Ruby frozen string interning

console

$ ruby not_frozen.rb                
400600

# The string "a" is embedded inside the String object which is 40 bytes
#
# So 400600/40 = ~10,015 string objects
#
# (IIRC, up to 24 bytes of string may be embedded in the String)

$ ruby frozen.rb 
1280

# Strings may be created elsewhere so it is hard to be exact
#
# Still, this is much less than 400KB of String objects

frozen.rb

# frozen_string_literal: true

require "objspace"

GC.start

before = ObjectSpace.count_objects_size

array = Array.new(10_000) { "a" }

after = ObjectSpace.count_objects_size

p after[:T_STRING] - before[:T_STRING]

not_frozen.rb

# frozen_string_literal: false

require "objspace"

GC.start

before = ObjectSpace.count_objects_size

array = Array.new(10_000) { "a" }

after = ObjectSpace.count_objects_size

p after[:T_STRING] - before[:T_STRING]