def pipeline(
self,
dataset: tf.data.Dataset,
input_context: tf.distribute.InputContext = None
) -> tf.data.Dataset:
"""Build a pipeline fetching, shuffling, and preprocessing the dataset.
Args:
dataset: A `tf.data.Dataset` that loads raw files.
input_context: An optional context provided by `tf.distribute` for
cross-replica training. If set with more than one replica, this
function assumes `use_per_replica_batch_size=True`.
Returns:
A TensorFlow dataset outputting batched images and labels.
"""
if input_context and input_context.num_input_pipelines > 1:
dataset = dataset.shard(input_context.num_input_pipelines,
input_context.input_pipeline_id)
if self.is_training and not self.config.cache:
dataset = dataset.repeat()
if self.config.builder == 'records':
# Read the data from disk in parallel
buffer_size = 8 * 1024 * 1024 # Use 8 MiB per file
dataset = dataset.interleave(
lambda name: tf.data.TFRecordDataset(name,
buffer_size=buffer_size),
cycle_length=16,
num_parallel_calls=tf.data.experimental.AUTOTUNE)
if self.config.cache:
dataset = dataset.cache()
if self.is_training:
dataset = dataset.shuffle(self.config.shuffle_buffer_size)
dataset = dataset.repeat()
# Parse, pre-process, and batch the data in parallel
if self.config.builder == 'records':
preprocess = self.parse_record
else:
preprocess = self.preprocess
dataset = dataset.map(preprocess,
num_parallel_calls=tf.data.experimental.AUTOTUNE)
if input_context and self.config.num_devices > 1:
if not self.config.use_per_replica_batch_size:
raise ValueError(
'The builder does not support a global batch size with more than '
'one replica. Got {} replicas. Please set a '
'`per_replica_batch_size` and enable '
'`use_per_replica_batch_size=True`.'.format(
self.config.num_devices))
# The batch size of the dataset will be multiplied by the number of
# replicas automatically when strategy.distribute_datasets_from_function
# is called, so we use local batch size here.
dataset = dataset.batch(self.local_batch_size,
drop_remainder=self.is_training)
else:
dataset = dataset.batch(self.global_batch_size,
drop_remainder=self.is_training)
if self.is_training:
options = tf.data.Options()
options.experimental_deterministic = self.config.deterministic_train
options.experimental_slack = self.config.use_slack
options.experimental_optimization.parallel_batch = True
options.experimental_optimization.map_fusion = True
options.experimental_optimization.map_vectorization.enabled = True
options.experimental_optimization.map_parallelization = True
dataset = dataset.with_options(options)
# Prefetch overlaps in-feed with training
dataset = dataset.prefetch(tf.data.experimental.AUTOTUNE)
return dataset
def pipeline(
self,
dataset: tf.data.Dataset,
input_context: tf.distribute.InputContext = None
) -> tf.data.Dataset:
"""Build a pipeline fetching, shuffling, and preprocessing the dataset.
Args:
dataset: A `tf.data.Dataset` that loads raw files.
input_context: An optional context provided by `tf.distribute` for
cross-replica training. This isn't necessary if using Keras
compile/fit.
Returns:
A TensorFlow dataset outputting batched images and labels.
