A look at how ObjectSpace finalizers affect GC time

results.txt

$ ruby test.rb false
  0.210000   0.000000   0.210000 (  0.212155)
$ ruby test.rb true
 10.000000   0.280000  10.280000 ( 10.773232)

test.rb

require 'benchmark'

n = 10_000_000
finalizer = proc { } if ARGV[0] == 'true'

GC.disable
n.times {
  o = Object.new
  ObjectSpace.define_finalizer(o, finalizer) if finalizer
}

puts Benchmark.measure {
  GC.enable
  GC.start
}