[ruby-core:122749] [Ruby Bug#21383] Prism leaks memory with invalid yield

14 Jul 2025

      Issue #21383 has been updated by k0kubun (Takashi Kokubun).

Backport changed from 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED to 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONE

ruby_3_4 commit:cdb039d3e4f76ee01744814e5f08395835fa8e63 merged revision(s) commit:9f91f3617bab2ee220d298ddb874ef73b10dac23.

----------------------------------------
Bug #21383: Prism leaks memory with invalid yield
https://bugs.ruby-lang.org/issues/21383#change-114028

* Author: peterzhu2118 (Peter Zhu)
* Status: Closed
* Backport: 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONE
----------------------------------------
Fix: https://github.com/ruby/ruby/pull/13464

The following script leaks memory:

```ruby
10.times do
  20_000.times do
    eval("class C; yield; end")
  rescue SyntaxError
  end

  puts `ps -o rss= -p #{$$}`
end
```

Before:

```
16464
25536
29424
35904
39552
44576
46736
51600
56096
59824
```

After:

```
13488
16160
18240
20528
19760
21808
21680
22272
22064
22336
```

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