bricksdont opened a new issue #19073:
URL: https://github.com/apache/incubator-mxnet/issues/19073
## Description
Multinomial sampling produces impossible values.
If I understand correctly, if `mx.random.multinomial` is given a
distribution such as:
dist = mx.nd.array([0.3, 0.2, 0.4, 0.1])
sample = mx.random.multinomial(dist)
Since, [according to the documentation, outputs are
0-indexed,](https://mxnet.incubator.apache.org/versions/1.6/api/python/docs/api/ndarray/random/index.html#mxnet.ndarray.random.multinomial)
the sample value can be either 0, 1, 2 or 3 - but never 4. But in Sockeye and
in simple tests (see below), very often 5 would be returned.
### Error Message
The actual error appears in Sockeye, please refer to this issue for details:
https://github.com/awslabs/sockeye/issues/866
To summarize, calling `random.multinomial` on some occasions returns
impossible values.
## To Reproduce
To reproduce the Sockeye error that is thrown:
https://gist.github.com/bricksdont/58dfa0964201c83961a30f23406baa5d
To reproduce the MXnet behaviour in isolation:
https://gist.github.com/bricksdont/e0304b9cc6ecbcc868368353d6e6262c
### Steps to reproduce
Run the shell scripts as indicated in the gists above, e.g.
python sample_mxnet.py --seed 1 --context cpu --num-trials 10
--dist-size 20
## 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/apache/incubator-mxnet/master/tools/diagnose.py
| python
----------Python Info----------
Version : 3.5.2
Compiler : GCC 5.4.0 20160609
Build : ('default', 'Apr 16 2020 17:47:17')
Arch : ('64bit', 'ELF')
------------Pip Info-----------
Version : 20.2.2
Directory :
/net/cephfs/scratch/mathmu/map-volatility/venvs/sockeye3-cpu/lib/python3.5/site-packages/pip
----------MXNet Info-----------
Version : 1.6.0
Directory :
/net/cephfs/scratch/mathmu/map-volatility/venvs/sockeye3-cpu/lib/python3.5/site-packages/mxnet
Commit Hash : 6eec9da55c5096079355d1f1a5fa58dcf35d6752
Library :
['/net/cephfs/scratch/mathmu/map-volatility/venvs/sockeye3-cpu/lib/python3.5/site-packages/mxnet/libmxnet.so']
Build features:
✖ CUDA
✖ CUDNN
✖ NCCL
✖ CUDA_RTC
✖ TENSORRT
✔ CPU_SSE
✔ CPU_SSE2
✔ CPU_SSE3
✔ CPU_SSE4_1
✔ CPU_SSE4_2
✖ CPU_SSE4A
✔ CPU_AVX
✖ CPU_AVX2
✔ OPENMP
✖ SSE
✔ F16C
✖ JEMALLOC
✔ BLAS_OPEN
✖ BLAS_ATLAS
✖ BLAS_MKL
✖ BLAS_APPLE
✔ LAPACK
✖ MKLDNN
✔ OPENCV
✖ CAFFE
✖ PROFILER
✔ DIST_KVSTORE
✖ CXX14
✖ INT64_TENSOR_SIZE
✔ SIGNAL_HANDLER
✖ DEBUG
✖ TVM_OP
----------System Info----------
Platform : Linux-4.15.0-101-generic-x86_64-with-Ubuntu-16.04-xenial
system : Linux
node : login0
release : 4.15.0-101-generic
version : #102~16.04.1-Ubuntu SMP Mon May 11 11:38:16 UTC 2020
----------Hardware Info----------
machine : x86_64
processor : x86_64
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 8
On-line CPU(s) list: 0-7
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 8
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 60
Model name: Intel Core Processor (Haswell, no TSX)
Stepping: 1
CPU MHz: 2394.454
BogoMIPS: 4788.90
Hypervisor vendor: KVM
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 4096K
NUMA node0 CPU(s): 0-7
Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx rdtscp lm constant_tsc
rep_good nopl cpuid tsc_known_freq pni pclmulqdq ssse3 fma cx16 pcid sse4_1
sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand
hypervisor lahf_lm abm invpcid_single pti fsgsbase bmi1 avx2 smep bmi2 erms
invpcid xsaveopt arat
----------Network Test----------
Setting timeout: 10
Timing for PYPI: https://pypi.python.org/pypi/pip, DNS: 0.0138 sec, LOAD:
0.4219 sec.
Error open Conda: https://repo.continuum.io/pkgs/free/, HTTP Error 403:
Forbidden, DNS finished in 0.003739595413208008 sec.
Timing for MXNet: https://github.com/apache/incubator-mxnet, DNS: 0.0034
sec, LOAD: 0.5792 sec.
Timing for Gluon Tutorial(cn): https://zh.gluon.ai, DNS: 0.0445 sec, LOAD:
0.7186 sec.
Timing for Gluon Tutorial(en): http://gluon.mxnet.io, DNS: 0.0868 sec, LOAD:
0.2290 sec.
Timing for FashionMNIST:
https://apache-mxnet.s3-accelerate.dualstack.amazonaws.com/gluon/dataset/fashion-mnist/train-labels-idx1-ubyte.gz,
DNS: 0.2111 sec, LOAD: 0.7232 sec.
----------Environment----------
```
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