Testing concurrent threading in the Rubinius hydra branch

Prime number generator

# Lucas–Lehmer primality test
# Retrieved from http://rosettacode.org/wiki/Lucas-Lehmer_test
def is_prime?(p)  
  if p == 2
    return true
  elsif p <= 1 || p % 2 == 0
    return false
  else
    (3 .. Math.sqrt(p)).step(2) do |i|
      if p % i == 0
        return false
      end
    end
    return true
  end
end

def generate_primes(low, high)
  puts "Generating primes between #{low} and #{high}"
  
  primes = (low..high).to_a

  primes.size.times do |i|
    unless is_prime?(primes[i])
      primes[i] = nil
    end
  end

  primes.compact
end

t1 = Thread.new { primes1 = generate_primes(0, 10000) }
t2 = Thread.new { primes2 = generate_primes(10001, 20000) }

t1.join
t2.join

puts "All done!"

# exit