Remaining arguments

examples/run_tf_glue.py

@@ -1,3 +1,22 @@
+# coding=utf-8
+# Copyright 2018 The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+""" Finetuning the library models for sequence classification on GLUE (Bert, XLM, XLNet, RoBERTa)."""
+
+
+import argparse
+import logging
 import os
 
 import tensorflow as tf
@@ -5,104 +24,309 @@ import tensorflow_datasets
 
 from transformers import (
     BertConfig,
-    BertForSequenceClassification,
     BertTokenizer,
+    DistilBertConfig,
+    DistilBertTokenizer,
+    RobertaConfig,
+    RobertaTokenizer,
     TFBertForSequenceClassification,
-    glue_convert_examples_to_features,
-    glue_processors,
+    TFDistilBertForSequenceClassification,
+    TFRobertaForSequenceClassification,
+    TFXLMForSequenceClassification,
+    TFXLNetForSequenceClassification,
+    XLMConfig,
+    XLMTokenizer,
+    XLNetConfig,
+    XLNetTokenizer,
+)
+from transformers import glue_convert_examples_to_features as convert_examples_to_features
+from transformers import glue_output_modes as output_modes
+from transformers import glue_processors as processors
+
+
+logger = logging.getLogger(__name__)
+
+ALL_MODELS = sum(
+    (
+        tuple(conf.pretrained_config_archive_map.keys())
+        for conf in (BertConfig, XLNetConfig, XLMConfig, RobertaConfig, DistilBertConfig)
+    ),
+    (),
 )
 
-
-# script parameters
-BATCH_SIZE = 32
-EVAL_BATCH_SIZE = BATCH_SIZE * 2
-USE_XLA = False
-USE_AMP = False
-EPOCHS = 3
-
-TASK = "mrpc"
-
-if TASK == "sst-2":
-    TFDS_TASK = "sst2"
-elif TASK == "sts-b":
-    TFDS_TASK = "stsb"
-else:
-    TFDS_TASK = TASK
-
-num_labels = len(glue_processors[TASK]().get_labels())
-print(num_labels)
-
-tf.config.optimizer.set_jit(USE_XLA)
-tf.config.optimizer.set_experimental_options({"auto_mixed_precision": USE_AMP})
-
-# Load tokenizer and model from pretrained model/vocabulary. Specify the number of labels to classify (2+: classification, 1: regression)
-config = BertConfig.from_pretrained("bert-base-cased", num_labels=num_labels)
-tokenizer = BertTokenizer.from_pretrained("bert-base-cased")
-model = TFBertForSequenceClassification.from_pretrained("bert-base-cased", config=config)
-
-# Load dataset via TensorFlow Datasets
-data, info = tensorflow_datasets.load(f"glue/{TFDS_TASK}", with_info=True)
-train_examples = info.splits["train"].num_examples
-
-# MNLI expects either validation_matched or validation_mismatched
-valid_examples = info.splits["validation"].num_examples
-
-# Prepare dataset for GLUE as a tf.data.Dataset instance
-train_dataset = glue_convert_examples_to_features(data["train"], tokenizer, 128, TASK)
-
-# MNLI expects either validation_matched or validation_mismatched
-valid_dataset = glue_convert_examples_to_features(data["validation"], tokenizer, 128, TASK)
-train_dataset = train_dataset.shuffle(128).batch(BATCH_SIZE).repeat(-1)
-valid_dataset = valid_dataset.batch(EVAL_BATCH_SIZE)
-
-# Prepare training: Compile tf.keras model with optimizer, loss and learning rate schedule
-opt = tf.keras.optimizers.Adam(learning_rate=3e-5, epsilon=1e-08)
-if USE_AMP:
-    # loss scaling is currently required when using mixed precision
-    opt = tf.keras.mixed_precision.experimental.LossScaleOptimizer(opt, "dynamic")
+MODEL_CLASSES = {
+    "bert": (BertConfig, TFBertForSequenceClassification, BertTokenizer),
+    "xlnet": (XLNetConfig, TFXLNetForSequenceClassification, XLNetTokenizer),
+    "xlm": (XLMConfig, TFXLMForSequenceClassification, XLMTokenizer),
+    "roberta": (RobertaConfig, TFRobertaForSequenceClassification, RobertaTokenizer),
+    "distilbert": (DistilBertConfig, TFDistilBertForSequenceClassification, DistilBertTokenizer),
+}
 
 
-if num_labels == 1:
-    loss = tf.keras.losses.MeanSquaredError()
-else:
-    loss = tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True)
+def load_and_cache_examples(args, data, task, tokenizer, split):
+    if task == "mnli" and split == "validation":
+        split = "validation_matched"
 
-metric = tf.keras.metrics.SparseCategoricalAccuracy("accuracy")
-model.compile(optimizer=opt, loss=loss, metrics=[metric])
+    features_output_dir = os.path.join(args.output_dir, "features")
+    cached_features_file = os.path.join(
+        features_output_dir,
+        "cached_{}_{}_{}_{}.tfrecord".format(
+            split, list(filter(None, args.model_name_or_path.split("/"))).pop(), str(args.max_seq_length), str(task)
+        ),
+    )
 
-# Train and evaluate using tf.keras.Model.fit()
-train_steps = train_examples // BATCH_SIZE
-valid_steps = valid_examples // EVAL_BATCH_SIZE
+    if not os.path.exists(cached_features_file) or args.overwrite_cache:
+        logger.info("Converting examples to features")
+        dataset = convert_examples_to_features(data[split], tokenizer, args.max_seq_length, task)
 
-history = model.fit(
-    train_dataset,
-    epochs=EPOCHS,
-    steps_per_epoch=train_steps,
-    validation_data=valid_dataset,
-    validation_steps=valid_steps,
-)
+        if not os.path.exists(features_output_dir):
+            os.makedirs(features_output_dir)
 
