def step_fn(ctx, inputs, targets):
"""Clones the model and calls make_predict_function."""
# TODO(anjalisridhar): Support predict input correctly as it will not
# contain targets, only inputs.
del targets
# TODO(priyag, sourabhbajaj): The model gets cloned every time
# fit/test/predict is called. We should look into caching this keyed on
# input shapes.
clone_model_on_towers(model,
current_strategy,
make_callback_model=False,
inputs=inputs)
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_tower(
_per_device_predict_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy, grouped_inputs, grouped_outputs,
grouped_updates, grouped_session_args)
combined_fn = K.Function(all_inputs,
all_outputs,
updates=all_updates,
name='distributed_predict_function',
**all_session_args)
for label, output in zip(model.output_names, combined_fn.outputs):
ctx.set_last_step_output(label, output)
return combined_fn.updates_op
def step_fn(ctx, *inputs):
"""Clones the model and calls make_predict_function."""
# TODO(priyag, sourabhbajaj): The model gets cloned every time
# fit/test/predict is called. We should look into caching this keyed on
# input shapes.
clone_model_on_replicas(model,
current_strategy,
make_callback_model=False,
inputs=inputs,
mode=_Mode.PREDICT)
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_replica(
_per_device_predict_function, model._grouped_model_predict)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy, grouped_inputs, grouped_outputs,
grouped_updates, grouped_session_args)
combined_fn = K.Function(all_inputs,
all_outputs,
updates=all_updates,
name='distributed_predict_function',
**all_session_args)
for label, output in zip(model.output_names, combined_fn.outputs):
ctx.set_last_step_output(label, output)
return combined_fn.updates_op
def step_fn(ctx, inputs, targets):
"""Clones the model and calls make_train_function."""
# TODO(priyag, sourabhbajaj): The model gets cloned every time
# fit/test/predict is called. We should look into caching this keyed on
# input shapes.
clone_model_on_towers(
model,
current_strategy,
make_callback_model=True,
inputs=inputs,
targets=targets)
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_tower(
_per_device_train_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy, grouped_inputs, grouped_outputs,
grouped_updates, grouped_session_args)
combined_fn = K.Function(
all_inputs, all_outputs,
updates=all_updates,
name='distributed_train_function',
**all_session_args)
out_labels = model.metrics_names or []
for label, output in zip(out_labels, combined_fn.outputs):
if label == 'loss':
aggregation = distribute_lib.get_loss_reduction()
else:
# We aggregate all other metrics using mean for now. This is temporary
# workaround until new metrics are in place.
aggregation = variable_scope.VariableAggregation.MEAN
ctx.set_last_step_output(label, output, aggregation)
# TODO(priyag, sourabhbajaj): Ignoring these things from the combined_fn:
# feed_dict, session kwargs, run options, run_metadata for now. These should
# be handled appropriately
return combined_fn.updates_op
def step_fn(ctx, inputs, targets):
"""Clones the model and calls make_test_function."""
# TODO(priyag, sourabhbajaj): The model gets cloned every time
# fit/test/predict is called. We should look into caching this keyed on
# input shapes.
clone_model_on_replicas(model,
current_strategy,
make_callback_model=False,
inputs=inputs,
targets=targets,
mode=_Mode.TEST)
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_replica(
_per_device_test_function, model._grouped_model_test)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy, grouped_inputs, grouped_outputs,
grouped_updates, grouped_session_args)
combined_fn = K.Function(all_inputs,
all_outputs,
updates=all_updates,
name='distributed_test_function',
**all_session_args)
for label, output in zip(model.metrics_names, combined_fn.outputs):
if label == 'loss':
aggregation = distribute_lib.get_loss_reduction()
else:
# We aggregate all other metrics using mean for now. This is temporary
# workaround until new metrics are in place.
aggregation = variable_scope.VariableAggregation.MEAN
ctx.set_last_step_output(label, output, aggregation)
return combined_fn.updates_op
def step_fn(ctx, inputs, targets):
"""Clones the model and calls make_train_function."""
