# coding=utf-8 # Copyright 2018 The Google AI Language Team Authors. # # 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. """Run masked LM/next sentence masked_lm pre-training for BERT.""" from __future__ import absolute_import from __future__ import division from __future__ import print_function import os import modeling import optimization import tensorflow as tf import argparse def model_fn_builder(bert_config, init_checkpoint, learning_rate, num_train_steps, num_warmup_steps, use_tpu, use_one_hot_embeddings): """Returns `model_fn` closure for TPUEstimator.""" def model_fn(features, labels, mode, params): # pylint: disable=unused-argument """The `model_fn` for TPUEstimator.""" tf.logging.info("*** Features ***") for name in sorted(features.keys()): tf.logging.info(" name = %s, shape = %s" % (name, features[name].shape)) input_ids = features["input_ids"] input_mask = features["input_mask"] segment_ids = features["segment_ids"] masked_lm_positions = features["masked_lm_positions"] masked_lm_ids = features["masked_lm_ids"] masked_lm_weights = features["masked_lm_weights"] next_sentence_labels = features["next_sentence_labels"] is_training = (mode == tf.estimator.ModeKeys.TRAIN) model = modeling.BertModel( config=bert_config, is_training=is_training, input_ids=input_ids, input_mask=input_mask, token_type_ids=segment_ids, use_one_hot_embeddings=use_one_hot_embeddings) (masked_lm_loss, masked_lm_example_loss, masked_lm_log_probs) = get_masked_lm_output( bert_config, model.get_sequence_output(), model.get_embedding_table(), masked_lm_positions, masked_lm_ids, masked_lm_weights) (next_sentence_loss, next_sentence_example_loss, next_sentence_log_probs) = get_next_sentence_output( bert_config, model.get_pooled_output(), next_sentence_labels) total_loss = masked_lm_loss + next_sentence_loss tvars = tf.trainable_variables() initialized_variable_names = {} scaffold_fn = None if init_checkpoint: (assignment_map, initialized_variable_names) = modeling.get_assigment_map_from_checkpoint( tvars, init_checkpoint) if use_tpu: def tpu_scaffold(): tf.train.init_from_checkpoint(init_checkpoint, assignment_map) return tf.train.Scaffold() scaffold_fn = tpu_scaffold else: tf.train.init_from_checkpoint(init_checkpoint, assignment_map) tf.logging.info("**** Trainable Variables ****") for var in tvars: init_string = "" if var.name in initialized_variable_names: init_string = ", *INIT_FROM_CKPT*" tf.logging.info(" name = %s, shape = %s%s", var.name, var.shape, init_string) output_spec = None if mode == tf.estimator.ModeKeys.TRAIN: train_op = optimization.create_optimizer( total_loss, learning_rate, num_train_steps, num_warmup_steps, use_tpu) output_spec = tf.contrib.tpu.TPUEstimatorSpec( mode=mode, loss=total_loss, train_op=train_op, scaffold_fn=scaffold_fn) elif mode == tf.estimator.ModeKeys.EVAL: def metric_fn(masked_lm_example_loss, masked_lm_log_probs, masked_lm_ids, masked_lm_weights, next_sentence_example_loss, next_sentence_log_probs, next_sentence_labels): """Computes the loss and accuracy of the model.""" masked_lm_log_probs = tf.reshape(masked_lm_log_probs, [-1, masked_lm_log_probs.shape[-1]]) masked_lm_predictions = tf.argmax( masked_lm_log_probs, axis=-1, output_type=tf.int32) masked_lm_example_loss = tf.reshape(masked_lm_example_loss, [-1]) masked_lm_ids = tf.reshape(masked_lm_ids, [-1]) masked_lm_weights = tf.reshape(masked_lm_weights, [-1]) masked_lm_accuracy = tf.metrics.accuracy( labels=masked_lm_ids, predictions=masked_lm_predictions, weights=masked_lm_weights) masked_lm_mean_loss = tf.metrics.mean( values=masked_lm_example_loss, weights=masked_lm_weights) next_sentence_log_probs = tf.reshape( next_sentence_log_probs, [-1, next_sentence_log_probs.shape[-1]]) next_sentence_predictions = tf.argmax( next_sentence_log_probs, axis=-1, output_type=tf.int32) next_sentence_labels = tf.reshape(next_sentence_labels, [-1]) next_sentence_accuracy = tf.metrics.accuracy( labels=next_sentence_labels, predictions=next_sentence_predictions) next_sentence_mean_loss = tf.metrics.mean( values=next_sentence_example_loss) return { "masked_lm_accuracy": masked_lm_accuracy, "masked_lm_loss": masked_lm_mean_loss, "next_sentence_accuracy": next_sentence_accuracy, "next_sentence_loss": next_sentence_mean_loss, } eval_metrics = (metric_fn, [ masked_lm_example_loss, masked_lm_log_probs, masked_lm_ids, masked_lm_weights, next_sentence_example_loss, next_sentence_log_probs, next_sentence_labels ]) output_spec = tf.contrib.tpu.TPUEstimatorSpec( mode=mode, loss=total_loss, eval_metrics=eval_metrics, scaffold_fn=scaffold_fn) else: raise ValueError("Only TRAIN and EVAL modes are supported: %s" % (mode)) return output_spec return model_fn def get_masked_lm_output(bert_config, input_tensor, output_weights, positions, label_ids, label_weights): """Get loss and log probs for the masked LM.""" input_tensor = gather_indexes(input_tensor, positions) with tf.variable_scope("cls/predictions"): # We apply one more non-linear transformation before the output layer. # This matrix is not used after pre-training. with tf.variable_scope("transform"): input_tensor = tf.layers.dense( input_tensor, units=bert_config.hidden_size, activation=modeling.get_activation(bert_config.hidden_act), kernel_initializer=modeling.create_initializer( bert_config.initializer_range)) input_tensor = modeling.layer_norm(input_tensor) # The output weights are the same as the input embeddings, but there is # an output-only bias for each token. output_bias = tf.get_variable( "output_bias", shape=[bert_config.vocab_size], initializer=tf.zeros_initializer()) logits = tf.matmul(input_tensor, output_weights, transpose_b=True) logits = tf.nn.bias_add(logits, output_bias) log_probs = tf.nn.log_softmax(logits, axis=-1) label_ids = tf.reshape(label_ids, [-1]) label_weights = tf.reshape(label_weights, [-1]) one_hot_labels = tf.one_hot( label_ids, depth=bert_config.vocab_size, dtype=tf.float32) # The `positions` tensor might be zero-padded (if the sequence is too # short to have the maximum number of predictions). The `label_weights` # tensor has a value of 1.0 for every real prediction and 0.0 for the # padding predictions. per_example_loss = -tf.reduce_sum(log_probs * one_hot_labels, axis=[-1]) numerator = tf.reduce_sum(label_weights * per_example_loss) denominator = tf.reduce_sum(label_weights) + 1e-5 loss = numerator / denominator return (loss, per_example_loss, log_probs) def get_next_sentence_output(bert_config, input_tensor, labels): """Get loss and log probs for the next sentence prediction.""" # Simple binary classification. Note that 0 is "next sentence" and 1 is # "random sentence". This weight matrix is not used after pre-training. with tf.variable_scope("cls/seq_relationship"): output_weights = tf.get_variable( "output_weights", shape=[2, bert_config.hidden_size], initializer=modeling.create_initializer(bert_config.initializer_range)) output_bias = tf.get_variable( "output_bias", shape=[2], initializer=tf.zeros_initializer()) logits = tf.matmul(input_tensor, output_weights, transpose_b=True) logits = tf.nn.bias_add(logits, output_bias) log_probs = tf.nn.log_softmax(logits, axis=-1) labels = tf.reshape(labels, [-1]) one_hot_labels = tf.one_hot(labels, depth=2, dtype=tf.float32) per_example_loss = -tf.reduce_sum(one_hot_labels * log_probs, axis=-1) loss = tf.reduce_mean(per_example_loss) return (loss, per_example_loss, log_probs) def gather_indexes(sequence_tensor, positions): """Gathers the vectors at the specific positions over a minibatch.""" sequence_shape = modeling.get_shape_list(sequence_tensor, expected_rank=3) batch_size = sequence_shape[0] seq_length = sequence_shape[1] width = sequence_shape[2] flat_offsets = tf.reshape( tf.range(0, batch_size, dtype=tf.int32) * seq_length, [-1, 1]) flat_positions = tf.reshape(positions + flat_offsets, [-1]) flat_sequence_tensor = tf.reshape(sequence_tensor, [batch_size * seq_length, width]) output_tensor = tf.gather(flat_sequence_tensor, flat_positions) return output_tensor def input_fn_builder(input_files, max_seq_length, max_predictions_per_seq, is_training, num_cpu_threads=4): """Creates an `input_fn` closure to be passed to