def predict(self,
model,
x,
batch_size=None,
verbose=0,
steps=None,
callbacks=None,
**kwargs):
"""Predict loop for Distribution Strategies."""
dist_utils.validate_inputs(x=x, y=None)
batch_size, steps = dist_utils.process_batch_and_step_size(
model._distribution_strategy, x, batch_size, steps,
ModeKeys.PREDICT)
batch_size = model._validate_or_infer_batch_size(batch_size, steps, x)
dataset = model._distribution_standardize_user_data(
x, batch_size=batch_size, allow_partial_batch=True)
if dist_utils_v2.is_tpu_strategy(model._distribution_strategy):
steps = training_utils_v1.infer_steps_for_dataset(
model, dataset, steps, steps_name='steps')
if steps is None:
raise ValueError(
'Number of steps could not be inferred from the data, '
'please pass the steps argument.')
if not tf.executing_eagerly():
return experimental_tpu_predict_loop(model,
dataset,
verbose=verbose,
steps=steps,
callbacks=callbacks)
return training_arrays_v1.predict_loop(model,
dataset,
batch_size=batch_size,
verbose=verbose,
steps=steps,
callbacks=callbacks)
def unwrap_output_dict(strategy, grouped_outputs, mode):
"""Unwrap the list of outputs contained in the PerReplica parameters."""
if mode == ModeKeys.PREDICT:
return flatten_per_replica_values(strategy, grouped_outputs)
# In the case of fit/eval, the grouped_outputs is a dict, whereas in predict,
# the output is as same structure as model output. They need to be treated
# differently
total_loss = strategy.reduce(tf.distribute.ReduceOp.SUM,
grouped_outputs['total_loss'][0], axis=None)
output_losses = flatten_per_replica_values(strategy,
grouped_outputs['output_losses'])
metrics = flatten_per_replica_values(strategy,
grouped_outputs['metrics'])
batch_size = strategy.reduce(tf.distribute.ReduceOp.SUM,
grouped_outputs['batch_size'], axis=None)
if (dist_utils.is_tpu_strategy(strategy) and
tf.compat.v1.executing_eagerly_outside_functions()):
# Choose 1 value per replica in the TPU case since all replicas produce the
# same output.
# We only do this in eager mode for now since this function is used in
# both graph and eager mode and in the graph case we currently don't use
# experimental_run so would need to be removed when we converge the graph
# code path as well.
output_losses = output_losses[::strategy.num_replicas_in_sync]
metrics = metrics[::strategy.num_replicas_in_sync]
return {'total_loss': [total_loss],
'output_losses': output_losses,
'metrics': metrics,
'batch_size': batch_size}
def _prepare_feed_values(model, inputs, targets, sample_weights, mode):
"""Prepare feed values to the model execution function.
Arguments:
model: Model to prepare feed values for.
inputs: List or dict of model inputs.
targets: Optional list of model targets.
sample_weights: Optional list of sample weight arrays.
mode: One of ModeKeys.TRAIN/ModeKeys.TEST/ModeKeys.PREDICT.
Returns:
Feed values for the model in the given mode.
"""
strategy = model._distribution_strategy
inputs, targets, sample_weights = _get_input_from_iterator(inputs, model)
if dist_utils.is_tpu_strategy(strategy):
if sample_weights is not None:
raise ValueError('TPUStrategy does not support sample weights.')
# When the inputs are dict, then we want to flatten it in the same order as
# the input layers, such that the data are fed into the input layers in the
# correct order.
if isinstance(inputs, dict):
inputs = [inputs[key] for key in model._feed_input_names]
if is_distributing_by_cloning(model):
inputs = flatten_per_replica_values(strategy, inputs)
targets = flatten_per_replica_values(strategy, targets)
# Expand 1-dimensional inputs.
# TODO(b/124535720): Remove once this standarize data logic is shared with
# main flow.
inputs, targets = tf.nest.map_structure(
training_utils_v1.standardize_single_array, (inputs, targets))
else:
inputs = training_utils_v1.ModelInputs(inputs).as_list()
if mode == ModeKeys.PREDICT:
sample_weights = []
targets = []
elif sample_weights is not None and is_distributing_by_cloning(model):
if tf.executing_eagerly() and not model._compile_distribution:
raise NotImplementedError(
'`sample_weight` is not supported when using '
'tf.distribute.Strategy in eager mode and '
'cloning=True.')
sample_weights = flatten_per_replica_values(strategy, sample_weights)
ins = [inputs, targets, sample_weights]
return tuple(ins)
def is_distributing_by_cloning(model):
"""Decide whether this model is going to be distributed via cloning.
We are going to distribute the model by cloning in graph mode.
Args:
model: Keras model to distribute.
Returns:
True if the `model` is going to be distributed using cloning and False
otherwise.
