[GitHub] lightingghost opened a new issue #10220: Check failed: !ndinputs.back()->is_none()

[GitBox <gi...@apache.org>]

lightingghost opened a new issue #10220: Check failed: !ndinputs.back()->is_none()
URL: https://github.com/apache/incubator-mxnet/issues/10220
 
 
   I came across with an error of `Check failed: !ndinputs.back()->is_none() node_58 0`. The full code is too complicated to post here. I am trying a minimum sample for reproduce this error. Briefly, the model is the input variable going through a gluon `Block`, and some `ndarray` ops are used to calculate the loss. 
   
   Something I have tried:
   1. I tried to call `hybridize()` for the Block, and the error disappears.
   2. It seems to be related to the function below when calculating the loss:
   
   ```python
       def binarize(self, x, i):
           rand = mx.nd.random_uniform(low=0, high=1,
                                           shape=self.rand_shape[i],
                                           ctx=self.model.ctx)
           sample = mx.nd.broadcast_lesser_equal(rand, mx.nd.sigmoid(x))
           sample_shape = [-1] + list(self.model.data_shape[i])[1:]
           return sample.reshape(sample_shape)
   ```
   If I replace the function with 
   ```python
       def binarize(self, x, i):
           return x
   ```
   The error disappears.
   
   Besides, I found there is `tojson()` method for `symbol`, but not for `ndarray`. Is there a way to visualize the computation graph so that I can know what operation of `node_58` is?

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