-# Save TF2 model
-os.makedirs("./save/", exist_ok=True)
-model.save_pretrained("./save/")
+        with tf.compat.v1.python_io.TFRecordWriter(cached_features_file) as tfwriter:
+            for feature in dataset:
+                example, label = feature
+                feature_key_value_pair = {
+                    "input_ids": tf.train.Feature(int64_list=tf.train.Int64List(value=example["input_ids"])),
+                    "attention_mask": tf.train.Feature(int64_list=tf.train.Int64List(value=example["attention_mask"])),
+                    "token_type_ids": tf.train.Feature(int64_list=tf.train.Int64List(value=example["token_type_ids"])),
+                    "label": tf.train.Feature(int64_list=tf.train.Int64List(value=[label])),
+                }
+                features = tf.train.Features(feature=feature_key_value_pair)
+                example = tf.train.Example(features=features)
 
-if TASK == "mrpc":
-    # Load the TensorFlow model in PyTorch for inspection
-    # This is to demo the interoperability between the two frameworks, you don't have to
-    # do this in real life (you can run the inference on the TF model).
-    pytorch_model = BertForSequenceClassification.from_pretrained("./save/", from_tf=True)
+                tfwriter.write(example.SerializeToString())
 
-    # Quickly test a few predictions - MRPC is a paraphrasing task, let's see if our model learned the task
-    sentence_0 = "This research was consistent with his findings."
-    sentence_1 = "His findings were compatible with this research."
-    sentence_2 = "His findings were not compatible with this research."
-    inputs_1 = tokenizer.encode_plus(sentence_0, sentence_1, add_special_tokens=True, return_tensors="pt")
-    inputs_2 = tokenizer.encode_plus(sentence_0, sentence_2, add_special_tokens=True, return_tensors="pt")
+        logger.info("Features saved to cache")
 
-    del inputs_1["special_tokens_mask"]
-    del inputs_2["special_tokens_mask"]
+    features = {
+        "input_ids": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+        "attention_mask": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+        "token_type_ids": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+        "label": tf.io.FixedLenFeature([], tf.int64),
+    }
 
