Using Mutex to Give Work to Threads

threads_increase_balance_use_mutex.rb

user = User.find_by!(email: "[email protected]")

mutex = Thread::Mutex.new

threads = []
5.times do
  threads << Thread.new do
    CalculateUserBalanceJob.perform_now(user.id, mutex)
  end
end

threads.each(&:join)

user.reload

puts "user_balance: #{user.user_balance.balance}"