FixedThreadPool / Concurrent::Future usage example (concurrent-ruby gem)

fixed_thread_pool_example.rb

# For more: https://github.com/ruby-concurrency/concurrent-ruby
num_threads = Concurrent.processor_count # or whatever you prefer like 4
thread_pool = Concurrent::FixedThreadPool.new(num_threads)

products = Product.all

executors = products.map { |product|
  Concurrent::Future.execute({executor: thread_pool}) do
    p "processing #{product.id}"
  end
}

executors.map(&:value!)