-    pred_1 = pytorch_model(**inputs_1)[0].argmax().item()
-    pred_2 = pytorch_model(**inputs_2)[0].argmax().item()
-    print("sentence_1 is", "a paraphrase" if pred_1 else "not a paraphrase", "of sentence_0")
-    print("sentence_2 is", "a paraphrase" if pred_2 else "not a paraphrase", "of sentence_0")
+    def select_data_from_record(record):
+        record = tf.io.parse_single_example(record, features)
+        x = {
+            "input_ids": record["input_ids"],
+            "attention_mask": record["attention_mask"],
+            "token_type_ids": record["token_type_ids"],
+        }
+        y = record["label"]
+        return (x, y)
+
+    dataset = tf.data.TFRecordDataset(cached_features_file)
+    dataset = dataset.map(select_data_from_record)
+
+    logger.info("Created dataset %s from TFRecord" % split)
+    return dataset
+
+
+def main():
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument(
+        "--model_type",
+        default=None,
+        type=str,
+        required=True,
+        help="Model type selected in the list: " + ", ".join(MODEL_CLASSES.keys()),
+    )
+    parser.add_argument(
+        "--model_name_or_path",
+        default=None,
+        type=str,
+        required=True,
+        help="Path to pre-trained model or shortcut name selected in the list: " + ", ".join(ALL_MODELS),
+    )
+    parser.add_argument(
+        "--task_name",
+        default=None,
+        type=str,
+        required=True,
+        help="The name of the task to train selected in the list: " + ", ".join(processors.keys()),
+    )
+    parser.add_argument(
+        "--output_dir",
+        default=None,
+        type=str,
+        required=True,
+        help="The output directory where the model predictions and checkpoints will be written.",
+    )
+    parser.add_argument(
+        "--overwrite_output_dir", action="store_true", help="Overwrite the content of the output directory"
+    )
+
+    parser.add_argument("--do_train", action="store_true", help="Whether to run training.")
+    parser.add_argument("--do_eval", action="store_true", help="Whether to run eval on the dev set.")
+    parser.add_argument(
+        "--evaluate_during_training", action="store_true", help="Rul evaluation during training at each logging step."
+    )
+
+    parser.add_argument("--train_batch_size", default=8, type=int, help="Batch size per GPU/CPU for training.")
+    parser.add_argument(
+        "--valid_batch_size", default=8, type=int, help="Batch size per GPU/CPU for validation during training."
+    )
+    parser.add_argument(
+        "--test_batch_size", default=8, type=int, help="Batch size per GPU/CPU for evaluation after training."
+    )
+    parser.add_argument(
+        "--overwrite_cache", action="store_true", help="Overwrite the cached training and evaluation sets"
+    )
+
+    parser.add_argument("--num_train_epochs", default=3, type=int, help="Total number of training epochs to perform.")
+    parser.add_argument("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.")
+    parser.add_argument("--adam_epsilon", default=1e-8, type=float, help="Epsilon for Adam optimizer.")
+    parser.add_argument(
+        "--max_seq_length",
+        default=128,
+        type=int,
+        help="The maximum total input sequence length after tokenization. Sequences longer "
+        "than this will be truncated, sequences shorter will be padded.",
+    )
+    parser.add_argument(
+        "--do_lower_case", action="store_true", help="Set this flag if you are using an uncased model."
+    )
+
+    parser.add_argument(
+        "--config_name", default="", type=str, help="Pretrained config name or path if not the same as model_name"
+    )
+    parser.add_argument(
+        "--tokenizer_name",
+        default="",
+        type=str,
+        help="Pretrained tokenizer name or path if not the same as model_name",
+    )
+    parser.add_argument(
+        "--cache_dir",
+        default="",
+        type=str,
+        help="Where do you want to store the pre-trained models downloaded from s3",
+    )
+    parser.add_argument("--xla", action="store_true", help="Whether to use XLA (Accelerated Linear Algebra).")
+    parser.add_argument("--amp", action="store_true", help="Whether to use AMP (Automatic Mixed Precision).")
+    parser.add_argument(
+        "--force_download",
+        action="store_true",
+        help="Whether to force download the weights from S3 (useful if the file is corrupted).",
+    )
+    args = parser.parse_args()
+
+    # Setup logging
+    logging.basicConfig(
+        format="%(asctime)s - %(levelname)s - %(name)s -   %(message)s",
+        datefmt="%m/%d/%Y %H:%M:%S",
+        level=logging.INFO,
+    )
+
+    if os.path.exists(args.output_dir) and args.do_train:
+        if not args.overwrite_output_dir and bool(
+            [file for file in os.listdir(args.output_dir) if "features" not in file]
+        ):
+            raise ValueError(
+                "Output directory ({}) already exists and is not empty. Use --overwrite_output_dir to overcome.".format(
+                    args.output_dir
+                )
+            )
+
+    args.model_type = args.model_type.lower()
+    config_class, model_class, tokenizer_class = MODEL_CLASSES[args.model_type]
+
+    TASK = args.task_name.lower()
+
+    if TASK not in processors:
+        raise ValueError("Task not found: %s" % (TASK))
+
+    if TASK == "sst-2":
+        TFDS_TASK = "sst2"
+    elif TASK == "sts-b":
+        TFDS_TASK = "stsb"
+    else:
+        TFDS_TASK = TASK
+
+    num_labels = len(processors[TASK]().get_labels())
+    print(num_labels)
+
+    tf.config.optimizer.set_jit(args.xla)
+    tf.config.optimizer.set_experimental_options({"auto_mixed_precision": args.amp})
+
+    # Load tokenizer and model from pretrained model/vocabulary. Specify the number of labels to classify (2+: classification, 1: regression)
+    config = config_class.from_pretrained(
+        args.config_name if args.config_name else args.model_name_or_path,
+        num_labels=num_labels,
+        finetuning_task=args.task_name,
+        cache_dir=args.cache_dir if args.cache_dir else None,
+        force_download=args.force_download,
+    )
+
+    tokenizer = tokenizer_class.from_pretrained(
+        args.tokenizer_name if args.tokenizer_name else args.model_name_or_path,
+        do_lower_case=args.do_lower_case,
+        cache_dir=args.cache_dir if args.cache_dir else None,
+        force_download=args.force_download,
+    )
+
+    model = model_class.from_pretrained(
+        args.model_name_or_path,
+        config=config,
+        cache_dir=args.cache_dir if args.cache_dir else None,
+        force_download=args.force_download,
+    )
+
+    # Load dataset via TensorFlow Datasets
+    data, info = tensorflow_datasets.load("glue/%s" % TFDS_TASK, with_info=True)
+
+    # Prepare training: Compile tf.keras model with optimizer, loss and learning rate schedule
+    opt = tf.keras.optimizers.Adam(learning_rate=args.learning_rate, epsilon=args.adam_epsilon)
+
+    if args.amp:
+        # loss scaling is currently required when using mixed precision
+        opt = tf.keras.mixed_precision.experimental.LossScaleOptimizer(opt, "dynamic")
+
+    if num_labels == 1:
+        loss = tf.keras.losses.MeanSquaredError()
+    else:
+        loss = tf.keras.losses.SparseCategoricalCrossentropy(from_logits=True)
+
+    metric = tf.keras.metrics.SparseCategoricalAccuracy("accuracy")
+    model.compile(optimizer=opt, loss=loss, metrics=[metric])
+
+    class save_model(tf.keras.callbacks.Callback):
+        def on_epoch_end(self, epoch, logs=None):
+            print("Saving model at epoch {}".format(epoch))
+            output_dir = os.path.join(args.output_dir, "checkpoint-epoch-{}".format(epoch))
+            if not os.path.exists(output_dir):
+                os.makedirs(output_dir)
+            self.model.save_pretrained(output_dir)
+
+    if args.do_train:
+        train_dataset = load_and_cache_examples(args, data=data, task=TASK, tokenizer=tokenizer, split="train")
+        train_dataset = train_dataset.batch(args.train_batch_size).repeat(args.num_train_epochs)
+        train_examples = info.splits["train"].num_examples / args.train_batch_size
+
+        validation_identifier = "validation_mismatched" if TASK == "mnli" else "validation"
+        valid_dataset = load_and_cache_examples(
+            args, data=data, task=TASK, tokenizer=tokenizer, split=validation_identifier
+        )
+        valid_dataset = valid_dataset.batch(args.valid_batch_size)
+        valid_examples = info.splits[validation_identifier].num_examples / args.valid_batch_size
+
+        history = model.fit(
+            train_dataset,
+            steps_per_epoch=train_examples,
+            epochs=args.num_train_epochs,
+            validation_data=valid_dataset if args.evaluate_during_training else None,
+            validation_steps=valid_examples if args.evaluate_during_training else None,
+            callbacks=[save_model()],
+        )
+
+    if args.do_eval:
+        test_dataset = load_and_cache_examples(args, data=data, task=TASK, tokenizer=tokenizer, split="test")
+        test_dataset = test_dataset.batch(args.test_batch_size)
+        test_examples = info.splits["test"].num_examples / args.test_batch_size
+
+        results = model.evaluate(test_dataset, steps=test_examples)
+
+
+if __name__ == "__main__":
+    main()

