python - keras multiple_gpu_model 导致 "Can' t pickle 模块对象“错误

Question

这是此 question 的后续内容。我正在尝试利用 8 个 GPU 进行训练，并使用 Keras 的 multiple_gpu_model。我指定的批量大小为 128，它将被分配到 8 个 GPU，从而每个 GPU 16 个。现在，使用此配置，我收到以下错误:

Train on 6120 samples, validate on 323 samples
Epoch 1/100
6120/6120 [==============================] - 42s 7ms/step - loss: 0.0996 - mean_iou: 0.6919 - val_loss: 0.0969 - val_mean_iou: 0.7198

Epoch 00001: val_loss improved from inf to 0.09686, saving model to test.h5

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-16-00e92d5b765a> in <module>()
      3 checkpointer = ModelCheckpoint('test.h5', verbose=1, save_best_only=True)
      4 results = parallel_model.fit(X_train, Y_train, validation_split=0.05, batch_size = 128, verbose=1, epochs=100, 
----> 5                     callbacks=[earlystopper, checkpointer])

~/anaconda/envs/dl/lib/python3.6/site-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, **kwargs)
   1703                               initial_epoch=initial_epoch,
   1704                               steps_per_epoch=steps_per_epoch,
-> 1705                               validation_steps=validation_steps)
   1706 
   1707     def evaluate(self, x=None, y=None,

~/anaconda/envs/dl/lib/python3.6/site-packages/keras/engine/training.py in _fit_loop(self, f, ins, out_labels, batch_size, epochs, verbose, callbacks, val_f, val_ins, shuffle, callback_metrics, initial_epoch, steps_per_epoch, validation_steps)
   1254                             for l, o in zip(out_labels, val_outs):
   1255                                 epoch_logs['val_' + l] = o
-> 1256             callbacks.on_epoch_end(epoch, epoch_logs)
   1257             if callback_model.stop_training:
   1258                 break

~/anaconda/envs/dl/lib/python3.6/site-packages/keras/callbacks.py in on_epoch_end(self, epoch, logs)
     75         logs = logs or {}
     76         for callback in self.callbacks:
---> 77             callback.on_epoch_end(epoch, logs)
     78 
     79     def on_batch_begin(self, batch, logs=None):

~/anaconda/envs/dl/lib/python3.6/site-packages/keras/callbacks.py in on_epoch_end(self, epoch, logs)
    445                             self.model.save_weights(filepath, overwrite=True)
    446                         else:
--> 447                             self.model.save(filepath, overwrite=True)
    448                     else:
    449                         if self.verbose > 0:

~/anaconda/envs/dl/lib/python3.6/site-packages/keras/engine/topology.py in save(self, filepath, overwrite, include_optimizer)
   2589         """
   2590         from ..models import save_model
-> 2591         save_model(self, filepath, overwrite, include_optimizer)
   2592 
   2593     def save_weights(self, filepath, overwrite=True):

~/anaconda/envs/dl/lib/python3.6/site-packages/keras/models.py in save_model(model, filepath, overwrite, include_optimizer)
    124         f.attrs['model_config'] = json.dumps({
    125             'class_name': model.__class__.__name__,
--> 126             'config': model.get_config()
    127         }, default=get_json_type).encode('utf8')
    128 

~/anaconda/envs/dl/lib/python3.6/site-packages/keras/engine/topology.py in get_config(self)
   2430             model_outputs.append([layer.name, new_node_index, tensor_index])
   2431         config['output_layers'] = model_outputs
-> 2432         return copy.deepcopy(config)
   2433 
   2434     @classmethod

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    148     copier = _deepcopy_dispatch.get(cls)
    149     if copier:
--> 150         y = copier(x, memo)
    151     else:
    152         try:

~/anaconda/envs/dl/lib/python3.6/copy.py in _deepcopy_dict(x, memo, deepcopy)
    238     memo[id(x)] = y
    239     for key, value in x.items():
--> 240         y[deepcopy(key, memo)] = deepcopy(value, memo)
    241     return y
    242 d[dict] = _deepcopy_dict

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    148     copier = _deepcopy_dispatch.get(cls)
    149     if copier:
--> 150         y = copier(x, memo)
    151     else:
    152         try:

