- ruby-core - ml.ruby-lang.org

[ruby-core:122615] [Ruby Misc#21458] Test 'make install'?
by MSP-Greg (Greg L) 23 Aug '25

23 Aug '25

Issue #21458 has been reported by MSP-Greg (Greg L). ---------------------------------------- Misc #21458: Test 'make install'? https://bugs.ruby-lang.org/issues/21458 * Author: MSP-Greg (Greg L) * Status: Open ---------------------------------------- Can `make install` be tested? Two items come to mind: 1. Test that all gems can be required? 2. Check that all gem binstubs are installed and work. Some of the above are being done in ruby-loco and https://github.com/ruby/ruby-dev-builder/blob/master/cli_test.rb. Both of these are cron jobs, they don't run on every commit. A long time ago, I think this was discussed, but it was back when CI was much more limited. It was also mixed in with the idea of running tests from the 'install' folder, rather than the 'build' folder. Maybe a few jobs could be added to check `make install` on the three main OS's (Ubuntu, macOS, Windows)? Lastly, with minimal changes, tests can be run from the install folder, which is what ruby-loco has done for years. Recently, two tests that I believe are skipped here started failing: ``` TestGemRequire#test_realworld_default_gem Line: 471 Expected "" to not be empty. TestGemRequire#test_realworld_upgraded_default_gem Line: 492 <"999.99.9"> expected but was <"/ruby/tmp/test_rubygems_20250628-8920-sifyoe/test_realworld_upgraded_default_gem.rb:3:in '<main>': undefined method 'version' for nil (NoMethodError)">. ``` -- https://bugs.ruby-lang.org/

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[ruby-core:122917] [Ruby Feature#21532] Define most of Pathname in Ruby code
by Eregon (Benoit Daloze) 22 Aug '25

22 Aug '25

Issue #21532 has been reported by Eregon (Benoit Daloze). ---------------------------------------- Feature #21532: Define most of Pathname in Ruby code https://bugs.ruby-lang.org/issues/21532 * Author: Eregon (Benoit Daloze) * Status: Open * Assignee: Eregon (Benoit Daloze) ---------------------------------------- There was discussion in #17473 and before to define most of Pathname in Ruby code and not in the C extension. I have made a PR to achieve that: https://github.com/ruby/pathname/pull/57 I would like to merge it soon to avoid conflicts. Once upon a time, Pathname was pure-Ruby: https://github.com/ruby/ruby/blob/95bc02237635d3fe42532bfe53038257575cee75/… This PR goes back to that, and reuses that original Ruby code, but keeps the C extension implementation of `<=>` and `sub` as those two are significantly faster. The other Pathname methods are actually faster in Ruby than in C, because all these methods just do `rb_funcall()` and `rb_ivar_get()` and those in C code have no inline cache, but the corresponding method calls and `@path` have inline caches in Ruby code. https://railsatscale.com/2023-08-29-ruby-outperforms-c/ is an explanation of that. Therefore having Pathname defined in Ruby seems a clear win for many reasons: * Much clearer implementation, so easier to read what the code does * Easier to maintain * Safer (no risk of accessing out of bounds memory or e.g. passing the wrong number of arguments to `rb_funcall`) * Actually faster, because of these inline caches, see numbers at the end of https://github.com/ruby/pathname/pull/57#issue-3234862768 * Better for JITs as they can optimize this, notably `...` vs the C extension being a blackbox * Works on JRuby (which does not support C extensions) * Faster on TruffleRuby (where a C extension for this is inefficient as it causes needless Ruby->C->Ruby transitions) -- https://bugs.ruby-lang.org/

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[ruby-core:122925] [Ruby Feature#21533] Introduce `Time#am?` and `Time#pm?`
by matheusrich (Matheus Richard) 22 Aug '25

22 Aug '25

Issue #21533 has been reported by matheusrich (Matheus Richard). ---------------------------------------- Feature #21533: Introduce `Time#am?` and `Time#pm?` https://bugs.ruby-lang.org/issues/21533 * Author: matheusrich (Matheus Richard) * Status: Open ---------------------------------------- This proposal adds two predicate methods to `Time`: ```ruby Time.utc(2000, 1, 1, 11, 59, 59).am? # => true Time.utc(2000, 1, 1, 12, 0, 0).pm? # => true ``` * `am?` returns true when the hour is less than 12. * `pm?` returns true when the hour is 12 or greater. These methods provide a clear and expressive way to branch logic based on time of day. For example: ```ruby def reminder_deferral_options options = [] options << ["Later today", "later_today"] if Time.now.am? options << ["Tomorrow morning", "tomorrow_morning"] options << ["Pick a date/time…", "custom"] options end ``` This is a common pattern in applications involving reminders and scheduling. The method names are intuitive, and the semantics are well understood. The implementation is in [this Pull Request](https://github.com/ruby/ruby/pull/14133). -- https://bugs.ruby-lang.org/

