update train.py

examples/distillation/train.py

@@ -13,7 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """
-Training DistilBERT.
+Training the distilled model.
+Supported architectures include: BERT -> DistilBERT, RoBERTa -> DistilRoBERTa, GPT2 -> DistilGPT2.
 """
 import os
 import argparse
@@ -23,68 +24,96 @@ import shutil
 import numpy as np
 import torch
 
-from transformers import BertTokenizer, BertForMaskedLM, RobertaTokenizer, RobertaForMaskedLM
+from transformers import BertConfig, BertForMaskedLM, BertTokenizer
-from transformers import DistilBertForMaskedLM, DistilBertConfig
+from transformers import RobertaConfig, RobertaForMaskedLM, RobertaTokenizer
+from transformers import DistilBertConfig, DistilBertForMaskedLM, DistilBertTokenizer
+from transformers import GPT2Config, GPT2LMHeadModel, GPT2Tokenizer
 
 from distiller import Distiller
 from utils import git_log, logger, init_gpu_params, set_seed
-from dataset import Dataset
+from lm_seqs_dataset import LmSeqsDataset
 
 
+MODEL_CLASSES = {
+    'distilbert': (DistilBertConfig, DistilBertForMaskedLM, DistilBertTokenizer),
+    'roberta': (RobertaConfig, RobertaForMaskedLM, RobertaTokenizer),
+    'bert': (BertConfig, BertForMaskedLM, BertTokenizer),
+    'gpt2': (GPT2Config, GPT2LMHeadModel, GPT2Tokenizer)
+}
+
+def sanity_checks(args):
+    """
+    A bunch of args sanity checks to perform even starting...
+    """
+    assert (args.mlm and args.alpha_mlm > 0.) or (not args.mlm and args.alpha_mlm == 0.)
+    assert (args.alpha_mlm > 0. and args.alpha_clm == 0.) or (args.alpha_mlm == 0. and args.alpha_clm > 0.)
+    if args.mlm:
+        assert os.path.isfile(args.token_counts)
+        assert (args.student_type in ['roberta', 'distilbert']) and (args.teacher_type in ['roberta', 'bert'])
+    else:
+        assert (args.student_type in ['gpt2']) and (args.teacher_type in ['gpt2'])
+
+    assert args.teacher_type == args.student_type or (args.student_type=='distilbert' and args.teacher_type=='bert')
+    assert os.path.isfile(args.student_config)
+    if args.student_pretrained_weights is not None:
+        assert os.path.isfile(args.student_pretrained_weights)
+
+    if args.freeze_token_type_embds: assert args.student_type in ['roberta']
+
+    assert args.alpha_ce >= 0.
+    assert args.alpha_mlm >= 0.
+    assert args.alpha_clm >= 0.
+    assert args.alpha_mse >= 0.
+    assert args.alpha_cos >= 0.
+    assert args.alpha_ce + args.alpha_mlm + args.alpha_clm + args.alpha_mse + args.alpha_cos > 0.
+
+def freeze_pos_embeddings(student, args):
+    if args.student_type == 'roberta':
+        student.roberta.embeddings.position_embeddings.weight.requires_grad = False
+    elif args.student_type == 'gpt2':
+        student.transformer.wpe.weight.requires_grad = False
+
+def freeze_token_type_embeddings(student, args):
+    if args.student_type == 'roberta':
+        student.roberta.embeddings.token_type_embeddings.weight.requires_grad = False
+
 def main():
     parser = argparse.ArgumentParser(description="Training")
+    parser.add_argument("--force", action='store_true',
+                        help="Overwrite dump_path if it already exists.")
 
     parser.add_argument("--dump_path", type=str, required=True,
                         help="The output directory (log, checkpoints, parameters, etc.)")
     parser.add_argument("--data_file", type=str, required=True,
                         help="The binarized file (tokenized + tokens_to_ids) and grouped by sequence.")
-    parser.add_argument("--token_counts", type=str, required=True,
-                        help="The token counts in the data_file for MLM.")
-    parser.add_argument("--force", action='store_true',
-                        help="Overwrite dump_path if it already exists.")
 