~/anaconda/envs/dl/lib/python3.6/copy.py in _deepcopy_list(x, memo, deepcopy)
    213     append = y.append
    214     for a in x:
--> 215         append(deepcopy(a, memo))
    216     return y
    217 d[list] = _deepcopy_list

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    148     copier = _deepcopy_dispatch.get(cls)
    149     if copier:
--> 150         y = copier(x, memo)
    151     else:
    152         try:

~/anaconda/envs/dl/lib/python3.6/copy.py in _deepcopy_dict(x, memo, deepcopy)
    238     memo[id(x)] = y
    239     for key, value in x.items():
--> 240         y[deepcopy(key, memo)] = deepcopy(value, memo)
    241     return y
    242 d[dict] = _deepcopy_dict

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    148     copier = _deepcopy_dispatch.get(cls)
    149     if copier:
--> 150         y = copier(x, memo)
    151     else:
    152         try:

~/anaconda/envs/dl/lib/python3.6/copy.py in _deepcopy_dict(x, memo, deepcopy)
    238     memo[id(x)] = y
    239     for key, value in x.items():
--> 240         y[deepcopy(key, memo)] = deepcopy(value, memo)
    241     return y
    242 d[dict] = _deepcopy_dict

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    148     copier = _deepcopy_dispatch.get(cls)
    149     if copier:
--> 150         y = copier(x, memo)
    151     else:
    152         try:

~/anaconda/envs/dl/lib/python3.6/copy.py in _deepcopy_tuple(x, memo, deepcopy)
    218 
    219 def _deepcopy_tuple(x, memo, deepcopy=deepcopy):
--> 220     y = [deepcopy(a, memo) for a in x]
    221     # We're not going to put the tuple in the memo, but it's still important we
    222     # check for it, in case the tuple contains recursive mutable structures.

~/anaconda/envs/dl/lib/python3.6/copy.py in <listcomp>(.0)
    218 
    219 def _deepcopy_tuple(x, memo, deepcopy=deepcopy):
--> 220     y = [deepcopy(a, memo) for a in x]
    221     # We're not going to put the tuple in the memo, but it's still important we
    222     # check for it, in case the tuple contains recursive mutable structures.

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    148     copier = _deepcopy_dispatch.get(cls)
    149     if copier:
--> 150         y = copier(x, memo)
    151     else:
    152         try:

~/anaconda/envs/dl/lib/python3.6/copy.py in _deepcopy_tuple(x, memo, deepcopy)
    218 
    219 def _deepcopy_tuple(x, memo, deepcopy=deepcopy):
--> 220     y = [deepcopy(a, memo) for a in x]
    221     # We're not going to put the tuple in the memo, but it's still important we
    222     # check for it, in case the tuple contains recursive mutable structures.

~/anaconda/envs/dl/lib/python3.6/copy.py in <listcomp>(.0)
    218 
    219 def _deepcopy_tuple(x, memo, deepcopy=deepcopy):
--> 220     y = [deepcopy(a, memo) for a in x]
    221     # We're not going to put the tuple in the memo, but it's still important we
    222     # check for it, in case the tuple contains recursive mutable structures.

~/anaconda/envs/dl/lib/python3.6/copy.py in deepcopy(x, memo, _nil)
    167                     reductor = getattr(x, "__reduce_ex__", None)
    168                     if reductor:
--> 169                         rv = reductor(4)
    170                     else:
    171                         reductor = getattr(x, "__reduce__", None)

TypeError: can't pickle module objects

当我指定批量大小为 256 时，网络甚至不会运行(请参阅其他链接的问题)。但单个 GPU 能够处理 32 的批量大小。我无法指出这里出了什么问题以及如何修复此错误。仅仅是批量大小吗？对我来说，这更像是一个并行化问题。

Answer 1

如果您在回调中使用 ModelCheckpoint 函数，则应在 ModelCheckpoint 函数中添加“save_weights_only=True”参数:

 from keras.callbacks import ModelCheckpoint

 callbacks_list = [ModelCheckpoint(top_weights_path, monitor='val_loss',
                              verbose=1, save_best_only=True, save_weights_only=True)]

希望有用