Tensorflow 错误：FailedPeconditionError：尝试使用未初始化的变量

我想将立体图像放入优化器中。这是我的代码：

tf.reset_default_graph()

# config
learning_rate = 0.5
training_epochs = 5

# init
init = tf.global_variables_initializer()

def conv2d(input_layer):
    conv1 = tf.layers.conv2d(
        inputs=input_layer,
        filters=32,
        kernel_size=[3, 3],
        padding='same',
        activation=tf.tanh,
        use_bias=False
    )

    conv2 = tf.layers.conv2d(
        inputs=conv1,
        filters=32,
        kernel_size=[3, 3],
        padding='same',
        activation=tf.tanh,
        use_bias=False
    )

    conv3 = tf.layers.conv2d(
        inputs=conv2,
        filters=32,
        kernel_size=[3, 3],
        padding='same',
        activation=tf.tanh,
        use_bias=False
    )

    conv4 = tf.layers.conv2d(
        inputs=conv3,
        filters=32,
        kernel_size=[3, 3],
        padding='same',
        activation=tf.tanh,
        use_bias=False
    )

    logits = tf.layers.conv2d(
        inputs=conv4,
        filters=32,
        kernel_size=[3, 3],
        padding='same',
        activation=tf.sigmoid,
        use_bias=False
    )

    return logits


if __name__ == '__main__':
    # read images
    # preprocessing: rgb converted to float, zero_mean, uni_variance
    images = reading_images()
    mask_tensor = images["mask"][1]

    # reshape images
    img0 = images["img0"][1]
    img1 = images["img1"][1]
    img0_rs = tf.reshape(img0, [1, int(1988 / 2), int(2880 / 2), 3])
    img1_rs = tf.reshape(img1, [1, int(1988 / 2), int(2880 / 2), 3])

    # define symbolic placeholders
    t_im0 = tf.placeholder(tf.float32, [1, None, None, 3])
    t_im1 = tf.placeholder(tf.float32, [1, None, None, 3])
    t_img = tf.concat([t_im0, t_im1], axis=3)

    input_layer = tf.reshape(t_img, [1, int(1988 / 2), int(2880 / 2), 6])
    logits = conv2d(input_layer)

    with tf.name_scope("cost_function") as scope:
        mask_tensor = tf.tile(mask_tensor, [1, 1, 3])
        cost_function = -tf.reduce_mean(mask_tensor * tf.log(logits) + (1. - mask_tensor) * tf.log(1. - logits))
    tf.summary.scalar("cost_function", cost_function)

    with tf.name_scope("train") as scope:
        optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost_function)
    merged_summary_op = tf.summary.merge_all()

    with tf.Session() as sess:
        coord = tf.train.Coordinator()
        threads = tf.train.start_queue_runners(sess=sess, coord=coord)

        sess.run(init)
        # summary_writer = tf.summary.FileWriter('/tmp/tensorflow_logs', graph=sess.graph)
        for epoch in range(training_epochs):
            print("epoch ", epoch)

            avg_cost = 0.0
            mask = sess.run(mask_tensor)
            np_img0_rs = sess.run(img0_rs)
            np_img1_rs = sess.run(img1_rs)

            # res = t_img.eval(feed_dict={t_im0: img0_rs_, t_im1: img1_rs_})

            sess.run([optimizer], feed_dict={t_im0: np_img0_rs, t_im1: np_img1_rs})
    coord.request_stop()
    coord.join(threads)