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[ruby-core:123045] [Ruby Feature#14718] Use jemalloc by default?
by mame (Yusuke Endoh) 22 Aug '25

22 Aug '25

Issue #14718 has been updated by mame (Yusuke Endoh). Status changed from Open to Rejected jemalloc development has been discontinued. https://jasone.github.io/2025/06/12/jemalloc-postmortem/ ---------------------------------------- Feature #14718: Use jemalloc by default? https://bugs.ruby-lang.org/issues/14718#change-114362 * Author: mperham (Mike Perham) * Status: Rejected ---------------------------------------- I know Sam opened #9113 4 years ago to suggest this but I'm revisiting the topic to see if there's any movement here for Ruby 2.6 or 2.7. I supply a major piece of Ruby infrastructure (Sidekiq) and I keep hearing over and over how Ruby is terrible with memory, a huge memory hog with their Rails apps. My users switch to jemalloc and a miracle occurs: their memory usage drops massively. Some data points: https://twitter.com/brandonhilkert/status/987400365627801601 https://twitter.com/d_jones/status/989866391787335680 https://github.com/mperham/sidekiq/issues/3824#issuecomment-383072469 Redis moved to jemalloc many years ago and it solved all of their memory issues too. Their conclusion: the glibc allocator "sucks really really hard". http://oldblog.antirez.com/post/everything-about-redis-24.html This is a real pain point for the entire Rails community and would improve Ruby's reputation immensely if we can solve this problem. ---Files-------------------------------- glibc_arena_2.png (7.23 KB) jemalloc.png (21.1 KB) glibc-arena-2.log (60.3 KB) glibc.log (62.3 KB) jemalloc-3-5.log (58.5 KB) glibc.png (9.03 KB) -- https://bugs.ruby-lang.org/

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[ruby-core:120873] [Ruby master Bug#21111] RbConfig::CONFIG['CXX'] quietly set to "false" when Ruby cannot build C++ programs
by stanhu (Stan Hu) 22 Aug '25

22 Aug '25

Issue #21111 has been reported by stanhu (Stan Hu). ---------------------------------------- Bug #21111: RbConfig::CONFIG['CXX'] quietly set to "false" when Ruby cannot build C++ programs https://bugs.ruby-lang.org/issues/21111 * Author: stanhu (Stan Hu) * Status: Open * ruby -v: ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +YJIT +PRISM [arm64-darwin24] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- As reported in https://gitlab.com/gitlab-org/gitlab-development-kit/-/issues/2222 and https://trac.macports.org/ticket/70750, we've had numerous macOS users experience problems with compiling Ruby C++ extensions after upgrading to XCode 16. Users have had to fix their XCode setups and reinstall Ruby when this happens. It turns out that when Ruby can't build a CXX program, it essentially sets CXX to the `false` string. From https://github.com/ruby/ruby/blob/7317f96727725ca37ddb06011918deb841de371c/…: ``` AS_IF([test -n "${rb_there_is_in_fact_no_gplusplus_but_autoconf_is_cheating_us}"], [ AC_MSG_NOTICE([Test skipped due to lack of a C++ compiler.]) ], [test -n "${CXX}"], [ RUBY_WERROR_FLAG([ AC_MSG_CHECKING([whether CXXFLAGS is valid]) AC_LANG_PUSH(C++) AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[@%:@include <cstdio>]], [[]])], [AC_MSG_RESULT(yes)],[ AC_MSG_RESULT(no) # The message mentions CXXFLAGS, but CPPFLAGS might also affects. AC_MSG_WARN([something wrong with CXXFLAGS="$CXXFLAGS"]) CXX=false ``` This causes C++ extensions, such as `unf_ext`, to fail while attempting to compile native extensions. There are no error messages because `false` is executed, so users only see: ``` Installing unf_ext 0.0.8.2 with native extensions Gem::Ext::BuildError: ERROR: Failed to build gem native extension. current directory: /Users/myuser/.rvm/gems/ruby-3.3.7/gems/unf_ext-0.0.8.2/ext/unf_ext /Users/kerrizor/.rvm/rubies/ruby-3.3.7/bin/ruby extconf.rb checking for -lstdc++... yes creating Makefile current directory: /Users/myuser/.rvm/gems/ruby-3.3.7/gems/unf_ext-0.0.8.2/ext/unf_ext make DESTDIR\= sitearchdir\=./.gem.20250203-69237-u2oi17 sitelibdir\=./.gem.20250203-69237-u2oi17 clean current directory: /Users/myuser/.rvm/gems/ruby-3.3.7/gems/unf_ext-0.0.8.2/ext/unf_ext make DESTDIR\= sitearchdir\=./.gem.20250203-69237-u2oi17 sitelibdir\=./.gem.20250203-69237-u2oi17 compiling unf.cc make: *** [unf.o] Error 1 ``` `unf_ext` only checks whether `RbConfig::CONFIG['CXX']` is defined, not that it is `false`: https://github.com/knu/ruby-unf_ext/blob/c72a36d0a5ea9fe3950611b0f289fc68a2…. Questions: 1. Should CXX just be set to `nil`? Or should all C++ extensions be expected to check for `false`? The latter seems surprising to me. 2. Should there be a way to fail the Ruby build if a valid C++ compiler is not found? -- https://bugs.ruby-lang.org/

