incorrect_usage_question_mark.rb

require 'concurrent'
require 'benchmark'

def process_sheets(sheets)
  all_dependencies = Concurrent::Array.new

  sheets.each_pair do |name, rows|
    rows.each do |val|
      all_dependencies.push(Concurrent::Future.execute {val*2})
    end
  end

  ftr = Concurrent::dataflow(*all_dependencies) {|*vals| vals.reduce(:+) }
  ftr.value
#   puts ftr.value
#   puts ftr.rejected?
#   puts ftr.reason
end

spread_1 = {
  "A" => Concurrent::Array.new(10){|i|i},
  "B" => Concurrent::Array.new(10){|i|i},
  "C" => Concurrent::Array.new(10){|i|i}
}
spread_2 = {
  "A" => Concurrent::Array.new(100){|i|i},
  "B" => Concurrent::Array.new(100){|i|i},
  "C" => Concurrent::Array.new(100){|i|i}
}
spread_3 = {
  "A" => Concurrent::Array.new(1000){|i|i},
  "B" => Concurrent::Array.new(1000){|i|i},
  "C" => Concurrent::Array.new(1000){|i|i}
}
spread_4 = {
  "A" => Concurrent::Array.new(10000){|i|i},
  "B" => Concurrent::Array.new(10000){|i|i},
  "C" => Concurrent::Array.new(10000){|i|i}
}

Benchmark.bm do |x|
  x.report { process_sheets(spread_1) }
  x.report { process_sheets(spread_2) }
  x.report { process_sheets(spread_3) }
  x.report { process_sheets(spread_4) }
end

# ruby 2.3
#       user     system      total        real
#  0.010000   0.010000   0.020000 (  0.023191)
#  0.080000   0.020000   0.100000 (  0.103426)
#  0.630000   0.210000   0.840000 (  0.791183)
#  5.280000   2.170000   7.450000 (  6.713608)

# jruby 9.1.5.0 (2.3.1) 2016-09-07 036ce39 Java HotSpot(TM) 64-Bit Server VM 25.71-b15 on 1.8.0_71-b15 +jit [darwin-x86_64]
#       user     system      total        real
#  0.360000   0.010000   0.370000 (  0.425416)
#  0.790000   0.030000   0.820000 (  0.617765)
#  2.560000   0.050000   2.610000 (  1.574381)
#  9.540000   0.240000   9.780000 (  5.557661)