examples/run_tf_squad.py

@@ -0,0 +1,699 @@
+# Copyright 2018 The HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+""" Finetuning the library models for sequence classification on GLUE (Bert, XLM, XLNet, RoBERTa)."""
+from __future__ import absolute_import, division, print_function
+
+import argparse
+import datetime
+import glob
+import logging
+import math
+import os
+import pickle
+
+import regex as re
+import tensorflow as tf
+from fastprogress import master_bar, progress_bar
+from seqeval import metrics
+from tqdm import tqdm, trange
+
+from transformers import (
+    TF2_WEIGHTS_NAME,
+    BertConfig,
+    BertTokenizer,
+    DistilBertConfig,
+    DistilBertTokenizer,
+    GradientAccumulator,
+    SquadV1Processor,
+    SquadV2Processor,
+    TFBertForQuestionAnswering,
+    TFDistilBertForQuestionAnswering,
+    TFXLMForQuestionAnsweringSimple,
+    TFXLNetForQuestionAnsweringSimple,
+    XLMConfig,
+    XLMTokenizer,
+    XLNetConfig,
+    XLNetTokenizer,
+    create_optimizer,
+    squad_convert_examples_to_features,
+)
+from transformers.data.metrics.squad_metrics import compute_predictions_logits, squad_evaluate
+from transformers.data.processors.squad import SquadResult
+
+
+logger = logging.getLogger(__name__)
+
+ALL_MODELS = sum(
+    (
+        tuple(conf.pretrained_config_archive_map.keys())
+        for conf in (BertConfig, XLNetConfig, XLMConfig, DistilBertConfig)
+    ),
+    (),
+)
+
+MODEL_CLASSES = {
+    "bert": (BertConfig, TFBertForQuestionAnswering, BertTokenizer),
+    "xlnet": (XLNetConfig, TFXLNetForQuestionAnsweringSimple, XLNetTokenizer),
+    "xlm": (XLMConfig, TFXLMForQuestionAnsweringSimple, XLMTokenizer),
+    "distilbert": (DistilBertConfig, TFDistilBertForQuestionAnswering, DistilBertTokenizer),
+}
+
+
+def train(args, strategy, train_dataset, tokenizer, model, num_train_examples, train_batch_size):
+    if args.max_steps > 0:
+        num_train_steps = args.max_steps * args.gradient_accumulation_steps
+        args.num_train_epochs = 1
+    else:
+        num_train_steps = (
+            math.ceil(num_train_examples / train_batch_size)
+            // args.gradient_accumulation_steps
+            * args.num_train_epochs
+        )
+
+    writer = tf.summary.create_file_writer("/tmp/mylogs")
+
+    with strategy.scope():
+        loss_fct = tf.keras.losses.SparseCategoricalCrossentropy(
+            reduction=tf.keras.losses.Reduction.NONE, from_logits=True
+        )
+        optimizer = create_optimizer(args.learning_rate, num_train_steps, args.warmup_steps)
+
+        if args.xla:
+            tf.config.optimizer.set_jit(True)
+
+        if args.amp:
+            optimizer = tf.keras.mixed_precision.experimental.LossScaleOptimizer(optimizer, "dynamic")
+
+        loss_metric = tf.keras.metrics.Mean(name="loss", dtype=tf.float32)
+        gradient_accumulator = GradientAccumulator()
+
+    logging.info("***** Running training *****")
+    logging.info("  Num examples = %d", num_train_examples)
+    logging.info("  Num Epochs = %d", args.num_train_epochs)
+    logging.info("  Instantaneous batch size per device = %d", args.per_device_train_batch_size)
+    logging.info(
+        "  Total train batch size (w. parallel, distributed & accumulation) = %d",
+        train_batch_size * args.gradient_accumulation_steps,
+    )
+    logging.info("  Gradient Accumulation steps = %d", args.gradient_accumulation_steps)
+    logging.info("  Total training steps = %d", num_train_steps)
+
+    model.summary()
+
+    @tf.function
+    def apply_gradients():
+        grads_and_vars = []
+
+        for gradient, variable in zip(gradient_accumulator.gradients, model.trainable_variables):
+            if gradient is not None:
+                scaled_gradient = gradient / (args.n_device * args.gradient_accumulation_steps)
+                grads_and_vars.append((scaled_gradient, variable))
+            else:
+                grads_and_vars.append((gradient, variable))
+
+        optimizer.apply_gradients(grads_and_vars, args.max_grad_norm)
+        gradient_accumulator.reset()
+
+    @tf.function
+    def train_step(train_features, train_labels):
+        def step_fn(train_features, train_labels):
+            with tf.GradientTape() as tape:
+                start_logits, end_logits = model(train_features)
+                start_logits = tf.multiply(
+                    start_logits, tf.dtypes.cast((train_features["attention_mask"]), tf.float32)
+                )
+                end_logits = tf.multiply(end_logits, tf.dtypes.cast((train_features["attention_mask"]), tf.float32))
+                start_loss = loss_fct(train_labels["start_position"], start_logits)
+                end_loss = loss_fct(train_labels["end_position"], end_logits)
+                total_loss = (start_loss + end_loss) / 2
+
+                loss = tf.reduce_sum(total_loss) * (1.0 / train_batch_size)
+                grads = tape.gradient(loss, model.trainable_variables)
+
+                gradient_accumulator(grads)
+
+            return total_loss
+
+        per_example_losses = strategy.experimental_run_v2(step_fn, args=(train_features, train_labels))
+        mean_loss = strategy.reduce(tf.distribute.ReduceOp.MEAN, per_example_losses, axis=0)
+
+        return mean_loss
+
+    current_time = datetime.datetime.now()
+    train_iterator = master_bar(range(args.num_train_epochs))
+    global_step = 0
+    logging_loss = 0.0
+
+    for epoch in train_iterator:
+        epoch_iterator = progress_bar(
+            train_dataset,
+            total=num_train_steps / args.num_train_epochs,
+            parent=train_iterator,
+            display=args.n_device > 1,
+        )
+        step = 1
+
+        with strategy.scope():
+            for train_features, train_labels in tqdm(
+                epoch_iterator,
+                desc="Training, epoch {}".format(epoch),
+                total=int(num_train_steps / args.num_train_epochs),
+            ):
+                loss = train_step(train_features, train_labels)
+
+                if step % args.gradient_accumulation_steps == 0:
+                    strategy.experimental_run_v2(apply_gradients)
+
+                    loss_metric(loss)
+
+                    global_step += 1
+
+                    if args.logging_steps > 0 and global_step % args.logging_steps == 0:
+                        # Log metrics
+                        if args.n_device == 1 and args.evaluate_during_training:
+                            # Only evaluate when single GPU otherwise metrics may not average well
+                            results = evaluate(args, strategy, model, tokenizer, global_step)
+
+                            with writer.as_default():
+                                tf.summary.scalar("exact", results[0], global_step)
+                                tf.summary.scalar("f1", results[1], global_step)
+
+                        lr = optimizer.learning_rate
+                        learning_rate = lr(step)
+
+                        with writer.as_default():
