Workers with Concurrent::Future in Ruby

concurrent_workers_demo.rb

require 'concurrent'
require 'benchmark'

max = 20  # number of tasks to process
n_workers = 4  # number of concurrent workers
results = []  # 
lambda = -> (iter, i) { results << ('%04d' % i); d = rand(0.005)+0.001; puts("Iteration #{iter}. sleep %.3f" % d); sleep(d) }
workers = Array.new(n_workers, lambda)
iter = 0

(max / n_workers).times do |v|
  iter += 1
  t = Benchmark.realtime do
    workers.map do |executor|
      Concurrent::Future.execute { executor.call(iter, v) }
    end.map(&:value)
  end
  puts "Elapsed %.3f" % t
end
p results

output.log

Iteration 1. sleep 0.328
Iteration 1. sleep 0.883
Iteration 1. sleep 0.553
Iteration 1. sleep 0.017
Elapsed 0.884
Iteration 2. sleep 0.556
Iteration 2. sleep 0.262
Iteration 2. sleep 0.092
Iteration 2. sleep 0.326
Elapsed 0.557
Iteration 3. sleep 0.768Iteration 3. sleep 0.611
Iteration 3. sleep 0.149
Iteration 3. sleep 0.036

Elapsed 0.769
Iteration 4. sleep 0.299
Iteration 4. sleep 0.194
Iteration 4. sleep 0.465
Iteration 4. sleep 0.821
Elapsed 0.823
Iteration 5. sleep 0.308
Iteration 5. sleep 0.636
Iteration 5. sleep 0.694Iteration 5. sleep 0.554

Elapsed 0.696
["0000", "0000", "0000", "0000", "0001", "0001", "0001", "0001", "0002", "0002", "0002", "0002", "0003", "0003", "0003", "0003", "0004", "0004", "0004", "0004"]