我想在类中实例中使用全局变量队列,我创建的队列mybuffer作为全局变量,然后Producer和Consume两个类的实例中使用这个全局变量,实际在windows的cmd中的的执行情况是class Producer中的的queue.put()一直在执行,但是class Consumer中的get()确一直没有得到队列中的元素,感觉这个mybuffer到两个类中变成了局部变量。
如果我把mybuffer队列做为成员变量分别传到两个类的实例中是可以正常的put()和get()
不知道全局变量的队列在类里面却不能用了。。。。。。
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from multiprocessing import Process, Semaphore, Lock, Queue
import time
mybuffer = Queue(10)
class Consumer(Process):
def __init__(self,lock):
Process.__init__(self)
self.lock = lock
def run(self):
global mybuffer
while True:
mybuffer.get()
self.lock.acquire()
print('Consumer pop an element')
self.lock.release()
time.sleep(1)
class Producer(Process):
def __init__(self,lock):
Process.__init__(self)
self.lock = lock
def run(self):
global mybuffer
while True:
mybuffer.put('1')
self.lock.acquire()
print('Producer append an element')
self.lock.release()
time.sleep(1)
if __name__ == '__main__':
#mybuffer = Queue(10)
lock = Lock()
p = Producer(lock)
c = Consumer(lock)
c.start()
p.start()
p.join()
c.join()
print 'Ended!'
The above code is correct when I execute it under macOS.
Is it because of windows?
I remember that windows does not support fork, windows simulates fork. What's even weirder is that when window creates a new process, it will import the file that created it (see another answer https://segmentfault.com/q/10... for details). And you create a queue at the beginning of the file. When both Productor and Consumer imported in, they each created a variable called mybuffer?
That should be the reason.
Under Windows, I printed the ID (mybuffer) in Customer and Product respectively, and they are different.
I don’t know what’s right or wrong, I hope it helps.