+                            tf.summary.scalar("lr", learning_rate, global_step)
+                            tf.summary.scalar(
+                                "loss", (loss_metric.result() - logging_loss) / args.logging_steps, global_step
+                            )
+
+                        logging_loss = loss_metric.result()
+
+                    with writer.as_default():
+                        tf.summary.scalar("loss", loss_metric.result(), step=step)
+
+                    if args.save_steps > 0 and global_step % args.save_steps == 0:
+                        # Save model checkpoint
+                        output_dir = os.path.join(args.output_dir, "checkpoint-{}".format(global_step))
+
+                        if not os.path.exists(output_dir):
+                            os.makedirs(output_dir)
+
+                        model.save_pretrained(output_dir)
+                        logging.info("Saving model checkpoint to %s", output_dir)
+
+                train_iterator.child.comment = f"loss : {loss_metric.result()}"
+                step += 1
+
+        train_iterator.write(f"loss epoch {epoch + 1}: {loss_metric.result()}")
+
+        loss_metric.reset_states()
+
+    logging.info("  Training took time = {}".format(datetime.datetime.now() - current_time))
+
+
+def evaluate(args, strategy, model, tokenizer, prefix):
+    eval_batch_size = args.per_device_eval_batch_size * args.n_device
+    eval_dataset, size, examples, features = load_and_cache_examples(
+        args, tokenizer, evaluate=True, output_examples=True
+    )
+    eval_dataset = eval_dataset.batch(args.per_device_eval_batch_size)
+    eval_dataset = strategy.experimental_distribute_dataset(eval_dataset)
+    num_eval_steps = math.ceil(size / eval_batch_size)
+    master = master_bar(range(1))
+    eval_iterator = progress_bar(eval_dataset, total=num_eval_steps, parent=master, display=args.n_device > 1)
+
+    logging.info("***** Running evaluation *****")
+    logging.info("  Num examples = %d", size)
+    logging.info("  Batch size = %d", eval_batch_size)
+
+    all_results = []
+    for index, (eval_features, eval_labels) in tqdm(
+        enumerate(eval_iterator), total=size / args.per_device_eval_batch_size
+    ):
+        with strategy.scope():
+            start_logits, end_logits = model(eval_features)
+
+            for sample_index in range(args.per_device_eval_batch_size):
+                if index * args.per_device_eval_batch_size + sample_index < len(features):
+                    result = SquadResult(
+                        features[index * args.per_device_eval_batch_size + sample_index].unique_id,
+                        start_logits[sample_index],
+                        end_logits[sample_index],
+                    )
+                    all_results.append(result)
+
+    output_prediction_file = os.path.join(args.output_dir, "predictions_{}.json".format(prefix))
+    output_nbest_file = os.path.join(args.output_dir, "nbest_predictions_{}.json".format(prefix))
+
+    if args.version_2_with_negative:
+        output_null_log_odds_file = os.path.join(args.output_dir, "null_odds_{}.json".format(prefix))
+    else:
+        output_null_log_odds_file = None
+
+    predictions = compute_predictions_logits(
+        examples,
+        features,
+        all_results,
+        args.n_best_size,
+        args.max_answer_length,
+        args.do_lower_case,
+        output_prediction_file,
+        output_nbest_file,
+        output_null_log_odds_file,
+        args.verbose_logging,
+        args.version_2_with_negative,
+        args.null_score_diff_threshold,
+        tokenizer,
+    )
+
+    # Compute the F1 and exact scores.
+    results = squad_evaluate(examples, predictions)
+    return results
+
+
+def load_and_cache_examples(args, tokenizer, evaluate=False, output_examples=False):
+    features_output_dir = os.path.join(args.output_dir, "features")
+    cached_features_file = os.path.join(
+        features_output_dir,
+        "cached_{}_{}_{}.tfrecord".format(
+            "dev" if evaluate else "train",
+            list(filter(None, args.model_name_or_path.split("/"))).pop(),
+            str(args.max_seq_length),
+        ),
+    )
+
+    if not os.path.exists(cached_features_file) or args.overwrite_cache:
+        if args.version_2_with_negative:
+            processor = SquadV2Processor()
+        else:
+            processor = SquadV1Processor()
+
+        if args.data_dir:
+            directory = args.directory
+            examples = processor.get_dev_examples(directory) if evaluate else processor.get_train_examples(directory)
+        else:
+            try:
+                import tensorflow_datasets as tfds
+            except ImportError:
+                raise ImportError("If not data_dir is specified, tensorflow_datasets needs to be installed.")
+
+            if args.version_2_with_negative:
+                logger.warning("tensorflow_datasets does not handle version 2 of SQuAD.")
+
+            examples = processor.get_examples_from_dataset(tfds.load("squad"), evaluate=evaluate)
+            examples = examples
+
+        logger.info("Converting examples to features")
+        features, dataset = squad_convert_examples_to_features(
+            examples,
+            tokenizer,
+            args.max_seq_length,
+            args.doc_stride,
+            args.max_query_length,
+            is_training=not evaluate,
+            return_dataset="tf",
+        )
+
+        if not os.path.exists(features_output_dir):
+            os.makedirs(features_output_dir)
+
+        with tf.compat.v1.python_io.TFRecordWriter(cached_features_file) as tfwriter:
+            for feature in tqdm(dataset, desc="Building tfrecord dataset", total=len(features)):
+                example, result = feature
+                feature_key_value_pair = {
+                    "input_ids": tf.train.Feature(int64_list=tf.train.Int64List(value=example["input_ids"])),
+                    "attention_mask": tf.train.Feature(int64_list=tf.train.Int64List(value=example["attention_mask"])),
+                    "token_type_ids": tf.train.Feature(int64_list=tf.train.Int64List(value=example["token_type_ids"])),
+                    "start_position": tf.train.Feature(
+                        int64_list=tf.train.Int64List(value=[result["start_position"]])
+                    ),
+                    "end_position": tf.train.Feature(int64_list=tf.train.Int64List(value=[result["end_position"]])),
+                    "cls_index": tf.train.Feature(int64_list=tf.train.Int64List(value=[result["cls_index"]])),
+                    "p_mask": tf.train.Feature(int64_list=tf.train.Int64List(value=result["p_mask"])),
+                }
+                feature_skeleton = tf.train.Features(feature=feature_key_value_pair)
+                example = tf.train.Example(features=feature_skeleton)
+
+                tfwriter.write(example.SerializeToString())
+
+            with open("{}.pickle".format(cached_features_file.replace(".tfrecord", "_examples")), "wb") as handle:
