Issue #21394 has been reported by peterzhu2118 (Peter Zhu). ---------------------------------------- Bug #21394: Memory leak in Prism's RubyVM::InstructionSequence.new https://bugs.ruby-lang.org/issues/21394 * Author: peterzhu2118 (Peter Zhu) * Status: Open * Backport: 3.2: DONTNEED, 3.3: DONTNEED, 3.4: REQUIRED ---------------------------------------- Fix: https://github.com/ruby/ruby/pull/13496 There are two ways to make RubyVM::InstructionSequence.new raise which would cause the options->scopes to leak memory: 1. Passing in any (non T_FILE) object where the to_str raises. 2. Passing in a T_FILE object where String#initialize_dup raises. This is because rb_io_path dups the string. Example 1: ```ruby 10.times do 100_000.times do RubyVM::InstructionSequence.new(nil) rescue TypeError end puts `ps -o rss= -p #{$$}` end ``` Before: ``` 13392 17104 20256 23920 27264 30432 33584 36752 40032 43232 ``` After: ``` 9392 11072 11648 11648 11648 11712 11712 11712 11744 11744 ``` Example 2: ```ruby require "tempfile" MyError = Class.new(StandardError) String.prepend(Module.new do def initialize_dup(_) if $raise_on_dup raise MyError else super end end end) Tempfile.create do |f| 10.times do 100_000.times do $raise_on_dup = true RubyVM::InstructionSequence.new(f) rescue MyError else raise "MyError was not raised during RubyVM::InstructionSequence.new" end puts `ps -o rss= -p #{$$}` ensure $raise_on_dup = false end end ``` Before: ``` 14080 18512 22000 25184 28320 31600 34736 37904 41088 44256 ``` After: ``` 12016 12464 12880 12880 12880 12912 12912 12912 12912 12912 ``` -- https://bugs.ruby-lang.org/