Bug #18065: 3.0.2 - possible memory leak in Hash#transform_keys!

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.0.2p107 (2021-07-07 revision 0db68f0233) [x86_64-linux]
• Backport: 2.6: DONTNEED, 2.7: DONTNEED, 3.0: DONE

[[e-mail] (Sean Dilda)]

I found what may be a memory leak in Hash#transform_keys! in version 3.0.2

This sample code will reproduce the issue. It quickly consumes gigabytes of memory when running on 3.0.2, but has very normal memory usage on 3.0.1. I tested using the ruby:3.0.2 docker image.

h = { value1: 1, value2: 2 }
loop { h.transform_keys!(&:to_s) }

The issue doesn't appear if there is only one key in the hash.

[jeremyevans0 (Jeremy Evans)]

• Backport changed from 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN to 2.6: DONTNEED, 2.7: DONTNEED, 3.0: REQUIRED

It looks likely related to 84d9a9afc0b49d095541acb9832f8b12fb506e19.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset git|e5dd40b1f3a11f48d566413ab347ce0cfdd94960.

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Stop force-recycling evacuated array [Bug #18065]

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.6: DONTNEED, 2.7: DONTNEED, 3.0: REQUIRED to 2.6: DONTNEED, 2.7: DONTNEED, 3.0: DONE

ruby_3_0 d6b8b37a2608a0fbb8bcfd10356bb25f9ebbe1fe merged revision(s) e5dd40b1f3a11f48d566413ab347ce0cfdd94960.