playin-with-the-ruby-gc

gist-1.rb

# './gc_test.rb'

@m = 1000000
@b = 2 * 5 * (4**3) + 1
@a = 100001

def make_fragmentation(h, seed)
  i = seed
  10000.times {|m| h << Object.new}
  10000.times do |m|
    i = ((@a * i) + @b) % @m
    h[i % h.length] = nil
 end
end

def run_test
  GC::Profiler.enable
  heaps = []
  100.times{|i| make_fragmentation(heaps, i) }
  GC::Profiler.result
end

puts run_test

gist-2.rb

require 'bigdecimal'
require 'pp'

output = Hash.new([])
@totals = {}

path = './gc_test.rb'

100.times do |test_run|
 result_set = `ruby #{path}` # this is where we get the result from the previous script
 result_set.split("\n").each_with_index do |result, index|
   next if [0,1].include?(index)
   result = result.split(" ")
   output[result[0]] += [result[5]]
 end
end

# This is where we take the cumulative values of the previous 100 results sets by GC cycle
# and grab the average.  Big decimal because we want to be precise and the numbers are already
# strings.

output.each do |k,v|
  length = BigDecimal.new(v.length.to_s)
  nv = v.map! {|i| BigDecimal.new(i)}
  @totals[k] = (nv.inject(:+) / length).to_s("F")
end
puts @totals.map{|k,v| v + "\n"}