59a4024bdd20) at src/ruby-3.4.0-preview2/insns.def:1632 #16 0x00007836eed34c1a in rb_vm_exec (ec=0x59a4024bdd20) at vm.c:2564 #17 0x00007836eed3b222 in vm_call0_cc (ec=0x59a4024bdd20, recv=132176890167200, id=<optimised out>, argc=<optimised out>, argv=<optimised out>, cc=<optimised out>, kw_splat=0) at src/ruby-3.4.0-preview2/vm_eval.c:101 #18 0x00007836eed3d9e4 in rb_call0 (ec=0x59a4024bdd20, recv=132176890167200, mid=6081, argc=0, argv=<optimised out>, call_scope=<optimised out>, self=132177315121880) at src/ruby-3.4.0-preview2/vm_eval.c:554 #19 0x00007836eed3e6f6 in rb_call (scope=<optimised out>, argv=0x7ffcaa1e7b40, argc=0, mid=6081, recv=132176890167200) at src/ruby-3.4.0-preview2/vm_eval.c:873 #20 rb_funcall_with_block_kw (recv=132176890167200, mid=6081, argc=0, argv=0x7ffcaa1e7b40, passed_procval=4, kw_splat=<optimised out>) at src/ruby-3.4.0-preview2/vm_eval.c:1192 #21 0x00007836eed39e38 in vm_yield_with_cref (is_lambda=0, cref=0x0, kw_splat=0, argv=0x7ffcaa1e7b38, argc=1, ec=<optimised out>) at vm.c:1646 #22 vm_yield (kw_splat=0, argv=0x7ffcaa1e7b38, argc=1, ec=<optimised out>) at vm.c:1654 #23 rb_yield_0 (argv=0x7ffcaa1e7b38, argc=1) at src/ruby-3.4.0-preview2/vm_eval.c:1344 #24 rb_yield (val=<optimised out>) at src/ruby-3.4.0-preview2/vm_eval.c:1360 #25 0x00007836eea68efc in rb_ary_collect (ary=132177315121880) at array.c:3714 #26 0x00007836eed1b03c in vm_call_cfunc_with_frame_ (stack_bottom=<optimised out>, argv=<optimised out>, argc=0, calling=<optimised out>, reg_cfp=0x7836edffefa0, ec=0x59a4024bdd20) at src/ruby-3.4.0-preview2/vm_insnhelper.c:3788 #27 vm_call_cfunc_with_frame (ec=0x59a4024bdd20, reg_cfp=0x7836edffefa0, calling=<optimised out>) at src/ruby-3.4.0-preview2/vm_insnhelper.c:3834 #28 0x00007836eed217f0 in vm_sendish (ec=0x59a4024bdd20, reg_cfp=0x7836edffefa0, cd=0x59a4027833f0, block_handler=<optimised out>, method_explorer=mexp_search_method) at src/ruby-3.4.0-preview2/vm_callinfo.h:415 #29 0x00007836eed2edd1 in vm_exec_core (ec=0x59a4024bdd20) at src/ruby-3.4.0-preview2/insns.def:851 #30 0x00007836eed34c1a in rb_vm_exec (ec=0x59a4024bdd20) at vm.c:2564 #31 0x00007836eed46e8b in rb_iseq_eval_main (iseq=iseq@entry=0x7836edea70f8) at vm.c:2830 #32 0x00007836eeb3d895 in rb_ec_exec_node (ec=ec@entry=0x59a4024bdd20, n=n@entry=0x7836edea70f8) at eval.c:281 #33 0x00007836eeb4140b in ruby_run_node (n=0x7836edea70f8) at eval.c:319 #34 0x000059a400cd1187 in rb_main (argv=0x7ffcaa1e8118, argc=2) at ./main.c:43 #35 main (argc=<optimised out>, argv=<optimised out>) at ./main.c:62 ``` -- https://bugs.ruby-lang.org/

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[ruby-core:122356] [Ruby Feature#21390] Deprecate passing arguments to Set#to_set and Enumerable#to_set
by jeremyevans0 (Jeremy Evans) 05 Jun '25

