[ruby-core:122546] [Ruby Bug#20452] Ruby 3.3 on Alpine Linux results in a relatively shallow SystemStackError exception

17 Jun 2025

      Issue #20452 has been updated by Earlopain (Earlopain _).

Halfway on the way to 3.5 now. I want to help out if I am able to, but right now I'm not sure what the holdup is.

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Bug #20452: Ruby 3.3 on Alpine Linux results in a relatively shallow SystemStackError exception
https://bugs.ruby-lang.org/issues/20452#change-113777

* Author: Earlopain (Earlopain _)
* Status: Open
* ruby -v: 3.3.1
* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
This is a redo of https://bugs.ruby-lang.org/issues/14387, reported against a non-eol version. The same issue still applies on recent rubies, though I personally only have tested 3.3 and 3.2:

```rb
n = 100000
res = {}
1.upto(n).to_a.inject(res) do |r, i|
  r[i] = {}
end

def f(x)
  x.each_value { |v| f(v) }
end

f(res)
```

The patch from https://bugs.ruby-lang.org/issues/14387#note-13 still works, though as per https://bugs.ruby-lang.org/issues/14387#note-16 it can't be accepted as is.

With the patch applied:
```
(irb):8:in `block in f': stack level too deep (SystemStackError)
        from (irb):8:in `each_value'
        from (irb):8:in `f'
        from (irb):8:in `block in f'
        from (irb):8:in `each_value'
        from (irb):8:in `f'
        from (irb):8:in `block in f'
        from (irb):8:in `each_value'
        from (irb):8:in `f'
         ... 11549 levels...
        from /usr/local/lib/ruby/gems/3.3.0/gems/irb-1.11.0/exe/irb:9:in `<top (required)>'
        from /usr/local/bin/irb:25:in `load'
        from /usr/local/bin/irb:25:in `<main>'
```

Without the patch:

```
(irb):8:in `each_value': stack level too deep (SystemStackError)
        from (irb):8:in `f'
        from (irb):8:in `block in f'
        from (irb):8:in `each_value'
        from (irb):8:in `f'
        from (irb):8:in `block in f'
        from (irb):8:in `each_value'
        from (irb):8:in `f'
        from (irb):8:in `block in f'
         ... 286 levels...
        from /usr/local/lib/ruby/gems/3.3.0/gems/irb-1.11.0/exe/irb:9:in `<top (required)>'
        from /usr/local/bin/irb:25:in `load'
        from /usr/local/bin/irb:25:in `<main>'
```

To reproduce, I have removed lines 102-105 from https://github.com/docker-library/ruby/blob/f5753434bb23041dd9913bb7b650e7be.... Check out the previous ticket for more information, there are a few conversations about possible solutions.

-- 
https://bugs.ruby-lang.org/