# TODO(priyag, sourabhbajaj): Should cache this keyed on input shapes.
clone_model_on_towers(model,
current_strategy,
make_callback_model=True,
inputs=inputs,
targets=targets)
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_tower(
_per_device_train_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy,
grouped_inputs,
grouped_outputs,
grouped_updates,
grouped_session_args,
with_loss_tensor=True)
combined_fn = K.Function(all_inputs,
all_outputs,
updates=all_updates,
name='distributed_train_function',
**all_session_args)
# TODO(priyag, sourabhbajaj): Perhaps the aggregation type needs to be
# something else for different outputs.
out_labels = model.metrics_names or []
for label, output in zip(out_labels, combined_fn.outputs):
ctx.set_last_step_output(
label, output, aggregation=distribute_lib.get_loss_reduction())
# TODO(priyag, sourabhbajaj): Ignoring these things from the combined_fn:
# feed_dict, session kwargs, run options, run_metadata for now. These should
# be handled appropriately
return combined_fn.updates_op
def predict_loop(model, iterator, verbose=0, steps=None):
"""Predict loop for predicting with DistributionStrategy.
Arguments:
model: Keras Model instance.
iterator: Iterator for input data.
verbose: Integer, Verbosity mode 0 or 1.
steps: Total number of steps (batches of samples)
before declaring `_predict_loop` finished.
Ignored with the default value of `None`.
Returns:
Array of predictions (if the model has a single output)
or list of arrays of predictions
(if the model has multiple outputs).
"""
current_strategy = model._distribution_strategy
# TODO(priyag, sourabhbajaj): Remove this when the codepaths are merged.
if current_strategy.__class__.__name__ == 'TPUStrategy':
return _experimental_predict_loop(model, iterator, verbose, steps)
if not model._grouped_model:
clone_model_on_replicas(model, current_strategy)
def _per_device_predict_function(model):
model._make_predict_function()
return (model.predict_function.inputs, model.predict_function.outputs,
model.predict_function.updates_op,
model.predict_function.session_kwargs)
inputs, _, _ = _get_input_from_iterator(iterator, model)
with current_strategy.scope():
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_replica(
_per_device_predict_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy, grouped_inputs, grouped_outputs,
grouped_updates, grouped_session_args)
dataset_inputs = distributed_training_utils.flatten_perdevice_values(
current_strategy, inputs)
distributed_predict_function = K.Function(
all_inputs,
all_outputs,
updates=all_updates,
name='distributed_predict_function',
**all_session_args)
if model.uses_learning_phase and not isinstance(
K.learning_phase(), int):
ins = dataset_inputs + [0]
else:
ins = dataset_inputs
if verbose == 1:
progbar = Progbar(target=steps)
# Copy the weights from the original model to each of the replicated models.
orig_model_weights = model.get_weights()
distributed_model = current_strategy.unwrap(model._grouped_model)[0]
distributed_training_utils.set_weights(current_strategy,
distributed_model,
orig_model_weights)
num_towers = current_strategy.num_towers
# Since we do not know how many samples we will see, we cannot
# pre-allocate the returned Numpy arrays. Instead, we store one array per
# batch seen and concatenate them upon returning.
unconcatenated_outs = []
assert steps is not None
for step in range(steps):
batch_outs = distributed_predict_function(ins)
if not isinstance(batch_outs, list):
batch_outs = [batch_outs]
if step == 0:
# batch_outs gives you the number of model outputs. In the distributed
# case this will be number of model_outputs * num_towers.
for _ in range(len(model.outputs)):
unconcatenated_outs.append([])
for i in range(len(model.outputs)):
nested_outs = batch_outs[i * num_towers:i * num_towers +
num_towers]
outs = nest.flatten(nested_outs)
unconcatenated_outs[i].extend(outs)
if verbose >= 1:
progbar.update(step + 1)
if len(unconcatenated_outs) == 1:
return np.concatenate(unconcatenated_outs[0], axis=0)
return [
np.concatenate(unconcatenated_outs[i], axis=0)
for i in range(len(unconcatenated_outs))
]
def fit_loop(model,
iterator,
epochs=100,
verbose=1,
callbacks=None,
val_iterator=None,
initial_epoch=0,
steps_per_epoch=None,
validation_steps=None):
"""Fit loop for training with DistributionStrategy.