+                pickle.dump(examples, handle, protocol=pickle.HIGHEST_PROTOCOL)
+
+            with open("{}.pickle".format(cached_features_file.replace(".tfrecord", "_features")), "wb") as handle:
+                pickle.dump(features, handle, protocol=pickle.HIGHEST_PROTOCOL)
+
+        logger.info("Features saved to cache")
+
+    feature_skeleton = {
+        "input_ids": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+        "attention_mask": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+        "token_type_ids": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+        "start_position": tf.io.FixedLenFeature([], tf.int64),
+        "end_position": tf.io.FixedLenFeature([], tf.int64),
+        "cls_index": tf.io.FixedLenFeature([], tf.int64),
+        "p_mask": tf.io.FixedLenFeature([args.max_seq_length], tf.int64),
+    }
+
+    def select_data_from_record(record):
+        record = tf.io.parse_single_example(record, feature_skeleton)
+        x = {
+            "input_ids": record["input_ids"],
+            "attention_mask": record["attention_mask"],
+            "token_type_ids": record["token_type_ids"],
+        }
+        y = {
+            "start_position": record["start_position"],
+            "end_position": record["end_position"],
+            "cls_index": record["cls_index"],
+            "p_mask": record["p_mask"],
+        }
+        return x, y
+
+    dataset = tf.data.TFRecordDataset(cached_features_file)
+    dataset = dataset.map(select_data_from_record)
+
+    with open("{}.pickle".format(cached_features_file.replace(".tfrecord", "_examples")), "rb") as handle:
+        examples = pickle.load(handle)
+
+    with open("{}.pickle".format(cached_features_file.replace(".tfrecord", "_features")), "rb") as handle:
+        features = pickle.load(handle)
+
+    logger.info("Created dataset %s from TFRecord" % "dev" if evaluate else "train")
+
+    if output_examples:
+        return dataset, len(list(dataset.__iter__())), examples, features
+    return dataset, len(list(dataset.__iter__()))
+
+
+def main():
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument(
+        "--model_type",
+        default=None,
+        type=str,
+        required=True,
+        help="Model type selected in the list: " + ", ".join(MODEL_CLASSES.keys()),
+    )
+    parser.add_argument(
+        "--model_name_or_path",
+        default=None,
+        type=str,
+        required=True,
+        help="Path to pre-trained model or shortcut name selected in the list: " + ", ".join(ALL_MODELS),
+    )
+    parser.add_argument(
+        "--output_dir",
+        default=None,
+        type=str,
+        required=True,
+        help="The output directory where the model predictions and checkpoints will be written.",
+    )
+    parser.add_argument(
+        "--data_dir",
+        default=None,
+        type=str,
+        required=False,
+        help="The input data directory containing the .json files. If no data dir is specified, uses tensorflow_datasets to load the data."
+        + ", ".join(MODEL_CLASSES.keys()),
+    )
+    parser.add_argument(
+        "--overwrite_output_dir", action="store_true", help="Overwrite the content of the output directory"
+    )
+
+    parser.add_argument("--do_train", action="store_true", help="Whether to run training.")
+    parser.add_argument("--do_eval", action="store_true", help="Whether to run eval on the dev set.")
+    parser.add_argument(
+        "--evaluate_during_training", action="store_true", help="Rul evaluation during training at each logging step."
+    )
+
+    parser.add_argument(
+        "--per_device_train_batch_size", default=8, type=int, help="Batch size per GPU/CPU for training."
+    )
+    parser.add_argument(
+        "--per_device_eval_batch_size",
+        default=8,
+        type=int,
+        help="Batch size per GPU/CPU for validation during training.",
+    )
+    parser.add_argument(
+        "--per_device_test_batch_size",
+        default=8,
+        type=int,
+        help="Batch size per GPU/CPU for evaluation after training.",
+    )
+    parser.add_argument(
+        "--overwrite_cache", action="store_true", help="Overwrite the cached training and evaluation sets"
+    )
+
+    parser.add_argument("--num_train_epochs", default=3, type=int, help="Total number of training epochs to perform.")
+    parser.add_argument("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.")
+    parser.add_argument("--adam_epsilon", default=1e-8, type=float, help="Epsilon for Adam optimizer.")
+    parser.add_argument(
+        "--max_seq_length",
+        default=128,
+        type=int,
+        help="The maximum total input sequence length after tokenization. Sequences longer "
+        "than this will be truncated, sequences shorter will be padded.",
+    )
+    parser.add_argument(
+        "--doc_stride",
+        default=128,
+        type=int,
+        help="When splitting up a long document into chunks, how much stride to take between chunks.",
+    )
+    parser.add_argument(
+        "--max_query_length",
+        default=64,
+        type=int,
+        help="The maximum number of tokens for the question. Questions longer than this will "
+        "be truncated to this length.",
+    )
+    parser.add_argument(
+        "--do_lower_case", action="store_true", help="Set this flag if you are using an uncased model."
+    )
+
+    parser.add_argument(
+        "--config_name", default="", type=str, help="Pretrained config name or path if not the same as model_name"
+    )
+    parser.add_argument(
+        "--tokenizer_name",
+        default="",
+        type=str,
+        help="Pretrained tokenizer name or path if not the same as model_name",
+    )
+    parser.add_argument(
+        "--cache_dir",
+        default="",
+        type=str,
+        help="Where do you want to store the pre-trained models downloaded from s3",
+    )
+    parser.add_argument("--xla", action="store_true", help="Whether to use XLA (Accelerated Linear Algebra).")
+    parser.add_argument("--amp", action="store_true", help="Whether to use AMP (Automatic Mixed Precision).")
+    parser.add_argument(
+        "--force_download",
+        action="store_true",
+        help="Whether to force download the weights from S3 (useful if the file is corrupted).",
+    )
+
+    parser.add_argument(
+        "--tpu",
+        default=None,
+        help="The Cloud TPU to use for training. This should be either the name "
+        "used when creating the Cloud TPU, or a grpc://ip.address.of.tpu:8470 "
+        "url.",
+    )
+    parser.add_argument("--num_tpu_cores", default="8", help="Total number of TPU cores to use.")
+    parser.add_argument(
+        "--gpus",
+        default="0",
+        help="Comma separated list of gpus devices. If only one, switch to single gpu strategy, if None takes all the gpus available.",
+    )
+    parser.add_argument("--no_cuda", action="store_true", help="Whether not to use CUDA when available")
+    parser.add_argument(
