Bug #19381: SEGV - ivars, both Ubuntu & Windows

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.3.0dev (2023-01-26T07:31:08Z master 6422fef90c) [x86_64-linux]
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[MSP-Greg (Greg L)]

I've used code similar to the below for a long time. When max is set to 50, it runs. When max is set to 51, it SEGV faults.

Rubies tested:
ruby 3.3.0dev (2023-01-26T07:31:08Z master 6422fef90c) [x86_64-linux]
ruby 3.3.0dev (2023-01-26T07:31:08Z master 6422fef90c) [x64-mingw-ucrt]
ruby 3.3.0dev (2023-01-26T07:31:08Z master 6422fef90c) [x64-mswin64_140]

I suspect it involves the changes in https://github.com/ruby/ruby/pull/7183 'Limit maximum number of IVs on a shape'

module Test
  class << self
    def run
      max = 51
      (1..max).each do |v|
        instance_variable_set("@iv#{v}".to_sym, nil)
      end
    end
  end
end
Test.run
puts Test.instance_variables

[luke-gru (Luke Gruber)]

Recently there was a change to object shapes, and there were no tests made for that commit. I think they'll add some now :)
The change is here, made on Jan. 25: https://github.com/ruby/ruby/commit/78fcc9847a9db6d42c8c263154ec05903a370b6b

It looks like objects other than T_OBJECTs are being set to TOO_COMPLEX shape.

EDIT: oh sorry I didn't see you added the PR in your ticket MSP-Greg.

[MSP-Greg (Greg L)]

Thanks. That's the commit for the PR I listed (#7183). I should have listed it...

[tenderlovemaking (Aaron Patterson)]

Thanks. I'm going to revert the commit for now. 🙇🏻‍♀️

[Eregon (Benoit Daloze)]

• Related to Bug #19334: Defining many instance variables and accessing them is slow in Ruby 3.2.0 added

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

Fixed by 28da9909849dc02abe74de8170fe4036534361ba