Arguments:
model: Keras Model instance.
iterator: Iterator for input data.
epochs: Number of times to iterate over the data
verbose: Integer, Verbosity mode, 0, 1 or 2
callbacks: List of callbacks to be called during training
val_iterator: Iterator for validation data.
initial_epoch: Epoch at which to start training
(useful for resuming a previous training run)
steps_per_epoch: Total number of steps (batches of samples)
before declaring one epoch finished and starting the
next epoch. Ignored with the default value of `None`.
validation_steps: Number of steps to run validation for
(only if doing validation from data tensors).
Ignored with the default value of `None`.
Returns:
`History` object.
Raises:
ValueError: in case of invalid arguments.
"""
current_strategy = model._distribution_strategy
# TODO(priyag, sourabhbajaj): Remove this when the codepaths are merged.
if current_strategy.__class__.__name__ == 'TPUStrategy':
return _experimental_fit_loop(model, iterator, epochs, verbose,
callbacks, initial_epoch,
steps_per_epoch, val_iterator,
validation_steps)
if not model._grouped_model:
clone_model_on_replicas(model,
current_strategy,
make_callback_model=True)
def _per_device_train_function(model):
model._make_train_function()
return (model.train_function.inputs, model.train_function.outputs,
model.train_function.updates_op,
model.train_function.session_kwargs)
inputs, targets, sample_weights = _get_input_from_iterator(iterator, model)
with current_strategy.scope():
# Create train ops on each of the devices when we call
# `_per_device_train_function`.
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_replica(
_per_device_train_function, model._grouped_model)
# Unwrap all the per device values returned from `call_for_each_replica`.
# Unwrapping per device values gives you a list of values that can be
# used to construct a new train function that is composed of update ops on
# all the devices over which the model is distributed.
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy,
grouped_inputs,
grouped_outputs,
grouped_updates,
grouped_session_args,
with_loss_tensor=True)
# Dataset inputs and targets are also per devices values that need to be
# unwrapped.
dataset_inputs = distributed_training_utils.flatten_perdevice_values(
current_strategy, inputs)
dataset_targets = distributed_training_utils.flatten_perdevice_values(
current_strategy, targets)
# Create a train function that is composed of all the parameters above.
distributed_train_function = K.Function(
all_inputs,
all_outputs,
updates=all_updates,
name='distributed_train_function',
**all_session_args)
# We need to set sample_weights to None since there are sample weight
# placeholders that are created with default values.
sample_weights = [
None
for _ in range(len(model.outputs) * current_strategy.num_replicas)
]
if model.uses_learning_phase and not isinstance(
K.learning_phase(), int):
ins = dataset_inputs + dataset_targets + sample_weights + [1]
else:
ins = dataset_inputs + dataset_targets
do_validation = False
if validation_steps:
do_validation = True
# Copy the weights from the original model to each of the replicated models.
orig_model_weights = model.get_weights()
distributed_model = current_strategy.unwrap(model._grouped_model)[0]
distributed_training_utils.set_weights(current_strategy,
distributed_model,
orig_model_weights)
callbacks = cbks.configure_callbacks(callbacks,
model,
do_validation=do_validation,
val_inputs=None,
val_targets=None,
epochs=epochs,
steps_per_epoch=steps_per_epoch,
verbose=verbose)
out_labels = model.metrics_names or []
callbacks.on_train_begin()
assert steps_per_epoch is not None
for epoch in range(initial_epoch, epochs):
# Reset stateful metrics
for m in model.stateful_metric_functions:
m.reset_states()
callbacks.on_epoch_begin(epoch)
epoch_logs = {}
for step_index in range(steps_per_epoch):
batch_logs = {'batch': step_index, 'size': 1}
callbacks.on_batch_begin(step_index, batch_logs)
try:
outs = distributed_train_function(ins)
except errors.OutOfRangeError:
logging.warning(
'Your dataset iterator ran out of data; '
'interrupting training. Make sure that your dataset '
'can generate at least `steps_per_epoch * epochs` '
'batches (in this case, %d batches).' %
steps_per_epoch * epochs)
break
if not isinstance(outs, list):
outs = [outs]
outs = _aggregate_metrics_across_replicas(
current_strategy.num_replicas, out_labels,
model.stateful_metric_names, outs)
for l, o in zip(out_labels, outs):
batch_logs[l] = o
callbacks.on_batch_end(step_index, batch_logs)
if callbacks.model.stop_training:
break
if do_validation:
val_outs = test_loop(model,
val_iterator,
steps=validation_steps,
verbose=0)
if not isinstance(val_outs, list):
val_outs = [val_outs]
