进程间的通信

弋兮灬夜丶

from multiprocessing import Process,Queue

def plus():
    global g_num
    g_num += 50
    q.put(g_num)
    print(g_num)

def minus():
    global g_num
    g_num=q.get(True,2)
    g_num -= 50
    print(g_num)

if __name__ == '__main__':
    g_num = 100
    q = Queue()
    process = [Process(target=eval(i)) for i in 'plus minus'.split()]
    for i in process:
        i.start()
    for i in process:
        i.join()


E:\Users\Administrator\PycharmProjects\Python\venv\Scripts\python.exe F:/新建文件夹/未命名.py
Process Process-1:
Traceback (most recent call last):
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\process.py", line 297, in _bootstrap
    self.run()
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "F:\新建文件夹\未命名.py", line 5, in plus
    g_num += 50
NameError: name 'g_num' is not defined
Process Process-2:
Traceback (most recent call last):
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\process.py", line 297, in _bootstrap
    self.run()
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\process.py", line 99, in run
    self._target(*self._args, **self._kwargs)
  File "F:\新建文件夹\未命名.py", line 11, in minus
    g_num=q.get(True,2)
NameError: name 'q' is not defined

Process finished with exit code 0


一直报错说 q 没定义
可 q=Queue()
不是定义了么

求大神解惑

zltzlt

我运行没有报错？试下这样：

1. from multiprocessing import Process,Queue
   
2. 
   
3. if __name__ == '__main__':
   
4.     def plus():
   
5.         global g_num
   
6.         g_num += 50
   
7.         q.put(g_num)
   
8.         print(g_num)
   
9. 
   
10.     def minus():
    
11.         global g_num
    
12.         g_num=q.get(True,2)
    
13.         g_num -= 50
    
14.         print(g_num)
    
15.     g_num = 100
    
16.     q = Queue()
    
17.     process = [Process(target=eval(i)) for i in 'plus minus'.split()]
    
18.     for i in process:
    
19.         i.start()
    
20.     for i in process:
    
21.         i.join()

复制代码

塔利班

多进程通信，一般是要把队列给args传入的

弋兮灬夜丶

zltzlt 发表于 2019-10-24 20:01
我运行没有报错？试下这样：

感谢大佬
用了您给的代码
可还是报错了
我用cmd pycharm 都试了
都这样 报相同的错误
不会是我的Python出问题了吧

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\spawn.py", line 105, in spawn_
main
    exitcode = _main(fd)
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\spawn.py", line 115, in _main
    self = reduction.pickle.load(from_parent)
AttributeError: Can't get attribute 'plus' on <module '__mp_main__' from 'F:\\新建文件夹\\未命名.py'>
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\spawn.py", line 105, in spawn_
main
    exitcode = _main(fd)
  File "E:\Users\Administrator\AppData\Local\Programs\Python\Python37\lib\multiprocessing\spawn.py", line 115, in _main
    self = reduction.pickle.load(from_parent)
AttributeError: Can't get attribute 'minus' on <module '__mp_main__' from 'F:\\新建文件夹\\未命名.py'>