05 Jun '25

Issue #21390 has been reported by jeremyevans0 (Jeremy Evans). ---------------------------------------- Feature #21390: Deprecate passing arguments to Set#to_set and Enumerable#to_set https://bugs.ruby-lang.org/issues/21390 * Author: jeremyevans0 (Jeremy Evans) * Status: Open ---------------------------------------- Array#to_a, Hash#to_h, Enumerable#to_a, and Enumerable#to_h do not allow you to specify subclasses. This has undesired behavior when passing non-Set subclasses. All of these are currently allowed, and none make sense: ```ruby enum = [1,2,3].to_enum enum.to_set(Hash) enum.to_set(Struct.new("A", :a)) enum.to_set(ArgumentError) enum.to_set(Thread){} ``` Users who want to create instances of a subclass of Set from an enumerable should pass the enumerable to SetSubclass.new instead of using to_set, similar to how they would have to handle subclasses of Array or Hash. I've submitted a pull request that implements this: https://github.com/ruby/ruby/pull/13489 With the pull request, block arguments are still allowed (no warning). Positional and keyword argument use results in a deprecation warning. I would like to deprecate this in Ruby 3.5 (next feature release), and remove it in Ruby 3.6 (following feature release). -- https://bugs.ruby-lang.org/

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[ruby-core:122458] [Ruby Bug#21400] rb_bug() hit when killing current root fiber on non-main thread
by luke-gru (Luke Gruber) 05 Jun '25

05 Jun '25

Issue #21400 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #21400: rb_bug() hit when killing current root fiber on non-main thread https://bugs.ruby-lang.org/issues/21400 * Author: luke-gru (Luke Gruber) * Status: Open * ruby -v: 3.5.0dev * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- This following code hits an `rb_bug`: ```ruby Thread.new { Fiber.current.kill }.join ``` Normally fibers gracefully handle this case by terminating and switching to another fiber, but if there is no other fiber it raises the `FIBER_FATAL_FIBER_KILLED` error and this is not caught by the starting thread, resulting in a bug. -- https://bugs.ruby-lang.org/

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[ruby-core:122305] [Ruby Bug#21376] Inconsistent equality between Sets with different compare_by_identity, different classes
by Ethan (Ethan -) 05 Jun '25

05 Jun '25

Issue #21376 has been reported by Ethan (Ethan -). ---------------------------------------- Bug #21376: Inconsistent equality between Sets with different compare_by_identity, different classes https://bugs.ruby-lang.org/issues/21376 * Author: Ethan (Ethan -) * Status: Open * ruby -v: ruby 3.5.0dev (2025-05-26T17:42:35Z master 909a0daab6) +PRISM [x86_64-darwin22] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- This is an inconsistency between the new core Set and the ruby-implemented Set. I think probably the new implementation's behavior seems correct and the ruby implementation is an incorrect edge case. ```ruby class MySet < Set end o = Object.new Set.new([o]).compare_by_identity == MySet.new([o]) # => false on 3.5.0; true with the ruby implementation ``` My understanding is that, for Hash, if two hashes have unequal `compare_by_identity?` they are never equal (even if containing identical contents), unless both are empty. It would make sense for Set to be the same. Hmm, analyzing the ruby Set#== a bit more, I see a further edge case where a non-identity set is considered equal to an identity set with as few as one element in common. ```ruby set_by_eq = Set.new(['a', 'b', 'c']) # => #<Set: {"a", "b", "c"}> set_by_id = MySet.new.compare_by_identity.merge(['a', 'a'.dup, 'a'.dup]) # => #<MySet: {"a", "a", "a"}> set_by_eq == set_by_id # => true in the ruby set, false in core set set_by_id == set_by_eq # => false in both ``` The latter seems unlikely it would ever be triggered unintentionally. The former I did happen across, but since I think the new behavior is correct, I will not be affected when I fix my code to consistently compare_by_identity. Given that, it may be questionable whether it's worth fixing. -- https://bugs.ruby-lang.org/

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[ruby-core:122369] [Ruby Bug#21392] Data classes do not allow overriding #inspect
by austin (Austin Ziegler) 05 Jun '25

05 Jun '25

Issue #21392 has been reported by austin (Austin Ziegler). ---------------------------------------- Bug #21392: Data classes do not allow overriding #inspect https://bugs.ruby-lang.org/issues/21392 * Author: austin (Austin Ziegler) * Status: Open * ruby -v: 3.4.4 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I'm preparing a new version of Color and I have decided to make all of the colour classes Data classes. However, it does not appear that `#inspect` can be overridden: ```ruby module Color CIELAB = Data.define(:l, :a, :b) do def inspect "CIELAB [%.4f%% %.4f %.4f]" % [l, a, b] end end end p Color::CIELAB[1,2,3] # Expected => CIELAB[1.000% 2.000 3.000] # Actual #<data Color::CIELAB l=10, a=-125.0, b=20.5> ``` This feels like it should be permitted. -- https://bugs.ruby-lang.org/

