Some concurrency samples in Ruby.

celluloid.rb

require "./lib/mailer"
require "benchmark"
require "celluloid"

class MailWorker
  include Celluloid

  def send_email(id)
    Mailer.deliver do 
      from    "eki_#{id}@eqbalq.com"
      to      "jill_#{id}@example.com"
      subject "Threading and Forking (#{id})"
      body    "Some content"
    end       
  end
end

mailer_pool = MailWorker.pool(size: 10)

10_000.times do |i|
  mailer_pool.async.send_email(i)
end

concurrency.rb

require 'benchmark'

class Mailer

  def self.deliver(&block)
    mail = MailBuilder.new(&block).mail
    mail.send_mail
  end

  Mail = Struct.new(:from, :to, :subject, :body) do 
    def send_mail
      fib(30)
      puts "Email from: #{from}"
      puts "Email to  : #{to}"
      puts "Subject   : #{subject}"
      puts "Body      : #{body}"
    end

    def fib(n)
      n < 2 ? n : fib(n-1) + fib(n-2)
    end  
  end

  class MailBuilder
    def initialize(&block)
      @mail = Mail.new
      instance_eval(&block)
    end

    attr_reader :mail

    %w(from to subject body).each do |m|
      define_method(m) do |val|
        @mail.send("#{m}=", val)
      end
    end
  end
end

# Sequential:
# puts Benchmark.measure {
#   100.times do |i|
#     Mailer.deliver do 
#       from    "[email protected]"
#       to      "[email protected]"
#       subject "Threading and Forking"
#       body    "Some content"
#     end
#   end
# } #=> It takes about 13s to get done.

# Multiprocesses:
# puts Benchmark.measure {
#   100.times do |i|
#     fork do
#       Mailer.deliver do 
#         from    "[email protected]"
#         to      "[email protected]"
#         subject "Threading and Forking"
#         body    "Some content"
#       end
#     end
#   end
#   Process.waitall
# } #=> It takes about 6s to get done.

# Multithreading:
threads = []
puts Benchmark.measure{
  100.times do |i|
    threads << Thread.new do
      Mailer.deliver do 
        from    "eki_#{i}@eqbalq.com"
        to      "jill_#{i}@example.com"
        subject "Threading and Forking (#{i})"
        body    "Some content"
      end
    end
  end
  threads.map(&:join)
} #=> It takes about 6s to get done.

concurrency_thread_pooling.rb

POOL_SIZE = 10

jobs = Queue.new

10_0000.times{|i| jobs.push i}

workers = (POOL_SIZE).times.map do
  Thread.new do
    begin      
      while x = jobs.pop(true)
        Mailer.deliver do 
          from    "eki_#{x}@eqbalq.com"
          to      "jill_#{x}@example.com"
          subject "Threading and Forking (#{x})"
          body    "Some content"
        end        
      end
    rescue ThreadError
    end
  end
end

workers.map(&:join)

sidekiq.rb

require_relative "../lib/mailer"
require "sidekiq"

class MailWorker
  include Sidekiq::Worker
  
  def perform(id)
    Mailer.deliver do 
      from    "eki_#{id}@eqbalq.com"
      to      "jill_#{id}@example.com"
      subject "Threading and Forking (#{id})"
      body    "Some content"
    end  
  end
end

# sidekiq  -r ./mail_worker.rb

# $ irb
# >> require_relative "mail_worker"
# => true
# >> 100.times{|i| MailWorker.perform_async(i)}
# 2014-12-20T02:42:30Z 46549 TID-ouh10w8gw INFO: Sidekiq client with redis options {}
# => 100