Ruby hash benchmarking

ruby_hashes.rb

#!/usr/bin/env ruby
require 'benchmark'

RUNS = 10_000
OUTER_KEYS = 10
INNER_STRUCTURES = 3
INNER_KEYS = 5

GC::Profiler.enable

def random_string(len=12)
  len.times.inject(''){|s,n| s << ((rand(2)==1?65:97) + rand(25)).chr}
end

def random_symbol(len=12)
  random_string(len).to_sym
end

def get_structure(type=:hash_with_symbols)
  case type.to_sym
    when :hash_with_indifferent_access then HashWithIndifferentAccess.new
    else {}
  end
end

def build_structure(type=:hash_with_symbols)
  type = type.to_sym
  structure = get_structure(type)
  # Randomly put some key/val pairs into the structure at the top level
  OUTER_KEYS.times do
    key = type == :hash_with_strings ? random_string : random_symbol
    structure[key] = random_string
  end
  # Randomly put some inner structures into the structure
  INNER_STRUCTURES.times do
    namespace = type == :hash_with_strings ? random_string : random_symbol
    structure[namespace] = get_structure(type)
    INNER_KEYS.times do
      key = type == :hash_with_strings ? random_string : random_symbol
      structure[namespace][key] = random_string
    end
  end
  structure
end

puts "Benchmark:\n\n"

gc_results = {}
elapsed = {}

Benchmark.bmbm do |x|
  x.report('Hash with symbols') do
    start_time = Time.now
    GC.start
    RUNS.times{build_structure(:hash_with_symbols)}
    gc_results[:hash_with_symbols] = GC::Profiler.result
    elapsed[:hash_with_symbols] = Time.now - start_time
  end
  x.report('Hash with strings') do
    start_time = Time.now
    GC.start
    RUNS.times{build_structure(:hash_with_strings)}
    gc_results[:hash_with_strings] = GC::Profiler.result
    elapsed[:hash_with_strings] = Time.now - start_time
  end
  x.report('Hash with indifferent access') do
    start_time = Time.now
    GC.start
    RUNS.times{build_structure(:hash_with_indiffent_access)}
    gc_results[:hash_with_indifferent_access] = GC::Profiler.result
    elapsed[:hash_with_indifferent_access] = Time.now - start_time
  end
end

puts "\n\nGC Stats:\n\n"

gc_results.each do |label,result|
  puts label.upcase
  lines = result.split("\n")
  puts lines[1]
  puts lines[-1]
  puts
end

puts "\n\nElapsed times:\n\n"
elapsed.each do |label,time|
  puts "#{label.upcase}: #{time} secs"
end

Very useful! Thanks.