March 2024 - ruby-core - ml.ruby-lang.org

[ruby-core:116382] [Ruby master Feature#20205] Enable `frozen_string_literal` by default
by byroot (Jean Boussier) 28 Oct '25

28 Oct '25

Issue #20205 has been reported by byroot (Jean Boussier). ---------------------------------------- Feature #20205: Enable `frozen_string_literal` by default https://bugs.ruby-lang.org/issues/20205 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal ---------------------------------------- ### Context The `frozen_string_literal: true` pragma was introduced in Ruby 2.3, and as far as I'm aware the plan was initially to make it the default for Ruby 3.0, but this plan was abandoned because it would be too much of a breaking change without any real further notice. According to Matz, he still wishes to enable `frozen_string_literal` by default in the future, but a reasonable migration plan is required. The main issue is backward compatibility, flipping the switch immediately would break a lot of code, so there must be some deprecation period. The usual the path forward for this kind of change is to emit deprecation warnings one of multiple versions in advance. One example of that was the Ruby 2.7 keyword argument deprecation. It was quite verbose, and some users were initially annoyed, but I think the community pulled through it and I don't seem to hear much about it anymore. So for frozen string literals, the first step would be to start warning when a string that would be frozen in the future is mutated. ### Deprecation Warning Implementation I implemented a quick proof of concept with @etienne in https://github.com/Shopify/ruby/pull/549 In short: - Files with `# frozen_string_literal: true` or `# frozen_string_literal: false` don't change in behavior at all. - Files with no `# frozen_string_literal` comment are compiled to use `putchilledstring` opcode instead of regular `putstring`. - This opcode mark the string with a user flag, when these strings are mutated, a warning is issued. Currently the proof of concept issue the warning at the mutation location, which in some case can make locating where the string was allocated a bit hard. But it is possible to improve it so the message also include the location at which the literal string was allocated, and learning from the keyword argument warning experience, we can record which warnings were already issued to avoid spamming users with duplicated warnings. As currently implemented, there is almost no overhead. If we modify the implementation to record the literal location, we'd incur a small memory overhead for each literal string in a file without an explicit `frozen_string_literal` pragma. But I believe we could do it in a way that has no overhead if `Warning[:deprecated] = false`. ### Timeline The migration would happen in 3 steps, each step can potentially last multiple releases. e.g. `R0` could be `3.4`, `R1` be `3.7` and `R2` be `4.0`. I don't have a strong opinion on the pace. - Release `R0`: introduce the deprecation warning (only if deprecation warnings enabled). - Release `R1`: make the deprecation warning show up regardless of verbosity level. - Release `R2`: make string literals frozen by default. ### Impact Given that `rubocop` is quite popular in the community and it has enforced the usage of `# frozen_string_literal: true` for years now, I suspect a large part of the actively maintained codebases in the wild wouldn't see any warnings. And with recent versions of `minitest` enabling deprecation warnings by default (and [potentially RSpec too](https://github.com/rspec/rspec-core/issues/2867)) the few that didn't migrate will likely be made compatible quickly. The real problem of course are the less actively developed libraries and applications. For such cases, any codebase can remain compatible by setting `RUBYOPT="--disable=frozen_string_literal"`, and so even after `R2` release. The flag would never be removed any legacy codebase can continue upgrading Ruby without changing a single line of cod by just flipping this flag. ### Workflow for library maintainers As a library maintainer, fixing the deprecation warnings can be as simple as prepending `# frozen_string_literal: false` at the top of all their source files, and this will keep working forever. Alternatively they can of course make their code compatible with frozen string literals. Code that is frozen string literal compatible doesn't need to explicitly declare it. Only code that need it turned of need to do so. ### Workflow for application owners For application owners, the workflow is the same than for libraries. However if they depend on a gem that hasn't updated, or that they can't upgrade it, they can run their application with `RUBYOPT="--disable=frozen_string_literal"` and it will keep working forever. Any user running into an incompatibility issue can set `RUBYOPT="--disable=frozen_string_literal"` forever, even in `4.x`, the only thing changing is the default value. And any application for which all dependencies have been made fully frozen string literal compatible can set `RUBYOPT="--enable=frozen_string_literal"` and start immediately removing magic comment from their codebase. -- https://bugs.ruby-lang.org/

