我使用植物图像训练了一个 InceptionV3 模型。我使用了 Keras 库。开始训练时，第一个 epoch 每步耗时 29 秒，然后其他步骤每步耗时约 530 毫秒。所以这让我怀疑我的代码中是否存在错误。我检查了我的代码几次，但它的逻辑对我来说似乎是正确的。我在 Google Colab 上训练了我的模型。我想知道是否有记忆机制或我的代码包含错误。这是我的代码：

# Yields one image-target pair when called
def image_target_generator(files, labels):
assert len(files) == len(labels), 'Files and labels sizes don\'t match!'

for step in range(len(files)):
    img = cv2.imread(dataset_path + files[step])
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    item = (img, labels[step])
    yield item

# Generating batch
 def batch_generator(gen):

    batch_images = []
    batch_targets = []

    for item in gen:

      if len(batch_images) == BATCH_SIZE:
        yield batch_images, batch_targets
        batch_images = []
        batch_targets = []

      preprocessed_img = preprocess_image(item[0])
      batch_images.append(preprocessed_img)
      batch_targets.append(item[1])      

    yield batch_images, batch_targets

# Training generator
def training_generator(files, labels):

  # So that Keras can loop it as long as required
  while True:

    for batch in batch_generator(image_target_generator(files, labels)):
      batch_images = np.stack(batch[0], axis=0)
      batch_targets = keras.utils.np_utils.to_categorical(batch[1], NUM_CLASSES)
      yield batch_images, batch_targets


# Create model
def create_model():
  model = keras.applications.InceptionV3(include_top=False, input_shape= IMG_SIZE, IMG_SIZE, 3), weights='imagenet')

  new_output = keras.layers.GlobalAveragePooling2D()(model.output)
  new_output = keras.layers.Dense(NUM_CLASSES, activation='softmax') (new_output)
  model = keras.engine.training.Model(model.inputs, new_output)

  for layer in model.layers:
    layer.Trainable = True

    if isinstance(layer, keras.layers.BatchNormalization):
      layer.momentum = 0.9

  for layer in model.layers[:-50]:
    if not isinstance(layer, keras.layers.BatchNormalization):
      layer.trainable = False

  return model

# Compiling model
model = create_model()

model.compile(loss='categorical_crossentropy',optimizer=keras.optimizers.adamax(lr=1e-2), metrics=['accuracy'])

# Fitting model
model.fit_generator(
  training_generator(train_x, train_y),
  steps_per_epoch=len(train_x) // BATCH_SIZE,
  epochs = 30,
  validation_data=training_generator(test_x, test_y),
  validation_steps=len(test_x) // BATCH_SIZE
  )