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ALBERT

***************New January 7, 2020 ***************

v2 TF-Hub models should be working now with TF 1.15, as we removed the native Einsum op from the graph. See updated TF-Hub links below.

***************New December 30, 2019 ***************

Chinese models are released. We would like to thank CLUE team for providing the training data.

Version 2 of ALBERT models is released.

In this version, we apply 'no dropout', 'additional training data' and 'long training time' strategies to all models. We train ALBERT-base for 10M steps and other models for 3M steps.

The result comparison to the v1 models is as followings:

Average SQuAD1.1 SQuAD2.0 MNLI SST-2 RACE
V2
ALBERT-base 82.3 90.2/83.2 82.1/79.3 84.6 92.9 66.8
ALBERT-large 85.7 91.8/85.2 84.9/81.8 86.5 94.9 75.2
ALBERT-xlarge 87.9 92.9/86.4 87.9/84.1 87.9 95.4 80.7
ALBERT-xxlarge 90.9 94.6/89.1 89.8/86.9 90.6 96.8 86.8
V1
ALBERT-base 80.1 89.3/82.3 80.0/77.1 81.6 90.3 64.0
ALBERT-large 82.4 90.6/83.9 82.3/79.4 83.5 91.7 68.5
ALBERT-xlarge 85.5 92.5/86.1 86.1/83.1 86.4 92.4 74.8
ALBERT-xxlarge 91.0 94.8/89.3 90.2/87.4 90.8 96.9 86.5

The comparison shows that for ALBERT-base, ALBERT-large, and ALBERT-xlarge, v2 is much better than v1, indicating the importance of applying the above three strategies. On average, ALBERT-xxlarge is slightly worse than the v1, because of the following two reasons: 1) Training additional 1.5 M steps (the only difference between these two models is training for 1.5M steps and 3M steps) did not lead to significant performance improvement. 2) For v1, we did a little bit hyperparameter search among the parameters sets given by BERT, Roberta, and XLnet. For v2, we simply adopt the parameters from v1 except for RACE, where we use a learning rate of 1e-5 and 0 ALBERT DR (dropout rate for ALBERT in finetuning). The original (v1) RACE hyperparameter will cause model divergence for v2 models. Given that the downstream tasks are sensitive to the fine-tuning hyperparameters, we should be careful about so called slight improvements.

ALBERT is "A Lite" version of BERT, a popular unsupervised language representation learning algorithm. ALBERT uses parameter-reduction techniques that allow for large-scale configurations, overcome previous memory limitations, and achieve better behavior with respect to model degradation.

For a technical description of the algorithm, see our paper:

ALBERT: A Lite BERT for Self-supervised Learning of Language Representations

Zhenzhong Lan, Mingda Chen, Sebastian Goodman, Kevin Gimpel, Piyush Sharma, Radu Soricut

Release Notes

  • Initial release: 10/9/2019

Results

Performance of ALBERT on GLUE benchmark results using a single-model setup on dev:

Models MNLI QNLI QQP RTE SST MRPC CoLA STS
BERT-large 86.6 92.3 91.3 70.4 93.2 88.0 60.6 90.0
XLNet-large 89.8 93.9 91.8 83.8 95.6 89.2 63.6 91.8
RoBERTa-large 90.2 94.7 92.2 86.6 96.4 90.9 68.0 92.4
ALBERT (1M) 90.4 95.2 92.0 88.1 96.8 90.2 68.7 92.7
ALBERT (1.5M) 90.8 95.3 92.2 89.2 96.9 90.9 71.4 93.0

Performance of ALBERT-xxl on SQuaD and RACE benchmarks using a single-model setup:

Models SQuAD1.1 dev SQuAD2.0 dev SQuAD2.0 test RACE test (Middle/High)
BERT-large 90.9/84.1 81.8/79.0 89.1/86.3 72.0 (76.6/70.1)
XLNet 94.5/89.0 88.8/86.1 89.1/86.3 81.8 (85.5/80.2)
RoBERTa 94.6/88.9 89.4/86.5 89.8/86.8 83.2 (86.5/81.3)
UPM - - 89.9/87.2 -
XLNet + SG-Net Verifier++ - - 90.1/87.2 -
ALBERT (1M) 94.8/89.2 89.9/87.2 - 86.0 (88.2/85.1)
ALBERT (1.5M) 94.8/89.3 90.2/87.4 90.9/88.1 86.5 (89.0/85.5)

Pre-trained Models

TF-Hub modules are available:

Example usage of the TF-Hub module in code:

tags = set()
if is_training:
  tags.add("train")
albert_module = hub.Module("https://tfhub.dev/google/albert_base/1", tags=tags,
                           trainable=True)
albert_inputs = dict(
    input_ids=input_ids,
    input_mask=input_mask,
    segment_ids=segment_ids)
albert_outputs = albert_module(
    inputs=albert_inputs,
    signature="tokens",
    as_dict=True)

# If you want to use the token-level output, use
# albert_outputs["sequence_output"] instead.
output_layer = albert_outputs["pooled_output"]

Most of the fine-tuning scripts in this repository support TF-hub modules via the --albert_hub_module_handle flag.

Pre-training Instructions

To pretrain ALBERT, use run_pretraining.py:

pip install -r albert/requirements.txt
python -m albert.run_pretraining \
    --input_file=... \
    --output_dir=... \
    --init_checkpoint=... \
    --albert_config_file=... \
    --do_train \
    --do_eval \
    --train_batch_size=4096 \
    --eval_batch_size=64 \
    --max_seq_length=512 \
    --max_predictions_per_seq=20 \
    --optimizer='lamb' \
    --learning_rate=.00176 \
    --num_train_steps=125000 \
    --num_warmup_steps=3125 \
    --save_checkpoints_steps=5000

Fine-tuning on GLUE

To fine-tune and evaluate a pretrained ALBERT on GLUE, please see the convenience script run_glue.sh.

Lower-level use cases may want to use the run_classifier.py script directly. The run_classifier.py script is used both for fine-tuning and evaluation of ALBERT on individual GLUE benchmark tasks, such as MNLI:

pip install -r albert/requirements.txt
python -m albert.run_classifier \
  --data_dir=... \
  --output_dir=... \
  --init_checkpoint=... \
  --albert_config_file=... \
  --spm_model_file=... \
  --do_train \
  --do_eval \
  --do_predict \
  --do_lower_case \
  --max_seq_length=128 \
  --optimizer=adamw \
  --task_name=MNLI \
  --warmup_step=1000 \
  --learning_rate=3e-5 \
  --train_step=10000 \
  --save_checkpoints_steps=100 \
  --train_batch_size=128

Good default flag values for each GLUE task can be found in run_glue.sh.

You can fine-tune the model starting from TF-Hub modules instead of raw checkpoints by setting e.g. --albert_hub_module_handle=https://tfhub.dev/google/albert_base/1 instead of --init_checkpoint.

You can find the spm_model_file in the tar files or under the assets folder of the tf-hub module. The name of the model file is "30k-clean.model".

After evaluation, the script should report some output like this:

***** Eval results *****
  global_step = ...
  loss = ...
  masked_lm_accuracy = ...
  masked_lm_loss = ...
  sentence_order_accuracy = ...
  sentence_order_loss = ...

Fine-tuning on SQuAD

To fine-tune and evaluate a pretrained model on SQuAD v1, use the run_squad_v1.py script:

pip install -r albert/requirements.txt
python -m albert.run_squad_v1 \
  --albert_config_file=... \
  --output_dir=... \
  --train_file=... \
  --predict_file=... \
  --train_feature_file=... \
  --predict_feature_file=... \
  --predict_feature_left_file=... \
  --init_checkpoint=... \
  --spm_model_file=... \
  --do_lower_case \
  --max_seq_length=384 \
  --doc_stride=128 \
  --max_query_length=64 \
  --do_train=true \
  --do_predict=true \
  --train_batch_size=48 \
  --predict_batch_size=8 \
  --learning_rate=5e-5 \
  --num_train_epochs=2.0 \
  --warmup_proportion=.1 \
  --save_checkpoints_steps=5000 \
  --n_best_size=20 \
  --max_answer_length=30

You can fine-tune the model starting from TF-Hub modules instead of raw checkpoints by setting e.g. --albert_hub_module_handle=https://tfhub.dev/google/albert_base/1 instead of --init_checkpoint.

For SQuAD v2, use the run_squad_v2.py script:

pip install -r albert/requirements.txt
python -m albert.run_squad_v2 \
  --albert_config_file=... \
  --output_dir=... \
  --train_file=... \
  --predict_file=... \
  --train_feature_file=... \
  --predict_feature_file=... \
  --predict_feature_left_file=... \
  --init_checkpoint=... \
  --spm_model_file=... \
  --do_lower_case \
  --max_seq_length=384 \
  --doc_stride=128 \
  --max_query_length=64 \
  --do_train \
  --do_predict \
  --train_batch_size=48 \
  --predict_batch_size=8 \
  --learning_rate=5e-5 \
  --num_train_epochs=2.0 \
  --warmup_proportion=.1 \
  --save_checkpoints_steps=5000 \
  --n_best_size=20 \
  --max_answer_length=30

You can fine-tune the model starting from TF-Hub modules instead of raw checkpoints by setting e.g. --albert_hub_module_handle=https://tfhub.dev/google/albert_base/1 instead of --init_checkpoint.

Fine-tuning on RACE

For RACE, use the run_race.py script:

pip install -r albert/requirements.txt
python -m albert.run_race \
  --albert_config_file=... \
  --output_dir=... \
  --train_file=... \
  --eval_file=... \
  --data_dir=...\
  --init_checkpoint=... \
  --spm_model_file=... \
  --max_seq_length=512 \
  --max_qa_length=128 \
  --do_train \
  --do_eval \
  --train_batch_size=32 \
  --eval_batch_size=8 \
  --learning_rate=1e-5 \
  --train_step=12000 \
  --warmup_step=1000 \
  --save_checkpoints_steps=100

You can fine-tune the model starting from TF-Hub modules instead of raw checkpoints by setting e.g. --albert_hub_module_handle=https://tfhub.dev/google/albert_base/1 instead of --init_checkpoint.

SentencePiece

Command for generating the sentence piece vocabulary:

spm_train \
--input all.txt --model_prefix=30k-clean --vocab_size=30000 --logtostderr
--pad_id=0 --unk_id=1 --eos_id=-1 --bos_id=-1
--control_symbols=[CLS],[SEP],[MASK]
--user_defined_symbols=(,),\”,-,.,–,£,€
--shuffle_input_sentence=true --input_sentence_size=10000000
--character_coverage=0.99995 --model_type=unigram