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[ruby-core:116083] [Ruby master Feature#20163] Introduce #bit_count method on Integer
by garrison (Garrison Jensen) 24 Oct '25

24 Oct '25

Issue #20163 has been reported by garrison (Garrison Jensen). ---------------------------------------- Feature #20163: Introduce #bit_count method on Integer https://bugs.ruby-lang.org/issues/20163 * Author: garrison (Garrison Jensen) * Status: Open * Priority: Normal ---------------------------------------- This feature request is to implement a method called #bit_count on Integer that returns the number of ones in the binary representation of the absolute value of the integer. ``` n = 19 n.bit_count #=> 3 (-n).bit_count #=> 3 ``` This is often useful when you use an integer as a bitmask and want to count how many bits are set. This would be equivalent to ``` n.to_s(2).count("1") ``` However, this can be outperformed by ``` def bit_count(n) count = 0 while n > 0 n &= n - 1 # Flip the least significant 1 bit to 0 count += 1 end count end ``` I think this would be a useful addition because it would fit alongside the other bit-related methods defined on integer: `#bit_length,` `#allbits?`, `#anybits?`, `#nobits?`. Also, when working with bitmasks, a minor upgrade to performance often results in a significant improvement. Similar methods from other languages: https://docs.python.org/3/library/stdtypes.html#int.bit_count https://doc.rust-lang.org/std/primitive.i32.html#method.count_ones -- https://bugs.ruby-lang.org/

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[ruby-core:111742] [Ruby master Feature#19326] Please add a better API for passing a Proc to a Ractor
by sdwolfz 18 Oct '25

18 Oct '25

Issue #19326 has been reported by sdwolfz (Codruț Gușoi). ---------------------------------------- Feature #19326: Please add a better API for passing a Proc to a Ractor https://bugs.ruby-lang.org/issues/19326 * Author: sdwolfz (Codruț Gușoi) * Status: Open * Priority: Normal ---------------------------------------- Example 1: ```ruby class Worker def initialize(&block) @block = block end def run Ractor.new(@block, &:call) end end worker = Worker.new { 1 } puts worker.run.take ``` Errors with: ``` <internal:ractor>:271:in `new': allocator undefined for Proc (TypeError) from scripts/run.rb:9:in `run' from scripts/run.rb:14:in `<main>' ``` Example 2: ```ruby class Worker def initialize(&block) @block = Ractor.make_shareable(block) end def run Ractor.new(@block, &:call) end end worker = Worker.new { 1 } puts worker.run.take ``` Errors with: ``` <internal:ractor>:820:in `make_shareable': Proc's self is not shareable: #<Proc:0x00007f00394c38b8 scripts/run.rb:13> (Ractor::IsolationError) from scripts/run.rb:5:in `initialize' from scripts/run.rb:13:in `new' from scripts/run.rb:13:in `<main>' ``` Example 3: ```ruby class Worker def initialize(&block) @block = Ractor.make_shareable(block) end def run Ractor.new(@block, &:call) end end worker = Ractor.current.instance_eval { Worker.new { 1 } } puts worker.run.take ``` Works, but having `Ractor.current.instance_eval` as a wrapper around the block is not ideal, as Ractor is supposed to be only an implementation detail in Worker. I know about https://bugs.ruby-lang.org/issues/18243 and the discussion around `proc.bind(nil)`. That would actually be ideal, as for the purposes if why I want this functionality I don't care what `self` is in a block, and the less it has access to the better. The general idea is to have a Ractor be able to lazily execute an arbitrary proc. And all the bindings it would need would be passed explicitly, either through `args` in the constructor or through `send`/`receive`, so `self` would really not matter. The benefit: this would make it so concurrent code can be more easily be implemented with Ractors as currently you can execute an arbitrary proc by passing it to a Thread (but you don't get the nice data isolation). -- https://bugs.ruby-lang.org/

