February 2023 - ruby-core - ml.ruby-lang.org

[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:112552] [Ruby master Bug#19461] Time.local performance tanks in forked process (on macOS only?)
by ioquatix (Samuel Williams) 23 Aug '25

23 Aug '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: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:111789] [Ruby master Feature#19333] Setting (Fiber Local|Thread Local|Fiber Storage) to nil should delete value in order to avoid memory leaks.
by ioquatix (Samuel Williams) 07 Aug '25

07 Aug '25

Issue #19333 has been reported by ioquatix (Samuel Williams). ---------------------------------------- Feature #19333: Setting (Fiber Local|Thread Local|Fiber Storage) to nil should delete value in order to avoid memory leaks. https://bugs.ruby-lang.org/issues/19333 * Author: ioquatix (Samuel Williams) * Status: Open * Priority: Normal ---------------------------------------- As it stands, Fiber Locals, Thread Locals and Fiber Storage have no way of deleting key-value associations. ```ruby 100.times do |i| name = :"variable-#{i}" Thread.current[name] = 10 end ``` Because of this, dynamically generated associations can leak over time. This is worse for things like Threads that might be pooled (or maybe an argument against user-space pooling). In any case, having a way to delete those associations would allow application code to at least delete the associations when they no longer make sense. I propose that assigning `nil` to "locals" or "storage" should effectively delete them. e.g. ```ruby 100.times do |i| name = :"variable-#{i}" Thread.current[name] = 10 Thread.current[name] = nil # delete association end ``` A more invasive alternative would be to define new interfaces like `Thread::Local`, `Fiber::Local` and `Fiber::Storage::Local` (or something) which correctly clean up on GC. -- https://bugs.ruby-lang.org/

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[ruby-core:111027] [Ruby master Bug#19154] Specify require and autoload guarantees in ractors
by fxn (Xavier Noria) 14 Jul '25

14 Jul '25

Issue #19154 has been reported by fxn (Xavier Noria). ---------------------------------------- Bug #19154: Specify require and autoload guarantees in ractors https://bugs.ruby-lang.org/issues/19154 * Author: fxn (Xavier Noria) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.0preview3 (2022-11-27) [x86_64-darwin22] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Given a file `c.rb`: ```ruby class C end ``` the following script: ```ruby r1 = Ractor.new do require './c.rb' end r2 = Ractor.new do require './c.rb' end r1.take r2.take ``` raises: ``` % ruby -v foo.rb ruby 3.2.0preview3 (2022-11-27) [x86_64-darwin22] foo.rb:1: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues. #<Thread:0x000000010fee2928 run> terminated with exception (report_on_exception is true): #<Thread:0x00000001102acfe0 run> terminated with exception (report_on_exception is true): <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:164:in `ensure in require': can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (Ractor::IsolationError) from <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:167:in `require' from foo.rb:6:in `block in <main>' <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:37:in `require'<internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:164:in `ensure in require': : can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (Ractor::IsolationError) from <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:167:in `require' can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (Ractor::IsolationError) from foo.rb:2:in `block in <main>' <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:37:in `require': can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (Ractor::IsolationError) from foo.rb:2:in `block in <main>' from foo.rb:6:in `block in <main>' <internal:ractor>:698:in `take': thrown by remote Ractor. (Ractor::RemoteError) from foo.rb:9:in `<main>' <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:164:in `ensure in require': can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (Ractor::IsolationError) from <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:167:in `require' from foo.rb:2:in `block in <main>' <internal:/Users/fxn/.rbenv/versions/3.2.0-preview3/lib/ruby/3.2.0+3/rubygems/core_ext/kernel_require.rb>:37:in `require': can not access non-shareable objects in constant Kernel::RUBYGEMS_ACTIVATION_MONITOR by non-main ractor. (Ractor::IsolationError) from foo.rb:2:in `block in <main>' ``` Would it be possible to have documentation about their interaction? This is important also to understand autoloading within ractors, since constant references may trigger `require` calls. -- https://bugs.ruby-lang.org/

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[ruby-core:111809] [Ruby master Bug#19338] Ruby hangs when defining new constant in ractor
by luke-gru (Luke Gruber) 13 May '25

13 May '25

Issue #19338 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #19338: Ruby hangs when defining new constant in ractor https://bugs.ruby-lang.org/issues/19338 * Author: luke-gru (Luke Gruber) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- This code causes Ruby to hang: ``` ruby rs = [] 2.times do rs << Ractor.new do MYCONSTANT = 2 end end rs.each(&:take) ``` There is a problem when the warning is being outputted with multiple ractors. A thread is calling RB_VM_LOCK() while holding the VM lock in ractor.c (ractor_check_blocking()) If the code is changed to RB_VM_LOCK_ENTER() and RB_VM_LOCK_LEAVE() then it fixes it, but I don't know if there's a better way. Thanks! -- https://bugs.ruby-lang.org/

