前景回顾
抢票系统的代码优化，使用了Lock类
from multiprocessing import Process,Lock
import os,time,json
with open('user', 'w', encoding='utf-8')as f:
dic={'count':2}
json.dump(dic,f)
def search():
with open('user','r',encoding='utf-8')as f:
data=json.load(f)
print(data.get('count'))
def get():
with open('user','r',encoding='utf-8')as f:
data = json.load(f)
if data['count'] > 0:
data['count'] -= 1
with open('user','w',encoding='utf-8')as f:
json.dump(data,f)
print('success')
time.sleep(1)
else:
print('票已售空')
def piao(lock):
search()
lock.acquire()
get()
lock.release()
if __name__ == '__main__':
lock=Lock()
for i in range(5):
p=Process(target=piao,args=(lock,))
p.start()
队列
1
from multiprocessing import Queue,Process
q=Queue()
q.put(1)
print(q)
data=q.get()
print(data)
data=q.get()
print(data) #默认会一直等待拿值
q.put(5)
2
from multiprocessing import Queue,Process
q=Queue(4)
q.put(1)
q.put(5)
q.put(5)
q.put(5)
q.put(5) #此处队列满了，就会成阻塞状态
q.get()
q.get()
3
from multiprocessing import Queue,Process
q=Queue(4)
q.put(1)
q.put(5)
q.put(5)
q.put(5)
q.put(5,block=True,timeout=3) #此处队列满了，就会成阻塞状态,block为等待状态，timeout为等待时间，等不到就报错
q.get()
q.get()
4
from multiprocessing import Queue,Process
q=Queue(4)
q.put(1)
q.get()
q.get(block=True,timeout=3) #队列已被取空，此时再取就会阻塞，block为阻塞状态，timeout为阻塞时间
5
from multiprocessing import Queue,Process
q=Queue(1)
q.put(1)
q.put_nowait(5) #队列已满，此时再存就会阻塞，相当于put的默认block为False
生产者消费者模型
版本一
from multiprocessing import Queue,Process
import time
def produce(q,name,msg):
for i in range(3):
q.put(msg+str(i))
print(f'{name}生产了{msg+str(i)}')
time.sleep(1)
q.put(None) #用None来终止消费者
def cost(q,name):
while True:
msg=q.get()
if msg==None:
break
print(f'{name}吃了{msg}')
time.sleep(1)
if __name__ == '__main__':
q=Queue()
p1=Process(target=produce,args=(q,'wind','card'))
p2=Process(target=produce,args=(q,'nick','niunai'))
# p1=Process(target=Process,args=(q,'wind','card'))
c1=Process(target=cost,args=(q,'chanyuli'))
c2=Process(target=cost,args=(q,'zhongshifu'))
p1.start()
p2.start()
c1.start()
c2.start()
版本二
from multiprocessing import Queue,Process,JoinableQueue
import time
def produce(q,name,msg):
for i in range(3):
q.put(msg+str(i))
print(f'{name}生产了{msg+str(i)}')
time.sleep(1)
def cost(q,name):
while True:
msg=q.get()
q.task_done()
if msg==None:
break
print(f'{name}吃了{msg}')
time.sleep(1)
if __name__ == '__main__':
q=JoinableQueue()
p1=Process(target=produce,args=(q,'wind','card'))
p2=Process(target=produce,args=(q,'nick','niunai'))
# p1=Process(target=Process,args=(q,'wind','card'))
c1=Process(target=cost,args=(q,'chanyuli'))
c2=Process(target=cost,args=(q,'zhongshifu'))
c1.daemon=True
c2.daemon=True
p1.start()
p2.start()
c1.start()
c2.start()
p1.join()
p2.join()
q.join()