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[ruby-core:112552] [Ruby master Bug#19461] Time.local performance tanks in forked process (on macOS only?)
by ioquatix (Samuel Williams) 06 Oct '25

06 Oct '25

Issue #19461 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Bug #19461: Time.local performance tanks in forked process (on macOS only?) https://bugs.ruby-lang.org/issues/19461 * Author: ioquatix (Samuel Williams) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- The following program demonstrates a performance regression in forked child processes when invoking `Time.local`: ```ruby require 'benchmark' require 'time' def sir_local_alot result = Benchmark.measure do 10_000.times do tm = ::Time.local(2023) end end $stderr.puts result end sir_local_alot pid = fork do sir_local_alot end Process.wait(pid) ``` On Linux the performance is similar, but on macOS, the performance is over 100x worse on my M1 laptop. -- https://bugs.ruby-lang.org/

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[ruby-core:116946] [Ruby master Bug#20302] Multiple refinements cannot be applied to the same module
by mame (Yusuke Endoh) 06 Oct '25

06 Oct '25

Issue #20302 has been reported by mame (Yusuke Endoh). ---------------------------------------- Bug #20302: Multiple refinements cannot be applied to the same module https://bugs.ruby-lang.org/issues/20302 * Author: mame (Yusuke Endoh) * Status: Open * Assignee: shugo (Shugo Maeda) * ruby -v: ruby 3.4.0dev (2024-02-20T07:17:20Z master a605234bfa) [x86_64-linux] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- If we are using multiple refinements for the Kernel module, it seems that only the last refinement is enabled. In the following example, we can call `f2` of M2, which is enabled later. but cannot call `f1` of M1. ```ruby module M1 refine(Kernel) do def f1 = :f1 end end module M2 refine(Kernel) do def f2 = :f2 end end class Foo using M1 using M2 def test p f2 #=> :f2 p f1 # expected => :f1 # actual => undefined local variable or method 'f1' for an instance of Foo end end Foo.new.test ``` Note that if I change `refine(Kernel)` to `refine(Object)`, it works as expected. So I think there is a problem only when the refinement target is a module. -- https://bugs.ruby-lang.org/

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[ruby-core:115552] [Ruby master Misc#20032] Propose @kjtsanaktsidis as a commiter
by jeremyevans0 (Jeremy Evans) 27 Sep '25

