From: "peterzhu2118 (Peter Zhu) via ruby-core" <ruby-core@...>
Date: 2024-07-25T19:34:13+00:00
Subject: [ruby-core:118686] [Ruby master Bug#20653] Memory leak in String#start_with? when regexp times out

Issue #20653 has been reported by peterzhu2118 (Peter Zhu).

----------------------------------------
Bug #20653: Memory leak in String#start_with? when regexp times out
https://bugs.ruby-lang.org/issues/20653

* Author: peterzhu2118 (Peter Zhu)
* Status: Open
* Backport: 3.1: UNKNOWN, 3.2: WONTFIX, 3.3: REQUIRED
----------------------------------------
GitHub PR: https://github.com/ruby/ruby/pull/11247

This commit refactors how Onigmo handles timeout. Instead of raising a timeout error, onig_search will return a ONIGERR_TIMEOUT which the caller can free memory, and then raise a timeout error.

This fixes a memory leak in String#start_with when the regexp times out. For example:

```ruby
regex = Regexp.new("^#{"(a*)" * 10_000}x$", timeout: 0.000001)
str = "a" * 1000000 + "x"

10.times do
  100.times do
    str.start_with?(regex)
  rescue
  end

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

Before:

```
33216
51936
71152
81728
97152
103248
120384
133392
133520
133616
```

After:

```
14912
15376
15824
15824
16128
16128
16144
16144
16160
16160
```



-- 
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