class C attr_accessor :foo end long_lived = C.new if RUBY_VERSION >= "2.2.0" 3.times{ GC.start(full_mark: false, immediate_mark: true, immediate_sweep: true) } elsif GC.start end i = 0 short_lived = '' while i<30_000_000 # while loop 1 long_lived.foo = short_lived # write barrier i+=1 end