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[ruby-core:122338] [Ruby Bug#21384] const_added is triggered twice when using autoload
by petekinnecom (Pete Kinnecom) 05 Jun '25

05 Jun '25

Issue #21384 has been reported by petekinnecom (Pete Kinnecom). ---------------------------------------- Bug #21384: const_added is triggered twice when using autoload https://bugs.ruby-lang.org/issues/21384 * Author: petekinnecom (Pete Kinnecom) * Status: Open * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- As the title says, I've noticed that `const_added` is invoked twice when using `autoload`. I'm wondering if this behavior is intended or perhaps a bug. Here's a small script to reproduce what I'm seeing: ``` ruby require "tmpdir" dir = Dir.mktmpdir File.write( File.join(dir, "const.rb"), "class Const; end" ) def Object.const_added(const_name) super.tap { puts "const_added: #{const_name}" } end $LOAD_PATH << dir puts "before autoload call" autoload :Const, "const" puts "after autoload call" puts Const # Produces output: # # => before autoload call # => const_added: Const # => after autoload call # => const_added: Const # => Const ``` I'm seeing the behavior using the following docker containers ruby:3.2 and ruby:3.5-rc when running like so: `docker run -v ./:/home ruby:3.5-rc ruby /home/script.rb`. Thanks. -- https://bugs.ruby-lang.org/

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[ruby-core:122359] [Ruby Bug#21391] Inconsistent trailing slash behavior of File#join and Pathname#join with empty strings
by lovro-bikic 05 Jun '25

05 Jun '25

Issue #21391 has been reported by lovro-bikic (Lovro Bikić). ---------------------------------------- Bug #21391: Inconsistent trailing slash behavior of File#join and Pathname#join with empty strings https://bugs.ruby-lang.org/issues/21391 * Author: lovro-bikic (Lovro Bikić) * Status: Open * ruby -v: ruby 3.4.4 (2025-05-14 revision a38531fd3f) +PRISM [x86_64-darwin23] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- ```ruby File.join('/usr', '') # => "/usr/" Pathname.new('/usr').join('').to_s # => "/usr" # no trailing slash File.join('/usr', ' ') # => "/usr/ " Pathname.new('/usr').join(' ').to_s # => "/usr/ " ``` `File.join` with an empty string adds a trailing slash, `Pathname#join` doesn't. When `Pathname#join` argument is a string with empty whitespace, a trailing slash is added (plus whitespace). I think it's a common use-case to append a trailing slash to `Pathname`, and currently you have to resort to other methods such as string interpolation (e.g. in Rails, `"#{Rails.root}/"`) or `File.join` (e.g. `File.join(Rails.root, '')`). In other popular languages, both approaches have been taken: - [`os.path.join` in Python](https://docs.python.org/3.12/library/os.path.html#os.path.join) adds a trailing slash: ```python import os os.path.join('/usr', '') # '/usr/' ``` - [Path.join in Rust](https://doc.rust-lang.org/std/path/struct.Path.html#method.join) adds a trailing slash: ```rust use std::path::{Path}; fn main() { println!("{}", Path::new("/usr").join("").display()); // prints "/usr/" } ``` - [path.join in Node](https://nodejs.org/api/path.html#pathjoinpaths) doesn't add a trailing slash: ```js const path = require('path'); path.join('/usr', ''); // '/usr' ``` - [filepath.Join in Go](https://pkg.go.dev/path/filepath#Join) doesn't add a trailing slash: ```go package main import ("fmt"; "path/filepath") func main() { fmt.Println(filepath.Join("/usr", "")) // prints "/usr" } ``` -- https://bugs.ruby-lang.org/

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[ruby-core:122228] [Ruby Feature#21359] Introduce `Exception#cause=` for Post-Initialization Assignment
by ioquatix (Samuel Williams) 05 Jun '25

