Ruby Array memory

require "memory_profiler"
mem = MemoryProfiler.report do
  array = [*1..1_000_000]
end

mem2 = MemoryProfiler.report do
  array = [*1..1_000_000]
  b = array.select {|x| x % 3 == 0}
end

mem3 = MemoryProfiler.report do
  array = [*1..1_000_000]
  b = []
  1.upto(1_000_000) {|i| b << i if i % 3 == 0 }
end

puts mem.allocated_memory_by_class.first
puts mem2.allocated_memory_by_class.first
puts mem3.allocated_memory_by_class.first

#{:data=>"Array", :count=>19636352}
#{:data=>"Array", :count=>27636392}
#{:data=>"Array", :count=>23084168}