Pytorch中Dataloader踩坑:RuntimeError: DataLoader worker (pid(s) 6700, 10620) exited unexpectedly问题及解决

import torch
import torch.utils.data as Data

print(torch.__version__)
BATACH_SIZE = 5

x = torch.linspace(1,10,10)         # [1,  2, 3, 4, 5, 6, 7, 8, 9, 10]
y = torch.linspace(10,1,10)         # [10 ,9, 8, 7, 6, 5, 4, 3, 2, 1 ]
torch_dataset = Data.TensorDataset(x, y)
loader = Data.DataLoader(
    dataset = torch_dataset,
    batch_size=BATACH_SIZE,
    shuffle=True,
    num_workers=2,
)

# if __name__ == '__main__':
for epoch in range(3):
    for step, (batch_x, batch_y) in enumerate(loader):
        print('Epoch:', epoch, '|Step', step, '|batch x:', batch_x.numpy(), '|batch_y:', batch_y.numpy())

RuntimeError: 
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.
Traceback (most recent call last):
  File "C:\Softwares\Proware\Deeplearn\Anaconda3\envs\YOLOV5\lib\site-packages\torch\utils\data\dataloader.py", line 761, in _try_get_data
    data = self._data_queue.get(timeout=timeout)
  File "C:\Softwares\Proware\Deeplearn\Anaconda3\envs\YOLOV5\lib\multiprocessing\queues.py", line 105, in get
    raise Empty
_queue.Empty

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:/WorkSpace/Codes/Pycharm/2020/NPyTorch/Minibatchtraing.py", line 24, in <module>
    for step, (batch_x, batch_y) in enumerate(loader):
  File "C:\Softwares\Proware\Deeplearn\Anaconda3\envs\YOLOV5\lib\site-packages\torch\utils\data\dataloader.py", line 345, in __next__
    data = self._next_data()
  File "C:\Softwares\Proware\Deeplearn\Anaconda3\envs\YOLOV5\lib\site-packages\torch\utils\data\dataloader.py", line 841, in _next_data
    idx, data = self._get_data()
  File "C:\Softwares\Proware\Deeplearn\Anaconda3\envs\YOLOV5\lib\site-packages\torch\utils\data\dataloader.py", line 808, in _get_data
    success, data = self._try_get_data()
  File "C:\Softwares\Proware\Deeplearn\Anaconda3\envs\YOLOV5\lib\site-packages\torch\utils\data\dataloader.py", line 774, in _try_get_data
    raise RuntimeError('DataLoader worker (pid(s) {}) exited unexpectedly'.format(pids_str))
RuntimeError: DataLoader worker (pid(s) 8528, 8488) exited unexpectedly

This probably means that you are not using fork to start your
child processes and you have forgotten to use the proper idiom
in the main module:

    if __name__ == '__main__':
        freeze_support()
        ...