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annotate threaDemo.py @ 26:5488b5d3ba10

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author Henry Thompson <ht@markup.co.uk>
date Mon, 31 May 2021 15:01:38 +0100
parents e07789816ca5
children
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1 #!/usr/bin/python3
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2 import threading
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3 from queue import Queue
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4 import time
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6 # lock to serialize console output
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7 lock = threading.Lock()
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9 def do_work(item):
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10 time.sleep(.1) # pretend to do some lengthy work.
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11 # Make sure the whole print completes or threads can mix up output in one line.
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12 with lock:
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13 print(threading.current_thread().name,item)
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15 # The worker thread pulls an item from the queue and processes it
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16 def worker():
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17 while True:
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18 item = q.get()
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19 do_work(item)
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20 q.task_done()
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22 # Create the queue and thread pool.
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23 q = Queue()
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24 for i in range(4):
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25 t = threading.Thread(target=worker)
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26 t.daemon = True # thread dies when main thread (only non-daemon thread) exits.
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27 t.start()
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29 # stuff work items on the queue (in this case, just a number).
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30 start = time.perf_counter()
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31 for item in range(20):
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32 q.put(item)
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34 q.join() # block until all tasks are done
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36 # "Work" took .1 seconds per task.
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37 # 20 tasks serially would be 2 seconds.
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38 # With 4 threads should be about .5 seconds (contrived because non-CPU intensive "work")
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39 print('time:',time.perf_counter() - start)