Parallel Prime Palindrome Finder

from multiprocessing import Pool, cpu_count
import math
import time

def sieve_of_eratosthenes(limit):
    prime_flags = [True] * (limit + 1)
    prime_flags[0] = prime_flags[1] = False
    for base in range(2, int(math.sqrt(limit)) + 1):
        if prime_flags[base]:
            for multiple in range(base * base, limit + 1, base):
                prime_flags[multiple] = False
    return prime_flags

def generate_palindrome_prime(start, end, prime_flags):
    special_primes = []
    for i in range(start, end):
        str_i = str(i)
        palindrome = int(str_i + str_i[-2::-1])
        if palindrome > end:
            break
        if prime_flags[palindrome]:
            special_primes.append(palindrome)
    return special_primes

def parallel_processing(range_start, range_end):
    num_processes = cpu_count()
    pool = Pool(processes=num_processes)
    chunk_size = (range_end - range_start) // num_processes
    prime_flags = sieve_of_eratosthenes(range_end)
    tasks = [(range_start + i * chunk_size, min(range_start + (i + 1) * chunk_size, range_end), prime_flags) for i in range(num_processes)]
    results = pool.starmap(generate_palindrome_prime, tasks)
    pool.close()
    pool.join()
    return [prime for sublist in results for prime in sublist]

if __name__ == '__main__':
    range_start = 110000
    range_end = 150000

    start_time = time.time()
    special_primes = parallel_processing(range_start, range_end)
    end_time = time.time()

    print("Special numbers:", special_primes[:3], "...", special_primes[-3:])
    print("Total amount of special numbers:", len(special_primes))
    print("Time passed:", end_time - start_time, "seconds")