1，生產者與消費者模型的矛盾在於數據供需的不平衡

import time
import random
from multiprocessing import Queue
from multiprocessing import Process
def producer(q,food):
    for i in range(5):
        q.put(‘%s-%s‘%(food,i))
        print(‘生產了%s‘%food)
        time.sleep(random.random())
    q.put(None)
    q.put(None)
    q.put(None)#有三個消費者因此需要三個信號

 
def consumer(q,name):
    while True:
        food = q.get()
        if food == None:break
        print(‘%s 吃了 %s‘%(name,food))

if __name__ == ‘__main__‘:
    q = Queue()
    p1 = Process(target=producer,args=(q,‘菠蘿蜜幹‘))
    p1.start()
    p2 = Process(target=producer, args=(q, ‘酸奶‘))
    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()

生產者消費者模型
    1.消費者要處理多少數據是不確定的
    2.所以只能用while循環來處理數據 ，但是while循環無法結束
    3.需要生產者發送信號
    4.有多少個消費者 就需要發送多少個信號
    5.但是發送的信號數量需要根據 生產者和消費者的數量進行計算，所以非常不方便
2，JoinableQueue

import time
import random
from multiprocessing import Process
from multiprocessing import JoinableQueue

def producer(q,food):
    for i in range(5):
        q.put(‘%s-%s‘%(food,i))
        print(‘生產了%s‘%food)
        time.sleep(random.random())
    q.join()  # 等待消費者把所有的數據都處理完

def consumer(q,name):
    while True:
        food = q.get()   # 生產者不生產還是生產的慢
        print(‘%s 吃了 %s‘%(name,food))
        q.task_done()#JoinableQueue內部自帶計數功能，每執行一次task_done，計數減一。

if __name__ == ‘__main__‘:
    q = JoinableQueue()
    p1 = Process(target=producer,args=(q,‘炒河粉‘))
    p1.start()
    p2 = Process(target=producer, args=(q, ‘草莓‘))
    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()  # 等待p1執行完畢
    p2.join()  # 等待p2執行完畢

生產者生產的數據全部被消費 —— 生產者進程結束 —— 主進程代碼執行結束 —— 消費者守護進程結束

python：生產者與消費者模型