AttributeError: Can't pickle local object 'checkpoint.begin_background.<locals>.bg_target'

[DirtyLI]

HI
I will ask you a new question.
When i tried to use this code to test my own images, one error happened:
matplotlib.use('Agg')
Making model...
Download the model

Evaluation:
Traceback (most recent call last):

File "", line 1, in
runfile('F:/代码/EDSR-PyTorch-master/src/main.py', args='--data_test Demo --scale 4 --pre_train download --test_only --save_results', wdir='F:/代码/EDSR-PyTorch-master/src')

File "F:\anaconda\conda\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 668, in runfile
execfile(filename, namespace)

File "F:\anaconda\conda\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 108, in execfile
exec(compile(f.read(), filename, 'exec'), namespace)

File "F:/代码/EDSR-PyTorch-master/src/main.py", line 24, in
while not t.terminate():

File "F:\代码\EDSR-PyTorch-master\src\trainer.py", line 139, in terminate
self.test()

File "F:\代码\EDSR-PyTorch-master\src\trainer.py", line 83, in test
if self.args.save_results: self.ckp.begin_background()

File "F:\代码\EDSR-PyTorch-master\src\utility.py", line 141, in begin_background
for p in self.process: p.start()

File "F:\anaconda\conda\lib\multiprocessing\process.py", line 112, in start
self._popen = self._Popen(self)

File "F:\anaconda\conda\lib\multiprocessing\context.py", line 223, in _Popen
return _default_context.get_context().Process._Popen(process_obj)

File "F:\anaconda\conda\lib\multiprocessing\context.py", line 322, in _Popen
return Popen(process_obj)

File "F:\anaconda\conda\lib\multiprocessing\popen_spawn_win32.py", line 65, in init
reduction.dump(process_obj, to_child)

File "F:\anaconda\conda\lib\multiprocessing\reduction.py", line 60, in dump
ForkingPickler(file, protocol).dump(obj)

AttributeError: Can't pickle local object 'checkpoint.begin_background..bg_target'

[sanghyun-son]

Hi.

It seems there are some conflicts between multiprocessing and your system. Remove this and these lines to disable multiprocessing.

Thank you

[Drakael]

Hello,
I had the same error and worked it around by taking out the bg_target method inside begin_background() and making it a static method of the checkpoint class (in src/utility.py around line 130)

Code sample :

@staticmethod
def bg_target(queue):
    while True:
        if not queue.empty():
            filename, tensor = queue.get()
            if filename is None: break
            imageio.imwrite(filename, tensor.numpy())

def begin_background(self):
    self.queue = Queue()
    
    self.process = [
        Process(target=self.bg_target, args=(self.queue,)) \
        for _ in range(self.n_processes)
    ]
    
    for p in self.process: p.start()