counter/counter.py (26e8fa3) - testpython.git

counter.py

#!/usr/bin/env python3
# From https://pybay.com/site_media/slides/raymond2017-keynote/threading.html
import threading, queue

_counter = 0

counter_queue = queue.Queue()

def counter_manager():
    'I have EXCLUSIVE rights to update the _counter variable'
    global _counter

while True:
        increment = counter_queue.get()
        _counter += increment
        print_queue.put([
            'The count is %d' % _counter,
            '---------------'])
        counter_queue.task_done()

print_queue = queue.Queue()

def print_manager():
    'I have EXCLUSIVE rights to call the "print" keyword'
    while True:
        job = print_queue.get()
        for line in job:
            print(line)
        print_queue.task_done()

def worker():
    'My job is to increment the counter and print the current count'
    counter_queue.put(1)

def run():
    # Set up the counter manager
    t = threading.Thread(target=counter_manager)
    t.daemon = True
    t.start()
    del t

# Set up the print manager
    t = threading.Thread(target=print_manager)
    t.daemon = True
    t.start()
    del t

# Start doing work
    print_queue.put(['Starting up'])
    worker_threads = []
    for i in range(10):
        t = threading.Thread(target=worker)
        worker_threads.append(t)
        t.start()
    for t in worker_threads:
        t.join()

counter_queue.join()
    print_queue.put(['Finishing up'])
    print_queue.join()

if __name__ == '__main__':
    run()

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