apache/mxnet

Floating point exception in mxnet.ndarray.op.SequenceReverse

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#18,940 opened on Aug 16, 2020

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BugC++Operatorgood first issuev1.x

Description

Description

(A clear and concise description of what the bug is.) mxnet.ndarray.op.SequenceReverse has floating point exception when given data has 0 in its shape. Please see the provided code for example.

Error Message

(Paste the complete error message. Please also include stack trace by setting environment variable DMLC_LOG_STACK_TRACE_DEPTH=10 before running your script.)

Floating point exception (core dumped)

To Reproduce

(If you developed your own code, please provide a short script that reproduces the error. For existing examples, please provide link.)

import mxnet
import numpy as np
data = mxnet.nd.array(np.random.rand(0,1,1))
mxnet.ndarray.op.SequenceReverse(data)

Steps to reproduce

(Paste the commands you ran that produced the error.)

  1. run the provided code in python interpreter or as a script

What have you tried to solve it?

Environment

We recommend using our script for collecting the diagnositc information. Run the following command and paste the outputs below:

curl --retry 10 -s https://raw.githubusercontent.com/dmlc/gluon-nlp/master/tools/diagnose.py | python

# paste outputs here

Got 404 when trying to get the script.

Some environment information:

  • OS: ubuntu 18.04
  • Python: 3.7.6
  • pip: 20.0.2
  • numpy: 1.18.5
  • mxnet: 1.6.0

Contributor guide

Tech stack
cpppython
Domain
machine learningbackend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++MXNet internalsbasic debugging
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Locate the implementation of SequenceReverse operator, likely in `src/operator/sequence reverse.cc` or similar. The floating point exception occurs when the input tensor has a zero dimension (e.g., batch size 0). Check for division by zero or invalid computation on zero length sequences. A possible fix is to add a guard at the beginning of the operator's forward function that returns early or handles zero sized tensors gracefully. Review any existing tests for sequence operators to understand expected behavior.