"""
if (dist_utils.is_tpu_strategy(model._distribution_strategy) and
tf.executing_eagerly): # b/137580852
return False
elif tf.compat.v1.executing_eagerly_outside_functions():
return bool(model._compile_distribution)
return True
def evaluate(self,
model,
x=None,
y=None,
batch_size=None,
verbose=1,
sample_weight=None,
steps=None,
callbacks=None,
**kwargs):
"""Evaluate loop for Distribution Strategies."""
dist_utils.validate_inputs(x, y)
batch_size, steps = dist_utils.process_batch_and_step_size(
model._distribution_strategy, x, batch_size, steps, ModeKeys.TEST)
batch_size = model._validate_or_infer_batch_size(batch_size, steps, x)
dataset = model._distribution_standardize_user_data(
x,
y,
sample_weight=sample_weight,
batch_size=batch_size,
allow_partial_batch=True)
if dist_utils_v2.is_tpu_strategy(model._distribution_strategy):
steps = training_utils_v1.infer_steps_for_dataset(
model, dataset, steps, steps_name='steps')
if steps is None:
raise ValueError(
'Number of steps could not be inferred from the data, '
'please pass the steps argument.')
if not tf.executing_eagerly():
# Run TPU evaluation in a custom loop in graph mode.
return experimental_tpu_test_loop(model,
dataset,
verbose=verbose,
steps=steps,
callbacks=callbacks)
return training_arrays_v1.test_loop(model,
inputs=dataset,
batch_size=batch_size,
verbose=verbose,
steps=steps,
callbacks=callbacks)
def unwrap_outputs(distribution_strategy,
grouped_outputs,
with_loss_tensor=False):
"""Unwrap the list of outputs contained in the PerReplica parameters.
This function calls `flatten_per_replica_values` to parse each of the input
parameters into a list of outputs on the different devices. If we set
`with_loss_tensor` to be True, we also call `reduce` on the list of losses on
the different devices to give us one loss tensor.
Args:
distribution_strategy: DistributionStrategy used to distribute training and
validation.
grouped_outputs: PerReplica outputs returned from the train or test function
that we ran on each device.
with_loss_tensor: Boolean that indicates if we need to add the reduced loss
tensor as one of the outputs.
Returns:
Values of each of the PerReplica outputs.
"""
if not with_loss_tensor:
return flatten_per_replica_values(distribution_strategy,
grouped_outputs)
if not isinstance(grouped_outputs, list):
grouped_outputs = [grouped_outputs]
# reduce loss tensor before adding it to the list of fetches
loss = distribution_strategy.reduce(tf.distribute.ReduceOp.SUM,
grouped_outputs[0],
axis=None)
all_outputs = flatten_per_replica_values(distribution_strategy,
grouped_outputs[1:])
if (dist_utils.is_tpu_strategy(distribution_strategy)
and tf.compat.v1.executing_eagerly_outside_functions()):
# Choose 1 value per replica in the TPU case since all replicas produce the
# same output.
# We only do this in eager mode for now since this function is used in
# both graph and eager mode and in the graph case we currently don't use
# experimental_run so would need to be removed when we converge the graph
# code path as well.
all_outputs = all_outputs[::distribution_strategy.num_replicas_in_sync]
return [loss] + all_outputs
def fit(self,
model,
x=None,
y=None,
batch_size=None,
epochs=1,
verbose=1,
callbacks=None,
validation_split=0.,
validation_data=None,
shuffle=True,
class_weight=None,
sample_weight=None,
initial_epoch=0,
steps_per_epoch=None,
validation_steps=None,
validation_freq=1,
**kwargs):
"""Fit loop for Distribution Strategies."""
dist_utils.validate_callbacks(input_callbacks=callbacks,
optimizer=model.optimizer)
dist_utils.validate_inputs(x, y)
batch_size, steps_per_epoch = dist_utils.process_batch_and_step_size(
model._distribution_strategy,
x,
batch_size,
steps_per_epoch,
ModeKeys.TRAIN,
validation_split=validation_split)
batch_size = model._validate_or_infer_batch_size(
batch_size, steps_per_epoch, x)
dataset = model._distribution_standardize_user_data(
x,
y,
sample_weight=sample_weight,
class_weight=class_weight,
batch_size=batch_size,
validation_split=validation_split,
shuffle=shuffle,
epochs=epochs)
if not dist_utils.is_distributing_by_cloning(model):
with model._distribution_strategy.scope():
(dataset, _, _) = model._standardize_user_data(
dataset,
sample_weight=sample_weight,
class_weight=class_weight,
batch_size=batch_size,
validation_split=validation_split,
shuffle=shuffle)
val_dataset = None
if validation_data:
val_x, val_y, val_sample_weights = (
training_utils_v1.unpack_validation_data(validation_data))
dist_utils.validate_inputs(val_x, val_y)
_, validation_steps = dist_utils.process_batch_and_step_size(
model._distribution_strategy, val_x, batch_size,
validation_steps, ModeKeys.TEST)
val_dataset = model._distribution_standardize_user_data(
val_x,
val_y,
sample_weight=val_sample_weights,
class_weight=None,
batch_size=batch_size,
validation_split=validation_split,
shuffle=shuffle,
allow_partial_batch=True)
elif validation_split:
raise ValueError('validation_split argument is not supported with '
'distribution strategies.')
