Ruby 2.1.7 vs 2.2.3 garbage collection

Question

I see some weird potentially ruby ​​problems related to 2.2.3 gc, with creating prefix attempts from a list of words. Suspect code here:

def insert(word) return if word.nil? || word.empty? node = self counter = 0 l = word.length #TODO _ why is this not being garbage collected? word.bytes.each do |i| counter += 1 node.children[i] ||= Node.new(i.chr, node, counter == l) node = node.children[i] node.terminal = true if counter == l end end 

It is called from a list of strings - as such

 words.each_with_index do |word, i| @root.insert(word) 

When I do some memory profiling, I see the general use of mem in ruby ​​2.2.3-railsexpress as ~ 68MB:

 Measure Mode: memory Thread ID: 70102347546980 Fiber ID: 70102348363420 Total: 68688.375000 Sort by: self_time %self total self wait child calls name 20.03 13755.000 13755.000 0.000 0.000 293398 FastAutocomplete::Node#initialize 9.05 6218.875 6218.875 0.000 0.000 86036 String#bytes 6.26 66665.562 4298.438 0.000 62367.125 86040 *Array#each 1.50 1028.969 1028.969 0.000 0.000 230540 Hash#keys 0.98 677.219 676.438 0.000 0.781 1 Array#map 

When I used 2.1.7, I only see about 22 MB of use:

  Measure Mode: memory Thread ID: 70216772377340 Fiber ID: 70216782765400 Total: 22009.125000 Sort by: self_time %self total self wait child calls name 62.49 13754.391 13754.391 0.000 0.000 293398 FastAutocomplete::Node#initialize 28.25 6218.641 6218.641 0.000 0.000 86036 String#bytes 4.67 1028.078 1028.078 0.000 0.000 230540 Hash#keys 3.07 676.797 676.203 0.000 0.594 1 Array#map 1.27 280.203 280.203 0.000 0.000 116093 Thread::Queue#enq 0.07 19.297 15.516 0.000 3.781 9 JSON::Ext::Generator::GeneratorMethods::Hash#to_json 

I tried several things, such as tracking GC.stats throughout the creation process, but didn't notice anything. I also tried using string.each_char or string.split ('') each (i.e. different iterators).

Any ideas as to why 2.2.3 uses 3x memory? This leads to the explosion of some of our servers.