Issue #19894 has been reported by peterzhu2118 (Peter Zhu). ---------------------------------------- Bug #19894: Memory leak in complemented method entries https://bugs.ruby-lang.org/issues/19894 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Priority: Normal * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: REQUIRED ---------------------------------------- GitHub pull request: https://github.com/ruby/ruby/pull/8481 When a copy of a complemented method entry is created, there are two issues: 1. IMEMO_FL_USER3 is not copied, so the complemented status is not copied over. 2. In rb_method_entry_clone we increment both alias_count and complemented_count. However, when we free the method entry in rb_method_definition_release, we only decrement one of the two counters, resulting in the rb_method_definition_t being leaked. The following script reproduces this issue: ```ruby 10.times do 20_000.times do $c = Class.new do def foo; end end $m = Module.new do refine $c do def foo; end end end Class.new do using $m def initialize o = $c.new o.method(:foo).unbind end end.new end puts `ps -o rss= -p #{$$}` end ``` Before this fix: ``` 17328 19248 21408 23296 25600 27408 29424 31520 33728 35664 ``` After this fix: ``` 16240 17680 18800 19744 20640 21840 22896 24336 25280 26096 ``` -- https://bugs.ruby-lang.org/