if dist_utils_v2.is_tpu_strategy(model._distribution_strategy):
steps_per_epoch = training_utils_v1.infer_steps_for_dataset(
model,
dataset,
steps_per_epoch,
epochs,
steps_name='steps_per_epoch')
if steps_per_epoch is None:
raise ValueError(
'Number of steps could not be inferred from the data, '
'please pass the steps_per_epoch argument.')
if not tf.executing_eagerly():
# Run TPU training in a custom loop in graph mode.
return experimental_tpu_fit_loop(
model,
dataset,
epochs=epochs,
verbose=verbose,
callbacks=callbacks,
val_dataset=val_dataset,
initial_epoch=initial_epoch,
steps_per_epoch=steps_per_epoch,
validation_steps=validation_steps,
validation_freq=validation_freq)
return training_arrays_v1.fit_loop(model,
dataset,
batch_size=batch_size,
epochs=epochs,
verbose=verbose,
callbacks=callbacks,
val_inputs=val_dataset,
shuffle=shuffle,
initial_epoch=initial_epoch,
steps_per_epoch=steps_per_epoch,
validation_steps=validation_steps,
validation_freq=validation_freq,
steps_name='steps_per_epoch')
def get_input_params(distribution_strategy,
num_samples,
steps,
batch_size,
mode=None):
"""Calculate the number of batches and steps/steps_per_epoch.
Args:
distribution_strategy: The DistributionStrategy used to compile the model.
num_samples: The number of samples from which we determine the batch size
and steps.
steps: The specified number of steps.
batch_size: The specified batch_size.
mode: ModeKey representing whether input will be used for training,
evaluation, or prediction. This is used to relax the constraints on
consuming all the training samples to keep compatibility till we support
partial batches. If none, then partial batches are not allowed.
Returns:
steps: The steps or steps_per_epoch argument depending on if a user is
calling `fit`, `evaluate` or `predict`. If the is_training flag is set
we don't require the number of samples to be used completely.
batch_size: The batch size to be used in model iterations.
Raises:
ValueError: If the number of batches or steps evaluates to 0.
"""
# TODO(b/118776054): Use global batch size for Keras/DS support.
# Currently this is only supported in TPUStrategy and CoreMirroredStrategy.
use_per_replica_batch = not dist_utils.global_batch_size_supported(
distribution_strategy)
# TODO(b/128995245): In eager mode, uneven batch sizes are allowed except for
# `fit()` on TPUStrategy.
# In graph mode, the zero batch case in batch norm is not handled due to
# XLA-GPU regression. Uneven batch sizes are not allowed except
# for `test()` and `predict()` on TPUStrategy.
if tf.executing_eagerly():
allow_partial_batch = (
mode != ModeKeys.TRAIN or
not dist_utils.is_tpu_strategy(distribution_strategy))
else:
allow_partial_batch = (
mode == ModeKeys.TRAIN or
((mode == ModeKeys.PREDICT or mode == ModeKeys.TEST) and
dist_utils.is_tpu_strategy(distribution_strategy)))
if steps is None:
if batch_size is None:
# If neither the batch size or number of steps are set. We choose the
# global batch size as the minimum of number of samples and 32. 32 is
# chosen to provide backward compatibility.
global_batch_size = min(num_samples, 32)
else:
# If the user provided the batch size we need to handle the case
# between different strategies that use the global/per-replica batch size
global_batch_size = batch_size
if use_per_replica_batch:
global_batch_size *= distribution_strategy.num_replicas_in_sync
if allow_partial_batch:
steps = np.ceil(num_samples / global_batch_size).astype(int)
else:
if num_samples % global_batch_size:
raise ValueError('The number of samples %s is not divisible by '
'batch size %s.' % (num_samples, global_batch_size))
steps = num_samples // global_batch_size
else:
if batch_size is None:
# We calculate the batch size based on the number of steps specified
if num_samples % steps:
raise ValueError('The number of samples %s is not divisible by '
'steps %s. Please change the number of steps to a '
'value that can consume all the samples' % (
num_samples, steps))
global_batch_size = num_samples // steps
else:
# If the user provided the batch size we need to handle the case
# between different strategies that use the global/per-replica batch size
global_batch_size = batch_size
if use_per_replica_batch:
global_batch_size *= distribution_strategy.num_replicas_in_sync
min_num_samples = global_batch_size * steps
if allow_partial_batch:
min_num_samples = global_batch_size * (steps-1) + 1 if steps > 1 else 0
if num_samples < min_num_samples:
raise ValueError('Number of samples %s is less than samples required '
'for specified batch_size %s and steps %s' % (
num_samples, global_batch_size, steps))
# We need to return the per replica or global batch size based on the strategy
if use_per_replica_batch:
if global_batch_size % distribution_strategy.num_replicas_in_sync:
raise ValueError(
'The batch size (%s) could not be sharded evenly across the sync '
'replicas (%s) in the distribution strategy.' % (
global_batch_size, distribution_strategy.num_replicas_in_sync))
batch_size = global_batch_size // distribution_strategy.num_replicas_in_sync
else:
batch_size = global_batch_size
return steps, batch_size