Colab TPU 调用 model.fit() 时出错:UnimplementedError

2024-05-01

我正在尝试分类cifar10 图片 https://www.tensorflow.org/datasets/catalog/cifar10与谷歌 colab TPU 合作,根据官方教程 https://www.tensorflow.org/guide/tpu.

但是我收到以下错误。

UnimplementedError:发现 6 个根错误。

不使用 TPU,我没有看到任何错误。有人可以分享一些建议吗?

下面附上我的代码。

from tensorflow.keras.models import Model
from tensorflow.keras.preprocessing.image import ImageDataGenerator
from tensorflow.keras.applications.vgg16 import VGG16
import tensorflow as tf
import numpy as np

import os
import tensorflow_datasets as tfds

# preparing TPU
resolver = tf.distribute.cluster_resolver.TPUClusterResolver(tpu='')
tf.config.experimental_connect_to_cluster(resolver)
# This is the TPU initialization code that has to be at the beginning.
tf.tpu.experimental.initialize_tpu_system(resolver)
print("All devices: ", tf.config.list_logical_devices('TPU'))

strategy = tf.distribute.TPUStrategy(resolver)

# download cifar10 data
ds_test, ds_train = tfds.load('cifar10', split=['test', 'train'], )

# Preprocess the images
def resize_with_crop(ip):
    image = ip['image']
    label = ip['label']
    image = tf.expand_dims(image,0)
    label = tf.one_hot(label,10)
    label = tf.expand_dims(label,0)
    return (image, label)


ds_train_ = ds_train.map(resize_with_crop)
ds_test_ = ds_test.map(resize_with_crop)

with strategy.scope():
    model = VGG16(input_shape = (32, 32, 3), weights=None, classes=10)

    model.compile(optimizer='adam', loss = 'categorical_crossentropy', metrics= ['accuracy'])

    history = model.fit(ds_train_,
                        batch_size = 32,
                        steps_per_epoch = 64,
                        epochs = 1000,
                        validation_data = ds_test_,
                        shuffle = True,)

我得到的错误如下。

---------------------------------------------------------------------------
UnimplementedError                        Traceback (most recent call last)
<ipython-input-2-588bff080f0b> in <module>()
     25                         epochs = 1000,
     26                         validation_data = ds_test_,
---> 27                         shuffle = True,)
     28 
     29 '''

13 frames
/usr/local/lib/python3.7/dist-packages/keras/engine/training.py in fit(self, x, y, batch_size, epochs, verbose, callbacks, validation_split, validation_data, shuffle, class_weight, sample_weight, initial_epoch, steps_per_epoch, validation_steps, validation_batch_size, validation_freq, max_queue_size, workers, use_multiprocessing)
   1187               logs = tmp_logs  # No error, now safe to assign to logs.
   1188               end_step = step + data_handler.step_increment
-> 1189               callbacks.on_train_batch_end(end_step, logs)
   1190               if self.stop_training:
   1191                 break

/usr/local/lib/python3.7/dist-packages/keras/callbacks.py in on_train_batch_end(self, batch, logs)
    433     """
    434     if self._should_call_train_batch_hooks:
--> 435       self._call_batch_hook(ModeKeys.TRAIN, 'end', batch, logs=logs)
    436 
    437   def on_test_batch_begin(self, batch, logs=None):

/usr/local/lib/python3.7/dist-packages/keras/callbacks.py in _call_batch_hook(self, mode, hook, batch, logs)
    293       self._call_batch_begin_hook(mode, batch, logs)
    294     elif hook == 'end':
--> 295       self._call_batch_end_hook(mode, batch, logs)
    296     else:
    297       raise ValueError('Unrecognized hook: {}'.format(hook))

/usr/local/lib/python3.7/dist-packages/keras/callbacks.py in _call_batch_end_hook(self, mode, batch, logs)
    313       self._batch_times.append(batch_time)
    314 
--> 315     self._call_batch_hook_helper(hook_name, batch, logs)
    316 
    317     if len(self._batch_times) >= self._num_batches_for_timing_check:

/usr/local/lib/python3.7/dist-packages/keras/callbacks.py in _call_batch_hook_helper(self, hook_name, batch, logs)
    351     for callback in self.callbacks:
    352       hook = getattr(callback, hook_name)
--> 353       hook(batch, logs)
    354 
    355     if self._check_timing:

/usr/local/lib/python3.7/dist-packages/keras/callbacks.py in on_train_batch_end(self, batch, logs)
   1026 
   1027   def on_train_batch_end(self, batch, logs=None):
-> 1028     self._batch_update_progbar(batch, logs)
   1029 
   1030   def on_test_batch_end(self, batch, logs=None):

/usr/local/lib/python3.7/dist-packages/keras/callbacks.py in _batch_update_progbar(self, batch, logs)
   1098     if self.verbose == 1:
   1099       # Only block async when verbose = 1.
-> 1100       logs = tf_utils.sync_to_numpy_or_python_type(logs)
   1101       self.progbar.update(self.seen, list(logs.items()), finalize=False)
   1102 

/usr/local/lib/python3.7/dist-packages/keras/utils/tf_utils.py in sync_to_numpy_or_python_type(tensors)
    514     return t  # Don't turn ragged or sparse tensors to NumPy.
    515 
--> 516   return tf.nest.map_structure(_to_single_numpy_or_python_type, tensors)
    517 
    518 

