BERT-of-Theseus

Code for paper "BERT-of-Theseus: Compressing BERT by Progressive Module Replacing".

BERT-of-Theseus is a new compressed BERT by progressively replacing the components of the original BERT.

Citation

If you use this code in your research, please cite our paper:

@inproceedings{xu-etal-2020-bert,
    title = "{BERT}-of-Theseus: Compressing {BERT} by Progressive Module Replacing",
    author = "Xu, Canwen  and
      Zhou, Wangchunshu  and
      Ge, Tao  and
      Wei, Furu  and
      Zhou, Ming",
    booktitle = "Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP)",
    month = nov,
    year = "2020",
    address = "Online",
    publisher = "Association for Computational Linguistics",
    url = "https://www.aclweb.org/anthology/2020.emnlp-main.633",
    pages = "7859--7869"
}

NEW: We have uploaded a script for making predictions on GLUE tasks and preparing for leaderboard submission. Check out here!

How to run BERT-of-Theseus

Requirement

Our code is built on huggingface/transformers. To use our code, you must clone and install huggingface/transformers.

Compress a BERT

1. You should fine-tune a predecessor model following the instruction from huggingface and then save it to a directory if you haven't done so.
2. Run compression following the examples below:

# For compression with a replacement scheduler
export GLUE_DIR=/path/to/glue_data
export TASK_NAME=MRPC

python ./run_glue.py \
  --model_name_or_path /path/to/saved_predecessor \
  --task_name $TASK_NAME \
  --do_train \
  --do_eval \
  --do_lower_case \
  --data_dir "$GLUE_DIR/$TASK_NAME" \
  --max_seq_length 128 \
  --per_gpu_train_batch_size 32 \
  --per_gpu_eval_batch_size 32 \
  --learning_rate 2e-5 \
  --save_steps 50 \
  --num_train_epochs 15 \
  --output_dir /path/to/save_successor/ \
  --evaluate_during_training \
  --replacing_rate 0.3 \
  --scheduler_type linear \
  --scheduler_linear_k 0.0006

# For compression with a constant replacing rate
export GLUE_DIR=/path/to/glue_data
export TASK_NAME=MRPC

python ./run_glue.py \
  --model_name_or_path /path/to/saved_predecessor \
  --task_name $TASK_NAME \
  --do_train \
  --do_eval \
  --do_lower_case \
  --data_dir "$GLUE_DIR/$TASK_NAME" \
  --max_seq_length 128 \
  --per_gpu_train_batch_size 32 \
  --per_gpu_eval_batch_size 32 \
  --learning_rate 2e-5 \
  --save_steps 50 \
  --num_train_epochs 15 \
  --output_dir /path/to/save_successor/ \
  --evaluate_during_training \
  --replacing_rate 0.5 \
  --steps_for_replacing 2500 

For the detailed description of arguments, please refer to the source code.

Load Pretrained Model on MNLI

We provide a 6-layer pretrained model on MNLI as a general-purpose model, which can transfer to other sentence classification tasks, outperforming DistillBERT (with the same 6-layer structure) on six tasks of GLUE (dev set).

Method	MNLI	MRPC	QNLI	QQP	RTE	SST-2	STS-B
BERT-base	83.5	89.5	91.2	89.8	71.1	91.5	88.9
DistillBERT	79.0	87.5	85.3	84.9	59.9	90.7	81.2
BERT-of-Theseus	82.1	87.5	88.8	88.8	70.1	91.8	87.8

You can easily load our general-purpose model using huggingface/transformers.

from transformers import AutoTokenizer, AutoModel

tokenizer = AutoTokenizer.from_pretrained("canwenxu/BERT-of-Theseus-MNLI")

model = AutoModel.from_pretrained("canwenxu/BERT-of-Theseus-MNLI")

Bug Report and Contribution

If you'd like to contribute and add more tasks (only GLUE is available at this moment), please submit a pull request and contact me. Also, if you find any problem or bug, please report with an issue. Thanks!

Third-Party Implementations

We list some third-party implementations from the community here. Please kindly add your implementation to this list:

• Tensorflow Implementation (tested on NER): https://github.com/qiufengyuyi/bert-of-theseus-tf
• Keras Implementation (tested on text classification): https://github.com/bojone/bert-of-theseus