From: "nagachika (Tomoyuki Chikanaga) via ruby-core" <ruby-core@...>
Date: 2023-07-17T02:32:15+00:00
Subject: [ruby-core:114203] [Ruby master Bug#19550] Memory leak in iclass for 32 bit systems

Issue #19550 has been updated by nagachika (Tomoyuki Chikanaga).

Backport changed from 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED to 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONE

ruby_3_2 9fb94407b97bb85ea344e67606f8ae9ba0bdbd48 merged revision(s) 417b1a36447cb2c650de55b433ba623541fb8bb3.

----------------------------------------
Bug #19550: Memory leak in iclass for 32 bit systems
https://bugs.ruby-lang.org/issues/19550#change-103890

* Author: peterzhu2118 (Peter Zhu)
* Status: Closed
* Priority: Normal
* Backport: 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: DONE
----------------------------------------
If !RCLASS_EXT_EMBEDDED (e.g. 32 bit systems) then the rb_classext_t is allocated throug malloc so it must be freed.

The issue can be seen in the following script:

```ruby
20.times do
  100_000.times do
    mod = Module.new
    Class.new do
      include mod
    end
  end

  # Output the Resident Set Size (memory usage, in KB) of the current Ruby process
  puts `ps -o rss= -p #{$$}`
end
```

Before this fix, the max RSS is 280MB, while after this change, it's 30MB.



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