27 Sep '25

Issue #20032 has been reported by jeremyevans0 (Jeremy Evans). ---------------------------------------- Misc #20032: Propose @kjtsanaktsidis as a commiter https://bugs.ruby-lang.org/issues/20032 * Author: jeremyevans0 (Jeremy Evans) * Status: Open * Priority: Normal ---------------------------------------- I'd like to propose @kjtsanaktsidis as a committer, with a focus on bug triaging and fixing. During RubyKaigi 2023, KJ expressed interest in helping triage and fix bugs, and since then, he has fixed numerous bugs. What's most impressive about KJ's contributions is the difficulty of the bugs he has fixed, and the wide range of areas in which he has fixed bugs (GC, threading, FreeBSD support, ractors, rubygems, extensions, tests, old bugs, etc.). Here is a list of bugs KJ has fixed: * #20021 * #19994 * #19928 * #19873 * #19387 * #19680 * #4173 Here is a list of open pull requests submitted by KJ to fix bugs: * #20022 https://github.com/ruby/ruby/pull/9041 * #19991 https://github.com/ruby/ruby/pull/8949 and https://github.com/ruby/ruby/pull/8856 * #20001 https://github.com/ruby/ruby/pull/8903 * #19717 https://github.com/ruby/ruby/pull/8331 * #19144 https://github.com/ruby/ruby/pull/7295 * #18795 https://github.com/ruby/ruby/pull/5992 In addition to these Redmine issues, KJ has also fixed other bugs: * https://github.com/ruby/ruby/commit/9a62fd3cbae2ebb60e2f9cad782af1ad18db4319 * https://github.com/ruby/ruby/commit/76dc327eeffefe02577999fe5f8215f762a581b6 * https://github.com/ruby/ruby/commit/082962e857833dfc16881cb4dfb44caa175590ba * https://github.com/ruby/ruby/commit/edee9b6a12ac846d7b3de2d704e170bf28178cb3 * https://github.com/ruby/ruby/commit/dd406c5a911d2f4a16ce97016666760713540185 * https://github.com/ruby/ruby/commit/7bd7aee02e303de27d2cddfc5ef47e612d6782cb * https://github.com/ruby/ruby/commit/05ffc037ad15560cb2c683682c5bc374156571d7 * https://github.com/ruby/ruby/pull/7867 * https://github.com/ruby/ruby/pull/7865 * https://github.com/ruby/zlib/commit/3b9fe962d8 * https://github.com/ruby/zlib/commit/c96e8b9a57 In addition to bug fixing, KJ has also proposed and implemented a useful Socket feature: * #19179 https://github.com/ruby/ruby/pull/6822 -- https://bugs.ruby-lang.org/

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[ruby-core:111526] [Ruby master Bug#19288] Ractor JSON parsing significantly slower than linear parsing
by maciej.mensfeld (Maciej Mensfeld) 08 Sep '25

08 Sep '25

Issue #19288 has been reported by maciej.mensfeld (Maciej Mensfeld). ---------------------------------------- Bug #19288: Ractor JSON parsing significantly slower than linear parsing https://bugs.ruby-lang.org/issues/19288 * Author: maciej.mensfeld (Maciej Mensfeld) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.0 (2022-12-25 revision a528908271) [x86_64-linux] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- a simple benchmark: ```ruby require 'json' require 'benchmark' CONCURRENT = 5 RACTORS = true ELEMENTS = 100_000 data = CONCURRENT.times.map do ELEMENTS.times.map do { rand => rand, rand => rand, rand => rand, rand => rand }.to_json end end ractors = CONCURRENT.times.map do Ractor.new do Ractor.receive.each { JSON.parse(_1) } end end result = Benchmark.measure do if RACTORS CONCURRENT.times do |i| ractors[i].send(data[i], move: false) end ractors.each(&:take) else # Linear without any threads data.each do |piece| piece.each { JSON.parse(_1) } end end end puts result ``` Gives following results on my 8 core machine: ```shell # without ractors: 2.731748 0.003993 2.735741 ( 2.736349) # with ractors 12.580452 5.089802 17.670254 ( 5.209755) ``` I would expect Ractors not to be two times slower on the CPU intense work. -- 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:115438] [Ruby master Misc#20013] Travis CI status
by jaruga (Jun Aruga) 15 Aug '25

15 Aug '25

Issue #20013 has been reported by jaruga (Jun Aruga). ---------------------------------------- Misc #20013: Travis CI status https://bugs.ruby-lang.org/issues/20013 * Author: jaruga (Jun Aruga) * Status: Open * Priority: Normal ---------------------------------------- I would like to use this ticket to manage our activities to report Travis CI status. Because there is Travis CI status page provided by Travis CI. However, even when the page shows ok, I actually see infra issues. https://www.traviscistatus.com/ I would share my activities and report the Travis CI status on the ticket. The ticket's status is not closed until we stop using Travis CI. The easiest option to fix the Travis infra issue is to email Travis CI support `support _AT_ travis-ci.com`. You can check [this ruby/ruby Travis CI wiki page](https://github.com/ruby/ruby/wiki/CI-Servers#travis-ci) for details. -- https://bugs.ruby-lang.org/

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