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[ruby-core:123036] [Ruby Feature#17316] On memoization
by Dan0042 (Daniel DeLorme) 21 Aug '25

21 Aug '25

Issue #17316 has been updated by Dan0042 (Daniel DeLorme). The single-character syntax itself isn't a problem if limited to instance variables. `foo ?=` is already valid and shouldn't change, but `@foo ?=` isn't currently valid, so it could serve as "assign if ivar undefined." The problem is consistency. All operator-equals decompose uniformly (`a += b` -> `a = a + b`) but `?=` and its variations (like `@||=`) would be very different. What should happen with cases like: ```ruby foo ?= expr foo[key] ?= expr foo.bar ?= expr ``` If that's a syntax error, it's inconsistent with other operators like `+=` or `||=`. If it means "assign if not nil", it's inconsistent with `@foo ?= expr` as "assign if undefined". And if `@foo ?= expr` is changed to mean "assign if not nil" then we're back to the nil coalescing operator which is a different topic (#13820) An operator for "assign if undefined" is appealing, but the implications don't work out cleanly. ---------------------------------------- Feature #17316: On memoization https://bugs.ruby-lang.org/issues/17316#change-114347 * Author: sawa (Tsuyoshi Sawada) * Status: Open ---------------------------------------- I have seen so many attempts to memoize a value in the form: ```ruby @foo ||= some_heavy_calculation(...) ``` improperly, i.e., even when the value can potentially be falsy. This practice is wide spread, and since in most cases memoization is about efficiency and it would not be critical if it does not work correctly, people do not seem to care so much about correcting the wrong usage. In such case, the correct form would be: ```ruby unless instance_variable_defined?(:@foo) @foo = some_heavy_calculation(...) end ``` but this looks too long, and perhaps that is keeping people away from using it. What about allowing `Kernel#instance_variable_set` to take a block instead of the second argument, in which case the assignment should be done only when the instance variable is not defined? ```ruby instance_variable_set(:@foo){some_heavy_calculation(...)} ``` Or, if that does not look right or seems to depart from the original usage of `instance_variable_set`, then what about having a new method? ```ruby memoize(:foo){some_heavy_calculation(...)} ``` -- https://bugs.ruby-lang.org/

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[ruby-core:117216] [Ruby master Bug#20346] FiberScheduler.unblock not called by Thread#join when Thread body contains Ractor.take
by forthoney (Seong-Heon Jung) 21 Aug '25

21 Aug '25

Issue #20346 has been reported by forthoney (Seong-Heon Jung). ---------------------------------------- Bug #20346: FiberScheduler.unblock not called by Thread#join when Thread body contains Ractor.take https://bugs.ruby-lang.org/issues/20346 * Author: forthoney (Seong-Heon Jung) * Status: Open * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- When using a `Ractor.take` inside a different thread, `Thread#join` on the thread running `Ractor.take` fails to call `FiberScheduler.unblock`. The below code can replicate this behavior ```ruby require "async" class RactorWrapper def initialize @ractor = Ractor.new do Ractor.recv # Ractor doesn't start until explicitly told to # Do some calculations fib = ->(x) { x < 2 ? 1 : fib.call(x - 1) + fib.call(x - 2) } fib.call(20) end end def take_async @ractor.send(nil) Thread.new { @ractor.take }.join.value end end Async do |task| 10000.times do |i| task.async do RactorWrapper.new.take_async puts i end end end ``` The above code deadlocks, and when we leave a debugging print statement inside of `Async`'s scheduler's `block` and `unblock` method, we can confirm that we only call `Scheduler.block`, and never `Scheduler.unblock` -- https://bugs.ruby-lang.org/