# Same labels assumed.
for l, o in zip(out_labels, val_outs):
epoch_logs['val_' + l] = o
callbacks.on_epoch_end(epoch, epoch_logs)
if callbacks.model.stop_training:
break
callbacks.on_train_end()
# Copy the weights back from the replicated model to the original model.
updated_weights = current_strategy.unwrap(
model._grouped_model)[0].get_weights()
model.set_weights(updated_weights)
return model.history
def test_loop(model, iterator, verbose=0, steps=None):
"""Test loop for evaluating with DistributionStrategy.
Arguments:
model: Keras Model instance.
iterator: Iterator for input data.
verbose: Integer, Verbosity mode 0 or 1.
steps: Total number of steps (batches of samples)
before declaring predictions finished.
Ignored with the default value of `None`.
Returns:
Scalar loss (if the model has a single output and no metrics)
or list of scalars (if the model has multiple outputs
and/or metrics). The attribute `model.metrics_names` will give you
the display labels for the outputs.
"""
current_strategy = model._distribution_strategy
# TODO(priyag, sourabhbajaj): Remove this when the codepaths are merged.
if current_strategy.__class__.__name__ == 'TPUStrategy':
return _experimental_test_loop(model, iterator, verbose, steps)
if not model._grouped_model:
clone_model_on_replicas(model, current_strategy)
def _per_device_test_function(model):
model._make_test_function()
return (model.test_function.inputs, model.test_function.outputs,
model.test_function.updates_op,
model.test_function.session_kwargs)
inputs, targets, sample_weights = _get_input_from_iterator(iterator, model)
with current_strategy.scope():
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_replica(
_per_device_test_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy,
grouped_inputs,
grouped_outputs,
grouped_updates,
grouped_session_args,
with_loss_tensor=True)
dataset_inputs = distributed_training_utils.flatten_perdevice_values(
current_strategy, inputs)
dataset_targets = distributed_training_utils.flatten_perdevice_values(
current_strategy, targets)
distributed_test_function = K.Function(
all_inputs,
all_outputs,
updates=all_updates,
name='distributed_test_function',
**all_session_args)
# We need to set sample_weights to None since there are sample weight
# placeholders that are created with default values.
sample_weights = [
None
for _ in range(len(model.outputs) * current_strategy.num_replicas)
]
if model.uses_learning_phase and not isinstance(
K.learning_phase(), int):
ins = dataset_inputs + dataset_targets + sample_weights + [0]
else:
ins = dataset_inputs + dataset_targets
for m in model.stateful_metric_functions:
m.reset_states()
stateful_metric_indices = [
i for i, name in enumerate(model.metrics_names)
if str(name) in model.stateful_metric_names
]
outs = []
if verbose == 1:
progbar = Progbar(target=steps)
# Copy the weights from the original model to each of the replicated models.
orig_model_weights = model.get_weights()
distributed_model = current_strategy.unwrap(model._grouped_model)[0]
distributed_training_utils.set_weights(current_strategy,
distributed_model,
orig_model_weights)
assert steps is not None
for step in range(steps):
batch_outs = distributed_test_function(ins)
batch_outs = _aggregate_metrics_across_replicas(
current_strategy.num_replicas, model.metrics_names,
model.stateful_metric_names, batch_outs)
if isinstance(batch_outs, list):
if step == 0:
outs = [0.] * len(batch_outs)
for i, batch_out in enumerate(batch_outs):
if i in stateful_metric_indices:
outs[i] = batch_out
else:
outs[i] += batch_out
else:
if step == 0:
outs.append(0.)
outs[0] += batch_outs
if verbose >= 1:
progbar.update(step + 1)
for i in range(len(outs)):
if i not in stateful_metric_indices:
outs[i] /= steps
if len(outs) == 1:
return outs[0]
return outs
def predict_loop(model, iterator, verbose=0, steps=None):
"""Abstract method to loop over some data in batches.
