【成功解决！Ultralytics YOLO 训练报错：`AttributeError: ‘InfiniteDataLoader‘ object has no attribute ‘iterat】

1. 训练报错

Ultralytics YOLO 训练报错：AttributeError: 'InfiniteDataLoader' object has no attribute 'iterator'

albumentations: Blur(p=0.01, blur_limit=(3, 7)), MedianBlur(p=0.01, blur_limit=(3, 7)), ToGray(p=0.01, num_output_channels=3, method='weighted_average'), CLAHE(p=0.01, clip_limit=(1.0, 4.0), tile_grid_size=(8, 8))
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\spawn.py", line 122, in spawn_main
    exitcode = _main(fd, parent_sentinel)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\spawn.py", line 131, in _main
    prepare(preparation_data)
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\spawn.py", line 246, in prepare
    _fixup_main_from_path(data['init_main_from_path'])
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\spawn.py", line 297, in _fixup_main_from_path
    main_content = runpy.run_path(main_path,
                   ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen runpy>", line 291, in run_path
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "E:\project\YOLOv12\yolov12\train.py", line 6, in <module>
    results = model.train(
              ^^^^^^^^^^^^
  File "E:\project\YOLOv12\yolov12\ultralytics\engine\model.py", line 806, in train
    self.trainer.train()
  File "E:\project\YOLOv12\yolov12\ultralytics\engine\trainer.py", line 207, in train
    self._do_train(world_size)
  File "E:\project\YOLOv12\yolov12\ultralytics\engine\trainer.py", line 323, in _do_train
    self._setup_train(world_size)
  File "E:\project\YOLOv12\yolov12\ultralytics\engine\trainer.py", line 287, in _setup_train
    self.train_loader = self.get_dataloader(self.trainset, batch_size=batch_size, rank=LOCAL_RANK, mode="train")
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "E:\project\YOLOv12\yolov12\ultralytics\models\yolo\detect\train.py", line 55, in get_dataloader
    return build_dataloader(dataset, batch_size, workers, shuffle, rank)  # return dataloader
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "E:\project\YOLOv12\yolov12\ultralytics\data\build.py", line 143, in build_dataloader
    return InfiniteDataLoader(
           ^^^^^^^^^^^^^^^^^^^
  File "E:\project\YOLOv12\yolov12\ultralytics\data\build.py", line 39, in __init__
    self.iterator = super().__iter__()
                    ^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\site-packages\torch\utils\data\dataloader.py", line 491, in __iter__
    return self._get_iterator()
           ^^^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\site-packages\torch\utils\data\dataloader.py", line 422, in _get_iterator
    return _MultiProcessingDataLoaderIter(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\site-packages\torch\utils\data\dataloader.py", line 1146, in __init__
    w.start()
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\process.py", line 121, in start
    self._popen = self._Popen(self)
                  ^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\context.py", line 336, in _Popen
    return Popen(process_obj)
           ^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\popen_spawn_win32.py", line 46, in __init__
    prep_data = spawn.get_preparation_data(process_obj._name)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\spawn.py", line 164, in get_preparation_data
    _check_not_importing_main()
  File "D:\Anaconda\envs\yolov12\Lib\multiprocessing\spawn.py", line 140, in _check_not_importing_main
    raise RuntimeError('''
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.

        To fix this issue, refer to the "Safe importing of main module"
        section in https://docs.python.org/3/library/multiprocessing.html
        
Exception ignored in: <function InfiniteDataLoader.__del__ at 0x0000024196F74B80>
Traceback (most recent call last):
  File "E:\project\YOLOv12\yolov12\ultralytics\data\build.py", line 52, in __del__
    if hasattr(self.iterator, "_workers"):
               ^^^^^^^^^^^^^
AttributeError: 'InfiniteDataLoader' object has no attribute 'iterator'

2. 原因

workers默认为8，是为服务器设置的，对于非服务器的PC端来说太大。

3. 解决方法

将workers设置为零即可，workers=0。

results = model.train(
  data='ultralytics/cfg/datasets/PCB.yaml',
  epochs=300,
  batch=4,
  imgsz=640,
  scale=0.5,  # S:0.9; M:0.9; L:0.9; X:0.9
  mosaic=1.0,
  mixup=0.0,  # S:0.05; M:0.15; L:0.15; X:0.2
  copy_paste=0.1,  # S:0.15; M:0.4; L:0.5; X:0.6
  device="0",
  workers=0,    # AttributeError: 'InfiniteDataLoader' object has no attribute 'iterator'
)