Python 3 priority queues – source code examples

In the post FIFO and LIFO queues in python I shown how to use queues in python 3.
Python provides also priority queues.

You can use such a queue when the processing order of the items in a queue needs to be based on the importance of the items.
In a priority queue, the most important element will always be popped first, so in a priority queue you have to push a tuple of at least two elements: the priority and the content. The element with the lowest value for the priority will be popped.

The following program populates a priority queue with random priority values and some text.

if __name__ == '__main__':
    # python2 Queue.Queue() and Queue.LifoQueue()
    PRIO_QUEUE = queue.PriorityQueue()
    print('Populating the priority queue')
    for counter in range(10):
        time.sleep(0.4)
        prio = randint(0, 9)
        strn = "data - "+ str(prio) + " " + str(time.asctime())
        PRIO_QUEUE.put((prio, strn))
        print((prio, strn))

then it pops data from the priority queue and prints out the popped items

print('Getting data from the priority queue')
print('=========================')
for counter in range(10):
prio, strn = PRIO_QUEUE.get()
print((prio, strn))

You can find the full source code with the latest updates on my github: prio_queue.py

When you run the prio_queue.py program it will ouput something like the following

python prio_queue.py
Populating the priority queue
(8, 'data - 8 Fri Dec 15 06:51:31 2017')
(1, 'data - 1 Fri Dec 15 06:51:31 2017')
(4, 'data - 4 Fri Dec 15 06:51:32 2017')
(2, 'data - 2 Fri Dec 15 06:51:32 2017')
(6, 'data - 6 Fri Dec 15 06:51:32 2017')
(4, 'data - 4 Fri Dec 15 06:51:33 2017')
(6, 'data - 6 Fri Dec 15 06:51:33 2017')
(2, 'data - 2 Fri Dec 15 06:51:34 2017')
(4, 'data - 4 Fri Dec 15 06:51:34 2017')
(5, 'data - 5 Fri Dec 15 06:51:34 2017')

as you can see, it pushes data with random priority. And, then:

Getting data from the priority queue
=========================
(1, 'data - 1 Fri Dec 15 06:51:31 2017')
(2, 'data - 2 Fri Dec 15 06:51:32 2017')
(2, 'data - 2 Fri Dec 15 06:51:34 2017')
(4, 'data - 4 Fri Dec 15 06:51:32 2017')
(4, 'data - 4 Fri Dec 15 06:51:33 2017')
(4, 'data - 4 Fri Dec 15 06:51:34 2017')
(5, 'data - 5 Fri Dec 15 06:51:34 2017')
(6, 'data - 6 Fri Dec 15 06:51:32 2017')
(6, 'data - 6 Fri Dec 15 06:51:33 2017')
(8, 'data - 8 Fri Dec 15 06:51:31 2017')

it pops data starting with lowest priorities.

Gg1