Floating point exception in mxnet.ndarray.op.SequenceReverse

[leeyeetonn]

Description

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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

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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

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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

[szha]

So here's the problem:

% DMLC_LOG_STACK_TRACE_DEPTH=150 MXNET_ENGINE_TYPE=NaiveEngine lldb python3.7 -- test_18940.py
(lldb) target create "python3.7"
Current executable set to 'python3.7' (x86_64).
(lldb) settings set -- target.run-args  "test_18940.py"
(lldb) run
Process 78879 launched: '/usr/local/bin/python3.7' (x86_64)
Process 78879 stopped
* thread #2, stop reason = exec
    frame #0: 0x0000000100006000 dyld`_dyld_start
dyld`_dyld_start:
->  0x100006000 <+0>: popq   %rdi
    0x100006001 <+1>: pushq  $0x0
    0x100006003 <+3>: movq   %rsp, %rbp
    0x100006006 <+6>: andq   $-0x10, %rsp
(lldb) cont
Process 78879 resuming
[23:52:34] ../src/engine/engine.cc:55: MXNet start using engine: NaiveEngine
Process 78879 stopped
* thread #2, queue = 'com.apple.main-thread', stop reason = EXC_ARITHMETIC (code=EXC_I386_DIV, subcode=0x0)
    frame #0: 0x0000000115861a13 libmxnet.dylib`mxnet::op::SequenceReverseOp<mshadow::cpu, float, float>::Forward(this=0x0000000123da0db0, ctx=0x00007ffeefbfc2b0, in_data=0x0000000127b7a2f8, req=0x00007ffeefbfc310, out_data=0x0000000127b7a340, aux_args=0x0000000127b7a328) at sequence_reverse-inl.h:139
   136 	    auto max_seq_len = in_data[seq_reverse::kData].size(0);
   137 	    auto n = in_data[seq_reverse::kData].size(1);
   138 	    auto total_size = in_data[seq_reverse::kData].Size();
-> 139 	    auto rest_dim = static_cast<int>(total_size / n / max_seq_len);
   140
   141 	    Shape<3> s3 = Shape3(max_seq_len, n, rest_dim);
   142 	    Tensor<xpu, 3, DType> data =

https://github.com/apache/incubator-mxnet/blob/9bdd4d6347c284770ee5bfe5ae98f1dabc283829/src/operator/sequence_reverse-inl.h#L139

The code needs to guard against zero-size array for right operand of /, and we should add a smoke test to guard against such problem in this op, similar to https://github.com/apache/incubator-mxnet/pull/18972/files

[pranjii]

Could I get this assigned??

[vijaya-lakshmi-venkatraman]

Hello,
I see a PR merged for this issue.
Is this still open?

[Pheewww]

It seems like there is an arithmetic error in the code where the right operand of the division operator is zero, causing an EXC_ARITHMETIC exception. One way to guard against this error is to add a conditional statement that checks if the right operand is zero before executing the division operation.

can i work on it if it's still open?