[ruby-core:122740] [Ruby Bug#19154] Specify require and autoload guarantees in ractors

14 Jul 2025

      Issue #19154 has been updated by fxn (Xavier Noria).

Awesome John! Thanks very much!

----------------------------------------
Bug #19154: Specify require and autoload guarantees in ractors
https://bugs.ruby-lang.org/issues/19154#change-114021

* Author: fxn (Xavier Noria)
* Status: Closed
* Assignee: ractor
* 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.

-- 
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