/usr/local/lib/python3.7/dist-packages/tensorflow/python/util/nest.py in map_structure(func, *structure, **kwargs)
    867 
    868   return pack_sequence_as(
--> 869       structure[0], [func(*x) for x in entries],
    870       expand_composites=expand_composites)
    871 

/usr/local/lib/python3.7/dist-packages/tensorflow/python/util/nest.py in <listcomp>(.0)
    867 
    868   return pack_sequence_as(
--> 869       structure[0], [func(*x) for x in entries],
    870       expand_composites=expand_composites)
    871 

/usr/local/lib/python3.7/dist-packages/keras/utils/tf_utils.py in _to_single_numpy_or_python_type(t)
    510   def _to_single_numpy_or_python_type(t):
    511     if isinstance(t, tf.Tensor):
--> 512       x = t.numpy()
    513       return x.item() if np.ndim(x) == 0 else x
    514     return t  # Don't turn ragged or sparse tensors to NumPy.

/usr/local/lib/python3.7/dist-packages/tensorflow/python/framework/ops.py in numpy(self)
   1092     """
   1093     # TODO(slebedev): Consider avoiding a copy for non-CPU or remote tensors.
-> 1094     maybe_arr = self._numpy()  # pylint: disable=protected-access
   1095     return maybe_arr.copy() if isinstance(maybe_arr, np.ndarray) else maybe_arr
   1096 

/usr/local/lib/python3.7/dist-packages/tensorflow/python/framework/ops.py in _numpy(self)
   1060       return self._numpy_internal()
   1061     except core._NotOkStatusException as e:  # pylint: disable=protected-access
-> 1062       six.raise_from(core._status_to_exception(e.code, e.message), None)  # pylint: disable=protected-access
   1063 
   1064   @property

/usr/local/lib/python3.7/dist-packages/six.py in raise_from(value, from_value)

UnimplementedError: 6 root error(s) found.
  (0) Unimplemented: {{function_node __inference_train_function_127397}} File system scheme '[local]' not implemented (file: '/root/tensorflow_datasets/cifar10/3.0.2/cifar10-train.tfrecord-00000-of-00001')
     [[{{node MultiDeviceIteratorGetNextFromShard}}]]
     [[RemoteCall]]
     [[IteratorGetNext_2]]
  (1) Unimplemented: {{function_node __inference_train_function_127397}} File system scheme '[local]' not implemented (file: '/root/tensorflow_datasets/cifar10/3.0.2/cifar10-train.tfrecord-00000-of-00001')
     [[{{node MultiDeviceIteratorGetNextFromShard}}]]
     [[RemoteCall]]
     [[IteratorGetNext_6]]
  (2) Unimplemented: {{function_node __inference_train_function_127397}} File system scheme '[local]' not implemented (file: '/root/tensorflow_datasets/cifar10/3.0.2/cifar10-train.tfrecord-00000-of-00001')
     [[{{node MultiDeviceIteratorGetNextFromShard}}]]
     [[RemoteCall]]
     [[IteratorGetNext_3]]
     [[cluster_train_function/_execute_6_0/_187]]
  (3) Unimplemented: {{function_node __inference_train_function_127397}} File system scheme '[local]' not implemented (file: '/root/tensorflow_datasets/cifar10/3.0.2/cifar10-train.tfrecord-00000-of-00001')
     [[{{node MultiDeviceIteratorGetNextFromShard}}]]
     [[RemoteCall]]
     [[IteratorGetNext_3]]
     [[tpu_compile_succeeded_assert/_17093395999373799140/_5/_159]]
  (4) Unimplemented: {{function_node __inference_train_function_127397}} File system scheme '[local]' not implemented (file: '/root/tensorflow_datasets/cifar10/3.0.2/cifar10-train.tfrecord-00000-of-00001')
     [[{{node MultiDeviceIteratorGetNextFromShard}}]]
     [[RemoteCall]]
     [[IteratorGetNext_3]]
     [[tpu_compile_succeeded_assert/_17093395999373799140/_5/_111]]
  (5) Unimplemented: {{function_node __inference_train_function_127397}} File system scheme '[local]' not implemented (file: '/root/tensorflow_datasets/cifar10/3.0.2/cifar10-train.tfrecord-00000-of-00001')
     [[{{node MultiDeviceIteratorGetNextFromShard}}]]
     [[RemoteCall]]
     [[IteratorGetNext_3]]
0 successful operations.
3 derived errors ignored.

如果你查看错误,它会说File system scheme '[local]' not implemented.

tfds 通常不会托管所有数据集,而是从原始源下载一些数据集到本地计算机,而 TPU 无法访问这些数据集。

云 TPU 只能访问 GCS 中的数据,因为仅注册了 GCS 文件系统。请参见:https://cloud.google.com/tpu/docs/troubleshooting#cannot_use_local_filesystem https://cloud.google.com/tpu/docs/troubleshooting#cannot_use_local_filesystem更多细节。

您可以让tfds将数据下载到您的gs存储桶中(详细信息为here https://www.tensorflow.org/datasets/gcs):

# Authenticate your account to access GCS.
from google.colab import auth
auth.authenticate_user()

...

# download cifar10 data to a gs bucket.
ds_test, ds_train = tfds.load('cifar10', split=['test', 'train'], try_gcs=True, data_dir="gs://YOUR_BUCKET_NAME")

注意最近推出的TPU VMs https://cloud.google.com/blog/products/compute/introducing-cloud-tpu-vms可以访问本地文件。您可以在 GCP 中创建 TPU 虚拟机,但在 Colab/Kaggle 中尚不能。

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