Python: producer and consumer model, python producer model

Python: producer and consumer model, python producer model

1. the contradiction between producer and consumer models lies in the imbalance of data supply and demand.

Import timeimport randomfrom multiprocessing import Queuefrom multiprocessing import Processdef producer (q, food): for I in range (5): q. put ('% s-% s' % (food, I) print (' produced % s' % food) time. sleep (random. random () q. put (None) q. put (None) q. put (None) # Three consumers need three signals def consumer (q, name): while True: food = q. get () if food = None: break print ('% s has eaten % s' % (name, food )) if _ name _ = '_ main _': q = Queue () p1 = Process (target = producer, args = (q, 'jackfruit dry ')) p1.start () p2 = Process (target = producer, args = (q, 'yogurt ') p2.start () c1 = Process (target = consumer, args = (q, 'rabbit ') c1.start () c2 = Process (target = consumer, args = (q, 'orangecat') c2.start () c3 = Process (target = consumer, args = (q, 'cuihua') c3.start ()

Producer and consumer model
1. The amount of data to be processed by the consumer is uncertain.
2. Therefore, only the while loop can be used to process data, but the while LOOP cannot end.
3. The producer needs to send signals.
4. How many consumers need to send signals
5. However, the number of signals sent must be calculated based on the number of producers and consumers, which is inconvenient.
2, JoinableQueue

Import timeimport randomfrom multiprocessing import Processfrom multiprocessing import JoinableQueuedef producer (q, food): for I in range (5): q. put ('% s-% s' % (food, I) print (' produced % s' % food) time. sleep (random. random () q. join () # Wait for the consumer to finish processing all the data def consumer (q, name): while True: food = q. get () # producer does not produce or produce slow print ('% s eat % s' % (name, food) q. task_done () # JoinableQueue provides the internal counting function. Each execution of task_done reduces the count by one.

If _ name _ = '_ main __':
Q = JoinableQueue ()
P1 = Process (target = producer, args = (q, 'fried river powder '))
P1.start ()
P2 = Process (target = producer, args = (q, 'strawberry '))
P2.start ()
C1 = Process (target = consumer, args = (q, 'rabbit '))
C1.daemon = True
C1.start ()
C2 = Process (target = consumer, args = (q, 'Orange _ cat '))
C2.daemon = True
C2.start ()
C3 = Process (target = consumer, args = (q, 'Teddy '))
C3.daemon = True
C3.start ()

P1.join () # Wait for p1 to complete execution
P2.join () # Wait For p2 to finish executing

All data produced by the producer is consumed-the producer process ends-The Master Process Code Execution ends-the consumer daemon process ends