Bug #20145: Memory leak when duplicating identhash

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

[peterzhu2118 (Peter Zhu)]

GitHub PR: https://github.com/ruby/ruby/pull/9411

Both copy_compare_by_id and hash_copy will create a copy of the ST table, so the ST table created in copy_compare_by_id will be leaked.

h = { 1 => 2 }.compare_by_identity

10.times do
  1_000_000.times do
    h.select { false }
  end

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

Before:

110736
204352
300272
395520
460704
476736
542000
604704
682624
770528

After:

15504
16048
16144
16256
16320
16320
16752
16752
16752
16752

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

[naruse (Yui NARUSE)]

• Backport changed from 3.0: UNKNOWN, 3.1: REQUIRED, 3.2: REQUIRED, 3.3: REQUIRED to 3.0: UNKNOWN, 3.1: REQUIRED, 3.2: REQUIRED, 3.3: DONE

ruby_3_3 aeffb5e21de6000a3dcfa0ca88c6ba3c3c42d8db merged revision(s) 6c252912af4981f016a9abdb4c1689307a4f1d2f.

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 3.0: UNKNOWN, 3.1: REQUIRED, 3.2: REQUIRED, 3.3: DONE to 3.1: WONTFIX, 3.2: WONTFIX, 3.3: DONE

My trial backpoting to ruby_3_2 introduce Segmentation fault. See https://github.com/nagachika/ruby/actions/runs/9824962371/job/27124518333
I gave up to backport this to ruby_3_2.