TPUEstimator.""" def input_fn(params): """The actual input function.""" batch_size = params["batch_size"] name_to_features = { "input_ids": tf.FixedLenFeature([max_seq_length], tf.int64), "input_mask": tf.FixedLenFeature([max_seq_length], tf.int64), "segment_ids": tf.FixedLenFeature([max_seq_length], tf.int64), "masked_lm_positions": tf.FixedLenFeature([max_predictions_per_seq], tf.int64), "masked_lm_ids": tf.FixedLenFeature([max_predictions_per_seq], tf.int64), "masked_lm_weights": tf.FixedLenFeature([max_predictions_per_seq], tf.float32), "next_sentence_labels": tf.FixedLenFeature([1], tf.int64), } # For training, we want a lot of parallel reading and shuffling. # For eval, we want no shuffling and parallel reading doesn't matter. if is_training: d = tf.data.Dataset.from_tensor_slices(tf.constant(input_files)) d = d.repeat() d = d.shuffle(buffer_size=len(input_files)) # `cycle_length` is the number of parallel files that get read. cycle_length = min(num_cpu_threads, len(input_files)) # `sloppy` mode means that the interleaving is not exact. This adds # even more randomness to the training pipeline. d = d.apply( tf.contrib.data.parallel_interleave( tf.data.TFRecordDataset, sloppy=is_training, cycle_length=cycle_length)) d = d.shuffle(buffer_size=100) else: d = tf.data.TFRecordDataset(input_files) # Since we evaluate for a fixed number of steps we don't want to encounter # out-of-range exceptions. d = d.repeat() # We must `drop_remainder` on training because the TPU requires fixed # size dimensions. For eval, we assume we are evaling on the CPU or GPU # and we *don"t* want to drop the remainder, otherwise we wont cover # every sample. d = d.apply( tf.contrib.data.map_and_batch( lambda record: _decode_record(record, name_to_features), batch_size=batch_size, num_parallel_batches=num_cpu_threads, drop_remainder=True)) return d return input_fn def _decode_record(record, name_to_features): """Decodes a record to a TensorFlow example.""" example = tf.parse_single_example(record, name_to_features) # tf.Example only supports tf.int64, but the TPU only supports tf.int32. # So cast all int64 to int32. for name in list(example.keys()): t = example[name] if t.dtype == tf.int64: t = tf.to_int32(t) example[name] = t return example def main(_): parser = argparse.ArgumentParser() ## Required parameters parser.add_argument("--bert_config_file", default=None, type=str, required=True, help="The config json file corresponding to the pre-trained BERT model. " "This specifies the model architecture.") parser.add_argument("--input_file", default=None, type=str, required=True, help="Input TF example files (can be a glob or comma separated).") parser.add_argument("--output_dir", default=None, type=str, required=True, help="The output directory where the model checkpoints will be written.") ## Other parameters parser.add_argument("--init_checkpoint", default=None, type=str, help="Initial checkpoint (usually from a pre-trained BERT model).") parser.add_argument("--max_seq_length", default=128, type=int, help="The maximum total input sequence length after WordPiece tokenization. Sequences longer " "than this will be truncated, and sequences shorter than this will be padded. " "Must match data generation.") parser.add_argument("--max_predictions_per_seq", default=20, type=int, help="Maximum number of masked LM predictions per sequence. Must match data generation.") parser.add_argument("--do_train", default=False, action='store_true', help="Whether to run training.") parser.add_argument("--do_eval", default=False, action='store_true', help="Whether to run eval on the dev set.") parser.add_argument("--train_batch_size", default=32, type=int, help="Total batch size for training.") parser.add_argument("--eval_batch_size", default=8, type=int, help="Total batch size for eval.") parser.add_argument("--learning_rate", default=5e-5, type=float, help="The initial learning rate for Adam.") parser.add_argument("--num_train_steps", default=100000, type=int, help="Number of training steps.") parser.add_argument("--num_warmup_steps", default=10000, type=int, help="Number