-    parser.add_argument("--vocab_size", default=30522, type=int,
+    parser.add_argument("--student_type", type=str, choices=["distilbert", "roberta", "gpt2"], required=True,
-                        help="The vocabulary size.")
+                        help="The student type (DistilBERT, RoBERTa).")
-    parser.add_argument("--max_position_embeddings", default=512, type=int,
+    parser.add_argument("--student_config", type=str, required=True,
-                        help="Maximum sequence length we can model (including [CLS] and [SEP]).")
+                        help="Path to the student configuration.")
-    parser.add_argument("--sinusoidal_pos_embds", action='store_false',
+    parser.add_argument("--student_pretrained_weights", default=None, type=str,
-                        help="If true, the position embeddings are simply fixed with sinusoidal embeddings.")
-    parser.add_argument("--n_layers", default=6, type=int,
-                        help="Number of Transformer blocks.")
-    parser.add_argument("--n_heads", default=12, type=int,
-                        help="Number of heads in the self-attention module.")
-    parser.add_argument("--dim", default=768, type=int,
-                        help="Dimension through the network. Must be divisible by n_heads")
-    parser.add_argument("--hidden_dim", default=3072, type=int,
-                        help="Intermediate dimension in the FFN.")
-    parser.add_argument("--dropout", default=0.1, type=float,
-                        help="Dropout.")
-    parser.add_argument("--attention_dropout", default=0.1, type=float,
-                        help="Dropout in self-attention.")
-    parser.add_argument("--activation", default='gelu', type=str,
-                        help="Activation to use in self-attention")
-    parser.add_argument("--tie_weights_", action='store_false',
-                        help="If true, we tie the embeddings matrix with the projection over the vocabulary matrix. Default is true.")
-
-    parser.add_argument("--from_pretrained_weights", default=None, type=str,
                         help="Load student initialization checkpoint.")
-    parser.add_argument("--from_pretrained_config", default=None, type=str,
+
-                        help="Load student initialization architecture config.")
+    parser.add_argument("--teacher_type", choices=["bert", "roberta", "gpt2"], required=True,
-    parser.add_argument("--teacher_type", default="bert", choices=["bert", "roberta"],
                         help="Teacher type (BERT, RoBERTa).")
-    parser.add_argument("--teacher_name", default="bert-base-uncased", type=str,
+    parser.add_argument("--teacher_name", type=str, required=True,
                         help="The teacher model.")
 
     parser.add_argument("--temperature", default=2., type=float,
                         help="Temperature for the softmax temperature.")
     parser.add_argument("--alpha_ce", default=0.5, type=float,
                         help="Linear weight for the distillation loss. Must be >=0.")
-    parser.add_argument("--alpha_mlm", default=0.5, type=float,
+    parser.add_argument("--alpha_mlm", default=0.0, type=float,
-                        help="Linear weight for the MLM loss. Must be >=0.")
+                        help="Linear weight for the MLM loss. Must be >=0. Should be used in coonjunction with `mlm` flag.")
+    parser.add_argument("--alpha_clm", default=0.5, type=float,
+                        help="Linear weight for the CLM loss. Must be >=0.")
     parser.add_argument("--alpha_mse", default=0.0, type=float,
                         help="Linear weight of the MSE loss. Must be >=0.")
     parser.add_argument("--alpha_cos", default=0.0, type=float,
                         help="Linear weight of the cosine embedding loss. Must be >=0.")
+
+    parser.add_argument("--mlm", action="store_true",
+                        help="The LM step: MLM or CLM. If `mlm` is True, the MLM is used over CLM.")
     parser.add_argument("--mlm_mask_prop", default=0.15, type=float,
                         help="Proportion of tokens for which we need to make a prediction.")
     parser.add_argument("--word_mask", default=0.8, type=float,
@@ -95,17 +124,20 @@ def main():
                         help="Proportion of tokens to randomly replace.")
     parser.add_argument("--mlm_smoothing", default=0.7, type=float,
                         help="Smoothing parameter to emphasize more rare tokens (see XLM, similar to word2vec).")
+    parser.add_argument("--token_counts", type=str,
+                        help="The token counts in the data_file for MLM.")
+
     parser.add_argument("--restrict_ce_to_mask", action='store_true',
                         help="If true, compute the distilation loss only the [MLM] prediction distribution.")
+    parser.add_argument("--freeze_pos_embs", action="store_true",
+                        help="Freeze positional embeddings during distillation. For student_type in ['roberta', 'gpt2'] only.")
+    parser.add_argument("--freeze_token_type_embds", action="store_true",
+                        help="Freeze token type embeddings during distillation if existent. For student_type in ['roberta'] only.")
 
     parser.add_argument("--n_epoch", type=int, default=3,
                         help="Number of pass on the whole dataset.")
     parser.add_argument("--batch_size", type=int, default=5,
                         help="Batch size (for each process).")
-    parser.add_argument("--tokens_per_batch", type=int, default=-1,
-                        help="If specified, modify the batches so that they have approximately this number of tokens.")
-    parser.add_argument("--shuffle", action='store_false',
-                        help="If true, shuffle the sequence order. Default is true.")
     parser.add_argument("--group_by_size", action='store_false',
                         help="If true, group sequences that have similar length into the same batch. Default is true.")
 
@@ -141,6 +173,7 @@ def main():
     parser.add_argument("--checkpoint_interval", type=int, default=4000,
                         help="Checkpoint interval.")
     args = parser.parse_args()
+    sanity_checks(args)
 
 
     ## ARGS ##
@@ -164,21 +197,19 @@ def main():
         with open(os.path.join(args.dump_path, 'parameters.json'), 'w') as f:
             json.dump(vars(args), f, indent=4)
         git_log(args.dump_path)
-    assert (args.from_pretrained_weights is None and args.from_pretrained_config is None) or \
-           (args.from_pretrained_weights is not None and args.from_pretrained_config is not None)
 
+    student_config_class, student_model_class, _ = MODEL_CLASSES[args.student_type]
+    teacher_config_class, teacher_model_class, teacher_tokenizer_class = MODEL_CLASSES[args.teacher_type]
 