05 Jun '25

Issue #21359 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Feature #21359: Introduce `Exception#cause=` for Post-Initialization Assignment https://bugs.ruby-lang.org/issues/21359 * Author: ioquatix (Samuel Williams) * Status: Open * Assignee: ioquatix (Samuel Williams) ---------------------------------------- Ruby currently allows an exception’s `cause` to be explicitly set **only at the time of raising** using `raise ..., cause: ...`. However, there are valid use cases where it would be convenient to set the cause when creating an exception. ## The Problem Ruby supports exception chaining via the `cause:` keyword during a `raise`, like so: ```ruby raise StandardError.new("failure"), cause: original_exception ``` ## Proposed Solution Introduce `Exception#cause=` as a public setter method on `Exception`, allowing post-initialization assignment of the cause: ```ruby cause = RuntimeError.new("low-level error") error = StandardError.new("higher-level error") error.cause = cause ``` It would be semantically equivalent to the following implementation: ```ruby error = StandardError.new("error") cause = RuntimeError.new("cause") class Exception def cause= value backtrace = self.backtrace_locations raise self, cause: value rescue Exception self.set_backtrace(backtrace) end end p error.cause # nil error.cause = cause p error.cause # => #<RuntimeError: cause> ``` ### Benefits * Simplifies creation of rich exception objects in frameworks, tools, and tests. * Enables structured error chaining in asynchronous and deferred execution environments. * Avoids misuse of `raise`/`rescue` for control flow and metadata setting. -- https://bugs.ruby-lang.org/

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[ruby-core:121700] [Ruby Feature#21279] Bare "rescue" should not rescue NameError
by AMomchilov (Alexander Momchilov) 05 Jun '25

05 Jun '25

Issue #21279 has been reported by AMomchilov (Alexander Momchilov). ---------------------------------------- Feature #21279: Bare "rescue" should not rescue NameError https://bugs.ruby-lang.org/issues/21279 * Author: AMomchilov (Alexander Momchilov) * Status: Open ---------------------------------------- # Abstract Bare `rescue` keywords (either as a modifier like `foo rescue bar` or as clause of a `begin` block) should _not_ rescue `NameError` or `NoMethodError`. This behaviour is unexpected and hides bugs. ## Background Many Rubyists are surprised to learn that [`NameError`](https://docs.ruby-lang.org/en/master/NameError.html) is a subclass of [`StandardError`](https://docs.ruby-lang.org/en/master/StandardError.html), so it's caught whenever you use a "bare" `rescue` block. ```ruby begin DoesNotExist rescue => e p e # => #<NameError: uninitialized constant DoesNotExist> end ``` Similarly, [`NoMethodError`](https://docs.ruby-lang.org/en/master/NoMethodError.html) is also rescued, because it's a subclass of `NameError`. ```ruby begin does_not_exist() rescue => e p e # => #<NoMethodError: undefined method `does_not_exist' for main> end ``` This is almost never expected behaviour. `NameError`/`NoMethodError` is usually the result of a typo in the Ruby source, that cannot be reasonably recovered from at runtime. It's a programming error just like a [`SyntaxError`](https://docs.ruby-lang.org/en/master/SyntaxError.html), which _isn't_ a `StandandError`. ## Proposal No matter the solution, solving this problem will require a breaking change. Perhaps this could be part of Ruby 4? The most obvious solution is to change the superclass of `NameError` from `StandardError` to `Exception` (or perhaps [`ScriptError`](https://docs.ruby-lang.org/en/master/ScriptError.html), similar to `SyntaxError`). ### Alternatives considered If we want to avoid changing the inheritance hierarchy of standard library classes, we could instead change the semantics of bare `rescue` from "rescues any subtype of `StandardError`", to instead be "rescues any subtype of `StandardError` except `NameError` or its subtypes". This is worse in my opinion, as it complicates the semantics for no good reason. ## Use cases <details><summary>fun example</summary> The worst case I've seen of this came from a unit tesat like so: ```ruby test "aborts if create_user returns error" do mock_user_action(data: { user: { id: 123, ... }, errors: [{ code: "foo123" }] }) ex = assert_raises(StandardError) do CreateUser.perform(123) end assert_match(/foo123/, ex.message) end ``` This test passes, but not for the expected reason. It turns out that inside of the business logic of `CreateUser`, the error code data was accessed as a method call like `error.code`, rather than a key like `error[:code]`. This lead to: ``` NoMethodError (undefined method `code' for {:code=>"foo123"}:Hash) ``` The `NoMethodError` is a `StandardError`, and even more insidious, because `foo123` is part of the NoMethodError's default message, the `assert_match(/foo123/, ex.message)` also mathches! The correct fix here would be to introduce a specific error like `UserCreationError` that can be rescued specifically, with a field like `code` that can be matched instead of the message. Regardless, this illustrates the kind of confusion that comes from `NoMethodError` being a `StandardError`. </details> # Discussion It might be useful to distinguish between `NameError`s made in "static" code like `DoesNotExist` or `does_not_exist()`, versus those encountered dynamically via `Object.const_get(dynamic_value)` or `object.send(dynamic_value)`. In those metaprogramming cases, the error could be a consequence of bad runtime data, which is more recoverable than just some fundamental error with your Ruby code. -- https://bugs.ruby-lang.org/

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