Ruby 3 upgrade throws kernel error for the overwritten each method

🐞 Bug Report

Steps to reproduce

We have an item that is the first hyperlink to the actual media and need to iterate through the sub nodes of it:

item.sub_nodes.map(&:name).to_s

And then we get an error saying

SystemStackError:
        stack level too deep

since upgrading the rails app to ruby 3 (and rails 6.1)

Expected behavior

We would expect to get a string back that contains the name of each item sub node.

Possible Solution

We don't exactly have a solution, but suppose the answer would be somewhere in the definition of the each block here:

hyperclient/lib/hyperclient/link.rb

Line 28 in 0e445dc

def each(&block)

Start by adding Ruby 3 to https://github.com/codegram/hyperclient/blob/master/.travis.yml, do we have a repro of this out of the box with existing specs? If not, try building a repro?

We fixed this in one spot now with adding embedded:
https://github.com/artsy/impulse/pull/805#discussion_r783322301

@kajatiger

We fixed this in one spot now with adding embedded: https://github.com/artsy/impulse/pull/805#discussion_r783322301

Looks like impulse is a private repo @kajatiger.

@kajatiger

I fixed CI/CD with GHA on this repo and added Ruby 3.2 without issues. Interested in taking this on @kajatiger?

@dblock

👋 I'm an AI assistant, commenting on behalf of @dblock.

We were able to reproduce this SystemStackError locally. The root cause is in Link#each (link.rb#L28):

def each(&block)
  if block_given?
    current = self
    while current
      coll = current.respond_to?(@key) ? current.send(@key) : _resource
      coll.each(&block)
      break unless current._links[:next]

      current = current._links.next
    end
  else
    to_enum(:each)
  end
end

If current.send(@key) (via method_missing/delegation) resolves to something that ultimately calls back into the same Link#each again — for example, when a link's key name (like sub_nodes) matches a link/embedded name on the resource it points to, forming a cycle — coll.each(&block) recurses forever, eventually blowing the stack with SystemStackError: stack level too deep instead of a clear error.

We confirmed this with a minimal repro: a resource whose sub_nodes link points to another resource that itself links sub_nodes back to the same URL, so calling .each (or anything that delegates through each, like .map) recurses infinitely.

Two possible fixes, would like the maintainers' input on preferred approach:

Cycle detection — track visited resources/URLs during the each/pagination walk and raise a clear Hyperclient::CircularLinkError (or similar) instead of silently blowing the stack.
Iteration cap — a simpler, more generic safety valve that raises after some large number of iterations, without needing to track visited state.

Happy to submit a PR for either approach — let us know which you'd prefer, or if there's a different angle you'd like us to take.

cc @kajatiger — if you have a more specific real-world repro, it'd help confirm we're fixing the right scenario.

No sorry, I have not looked into this problem in 3-4 years and am working in a different codebase now 🤪

Navigation Menu

Repository navigation

Ruby 3 upgrade throws kernel error for the overwritten each method #232

🐞 Bug Report

Steps to reproduce

Expected behavior

Possible Solution

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Ruby 3 upgrade throws kernel error for the overwritten each method #232

Description

🐞 Bug Report

Steps to reproduce

Expected behavior

Possible Solution

Activity

dblock commented on Jan 12, 2022

kajatiger commented on Jan 13, 2022

dblock commented on Jan 13, 2022

dblock commented on Feb 16, 2023

dblock commented on Aug 26, 2026

kajatiger commented on Aug 27, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions