Python之路——并行编程之multiprocessing模块

Posted 2020-10-23 liuyankui163

Process

 1 import socket
 2 import time
 3 from multiprocessing import Process
 4 
 5 def talk(conn):
 6     if type(conn)==socket.socket():
 7         conn.send(b‘connected‘)
 8         msg = conn.recv(1024)
 9         print(msg)
10         conn.close()
11 
12 
13 if __name__ == ‘__main__‘:
14     sk = socket.socket()
15     sk.bind((‘127.0.0.1‘,8080))
16     sk.listen()
17     while True:
18         conn,addr = sk.accept()
19         print(addr,time.ctime())
20         p = Process(target=talk,args=(conn,))
21         p.start()
22 
23     sk.close()

Lock

 1 # from multiprocessing import Lock
 2 # lock = Lock()
 3 # lock.acquire()  # 需要锁，拿钥匙
 4 # lock.acquire()  # 需要锁，阻塞
 5 # lock.release()  # 释放锁，还钥匙
 6 
 7 # 锁 就是在并发编程中，保证数据安全
 8 
 9 # 多进程 实现并发
10 
11 import json
12 import time
13 import random
14 from multiprocessing import Lock
15 from multiprocessing import Process
16 
17 # with open(‘ticket‘,‘w‘) as f:
18 #     json.dump({‘count‘:20},f)
19 
20 
21 def search(i):
22     with open(‘ticket‘) as f:
23         print(i,json.load(f)[‘count‘])
24 def get(i):
25     with open(‘ticket‘) as f:
26         ticket_num = json.load(f)[‘count‘]
27     time.sleep(random.random())
28     if ticket_num>0:
29         with open(‘ticket‘,‘w‘) as f:
30             json.dump({‘count‘:ticket_num-1},f)
31         print(‘%s买到票了‘%i)
32     else:
33         print(‘%s没票了‘%i)
34 def task(i,lock):
35     search(i)
36     lock.acquire()
37     get(i)
38     lock.release()
39 if __name__ == ‘__main__‘:
40     pass
41 
42     lock = Lock()
43     for i in range(20):
44         p = Process(target=task,args=(i,lock))
45         p.start()

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Semaphore

 1 # from multiprocessing import Semaphore
 2 # sem = Semaphore(4)
 3 # sem.acquire()
 4 # print(0)
 5 # sem.acquire()
 6 # print(1)
 7 # sem.acquire()
 8 # print(2)
 9 # sem.acquire()
10 # print(3)
11 # sem.release()
12 # sem.acquire()
13 # print(4)
14 
15 import time
16 import random
17 from multiprocessing import Semaphore
18 from multiprocessing import Process
19 
20 def sing(i,sem):
21     sem.acquire()
22     print(‘%s : 进入ktv‘%i)
23     time.sleep(random.randint(1,3))
24     print(‘%s ：出ktv‘%i)
25     sem.release()
26 
27 if __name__ == ‘__main__‘:
28     sem = Semaphore(4)
29     for i in range(20):
30         Process(target=sing,args=(i,sem)).start()

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守护进程

 1 # start 开启一个进程
 2 # join 用join可以让主进程等待子进程结束
 3 
 4 # 守护进程
 5 # 守护进程会随着主进程的代码执行结束而结束
 6 # 正常的子进程没有执行完的时候主进程要一直等着
 7 
 8 # import time
 9 # from multiprocessing import Process
10 # def func():
11 #     print(‘--‘*10)
12 #     time.sleep(15)
13 #     print(‘--‘*10)
14 #
15 # def cal_time():
16 #     while True:
17 #         time.sleep(1)
18 #         print(‘过去了1秒‘)
19 #
20 # if __name__ == ‘__main__‘:
21 #     p = Process(target=cal_time)
22 #     p.daemon = True
23 #     p.start()
24 #     p2 = Process(target=func)
25 #     p2.start()
26 #     for i in range(100):
27 #         time.sleep(0.1)
28 #         print(‘*‘*i)
29 #     p2.join()
30 # 守护进程的作用：
31 #   会随着主进程的代码执行结束而结束，不会等待其他子进程
32 # 守护进程 要再start之前设置
33 # 守护进程中，不能再开启子进程
34 
35 
36 # is_alive  # 进程是否还活着，True代表进程还在， False代表进程不在了
37 # terminate #结束一个进程，但是这个进程不会立刻被杀死
38 
39 # import time
40 # from multiprocessing import Process
41 # def func():
42 #     print(‘wahaha‘)
43 #     time.sleep(5)
44 #     print(‘qqxing‘)
45 # if __name__ == ‘__main__‘:
46 #     p = Process(target=func)
47 #     p.start()
48 #     print(p.is_alive())
49 #     time.sleep(0.1)
50 #     p.terminate()
51 #     print(p.is_alive())
52 #     time.sleep(1)
53 #     print(p.is_alive())
54 
55 # 进程的其他属性
56 # pid 查看这个进程的进程id
57 # name 查看进程的名字,可以修改
58 # import time
59 # from multiprocessing import Process
60 # def func():
61 #     print(‘wahaha‘)
62 #     time.sleep(5)
63 #     print(‘qqxing‘)
64 # if __name__ == ‘__main__‘:
65 #     p = Process(target=func)
66 #     p.start()
67 #     print(p.name,p.pid)
68 #     p.name = ‘WAHAHAHA‘
69 #     print(p.name)

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Event

 1 import time
 2 import random
 3 from multiprocessing import Process
 4 from multiprocessing import Event
 5 
 6 # e = Event() # 实例化一个事件  标志/交通信号灯
 7 # e.set()     # 将标志变成非阻塞/交通灯变绿
 8 # e.wait()    # 刚实例化出来的一个事件对象，默认的信号是阻塞信号/默认是红灯
 9 #             # 执行到wait，要先看灯，绿灯行红灯停，如果在停的过程中灯绿了，
10 #             # 就变成非阻塞了
11 # e.clear()   # 将标志又变成阻塞/交通灯变红
12 #
13 # e.is_set() # 是否阻塞 True就是绿灯 False就是红灯
14 
15 def traffic_light(e):
16     while True:
17         if e.is_set():  # 是否阻塞，True就是绿灯，False就是红灯
18             e.clear()
19             print(‘红灯亮‘)
20             time.sleep(3)
21         else:
22             e.set()
23             print(‘绿灯亮‘)
24             time.sleep(3)
25 
26 def car(name,e):
27     e.wait()
28     print(‘%s 通过‘%name)
29 
30 if __name__ == ‘__main__‘:
31     e = Event()
32     Process(target=traffic_light,args=(e,)).start()
33     for i in range(50):
34         if i%random.randint(1,5)==0:
35             time.sleep(random.randint(1,3))
36         p = Process(target=car,args=(i,e))
37         p.start()

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