     ### TOKENIZER ###
-    if args.teacher_type == 'bert':
+    tokenizer = teacher_tokenizer_class.from_pretrained(args.teacher_name)
-        tokenizer = BertTokenizer.from_pretrained(args.teacher_name)
-    elif args.teacher_type == 'roberta':
-        tokenizer = RobertaTokenizer.from_pretrained(args.teacher_name)
     special_tok_ids = {}
     for tok_name, tok_symbol in tokenizer.special_tokens_map.items():
         idx = tokenizer.all_special_tokens.index(tok_symbol)
         special_tok_ids[tok_name] = tokenizer.all_special_ids[idx]
     logger.info(f'Special tokens {special_tok_ids}')
     args.special_tok_ids = special_tok_ids
+    args.max_model_input_size = tokenizer.max_model_input_sizes[args.teacher_name]
 
 
     ## DATA LOADER ##
@@ -187,35 +218,34 @@ def main():
         data = pickle.load(fp)
 
 
-    assert os.path.isfile(args.token_counts)
+    if args.mlm:
-    logger.info(f'Loading token counts from {args.token_counts} (already pre-computed)')
+        logger.info(f'Loading token counts from {args.token_counts} (already pre-computed)')
-    with open(args.token_counts, 'rb') as fp:
+        with open(args.token_counts, 'rb') as fp:
-        counts = pickle.load(fp)
+            counts = pickle.load(fp)
-        assert len(counts) == args.vocab_size
+        
-    token_probs = np.maximum(counts, 1) ** -args.mlm_smoothing
+        token_probs = np.maximum(counts, 1) ** -args.mlm_smoothing
-    for idx in special_tok_ids.values():
+        for idx in special_tok_ids.values():
-        token_probs[idx] = 0.  # do not predict special tokens
+            token_probs[idx] = 0.  # do not predict special tokens
-    token_probs = torch.from_numpy(token_probs)
+        token_probs = torch.from_numpy(token_probs)
+    else:
+        token_probs = None
 
 
-    train_dataloader = Dataset(params=args, data=data)
+    train_lm_seq_dataset = LmSeqsDataset(params=args, data=data)
     logger.info(f'Data loader created.')
 
 
     ## STUDENT ##
-    if args.from_pretrained_weights is not None:
+    logger.info(f'Loading student config from {args.student_config}')
-        assert os.path.isfile(args.from_pretrained_weights)
+    stu_architecture_config = student_config_class.from_pretrained(args.student_config)
-        assert os.path.isfile(args.from_pretrained_config)
+    stu_architecture_config.output_hidden_states = True
-        logger.info(f'Loading pretrained weights from {args.from_pretrained_weights}')
+
-        logger.info(f'Loading pretrained config from {args.from_pretrained_config}')
+    if args.student_pretrained_weights is not None:
-        stu_architecture_config = DistilBertConfig.from_json_file(args.from_pretrained_config)
+        logger.info(f'Loading pretrained weights from {args.student_pretrained_weights}')
-        stu_architecture_config.output_hidden_states = True
+        student = student_model_class.from_pretrained(args.student_pretrained_weights,
-        student = DistilBertForMaskedLM.from_pretrained(args.from_pretrained_weights,
+                                                      config=stu_architecture_config)
-                                                        config=stu_architecture_config)
     else:
-        args.vocab_size_or_config_json_file = args.vocab_size
+        student = student_model_class(stu_architecture_config)
-        stu_architecture_config = DistilBertConfig(**vars(args), output_hidden_states=True)
-        student = DistilBertForMaskedLM(stu_architecture_config)
 
 
     if args.n_gpu > 0:
@@ -224,18 +254,31 @@ def main():
 
 
     ## TEACHER ##
-    if args.teacher_type == 'bert':
+    teacher = teacher_model_class.from_pretrained(args.teacher_name, output_hidden_states=True)
-        teacher = BertForMaskedLM.from_pretrained(args.teacher_name, output_hidden_states=True)
-    elif args.teacher_type == 'roberta':
-        teacher = RobertaForMaskedLM.from_pretrained(args.teacher_name, output_hidden_states=True)
     if args.n_gpu > 0:
         teacher.to(f'cuda:{args.local_rank}')
     logger.info(f'Teacher loaded from {args.teacher_name}.')
 
+
+    ## FREEZING ##
+    if args.freeze_pos_embs:
+        freeze_pos_embeddings(student, args)
+    if args.freeze_token_type_embds:
+        freeze_token_type_embeddings(student, args)
+
+
+    ## SANITY CHECKS ##
+    assert student.config.vocab_size == teacher.config.vocab_size
+    assert student.config.hidden_size == teacher.config.hidden_size
+    assert student.config.max_position_embeddings == teacher.config.max_position_embeddings
+    if args.mlm:
+        assert token_probs.size(0) == stu_architecture_config.vocab_size
+
+
     ## DISTILLER ##
     torch.cuda.empty_cache()
     distiller = Distiller(params=args,
-                          dataloader=train_dataloader,
+                          dataset=train_lm_seq_dataset,
                           token_probs=token_probs,
                           student=student,
                           teacher=teacher)