Question

我有4个共享变量。我正根据正在运行的进程更新一对。以下是代码。

class App(multiprocessing.Process):
    def __init__ (self,process_id):
        multiprocessing.Process.__init__(self)
        self.process_id = process_id
   def run(self,X,Y,lock):
        while True: 
               with lock :
               #some calculations which returns x and y 
               print 'x and y returned are :',x,y
                 try:
                    X.value = x
                    Y.value = y
                 except Exception ,e:
                   print e



if __name__ == '__main__':
    xL = Value('d',0.0)
    xR = Value('d',0.0)
    yL = Value('d',0.0)
    yR = Value('d',0.0)

    lock = Lock()

    a = A('1')
    b = B('2')

    process_a = Process(target = a.run, args(xL,yL,lock, ))  
    process_b = Process(target = b.run, args(xR,yR,lock, ))

    process_a.start()
    process_b.start()

这是输出：

返回的x和y是：375 402

'float'对象没有属性'value'

任何帮助。？

Answer 1

看一下代码的三个部分，我在括号中用数字注释：

   def run(self,X,Y,lock):
        while True:
               #some calculations which returns x and y 
               with lock :
                 X.value = x
                 Y.value = y

                 # (3) you now try to access an attribute of the arguments
                 # called 'value'
                 print X.value , Y.value , self.process_id


if __name__ == '__main__':
    xL = Value('d',0.0) # (1) these variables are assigned some objects that
    xR = Value('d',0.0) # are returned by the function 'Value'
    yL = Value('d',0.0) 
    yR = Value('d',0.0) 

    lock = Lock()

    a = A('1')
    b = B('2')

    # (2) now your variables are being passed to the 'a.run' and 'b.run'
    # methods
    process_a = Process(target = a.run, args(xL,yL,lock, ))  
    process_b = Process(target = b.run, args(xR,yR,lock, ))

    process_a.start()
    process_b.start()

当您跟踪代码的执行时，您可以看到它正在尝试访问函数value返回的任何对象中名为Value的属性。您的错误消息告诉您Value正在返回float个对象，这些对象没有value属性。

以下情况之一（很可能）对您不利：

函数Value没有按照你的想法行事，并且当它不应该返回浮动时。
在你的＆＃34;一些返回x和y＆＃34;代码，你用浮点数覆盖X和Y参数。

python float对象没有属性n＃39; value＆＃39;

1 个答案: