Question

I programmed a GUI application who use the Unit testing framework.
The application shows all found unit tests in a tree-view.
If you click on a unit-test name, the program will run this test and show the result.
It works!

But now I want that every test case running in a new process.
I created a “Working Thread” (with the module threading) but this thread is also running in the same process.

The module “multiprocessing” is the solution but I got problems with my implementation.
I put my “test execute code” in a own function and tried:

item = self.GetSelection()
name = self.GetItemText(item)
p = multiprocessing.Process(target=ExecuteTest, args=(name, item))
p.daemon = True
p.start()

But then I got errors.

Traceback (most recent call last):
  File "C:\a\b\c\hhh\a.py", line 577, in OnLeftDClick
    p.start()
  File "C:\Python26\lib\multiprocessing\process.py", line 104, in start
    self._popen = Popen(self)
  File "C:\Python26\lib\multiprocessing\forking.py", line 239, in __init__
    dump(process_obj, to_child, HIGHEST_PROTOCOL)
  File "C:\Python26\lib\multiprocessing\forking.py", line 162, in dump
    ForkingPickler(file, protocol).dump(obj)
  File "C:\Python26\lib\pickle.py", line 224, in dump
    self.save(obj)
  File "C:\Python26\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python26\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Python26\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python26\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Python26\lib\pickle.py", line 681, in _batch_setitems
    save(v)
  File "C:\Python26\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python26\lib\pickle.py", line 548, in save_tuple
    save(element)
  File "C:\Python26\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python26\lib\pickle.py", line 419, in save_reduce
    save(state)
  File "C:\Python26\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python26\lib\pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "C:\Python26\lib\pickle.py", line 686, in _batch_setitems
    save(v)
  File "C:\Python26\lib\pickle.py", line 331, in save
    self.save_reduce(obj=obj, *rv)
  File "C:\Python26\lib\pickle.py", line 396, in save_reduce
    save(cls)
  File "C:\Python26\lib\pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "C:\Python26\lib\pickle.py", line 748, in save_global
    (obj, module, name))
pickle.PicklingError: Can't pickle <type 'PySwigObject'>: it's not found as __builtin__.PySwigObject

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Python26\lib\multiprocessing\forking.py", line 342, in main
    self = load(from_parent)
  File "C:\Python26\lib\pickle.py", line 1370, in load
    return Unpickler(file).load()
  File "C:\Python26\lib\pickle.py", line 858, in load
    dispatch[key](self)
  File "C:\Python26\lib\pickle.py", line 880, in load_eof
    raise EOFError
EOFError

Does anybody have any idea?

Answer 1

Obviously, you’re trying to “pickle” something that is not pickable (seems to be a wx object). Try to use as parameter only “simple” objects (ie without graphical object inside), and it should be working better.
You could also take a look to the python nose unitest library which allows you to run tests in multiprocesses automatically.