python使用threading.condition实现生产者消费者

旧城等待， 2022-06-15 08:43 90阅读 0赞

threading模块  
threading.Condition() ，返回condition对象，相当于高级锁对象，可以使一个或多个线程等待直到被其他线程调度或通知

condition条件对象提供如下方法：  
1.threading.Condition()  
2.acquire(\*args) 获取锁  
3.release()释放锁  
4.wait(\[timeout\]) 等待  
5.notify(n=1) / notifyAll() 唤醒

生产者与消费者问题  
ps：queue也可实现生产者消费者，[<<详情参考>>][Link 1]

#生产者
    # Consume one item
    cv.acquire()
    while not an_item_is_available():
        cv.wait()
    get_an_available_item()
    cv.release()

#消费者
    # Produce one item
    cv.acquire()
    make_an_item_available()
    cv.notify()
    cv.release()

示例：  
描述：  
一件产品。投放到市场上，市场需求可以看作一个箱子box，有一个容量限度  
当小于box大小，生产者可以生产，否则等待消费者消费，生产者有生产效率，使用speed表示  
当产品大于0，才可进行消费，否则就等待生产者生产

# encoding=utf8
    import threading
    import time
    from decimal import Decimal
    
    condition = threading.Condition()
    num = 0
    box_size=15
    
    class GoodsProduce(threading.Thread):
        def __init__(self,companyName,produceSpeed,info):
            super(GoodsProduce,self).__init__()
            self.companyName=companyName
            self.produceSpeed=Decimal(2/produceSpeed).quantize(Decimal('0.00'))
            self.info=info
    
        def run(self):
            global num
            while True:
                if condition.acquire():
                    if num < box_size:
                        time.sleep(self.produceSpeed)
                        num += 1;
                        print "GoodsProduce : %s create one , now box have :%d" %(self.companyName, num)
                        condition.notify()
                        condition.release()
                    else:
                        print "NOTE: BOX is full , size %d ,filled %d" %(box_size, num)
                        condition.wait();
    
        def show(self):
            print "companyName -- %s ,produceSpeed -- %s, infomation -- %s"%(self.companyName,self.produceSpeed,self.info)
    
    class GoodsConsume(threading.Thread):
        def __init__(self,cname,area,info):
            super(GoodsConsume,self).__init__()
            self.cname=cname
            self.area=area
            self.info=info
    
        def run(self):
            global num
            while True:
                if condition.acquire():
                    if num >= 1:
                        num -= 1
                        print "GoodsConsumer %s get one , now box have :%d" %(self.cname,num)
                        condition.notify()
                        condition.release()
                    else:
                        print "NOTE: BOX is null ,please wait ... size %d ,fillin %d" % (box_size, num)
                        time.sleep(1)
                        condition.wait();
                    time.sleep(1)
        def show(self):
            print "GoodsConsume %s area -- %s ,infomation -- %s"%(self.cname,self.area,self.info)
    
    
    if __name__ == "__main__":
        for server_num in range(0, 2):
            server = GoodsProduce("Prd-%d"%server_num,server_num+1,"this is %d prd company"%server_num)
            server.start()
            server.show()
    
        for customer_num in range(0, 5):
            customer = GoodsConsume("cus-%d"%customer_num,"area-%d"%customer_num,"this is %d customer"%customer_num)
            customer.start()
            customer.show()

结果：

companyName -- Prd-0 ,produceSpeed -- 2.00, infomation -- this is 0 prd company
    companyName -- Prd-1 ,produceSpeed -- 1.00, infomation -- this is 1 prd company
    GoodsConsume cus-0 area -- area-0 ,infomation -- this is 0 customer
    GoodsConsume cus-1 area -- area-1 ,infomation -- this is 1 customer
    GoodsConsume cus-2 area -- area-2 ,infomation -- this is 2 customer
    GoodsConsume cus-3 area -- area-3 ,infomation -- this is 3 customer
    GoodsConsume cus-4 area -- area-4 ,infomation -- this is 4 customer
    GoodsProduce : Prd-0 create one , now box have :1
    GoodsProduce : Prd-0 create one , now box have :2
    GoodsProduce : Prd-0 create one , now box have :15
    NOTE: BOX is full , size 15 ,filled 15
    GoodsConsumer cus-1 get one , now box have :14
    GoodsConsumer cus-2 get one , now box have :13
    GoodsConsumer cus-3 get one , now box have :12
    GoodsConsumer cus-4 get one , now box have :11
    GoodsProduce : Prd-1 create one , now box have :12
    GoodsProduce : Prd-1 create one , now box have :13
    GoodsProduce : Prd-1 create one , now box have :14
    GoodsProduce : Prd-1 create one , now box have :15
    NOTE: BOX is full , size 15 ,filled 15
    GoodsConsumer cus-2 get one , now box have :14
    GoodsConsumer cus-4 get one , now box have :13
    GoodsConsumer cus-0 get one , now box have :12
    GoodsProduce : Prd-0 create one , now box have :13
    GoodsProduce : Prd-0 create one , now box have :14
    GoodsProduce : Prd-0 create one , now box have :15
    NOTE: BOX is full , size 15 ,filled 15
    GoodsConsumer cus-1 get one , now box have :14
    GoodsConsumer cus-3 get one , now box have :13
    GoodsProduce : Prd-1 create one , now box have :14
    GoodsProduce : Prd-1 create one , now box have :15
    NOTE: BOX is full , size 15 ,filled 15

[Link 1]: http://blog.csdn.net/comprel/article/details/72811436