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[ruby-core:112206] [Ruby master Bug#19407] 2 threads taking from current ractor will hang forever
by luke-gru (Luke Gruber) 21 Aug '25

21 Aug '25

Issue #19407 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #19407: 2 threads taking from current ractor will hang forever https://bugs.ruby-lang.org/issues/19407 * Author: luke-gru (Luke Gruber) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- In the current implementation of Ractors, it's possible to `take` from the current ractor. This could be useful when co-ordinating threads: ```ruby t = Thread.new do obj = Ractor.current.take p obj # do some work with obj end t0 = Thread.new do obj = Ractor.current.take p obj # do some work with obj end Ractor.yield :go ``` However it hangs forever: ```ruby t = Thread.new do obj = Ractor.current.take p obj end t0 = Thread.new do obj = Ractor.current.take p obj end sleep 0.5 ``` Should "self-take" be disabled, or was it designed to allow it but this is just a bug? -- https://bugs.ruby-lang.org/

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[ruby-core:123030] [Ruby Feature#17316] On memoization
by matz (Yukihiro Matsumoto) 21 Aug '25

21 Aug '25

Issue #17316 has been updated by matz (Yukihiro Matsumoto). Currently, `?=` means "a single character =". We don't want to break current available syntax, unless absolutely necessary. Matz. ---------------------------------------- Feature #17316: On memoization https://bugs.ruby-lang.org/issues/17316#change-114340 * Author: sawa (Tsuyoshi Sawada) * Status: Open ---------------------------------------- I have seen so many attempts to memoize a value in the form: ```ruby @foo ||= some_heavy_calculation(...) ``` improperly, i.e., even when the value can potentially be falsy. This practice is wide spread, and since in most cases memoization is about efficiency and it would not be critical if it does not work correctly, people do not seem to care so much about correcting the wrong usage. In such case, the correct form would be: ```ruby unless instance_variable_defined?(:@foo) @foo = some_heavy_calculation(...) end ``` but this looks too long, and perhaps that is keeping people away from using it. What about allowing `Kernel#instance_variable_set` to take a block instead of the second argument, in which case the assignment should be done only when the instance variable is not defined? ```ruby instance_variable_set(:@foo){some_heavy_calculation(...)} ``` Or, if that does not look right or seems to depart from the original usage of `instance_variable_set`, then what about having a new method? ```ruby memoize(:foo){some_heavy_calculation(...)} ``` -- https://bugs.ruby-lang.org/

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[ruby-core:123028] [Ruby Feature#17316] On memoization
by matheusrich (Matheus Richard) 21 Aug '25

21 Aug '25

Issue #17316 has been updated by matheusrich (Matheus Richard). @matz I propose `?=` as the uninitialized assignment operator: ```rb @foo ?= some_heavy_calculation(...) ``` ---------------------------------------- Feature #17316: On memoization https://bugs.ruby-lang.org/issues/17316#change-114338 * Author: sawa (Tsuyoshi Sawada) * Status: Open ---------------------------------------- I have seen so many attempts to memoize a value in the form: ```ruby @foo ||= some_heavy_calculation(...) ``` improperly, i.e., even when the value can potentially be falsy. This practice is wide spread, and since in most cases memoization is about efficiency and it would not be critical if it does not work correctly, people do not seem to care so much about correcting the wrong usage. In such case, the correct form would be: ```ruby unless instance_variable_defined?(:@foo) @foo = some_heavy_calculation(...) end ``` but this looks too long, and perhaps that is keeping people away from using it. What about allowing `Kernel#instance_variable_set` to take a block instead of the second argument, in which case the assignment should be done only when the instance variable is not defined? ```ruby instance_variable_set(:@foo){some_heavy_calculation(...)} ``` Or, if that does not look right or seems to depart from the original usage of `instance_variable_set`, then what about having a new method? ```ruby memoize(:foo){some_heavy_calculation(...)} ``` -- https://bugs.ruby-lang.org/

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