Bug #20650: Memory leak in Regexp capture group when timeout

• Status: Closed
• Assignee: -
• Target version: -
• Backport: 3.1: UNKNOWN, 3.2: WONTFIX, 3.3: REQUIRED

[peterzhu2118 (Peter Zhu)]

GitHub PR: https://github.com/ruby/ruby/pull/11238

The capture group allocates memory that is leaked when it times out.

For example:

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

10.times do
  100.times do
    re =~ str
  rescue Regexp::TimeoutError
  end

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

Before:

34688
56416
78288
100368
120784
140704
161904
183568
204320
224800

After:

16288
16288
16880
16896
16912
16928
16944
17184
17184
17200

[peterzhu2118 (Peter Zhu)]

• Status changed from Open to Closed

Applied in changeset git|10574857ce167869524b97ee862b610928f6272f.

---

Fix memory leak in Regexp capture group when timeout

[Bug #20650]

The capture group allocates memory that is leaked when it times out.

For example:

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

10.times do
  100.times do
    re =~ str
  rescue Regexp::TimeoutError
  end

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

Before:

34688
56416
78288
100368
120784
140704
161904
183568
204320
224800

After:

16288
16288
16880
16896
16912
16928
16944
17184
17184
17200

[peterzhu2118 (Peter Zhu)]

• Backport changed from 3.1: UNKNOWN, 3.2: REQUIRED, 3.3: REQUIRED to 3.1: UNKNOWN, 3.2: WONTFIX, 3.3: REQUIRED

I opened a Ruby 3.3 backport here: https://github.com/ruby/ruby/pull/11244