example8.py

# ch6/example8.py

from math import sqrt
import multiprocessing

class Consumer(multiprocessing.Process):

    def __init__(self, task_queue, result_queue):
        multiprocessing.Process.__init__(self)
        self.task_queue = task_queue
        self.result_queue = result_queue

    def run(self):
        pname = self.name

        while True:
            temp_task = self.task_queue.get()

            if temp_task is None:
                print('Exiting %s...' % pname)
                self.task_queue.task_done()
                break

            print('%s processing task: %s' % (pname, temp_task))

            answer = temp_task.process()
            self.task_queue.task_done()
            self.result_queue.put(answer)

class Task():
    def __init__(self, x):
        self.x = x

    def process(self):
        if self.x < 2:
            return '%i is not a prime number.' % self.x

        if self.x == 2:
            return '%i is a prime number.' % self.x

        if self.x % 2 == 0:
            return '%i is not a prime number.' % self.x

        limit = int(sqrt(self.x)) + 1
        for i in range(3, limit, 2):
            if self.x % i == 0:
                return '%i is not a prime number.' % self.x

        return '%i is a prime number.' % self.x

    def __str__(self):
        return 'Checking if %i is a prime or not.' % self.x

if __name__ == '__main__':

    tasks = multiprocessing.JoinableQueue()
    results = multiprocessing.Queue()

    # spawning consumers with respect to the
    # number cores available in the system
    n_consumers = multiprocessing.cpu_count()
    print('Spawning %i consumers...' % n_consumers)
    consumers = [Consumer(tasks, results) for i in range(n_consumers)]
    for consumer in consumers:
        consumer.start()

    # enqueueing jobs
    my_input = [2, 36, 101, 193, 323, 513, 1327, 100000, 9999999, 433785907]
    for item in my_input:
        tasks.put(Task(item))

    for i in range(n_consumers):
        tasks.put(None)

    tasks.join()

    for i in range(len(my_input)):
        temp_result = results.get()
        print('Result:', temp_result)

    print('Done.')