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[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 May '25

09 May '25

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/

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[ruby-core:112207] [Ruby master Bug#19408] Object no longer frozen after moved from a ractor
by luke-gru (Luke Gruber) 08 May '25

08 May '25

Issue #19408 has been reported by luke-gru (Luke Gruber). ---------------------------------------- Bug #19408: Object no longer frozen after moved from a ractor https://bugs.ruby-lang.org/issues/19408 * Author: luke-gru (Luke Gruber) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- I think frozen objects should still be frozen after a move. ```ruby r = Ractor.new do obj = receive p obj.frozen? # should be true but is false p obj end obj = [Object.new].freeze r.send(obj, move: true) r.take ``` -- https://bugs.ruby-lang.org/

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[ruby-core:112301] [Ruby master Bug#19426] Endless `Range#step` of object with `#succ` method does not work
by nobu (Nobuyoshi Nakada) 13 Mar '25

13 Mar '25

Issue #19426 has been reported by nobu (Nobuyoshi Nakada). ---------------------------------------- Bug #19426: Endless `Range#step` of object with `#succ` method does not work https://bugs.ruby-lang.org/issues/19426 * Author: nobu (Nobuyoshi Nakada) * Status: Open * Priority: Normal * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- Consider this `c` object which hash `#succ` method. ```ruby c = Struct.new(:i) do def succ; self.class.new(i+1); end def <=>(other) i <=> other.i;end end.new(0) ``` This `Range#step` works. ```ruby (c..c.succ).step(1) do |d| p d.i # 0, 1 end ``` But it fails on an endless range. ```ruby (c..).step(1) do |d| p d.i break if d.i > 3 end ``` ``` -:3:in `<=>': undefined method `i' for nil:NilClass (NoMethodError) from -:10:in `step' from -:10:in `<main>' ``` -- https://bugs.ruby-lang.org/

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[ruby-core:111121] [Ruby master Bug#19165] Method (with no param) delegation with *, **, and ... is slow
by matsuda (Akira Matsuda) 16 Jan '25

16 Jan '25

Issue #19165 has been reported by matsuda (Akira Matsuda). ---------------------------------------- Bug #19165: Method (with no param) delegation with *, **, and ... is slow https://bugs.ruby-lang.org/issues/19165 * Author: matsuda (Akira Matsuda) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.0dev (2022-12-01T08:05:41Z master 4e68b59431) +YJIT [arm64-darwin21] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- I found that method delegation via Forwardable is much slower than normal method call when delegating a method that does not take parameters. Here's a benchmark that explains what I mean. ``` require 'forwardable' require 'pp' require 'benchmark/ips' class Obj extend Forwardable attr_accessor :other def initialize @other = Other.new end def foo_without_splat @other.foo end def foo_with_splat(*) @other.foo(*) end def foo_with_splat_with_name(*args) @other.foo(*args) end def foo_with_splat_and_double_splat(*, **) @other.foo(*, **) end def foo_with_triple_dots(...) @other.foo(...) end delegate :foo => :@other end class Other def foo() end end o = Obj.new Benchmark.ips do |x| x.report 'simple call' do o.other.foo end x.report 'delegate without splat' do o.foo_without_splat end x.report 'delegate with splat' do o.foo_with_splat end x.report 'delegate with splat with name' do o.foo_with_splat_with_name end x.report 'delegate with splat and double splat' do o.foo_with_splat_and_double_splat end x.report 'delegate with triple dots' do o.foo_with_triple_dots end x.report 'delegate via forwardable' do o.foo end end (result) simple call 38.918M (± 0.9%) i/s - 194.884M delegate without splat 31.933M (± 1.6%) i/s - 159.611M delegate with splat 10.269M (± 1.6%) i/s - 51.631M delegate with splat with name 9.888M (± 1.0%) i/s - 49.588M delegate with splat and double splat 4.117M (± 0.9%) i/s - 20.696M delegate with triple dots 4.169M (± 0.9%) i/s - 20.857M delegate via forwardable 9.204M (± 2.1%) i/s - 46.295M ``` It shows that Method delegation with a splat is 3-4 times slower (regardless of whether the parameter is named or not), and delegation with a triple-dot literal is 9-10 times slower than a method delegation without an argument. This may be because calling a method taking a splat always assigns an Array object even when no actual argument was given, and calling a method taking triple-dots assigns five Array objects and two Hash objects (this is equivalent to `*, **`). Are there any chance reducing these object assignments and making them faster? My concern is that the Rails framework heavily uses this kind of method delegations, and presumably it causes unignorable performance overhead. -- https://bugs.ruby-lang.org/

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