Arguments:
model: Keras Model instance.
iterator: Iterator for input data.
verbose: verbosity mode.
steps: Total number of steps (batches of samples)
before declaring `_predict_loop` finished.
Ignored with the default value of `None`.
Returns:
Array of predictions (if the model has a single output)
or list of arrays of predictions
(if the model has multiple outputs).
"""
current_strategy = model._distribution_strategy
clone_model_on_towers(model, current_strategy)
def _per_device_predict_function(model):
model._make_predict_function()
return (model.predict_function.inputs, model.predict_function.outputs,
model.predict_function.updates_op,
model.predict_function.session_kwargs)
inputs, _ = _get_input_from_iterator(iterator, model)
with current_strategy.scope():
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_tower(
_per_device_predict_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy, grouped_inputs, grouped_outputs,
grouped_updates, grouped_session_args)
dataset_inputs = distributed_training_utils.flatten_perdevice_values(
current_strategy, inputs)
distributed_predict_function = K.Function(
all_inputs,
all_outputs,
updates=all_updates,
name='distributed_predict_function',
**all_session_args)
if model.uses_learning_phase and not isinstance(K.learning_phase(), int):
ins = dataset_inputs + [0]
else:
ins = dataset_inputs
if verbose == 1:
progbar = Progbar(target=steps)
# Copy the weights from the original model to each of the replicated models.
orig_model_weights = model.get_weights()
with current_strategy.scope():
distributed_model = current_strategy.unwrap(model._grouped_model)[0]
distributed_training_utils.set_weights(current_strategy,
distributed_model,
orig_model_weights)
if steps is not None:
# Since we do not know how many samples we will see, we cannot pre-allocate
# the returned Numpy arrays. Instead, we store one array per batch seen
# and concatenate them upon returning.
unconcatenated_outs = []
for step in range(steps):
batch_outs = distributed_predict_function(ins)
if not isinstance(batch_outs, list):
batch_outs = [batch_outs]
if step == 0:
for _ in batch_outs:
unconcatenated_outs.append([])
for i, batch_out in enumerate(batch_outs):
unconcatenated_outs[i].append(batch_out)
if verbose == 1:
progbar.update(step + 1)
if len(unconcatenated_outs) == 1:
return np.concatenate(unconcatenated_outs[0], axis=0)
return [
np.concatenate(unconcatenated_outs[i], axis=0)
for i in range(len(unconcatenated_outs))
]
def test_loop(model, iterator, verbose=0, steps=None):
"""evaluate method to validate a model that uses DistributionStrategy.
Arguments:
model: Keras Model instance.
iterator: Iterator for input data.
verbose: verbosity mode.
steps: Total number of steps (batches of samples)
before declaring predictions finished.
Ignored with the default value of `None`.
Returns:
Scalar loss (if the model has a single output and no metrics)
or list of scalars (if the model has multiple outputs
and/or metrics). The attribute `model.metrics_names` will give you
the display labels for the scalar outputs.
"""
current_strategy = model._distribution_strategy
clone_model_on_towers(model, current_strategy)
def _per_device_test_function(model):
model._make_test_function()
return (model.test_function.inputs, model.test_function.outputs,
model.test_function.updates_op,
model.test_function.session_kwargs)
inputs, targets = _get_input_from_iterator(iterator, model)
with current_strategy.scope():
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_tower(
_per_device_test_function, model._grouped_model)
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy,
grouped_inputs,
grouped_outputs,
grouped_updates,
grouped_session_args,
with_loss_tensor=True)
dataset_inputs = distributed_training_utils.flatten_perdevice_values(
current_strategy, inputs)
dataset_targets = distributed_training_utils.flatten_perdevice_values(
current_strategy, targets)
