CODEWITHSUNDEEP
pythonpython-2.7wxpythonmultiprocessingwxwidgets
Deepa
Deepa

Reputation: 872

python: start a Multiprocessing process on wxbutton click

I have a wxpython app running, and I was wondering if I could start another instance of the app as a result of a button click when the previous ones continue to run?

something like : Start a wxpython app -> click on a button -> and the event spawns another process (a multiprocessing process) that starts another instance of this same app while the first one keeps on running?

I just wanted to know whether it is feasible because when I start a simple process inside a button click event handling, like 

def start_new_button(self,event):
    import multiprocessing
    worker2 = multiprocessing.Process(name = 'worker2', target = self.new)
    worker2.start()
def new():
    pass

it throws error

Traceback (most recent call last):
  File "main.py", line 470, in start_new_button
    worker2.start()
  File "C:\Python27\lib\multiprocessing\process.py", line 130, in start
    self._popen = Popen(self)
  File "C:\Python27\lib\multiprocessing\forking.py", line 277, in __init__
    dump(process_obj, to_child, HIGHEST_PROTOCOL)
  File "C:\Python27\lib\multiprocessing\forking.py", line 199, in dump
    ForkingPickler(file, protocol).dump(obj)
  File "C:\Python27\lib\pickle.py", line 224, in dump
    self.save(obj)
  File "C:\Python27\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python27\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Python27\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python27\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Python27\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Python27\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python27\lib\multiprocessing\forking.py", line 67, in dispatcher
    self.save_reduce(obj=obj, *rv)
  File "C:\Python27\lib\pickle.py", line 401, in save_reduce
    save(args)
  File "C:\Python27\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python27\lib\pickle.py", line 548, in save_tuple
    save(element)
  File "C:\Python27\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python27\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Python27\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python27\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Python27\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Python27\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python27\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Python27\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python27\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Python27\lib\pickle.py", line 686, in _batch_setitems
    save(v)
  File "C:\Python27\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python27\lib\pickle.py", line 396, in save_reduce
    save(cls)
  File "C:\Python27\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python27\lib\pickle.py", line 748, in save_global
    (obj, module, name))
pickle.PicklingError: Can't pickle <type 'PySwigObject'>: it's not found as __bu
iltin__.PySwigObject
C:\Python27\lib\site-packages\mpltools\style\__init__.py:42: FutureWarning:

    The style-sheet functionality in mpltools has been integrated into
    Matplotlib >= 1.4. This module will be removed in a future release.

    Note that style-sheets used by `matplotlib.style` use the standard
    Matplotlib rc-file syntax instead of the INI format used by `mpltools`.
    This mostly means un-quoting strings and changing '=' to ':'.


  """, FutureWarning)
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Python27\lib\multiprocessing\forking.py", line 381, in main
    self = load(from_parent)
  File "C:\Python27\lib\pickle.py", line 1378, in load
    return Unpickler(file).load()
  File "C:\Python27\lib\pickle.py", line 858, in load
    dispatch[key](self)
  File "C:\Python27\lib\pickle.py", line 880, in load_eof
    raise EOFError
EOFError

Am I going on the right path?

Iam using python 2.7 with wx 3.0.2.0 on windows 7

Upvotes: 0

Views: 629

Answers (1)

alsuna
alsuna

Reputation: 73

Python multiprocessing uses the pickle module to pass the information to the new process. The pickle documentation describes, what can be pickled and unpickled. With self.new you are trying to pass an instance method which cannot be pickled.

Try passing a non-instance method to multiprocessing.Process():

class YourButtonClass:
    def start_new_button(self,event):
        import multiprocessing
        worker2 = multiprocessing.Process(name = 'worker2', target = new)
        worker2.start()

def new():
    pass

Upvotes: 2

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