AmuNMT

A C++ inference engine for Neural Machine Translation (NMT) models trained with Theano-based scripts from Nematus (https://github.com/rsennrich/nematus) or DL4MT (https://github.com/nyu-dl/dl4mt-tutorial)

We aim at keeping compatibility with Nematus (at least as long as there is no training framework in AmunNMT), the continued compatbility with DL4MT will not be guaranteed.

If you use this, please cite:

Marcin Junczys-Dowmunt, Tomasz Dwojak, Hieu Hoang (2016). Is Neural Machine Translation Ready for Deployment? A Case Study on 30 Translation Directions (https://arxiv.org/abs/1610.01108)

Recommended for GPU version:

Tested on Ubuntu 14.04 LTS

• CMake 3.5.1 (due to CUDA related bugs in earlier versions)
• GCC/G++ 4.9
• Boost 1.54
• CUDA 7.5

Tested on Ubuntu 16.04 LTS

• CMake 3.5.1 (due to CUDA related bugs in earlier versions)
• GCC/G++ 5.4
• Boost 1.61
• CUDA 8.0

Also compiles the CPU version.

Recommended for CPU version:

The CPU-only version will automatically be compiled if CUDA cannot be detected by CMAKE. Tested on different machines and distributions:

• CMake 3.5.1
• The CPU version should be a lot more forgiving concerning GCC/G++ or Boost versions.

Compilation

The project is a standard Cmake out-of-source build:

mkdir build
cd build
cmake ..
make -j

If you want to compile only CPU version on a machine with CUDA, add -DNOCUDA=ON flag:

cmake -DNOCUDA=ON ..

Vocabulary files

Vocabulary files (and all other config files) in AmuNMT are by default YAML files. AmuNMT also reads gzipped yml.gz files.

• Vocabulary files from models trained with Nematus can be used directly as JSON is a proper subset of YAML.
• Vocabularies for models trained with DL4MT (*.pkl extension) need to be converted to JSON/YAML with either of the two scripts below:

python scripts/pkl2json.py vocab.en.pkl > vocab.json
python scripts/pkl2yaml.py vocab.en.pkl > vocab.yml

Running AmuNMT

./bin/amun -c config.yml <<< "This is a test ."

Configuration files

An example configuration:

# Paths are relative to config file location
relative-paths: yes

# performance settings
beam-size: 12
devices: [0]
normalize: yes
gpu-threads: 1

# scorer configuration
scorers:
  F0:
    path: model.en-de.npz
    type: Nematus

# scorer weights
weights:
  F0: 1.0

# vocabularies
source-vocab: vocab.en.yml.gz
target-vocab: vocab.de.yml.gz

BPE Support

AmuNMT has integrated support for BPE encoding. There are two option bpe and debpe. The bpe option receives a path to a file with BPE codes (here bpe.codes). To turn on desegmentation on the ouput, set debpe to true, e.g.

bpe: bpe.codes
debpe: true

Using GPU/CPU threads

AmuNMT can use GPUs, CPUs, or both, to distribute translation of different sentences.

cpu-threads: 8
gpu-threads: 2
devices: [0, 1]

The setting above uses 8 CPU threads and 4 GPU threads (2 GPUs x 2 threads). The gpu-threads and devices options are only available when AmuNMT has been compiled with CUDA support. Multiple GPU threads can be used to increase GPU saturation, but will likely not result in a large performance boost. By default, gpu-threads is set to 1 and cpu-threads to 0 if CUDA is available. Otherwise cpu-threads is set to 1. To disable the GPU set gpu-threads to 0. Setting both gpu-threads and cpu-threads to 0 will result in an exception.

Example usage

• Data and systems for our winning system in the WMT 2016 Shared Task on Automatic Post-Editing