+        "--version_2_with_negative",
+        action="store_true",
+        help="If true, the SQuAD examples contain some that do not have an answer.",
+    )
+    parser.add_argument(
+        "--max_steps",
+        default=-1,
+        help="If > 0: set total number of training steps to perform. Override num_train_epochs.",
+    )
+    parser.add_argument(
+        "--gradient_accumulation_steps",
+        default=1,
+        help="Number of updates steps to accumulate before performing a backward/update pass.",
+    )
+    parser.add_argument(
+        "--warmup_steps", default=0, help="Linear warmup over warmup_steps.",
+    )
+    parser.add_argument("--max_grad_norm", default=1.0, help="Max gradient norm.")
+    parser.add_argument("--logging_steps", default=500, type=int, help="Log every X updates.")
+    parser.add_argument("--save_steps", default=500, type=int, help="Save checkpoint every X updates.")
+    parser.add_argument(
+        "--eval_all_checkpoints",
+        action="store_true",
+        help="Evaluate all checkpoints starting with the same prefix as model_name ending and ending with step number",
+    )
+    parser.add_argument(
+        "--n_best_size",
+        default=20,
+        type=int,
+        help="The total number of n-best predictions to generate in the nbest_predictions.json output file.",
+    )
+    parser.add_argument(
+        "--max_answer_length",
+        default=30,
+        type=int,
+        help="The maximum length of an answer that can be generated. This is needed because the start "
+        "and end predictions are not conditioned on one another.",
+    )
+    parser.add_argument(
+        "--verbose_logging",
+        action="store_true",
+        help="If true, all of the warnings related to data processing will be printed. "
+        "A number of warnings are expected for a normal SQuAD evaluation.",
+    )
+    parser.add_argument(
+        "--null_score_diff_threshold",
+        type=float,
+        default=0.0,
+        help="If null_score - best_non_null is greater than the threshold predict null.",
+    )
+    args = parser.parse_args()
+
+    # Setup logging
+    logging.basicConfig(
+        format="%(asctime)s - %(levelname)s - %(name)s -   %(message)s",
+        datefmt="%m/%d/%Y %H:%M:%S",
+        level=logging.INFO,
+    )
+
+    if os.path.exists(args.output_dir) and args.do_train:
+        if not args.overwrite_output_dir and bool(
+            [file for file in os.listdir(args.output_dir) if "features" not in file]
+        ):
+            raise ValueError(
+                "Output directory ({}) already exists and is not empty. Use --overwrite_output_dir to overcome.".format(
+                    args.output_dir
+                )
+            )
+
+        if args.amp:
+            tf.config.optimizer.set_experimental_options({"auto_mixed_precision": True})
+
+    if args.tpu:
+        resolver = tf.distribute.cluster_resolver.TPUClusterResolver(tpu=args.tpu)
+        tf.config.experimental_connect_to_cluster(resolver)
+        tf.tpu.experimental.initialize_tpu_system(resolver)
+        strategy = tf.distribute.experimental.TPUStrategy(resolver)
+        args.n_device = args.num_tpu_cores
+    elif len(args.gpus.split(",")) > 1:
+        args.n_device = len([f"/gpu:{gpu}" for gpu in args.gpus.split(",")])
+        strategy = tf.distribute.MirroredStrategy(devices=[f"/gpu:{gpu}" for gpu in args.gpus.split(",")])
+    elif args.no_cuda:
+        args.n_device = 1
+        strategy = tf.distribute.OneDeviceStrategy(device="/cpu:0")
+    else:
+        args.n_device = len(args.gpus.split(","))
+        strategy = tf.distribute.OneDeviceStrategy(device="/gpu:" + args.gpus.split(",")[0])
+
+    logging.warning(
+        "n_device: %s, distributed training: %s, 16-bits training: %s",
+        args.n_device,
+        bool(args.n_device > 1),
+        args.amp,
+    )
+
+    args.model_type = args.model_type.lower()
+    config_class, model_class, tokenizer_class = MODEL_CLASSES[args.model_type]
+
+    config = config_class.from_pretrained(
+        args.config_name if args.config_name else args.model_name_or_path,
+        cache_dir=args.cache_dir if args.cache_dir else None,
+    )
+
+    logging.info("Training/evaluation parameters %s", args)
+
+    if args.do_train:
+        tokenizer = tokenizer_class.from_pretrained(
+            args.tokenizer_name if args.tokenizer_name else args.model_name_or_path,
+            do_lower_case=args.do_lower_case,
+            cache_dir=args.cache_dir if args.cache_dir else None,
+        )
+
+        with strategy.scope():
+            model = model_class.from_pretrained(
+                args.model_name_or_path,
+                from_pt=bool(".bin" in args.model_name_or_path),
+                config=config,
+                cache_dir=args.cache_dir if args.cache_dir else None,
+            )
+            model.layers[-1].activation = tf.keras.activations.softmax
+
+        train_batch_size = args.per_device_train_batch_size * args.n_device
+        train_dataset, num_train_examples = load_and_cache_examples(args, tokenizer, evaluate=False)
+
+        train_dataset = train_dataset.batch(train_batch_size)
+        train_dataset = train_dataset.prefetch(buffer_size=train_batch_size)
+        train_dataset = strategy.experimental_distribute_dataset(train_dataset)
+
+        train(
+            args, strategy, train_dataset, tokenizer, model, num_train_examples, train_batch_size,
+        )
+
+        if not os.path.exists(args.output_dir):
+            os.makedirs(args.output_dir)
+
+        logging.info("Saving model to %s", args.output_dir)
+
+        model.save_pretrained(args.output_dir)
+        tokenizer.save_pretrained(args.output_dir)
+
+    if args.do_eval:
+        tokenizer = tokenizer_class.from_pretrained(args.output_dir, do_lower_case=args.do_lower_case)
+        checkpoints = []
+        results = []
+
+        if args.eval_all_checkpoints:
+            checkpoints = list(
+                os.path.dirname(c)
+                for c in sorted(
+                    glob.glob(args.output_dir + "/**/" + TF2_WEIGHTS_NAME, recursive=True),
+                    key=lambda f: int("".join(filter(str.isdigit, f)) or -1),
+                )
+            )
+
+        logging.info("Evaluate the following checkpoints: %s", checkpoints)
+
+        if len(checkpoints) == 0:
+            checkpoints.append(args.output_dir)
+
+        for checkpoint in checkpoints:
+            global_step = checkpoint.split("-")[-1] if re.match(".*checkpoint-[0-9]", checkpoint) else "final"
+
+            with strategy.scope():
+                model = model_class.from_pretrained(checkpoint)
+                results = evaluate(args, strategy, model, tokenizer, prefix=global_step)
+
+            result = dict((k + ("_{}".format(global_step) if global_step else ""), v) for k, v in results.items())
+            results.update(result)
+
+        logger.info("Results: {}".format(results))
+
+
+if __name__ == "__main__":
+    main()

