It's true in practice but not in theory. Ruby can't defragment memory pages - if there is an active object in any heap page, it cannot be released back to the

It's true in practice but not in theory. Ruby can't defragment memory pages - if there is an active object in any heap page, it cannot be released back to the OS. Technically, Ruby does release empty pages back to the OS, but in practice, heap pages are rarely completely empty.