[GitHub] [incubator-mxnet] ThomasDelteil edited a comment on issue #14340: [bug] Bug in Gradient flow with backward(retain_graph=True) and split()

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ThomasDelteil edited a comment on issue #14340: [bug] Bug in Gradient flow with backward(retain_graph=True) and split()
URL: https://github.com/apache/incubator-mxnet/issues/14340#issuecomment-470298114
 
 
   @apeforest 
   
   The test does not seem enough to actual test that backward is working, I would add a check on the values of the actual gradients.
   
   Are you using a mkl version of mxnet?
   Are you running the first example or the second? I get the bug on ubuntu with a GPU build and also on my mac on CPU build with MXNet 1.4.0:
   
   ```
   > python test.py
   /Users/tdelteil/anaconda3/lib/python3.6/site-packages/h5py/__init__.py:36: FutureWarning: Conversion of the second argument of issubdtype from `float` to `np.floating` is deprecated. In future, it will be treated as `np.float64 == np.dtype(float).type`.
     from ._conv import register_converters as _register_converters
   [[1. 1. 1. 1. 1. 0. 0. 0. 0. 0.]]
   [[ 0.0000000e+00 -4.6566129e-10 -2.9563751e+35 -1.0844662e-19
     -2.9466291e+35  4.6577470e-10 -2.9332078e+35  1.5849492e+29
      7.3657442e+28  1.0597454e-38]]
   
   [[1. 1. 1. 1. 1. 0. 0. 0. 0. 0.]]
   [[ 0.00000000e+00 -4.65661287e-10  0.00000000e+00 -4.65661287e-10
      1.16116826e+33  1.78601853e+31  1.49938936e-43  0.00000000e+00
      0.00000000e+00  0.00000000e+00]]
   
   [[1. 1. 1. 1. 1. 0. 0. 0. 0. 0.]]
   [[ 0.0000000e+00 -4.6566129e-10 -2.9551057e+35 -2.5249697e-29
      4.2038954e-45  0.0000000e+00 -6.4196971e-16  4.5826664e-41
      0.0000000e+00 -4.6566129e-10]]
   
   python(78676,0x7fffb122c3c0) malloc: *** error for object 0x7fbfa3e432f8: incorrect checksum for freed object - object was probably modified after being freed.
   *** set a breakpoint in malloc_error_break to debug
   Abort trap: 6
   ```

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