distributed_test_function = K.Function(all_inputs,
all_outputs,
updates=all_updates,
name='distributed_test_function',
**all_session_args)
# We need to set sample_weights to None since there are sample weight
# placeholders that are created with default values.
sample_weights = [
None for _ in range(len(model.outputs) * current_strategy.num_towers)
]
if model.uses_learning_phase and not isinstance(K.learning_phase(), int):
ins = dataset_inputs + dataset_targets + sample_weights + [0]
else:
ins = dataset_inputs + dataset_targets
outs = []
if verbose == 1:
progbar = Progbar(target=steps)
# Copy the weights from the original model to each of the replicated models.
orig_model_weights = model.get_weights()
with current_strategy.scope():
distributed_model = current_strategy.unwrap(model._grouped_model)[0]
distributed_training_utils.set_weights(current_strategy,
distributed_model,
orig_model_weights)
if steps is not None:
for step in range(steps):
batch_outs = distributed_test_function(ins)
batch_outs = _aggregate_metrics_across_towers(
current_strategy.num_towers, model.metrics_names, batch_outs)
if isinstance(batch_outs, list):
if step == 0:
for _ in enumerate(batch_outs):
outs.append(0.)
for i, batch_out in enumerate(batch_outs):
outs[i] += batch_out
else:
if step == 0:
outs.append(0.)
outs[0] += batch_outs
if verbose == 1:
progbar.update(step + 1)
for i in range(len(outs)):
outs[i] /= steps
if len(outs) == 1:
return outs[0]
return outs
def fit_loop(model,
inputs,
targets,
epochs=100,
verbose=1,
callbacks=None,
val_inputs=None,
val_targets=None,
callback_metrics=None,
initial_epoch=0,
steps_per_epoch=None,
validation_steps=None):
"""fit function when using DistributionStrategy for training.
Arguments:
model: Keras Model instance.
inputs: List of input arrays.
targets: List of target arrays.
epochs: Number of times to iterate over the data
verbose: Verbosity mode, 0, 1 or 2
callbacks: List of callbacks to be called during training
val_inputs: List of input arrays.
val_targets: List of target arrays.
callback_metrics: List of strings, the display names of the metrics
passed to the callbacks. They should be the
concatenation of list the display names of the outputs of
`f` and the list of display names of the outputs of `f_val`.
initial_epoch: Epoch at which to start training
(useful for resuming a previous training run)
steps_per_epoch: Total number of steps (batches of samples)
before declaring one epoch finished and starting the
next epoch. Ignored with the default value of `None`.
validation_steps: Number of steps to run validation for
(only if doing validation from data tensors).
Ignored with the default value of `None`.
Returns:
`History` object.
Raises:
ValueError: in case of invalid arguments.
"""
current_strategy = model._distribution_strategy
def _per_device_train_function(model):
model._make_train_function()
return (model.train_function.inputs, model.train_function.outputs,
model.train_function.updates_op,
model.train_function.session_kwargs)
with current_strategy.scope():
# Create train ops on each of the devices when we call
# `_per_device_train_function`.
(grouped_inputs, grouped_outputs, grouped_updates,
grouped_session_args) = current_strategy.call_for_each_tower(
_per_device_train_function, model._grouped_model)
# Unwrap all the per device values returned from `call_for_each_tower`.
# Unwrapping per device values gives you a list of values that can be
# used to construct a new train function that is composed of update ops on
# all the devices over which the model is distributed.
(all_inputs, all_outputs, all_updates,
all_session_args) = distributed_training_utils.unwrap_values(
current_strategy,
grouped_inputs,
grouped_outputs,
grouped_updates,
grouped_session_args,
with_loss_tensor=True)
# Dataset inputs and targets are also per devices values that need to be
# unwrapped.
dataset_inputs = distributed_training_utils.flatten_perdevice_values(
current_strategy, inputs)
dataset_targets = distributed_training_utils.flatten_perdevice_values(
current_strategy, targets)
# Create a train function that is composed of all the parameters above.
distributed_train_function = K.Function(all_inputs,
all_outputs,
updates=all_updates,
name='distributed_train_function',
**all_session_args)
# We need to set sample_weights to None since there are sample weight
# placeholders that are created with default values.
sample_weights = [
None for _ in range(len(model.outputs) * current_strategy.num_towers)
]
if model.uses_learning_phase and not isinstance(K.learning_phase(), int):
ins = dataset_inputs + dataset_targets + sample_weights + [1]
else:
ins = dataset_inputs + dataset_targets
do_validation = False
if validation_steps:
do_validation = True
if steps_per_epoch is None:
raise ValueError('Can only use `validation_steps` '
'when doing step-wise '
'training, i.e. `steps_per_epoch` '
'must be set.')
