Issue #19550 has been reported by peterzhu2118 (Peter Zhu). ---------------------------------------- Bug #19550: Memory leak in iclass for 32 bit systems https://bugs.ruby-lang.org/issues/19550 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Priority: Normal * Backport: 2.7: DONTNEED, 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED ---------------------------------------- If !RCLASS_EXT_EMBEDDED (e.g. 32 bit systems) then the rb_classext_t is allocated throug malloc so it must be freed. The issue can be seen in the following script: ```ruby 20.times do 100_000.times do mod = Module.new Class.new do include mod end end # Output the Resident Set Size (memory usage, in KB) of the current Ruby process puts `ps -o rss= -p #{$$}` end ``` Before this fix, the max RSS is 280MB, while after this change, it's 30MB. -- https://bugs.ruby-lang.org/