但我总是收到这个错误。我不知道我必须改变什么。我可以尝试什么来调试它？我确实做了很多尝试来修复这个错误。

epoch  0
2017-07-17 10:26:03.719539: W tensorflow/core/kernels/queue_base.cc:294] _4_input_producer: Skipping cancelled enqueue attempt with queue not closed
2017-07-17 10:26:03.719610: W tensorflow/core/kernels/queue_base.cc:294] _5_input_producer_1: Skipping cancelled enqueue attempt with queue not closed
Traceback (most recent call last):
  File "/home/test/Dropbox/occlusion_thesis/occ_small/main.py", line 111, in <module>
    sess.run([optimizer], feed_dict={t_im0: np_img0_rs, t_im1: np_img1_rs})
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 789, in run
    run_metadata_ptr)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 997, in _run
    feed_dict_string, options, run_metadata)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1132, in _do_run
    target_list, options, run_metadata)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1152, in _do_call
    raise type(e)(node_def, op, message)
tensorflow.python.framework.errors_impl.FailedPreconditionError: Attempting to use uninitialized value conv2d_4/kernel
     [[Node: conv2d_4/kernel/read = Identity[T=DT_FLOAT, _class=["loc:@conv2d_4/kernel"], _device="/job:localhost/replica:0/task:0/cpu:0"](conv2d_4/kernel)]]

Caused by op u'conv2d_4/kernel/read', defined at:
  File "/home/test/Dropbox/occlusion_thesis/occ_small/main.py", line 84, in <module>
    logits = conv2d(input_layer)
  File "/home/test/Dropbox/occlusion_thesis/occ_small/main.py", line 60, in conv2d
    use_bias=False
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/layers/convolutional.py", line 551, in conv2d
    return layer.apply(inputs)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/layers/base.py", line 492, in apply
    return self.__call__(inputs, *args, **kwargs)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/layers/base.py", line 434, in __call__
    self.build(input_shapes[0])
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/layers/convolutional.py", line 137, in build
    dtype=self.dtype)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/layers/base.py", line 374, in add_variable
    trainable=trainable and self.trainable)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 1065, in get_variable
    use_resource=use_resource, custom_getter=custom_getter)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 962, in get_variable
    use_resource=use_resource, custom_getter=custom_getter)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 367, in get_variable
    validate_shape=validate_shape, use_resource=use_resource)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 352, in _true_getter
    use_resource=use_resource)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variable_scope.py", line 725, in _get_single_variable
    validate_shape=validate_shape)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variables.py", line 200, in __init__
    expected_shape=expected_shape)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/variables.py", line 319, in _init_from_args
    self._snapshot = array_ops.identity(self._variable, name="read")
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/ops/gen_array_ops.py", line 1303, in identity
    result = _op_def_lib.apply_op("Identity", input=input, name=name)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/framework/op_def_library.py", line 767, in apply_op
    op_def=op_def)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 2506, in create_op
    original_op=self._default_original_op, op_def=op_def)
  File "/home/test/Programs/anaconda2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 1269, in __init__
    self._traceback = _extract_stack()

FailedPreconditionError (see above for traceback): Attempting to use uninitialized value conv2d_4/kernel
     [[Node: conv2d_4/kernel/read = Identity[T=DT_FLOAT, _class=["loc:@conv2d_4/kernel"], _device="/job:localhost/replica:0/task:0/cpu:0"](conv2d_4/kernel)]]

我不确定您的代码是否完整，但错误消息对我来说似乎相当清楚：

FailedPreconditionError：尝试使用未初始化的值 conv2d_4/kernel

看看你的代码，我发现你有sess.run(init)但我找不到定义init任何地方。 尝试添加init = tf.global_variables_initializer() before with tf.Session() as sess:，这应该可以修复“未初始化值”错误。

Edit：通过完整的代码，我发现问题来自：

# init
init = tf.global_variables_initializer() # <<<<<<<<< 1

def conv2d(input_layer):
    ## Bunch of code defining layers
    return logits

if __name__ == '__main__':
    ## bunch of other code

    logits = conv2d(input_layer) # <<<<<<<<< 2

我标记为1定义初始化函数的点对于截至该点定义的所有变量, and 2您实际定义网络（以及其中的所有变量）的点。的定义init必须after变量的所有定义都已完成，否则您将得到未初始化的变量。

Update:

我在这里复制我对答案所做的评论，因为它可能是一个更好的放置位置。tf.global_variables_initializer()必须被称为定义图表后。如果您在开始时定义它，然后向网络添加层，添加的层的权重不会被初始化因为它们在您创建初始化操作时没有定义。始终将 init 定义为之前的最后一个操作with tf.Session() ...以确保您不会错过初始化中的任何内容。