src/transformers/data/metrics/squad_metrics.py

@@ -555,10 +555,10 @@ def compute_predictions_logits(
         all_nbest_json[example.qas_id] = nbest_json
 
     with open(output_prediction_file, "w") as writer:
-        writer.write(json.dumps(all_predictions, indent=4) + "\n")
+        writer.write(json.dumps(str(all_predictions), indent=4) + "\n")
 
     with open(output_nbest_file, "w") as writer:
-        writer.write(json.dumps(all_nbest_json, indent=4) + "\n")
+        writer.write(json.dumps(str(all_nbest_json), indent=4) + "\n")
 
     if version_2_with_negative:
         with open(output_null_log_odds_file, "w") as writer:

src/transformers/data/processors/squad.py

@@ -306,13 +306,15 @@ def squad_convert_examples_to_features(
             tqdm(
                 p.imap(annotate_, examples, chunksize=32),
                 total=len(examples),
-                desc="convert squad examples to features",
+                desc="Converting squad examples to features",
             )
         )
+
+    print("Converted {} examples into {} features".format(len(examples), len(features)))
     new_features = []
     unique_id = 1000000000
     example_index = 0
-    for example_features in tqdm(features, total=len(features), desc="add example index and unique id"):
+    for example_features in features:
         if not example_features:
             continue
         for example_feature in example_features:
@@ -376,31 +378,34 @@ def squad_convert_examples_to_features(
                     },
                 )
 
-        return tf.data.Dataset.from_generator(
-            gen,
-            (
-                {"input_ids": tf.int32, "attention_mask": tf.int32, "token_type_ids": tf.int32},
-                {
-                    "start_position": tf.int64,
-                    "end_position": tf.int64,
-                    "cls_index": tf.int64,
-                    "p_mask": tf.int32,
-                    "is_impossible": tf.int32,
-                },
-            ),
-            (
-                {
-                    "input_ids": tf.TensorShape([None]),
-                    "attention_mask": tf.TensorShape([None]),
-                    "token_type_ids": tf.TensorShape([None]),
-                },
-                {
-                    "start_position": tf.TensorShape([]),
-                    "end_position": tf.TensorShape([]),
-                    "cls_index": tf.TensorShape([]),
-                    "p_mask": tf.TensorShape([None]),
-                    "is_impossible": tf.TensorShape([]),
-                },
+        return (
+            features,
+            tf.data.Dataset.from_generator(
+                gen,
+                (
+                    {"input_ids": tf.int32, "attention_mask": tf.int32, "token_type_ids": tf.int32},
+                    {
+                        "start_position": tf.int64,
+                        "end_position": tf.int64,
+                        "cls_index": tf.int64,
+                        "p_mask": tf.int32,
+                        "is_impossible": tf.int32,
+                    },
+                ),
+                (
+                    {
+                        "input_ids": tf.TensorShape([None]),
+                        "attention_mask": tf.TensorShape([None]),
+                        "token_type_ids": tf.TensorShape([None]),
+                    },
+                    {
+                        "start_position": tf.TensorShape([]),
+                        "end_position": tf.TensorShape([]),
+                        "cls_index": tf.TensorShape([]),
+                        "p_mask": tf.TensorShape([None]),
+                        "is_impossible": tf.TensorShape([]),
+                    },
+                ),
             ),
         )
 

src/transformers/optimization_tf.py

@@ -56,7 +56,16 @@ class WarmUp(tf.keras.optimizers.schedules.LearningRateSchedule):
         }
 
 
-def create_optimizer(init_lr, num_train_steps, num_warmup_steps):
+def create_optimizer(
+    init_lr,
+    num_train_steps,
+    num_warmup_steps,
+    weight_decay=0.0,
+    adam_epsilon=1e-6,
+    beta_1=0.9,
+    beta_2=0.999,
+    exclude_from_weight_decay=("layer_norm", "bias"),
+):
     """Creates an optimizer with learning rate schedule."""
     # Implements linear decay of the learning rate.
     learning_rate_fn = tf.keras.optimizers.schedules.PolynomialDecay(
@@ -68,11 +77,11 @@ def create_optimizer(init_lr, num_train_steps, num_warmup_steps):
         )
     optimizer = AdamWeightDecay(
         learning_rate=learning_rate_fn,
-        weight_decay_rate=0.01,
-        beta_1=0.9,
-        beta_2=0.999,
-        epsilon=1e-6,
-        exclude_from_weight_decay=["layer_norm", "bias"],
+        weight_decay_rate=weight_decay,
+        beta_1=beta_1,
+        beta_2=beta_2,
+        epsilon=adam_epsilon,
+        exclude_from_weight_decay=exclude_from_weight_decay,
     )
     return optimizer
 

src/transformers/tokenization_utils.py

@@ -998,7 +998,7 @@ class PreTrainedTokenizer(object):
             for key, value in batch_outputs.items():
 
                 padded_value = value
-                if key != "input_len":
+                if key != "input_len" and self._pad_token is not None:
                     # Padding handle
                     padded_value = [
                         v + [self.pad_token_id if key == "input_ids" else 1] * (max_seq_len - len(v))