out_labels = model.metrics_names
if do_validation:
callback_metrics = copy.copy(out_labels) + [
'val_' + n for n in out_labels
]
else:
callback_metrics = copy.copy(out_labels)
model.history = cbks.History()
all_callbacks = [
cbks.BaseLogger(stateful_metrics=model.stateful_metric_names)
]
if verbose:
# We assume that `steps_per_epoch` is always set since we have to use
# Datasets.
count_mode = 'steps'
all_callbacks.append(
cbks.ProgbarLogger(count_mode,
stateful_metrics=model.stateful_metric_names))
all_callbacks += (callbacks or []) + [model.history]
callbacks = cbks.CallbackList(all_callbacks)
out_labels = out_labels or []
# We set the callback model to an instance of the `DistributedModel` that we
# create in the `compile` call. The `DistributedModel` is initialized with
# the first replicated model. We need to set the callback model to a
# DistributedModel to allow us to override saving and loading weights when
# we checkpoint the model during training.
callback_model = model._replicated_model
callbacks.set_model(callback_model)
callbacks.set_params({
'epochs': epochs,
'steps': steps_per_epoch,
'samples': None,
'verbose': verbose,
'do_validation': do_validation,
'metrics': callback_metrics or [],
})
callbacks.on_train_begin()
callback_model.stop_training = False
out_labels = out_labels or []
# Copy the weights from the original model to each of the replicated models.
orig_model_weights = model.get_weights()
with current_strategy.scope():
distributed_model = current_strategy.unwrap(model._grouped_model)[0]
distributed_training_utils.set_weights(current_strategy,
distributed_model,
orig_model_weights)
for epoch in range(initial_epoch, epochs):
callbacks.on_epoch_begin(epoch)
if steps_per_epoch is not None:
epoch_logs = {}
for step_index in range(steps_per_epoch):
batch_logs = {}
batch_logs['batch'] = step_index
batch_logs['size'] = 1
callbacks.on_batch_begin(step_index, batch_logs)
try:
outs = distributed_train_function(ins)
except errors.OutOfRangeError:
logging.warning(
'Your dataset iterator ran out of data; '
'interrupting training. Make sure that your dataset '
'can generate at least `steps_per_epoch * epochs` '
'batches (in this case, %d batches).' %
steps_per_epoch * epochs)
break
if not isinstance(outs, list):
outs = [outs]
# TODO(anjalisridhar): Temporary workaround for aggregating metrics
# across towers. Replace with the new metrics module eventually.
merged_output = []
# The first output is the total loss.
merged_output.append(outs[0])
current_index = 1
num_devices = len(current_strategy._devices)
# Each label in `out_labels` corresponds to one set of metrics. The
# number of metric values corresponds to the number of devices. We
# currently take the mean of the values.
for _ in out_labels[1:]:
m = np.mean(outs[current_index:current_index +
num_devices])
merged_output.append(m)
current_index += num_devices
for l, o in zip(out_labels, outs):
batch_logs[l] = o
callbacks.on_batch_end(step_index, batch_logs)
if callback_model.stop_training:
break
if do_validation:
val_outs = test_loop(model,
val_inputs,
val_targets,
steps=validation_steps,
verbose=0)
if not isinstance(val_outs, list):
val_outs = [val_outs]
# Same labels assumed.
for l, o in zip(out_labels, val_outs):
epoch_logs['val_' + l] = o
callbacks.on_epoch_end(epoch, epoch_logs)
if callback_model.stop_training:
break
callbacks.on_train_end()
# Copy the weights back from the replicated model to the original model.
with current_strategy.scope():
updated_weights = current_strategy.unwrap(
model._grouped_model)[0].get_weights()
model.set_weights(updated_weights)
return model.history
