Python-并行进程调用主进程函数

Question

我在多处理方面遇到了一些麻烦。这是我的程序的基本方案:

• 主要流程
• 从主进程调用的并行进程

• 并行进程尝试从主进程调用函数

  class MainProcess():
      def foo(self):
          # do something
  
      def main():
          p = ParallelProcess(self)
          p.start()
  
  
  class ParallelProcess(multiprocessing.Process):
      def __init__(self, mainProcess):
          multiprocessing.Process.__init__(self)
          self.mainProcess = mainProcess
  
      def run(self):
          self.mainProcess.foo()
  

我的实际程序要复杂得多，但这个例子完美地解释了我的代码的结构。我得到的错误与泡菜有关。据我了解，我收到此类错误是因为 mainProcess 不可选择。但是，除了上面显示的模式或代码结构之外，我不知道要使用哪种其他模式或代码结构。任何帮助将不胜感激。

按照要求，确切的错误是:

    Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Program Files\PsychoPy2\lib\multiprocessing\forking.py", line 342, in main
    self = load(from_parent)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 1370, in load
    return Unpickler(file).load()
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 858, in load
    dispatch[key](self)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 880, in load_eof
    raise EOFError
EOFError
Traceback (most recent call last):
  File "C:\Users\user\workspace\Eyelink1.1\gcwindow_main.py", line 17, in <module>
    main()
  File "C:\Users\user\workspace\Eyelink1.1\gcwindow_main.py", line 9, in main
    wrapper.run() # start collecting data on a separate process
  File "C:\Users\user\workspace\Eyelink1.1\pylinkwrapper.py", line 149, in run
    exp.start()
  File "C:\Program Files\PsychoPy2\lib\multiprocessing\process.py", line 104, in start
    self._popen = Popen(self)
  File "C:\Program Files\PsychoPy2\lib\multiprocessing\forking.py", line 239, in __init__
    dump(process_obj, to_child, HIGHEST_PROTOCOL)
  File "C:\Program Files\PsychoPy2\lib\multiprocessing\forking.py", line 162, in dump
    ForkingPickler(file, protocol).dump(obj)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 224, in dump
    self.save(obj)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 725, in save_inst
    save(stuff)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Program Files\PsychoPy2\lib\pickle.py", line 306, in save
    rv = reduce(self.proto)
ValueError: ctypes objects containing pointers cannot be pickled

Answer 1

要在您的类中使用 pickle，您需要定义 __getstate__、__setstate__ 行为。 More information in docs 。

但是(!)据我了解，这并不能解决您的实际问题。因为在这种情况下，您将在 ParallelProcess 内获得 MainProcess 的新(反序列化)实例，并且无法在父进程的上下文中调用函数。