Bug #19460
Updated by luke-gru (Luke Gruber) about 1 year ago
I'm working on something where I need to remove a class and release all memory related to that class.
I've stumbled upon a limitation where in some instances I cannot get the class to be GC'd. The problem
(I think) is that inline method caches cache the class, and even if the class would otherwise be gone, it stays.
For example:
```ruby
class A
def do_something
end
end
a = A.send(:new)
a_id = A.object_id
a = nil
Object.send(:remove_const, :A)
# A should be able to be released now.
10.times { GC.start }
a_ref = ObjectSpace._id2ref(a_id) rescue nil
puts "a_ref: #{a_ref.class}"
# we get NilClass, it is released
``` ```ruby
However: using `A.new` above, it can't be GC'd.
If there is an initialize method (even empty) it can't be GC'd.
If there's a method call inside the class to another instance method on self ex: `self.do_something`, it can't be GC'd.
I'm not sure exactly what is going on but it looks like an inline cache marking issue. Maybe caches are getting marked, even inside methods where the method itself doesn't get marked.