of warmup steps.") parser.add_argument("--save_checkpoints_steps", default=1000, type=int, help="How often to save the model checkpoint.") parser.add_argument("--iterations_per_loop", default=1000, type=int, help="How many steps to make in each estimator call.") parser.add_argument("--max_eval_steps", default=100, type=int, help="Maximum number of eval steps.") ### BEGIN - TO DELETE EVENTUALLY --> NO SENSE IN PYTORCH ### parser.add_argument("--use_tpu", default=False, action='store_true', help="Whether to use TPU or GPU/CPU.") parser.add_argument("--tpu_name", default=None, type=str, 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("--tpu_zone", default=None, type=str, help="[Optional] GCE zone where the Cloud TPU is located in. If not specified, we will attempt " "to automatically detect the GCE project from metadata.") parser.add_argument("--gcp_project", default=None, type=str, help="[Optional] Project name for the Cloud TPU-enabled project. If not specified, " "we will attempt to automatically detect the GCE project from metadata.") parser.add_argument("--master", default=None, type=str, help="[Optional] TensorFlow master URL.") parser.add_argument("--num_tpu_cores", default=8, type=int, help="Only used if `use_tpu` is True. Total number of TPU cores to use.") ### END - TO DELETE EVENTUALLY --> NO SENSE IN PYTORCH ### args = parser.parse_args() tf.logging.set_verbosity(tf.logging.INFO) if not args.do_train and not args.do_eval: raise ValueError("At least one of `do_train` or `do_eval` must be True.") bert_config = modeling.BertConfig.from_json_file(args.bert_config_file) tf.gfile.MakeDirs(args.output_dir) input_files = [] for input_pattern in args.input_file.split(","): input_files.extend(tf.gfile.Glob(input_pattern)) tf.logging.info("*** Input Files ***") for input_file in input_files: tf.logging.info(" %s" % input_file) tpu_cluster_resolver = None if args.use_tpu and args.tpu_name: tpu_cluster_resolver = tf.contrib.cluster_resolver.TPUClusterResolver( args.tpu_name, zone=args.tpu_zone, project=args.gcp_project) is_per_host = tf.contrib.tpu.InputPipelineConfig.PER_HOST_V2 run_config = tf.contrib.tpu.RunConfig( cluster=tpu_cluster_resolver, master=args.master, model_dir=args.output_dir, save_checkpoints_steps=args.save_checkpoints_steps, tpu_config=tf.contrib.tpu.TPUConfig( iterations_per_loop=args.iterations_per_loop, num_shards=args.num_tpu_cores, per_host_input_for_training=is_per_host)) model_fn = model_fn_builder( bert_config=bert_config, init_checkpoint=args.init_checkpoint, learning_rate=args.learning_rate, num_train_steps=args.num_train_steps, num_warmup_steps=args.num_warmup_steps, use_tpu=args.use_tpu, use_one_hot_embeddings=args.use_tpu) # If TPU is not available, this will fall back to normal Estimator on CPU # or GPU. estimator = tf.contrib.tpu.TPUEstimator( use_tpu=args.use_tpu, model_fn=model_fn, config=run_config, train_batch_size=args.train_batch_size, eval_batch_size=args.eval_batch_size) if args.do_train: tf.logging.info("***** Running training *****") tf.logging.info(" Batch size = %d", args.train_batch_size) train_input_fn = input_fn_builder( input_files=input_files, max_seq_length=args.max_seq_length, max_predictions_per_seq=args.max_predictions_per_seq, is_training=True) estimator.train(input_fn=train_input_fn, max_steps=args.num_train_steps) if args.do_eval: tf.logging.info("***** Running evaluation *****") tf.logging.info(" Batch size = %d", args.eval_batch_size) eval_input_fn = input_fn_builder( input_files=input_files, max_seq_length=args.max_seq_length, max_predictions_per_seq=args.max_predictions_per_seq, is_training=False) result = estimator.evaluate( input_fn=eval_input_fn, steps=args.max_eval_steps) output_eval_file = os.path.join(args.output_dir, "eval_results.txt") with tf.gfile.GFile(output_eval_file, "w") as writer: tf.logging.info("***** Eval results *****") for key in sorted(result.keys()): tf.logging.info(" %s = %s", key, str(result[key])) writer.write("%s = %s\n" % (key, str(result[key]))) if __name__ == "__main__": tf.app.run()