Load Balanced Parallel Prime Number Generator with Sieve of Eratosthenes on Cluster Computers

Algorithms of finding prime numbers up to some integer N by Sieve of Eratosthenes are simple and fast. However, even with the time complexity no greater than O(N In In N), it may take weeks or even years of CPU time if N is large like over 15 decimal digits. No known shortcut was reported yet. We develop efficient parallel algorithms to balance the workload of each computer, and to extend memory limit with disk storage to accommodate Giga-bytes of data. Our experiments show that a complete set of up to 14-digit prime numbers can be found in a week of computing time (CPU time) using our 8 1.6 GHz Pentium-4 PCs with Linux and MPI library. Also, by sieve of Eratosthenes, we think it is very unlikely that we can compute all primes up to 20 digits even using the fastest computers in the world.