"""
if input_context and input_context.num_input_pipelines > 1:
dataset = dataset.shard(input_context.num_input_pipelines,
input_context.input_pipeline_id)
if self.is_training and not self.config.cache:
dataset = dataset.repeat()
if self.config.builder == 'records':
# Read the data from disk in parallel
buffer_size = 8 * 1024 * 1024 # Use 8 MiB per file
dataset = dataset.interleave(
lambda name: tf.data.TFRecordDataset(name,
buffer_size=buffer_size),
cycle_length=16,
num_parallel_calls=tf.data.experimental.AUTOTUNE)
dataset = dataset.prefetch(self.global_batch_size)
if self.config.cache:
dataset = dataset.cache()
if self.is_training:
dataset = dataset.shuffle(self.config.shuffle_buffer_size)
dataset = dataset.repeat()
# Parse, pre-process, and batch the data in parallel
if self.config.builder == 'records':
preprocess = self.parse_record
else:
preprocess = self.preprocess
dataset = dataset.map(preprocess,
num_parallel_calls=tf.data.experimental.AUTOTUNE)
dataset = dataset.batch(self.batch_size,
drop_remainder=self.is_training)
# Note: we could do image normalization here, but we defer it to the model
# which can perform it much faster on a GPU/TPU
# TODO(dankondratyuk): if we fix prefetching, we can do it here
if self.is_training and self.config.deterministic_train is not None:
options = tf.data.Options()
options.experimental_deterministic = self.config.deterministic_train
options.experimental_slack = self.config.use_slack
options.experimental_optimization.parallel_batch = True
options.experimental_optimization.map_fusion = True
options.experimental_optimization.map_vectorization.enabled = True
options.experimental_optimization.map_parallelization = True
dataset = dataset.with_options(options)
# Prefetch overlaps in-feed with training
# Note: autotune here is not recommended, as this can lead to memory leaks.
# Instead, use a constant prefetch size like the the number of devices.
dataset = dataset.prefetch(self.config.num_devices)
return dataset
def pipeline(self, dataset: tf.data.Dataset) -> tf.data.Dataset:
"""Build a pipeline fetching, shuffling, and preprocessing the dataset.
Args:
dataset: A `tf.data.Dataset` that loads raw files.
Returns:
A TensorFlow dataset outputting batched images and labels.
"""
# This can help resolve OOM issues when using only 1 GPU for training
options = tf.data.Options()
options.experimental_optimization.map_parallelization = (
not self.disable_map_parallelization)
dataset = dataset.with_options(options)
if self._num_gpus > 1:
# For multi-host training, we want each hosts to always process the same
# subset of files. Each host only sees a subset of the entire dataset,
# allowing us to cache larger datasets in memory.
dataset = dataset.shard(self._num_gpus, hvd.rank())
if self.is_training:
# Shuffle the input files.
dataset.shuffle(buffer_size=self._file_shuffle_buffer_size)
if self.is_training and not self._cache:
dataset = dataset.repeat()
# Read the data from disk in parallel
dataset = dataset.interleave(
tf.data.TFRecordDataset,
cycle_length=10,
block_length=1,
num_parallel_calls=tf.data.experimental.AUTOTUNE)
if self._cache:
dataset = dataset.cache()
if self.is_training:
dataset = dataset.shuffle(self._shuffle_buffer_size)
dataset = dataset.repeat()
# Parse, pre-process, and batch the data in parallel
preprocess = self.parse_record
dataset = dataset.map(preprocess,
num_parallel_calls=tf.data.experimental.AUTOTUNE)
if self._num_gpus > 1:
# The batch size of the dataset will be multiplied by the number of
# replicas automatically when strategy.distribute_datasets_from_function
# is called, so we use local batch size here.
dataset = dataset.batch(self.local_batch_size,
drop_remainder=self.is_training)
else:
dataset = dataset.batch(self.global_batch_size,
drop_remainder=self.is_training)
# apply Mixup/CutMix only during training, if requested in the data pipeline,
# otherwise they will be applied in the model module on device
mixup_alpha = self.mixup_alpha if self.is_training else 0.0
cutmix_alpha = self.cutmix_alpha if self.is_training else 0.0
dataset = dataset.map(functools.partial(mixing, self.local_batch_size,
mixup_alpha, cutmix_alpha,
self.defer_img_mixing),
num_parallel_calls=64)
# Assign static batch size dimension
# dataset = dataset.map(
# functools.partial(self.set_shapes, batch_size),
# num_parallel_calls=tf.data.experimental.AUTOTUNE)
# Prefetch overlaps in-feed with training
dataset = dataset.prefetch(tf.data.experimental.AUTOTUNE)
return dataset
