038信号量

Posted 2020-10-26 Alos

步骤：1、新建信号量对象，设置信号量数量
2、线程执行方法中，如果能够获取信号量，则执行，信号量为0不可以获取

 1 import  threading,time
 2 
 3 class  MyThread(threading.Thread):
 4     def  run(self):
 5         if  sema.acquire():
 6             print(self.name)
 7             time.sleep(0.3)
 8             sema.release()
 9 
10 if __name__ == ‘__main__‘:
11     sema = threading.BoundedSemaphore(5)  # sema=threading.Semaphore(5)
12     thrs = []
13     for i in range(100):
14         thrs.append(MyThread())
15     for t in thrs:
16         t.start()

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例子：

### 强行改的信号量

 1 import threading
 2 import time
 3 class Tickets:
 4     def __init__(self):
 5     self.ticket = 100
 6 
 7     def sell_ticket(self):
 8         while self.ticket > 0:
 9             if loc.acquire():
10                 print(‘卖出‘,self.ticket,‘票‘,threading.current_thread())
11                 self.ticket -= 1
12                 loc.release()
13             time.sleep(0.0001)
14 
15 if __name__ == ‘__main__‘:
16     ticket = Tickets()
17     t1 = threading.Thread(target=ticket.sell_ticket)
18     t2 = threading.Thread(target=ticket.sell_ticket)
19     t3 = threading.Thread(target=ticket.sell_ticket)
20     loc = threading.Semaphore(1)
21     t1.start()
22     t2.start()
23     t3.start()

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##########38里面多生产多消费信号量实现

 1 import time
 2 import threading
 3 
 4 class Res:
 5     def __init__(self):
 6         self.flag = False
 7         self.count = 0
 8         self.product = ‘‘
 9 
10     def set(self,name):
11         lock_con.acquire()
12         while self.flag:
13             lock_con.wait()
14         time.sleep(0.00001)
15         self.count += 1
16         self.product = ‘‘.join([name,‘**‘,str(self.count)])
17         self.message = ‘‘.join([self.product,‘__生产者__‘,str(threading.current_thread())])
18         print(self.message)
19         self.flag = True
20         lock_con.notifyAll()
21         lock_con.release()
22 
23     def get_product(self):
24         lock_con.acquire()
25         time.sleep(0.00001)
26         while not self.flag:
27             lock_con.wait()
28         self.message = ‘‘.join([self.product,‘__消费者__‘,str(threading.current_thread())])
29         print(self.message)
30         self.flag = False
31         lock_con.notifyAll()
32         lock_con.release()
33 
34 class Producer(threading.Thread):
35     def __init__(self,r):
36         threading.Thread.__init__(self)
37         self.r = r
38 
39     def run(self):
40         for i in range(100):
41             self.r.set(‘大白兔奶糖‘)
42 
43 class Consumer(threading.Thread):
44     def __init__(self,r):
45         threading.Thread.__init__(self)
46         self.r = r
47 
48     def run(self):
49         for i in range(100):
50             self.r.get_product()
51 
52 if __name__ == ‘__main__‘:
53     lock_con = threading.Condition()
54     r = Res()
55     l = []
56     for i in range(5):
57         l.append(Consumer(r))
58     for i in range(5):
59         l.append(Producer(r))
60     for a in l:
61         a.start()

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