tensorflow – Keras TPU.编译失败:检测到不支持的操作

我尝试使用Google Colab TPU运行我的keras UNet模型,我遇到了UpSampling2D的这个问题.任何解决方案或解决方法?

要运行的代码:

import os
import numpy as np
import tensorflow as tf
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import UpSampling2D

model = Sequential()
model.add(UpSampling2D((2, 2), input_shape=(16, 16, 1)))
model.compile(optimizer=tf.train.RMSPropOptimizer(learning_rate=0.01), 
              loss='binary_crossentropy', metrics=['acc'])

TPU_WORKER = 'grpc://' + os.environ['COLAB_TPU_ADDR']
tf.logging.set_verbosity(tf.logging.INFO)


model = tf.contrib.tpu.keras_to_tpu_model(
    model,strategy=tf.contrib.tpu.TPUDistributionStrategy(
        tf.contrib.cluster_resolver.TPUClusterResolver(TPU_WORKER)))

X = np.zeros((1024, 16, 16, 1))
Y = np.zeros((1024, 32, 32, 1))

model.fit(X, Y, batch_size=1024)

错误:

RuntimeError: Compilation failed: Compilation failure: Detected
unsupported operations when trying to compile graph
cluster_3_5095732716396540171[] on XLA_TPU_JIT: ResizeNearestNeighbor
(No registered ‘ResizeNearestNeighbor’ OpKernel for XLA_TPU_JIT
devices compatible with node {{node
tpu_140211339657168/up_sampling2d_1/ResizeNearestNeighbor}} =
ResizeNearestNeighbor[T=DT_FLOAT, align_corners=false,
_device=”/device:TPU_REPLICATED_CORE”](infeed-train_1:1, tpu_140211339657168/up_sampling2d_1/mul)
. Registered: device=’CPU’; T in [DT_DOUBLE]
device=’CPU’; T in [DT_FLOAT]
device=’CPU’; T in [DT_BFLOAT16]
device=’CPU’; T in [DT_HALF]
device=’CPU’; T in [DT_INT8]
device=’CPU’; T in [DT_UINT8]
device=’CPU’; T in [DT_INT16]
device=’CPU’; T in [DT_UINT16]
device=’CPU’; T in [DT_INT32]
device=’CPU’; T in [DT_INT64]
){{node tpu_140211339657168/up_sampling2d_1/ResizeNearestNeighbor}}

最佳答案 从错误看,Keras的Tensorflow后端(ResizeNearestNeighbor)图中的操作之一当前与TPU不兼容.有少量Tensorflow操作目前不适用于TPU(
Cloud TPU FAQs).

您可以查看TPU兼容Tensorflow操作here的当前列表.您也可以使用Tensorboard查看TPU Compatibility Graphs.

作为一种解决方法,您可以尝试组合TPU兼容的Tensorflow操作来复制ResizeNearestNeighbor的行为.特别是,您可能对与TPU兼容的ResizeBilinear Op感兴趣.

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