[GitHub] [incubator-mxnet] wshuail opened a new issue #15512: possible bug in nd.gather_nd

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

wshuail opened a new issue #15512: possible bug in nd.gather_nd
URL: https://github.com/apache/incubator-mxnet/issues/15512
 
 
   When I use nd.gather_nd with gpu, a unexpected error happened sometimes. Generally it may raise error like RuntimeError: cuda runtime error (77) : an illegal memory access was encountered.
   
   An error "terminate called without an active exception" could happen with the code below. 
   
   `import os
   import sys
   import mxnet as mx
   from mxnet import nd
   sys.path.insert(0, os.path.expanduser('~/gluon_detector'))
   
   ctx = mx.gpu(0)
   
   for i in range(10000):
       if i % 100 == 0:
           print (i)
   
       batch_size = 2
       num_classes = 2
       width, height = 5, 5
       k = 3
                                                                                                                                  hm_origin = nd.random.uniform(0, 10, (batch_size, num_classes, width, height), ctx=ctx)
   
       hm = nd.reshape(hm_origin, (0, 0, -1))
   
       topk_scores, topk_idx = nd.topk(hm, k=k, ret_typ='both')
   
       topk_x_idx = nd.floor(topk_idx/width)
       topk_y_idx = (topk_idx%height)
   
       batch_idx = nd.repeat(nd.arange(batch_size), repeats=num_classes*k).reshape((1, -1))
       batch_idx = batch_idx.as_in_context(ctx)
       class_idx = nd.repeat(nd.arange(num_classes), repeats=batch_size*k).reshape((1, -1))
       class_idx = class_idx.as_in_context(ctx)
   
       topk_x_idx = nd.reshape(topk_x_idx, (1, -1))
       topk_y_idx = nd.reshape(topk_y_idx, (1, -1))
   
       indices = nd.concat(batch_idx, class_idx, topk_x_idx, topk_y_idx, dim=0)
   
       results = nd.gather_nd(hm_origin, indices)
       results = nd.reshape(results, (batch_size, num_classes, k))
   
   `
   
   when I add nd.waitall() at last, it works well. 
   
   any suggestions? 
   
   BTW, does mxnet has a function like torch.gather?  gather_nd works close, but not so convenient.  

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