def apply_gradients(self, grads_and_vars, global_step=None, name=None):
if self._num_micro_batches == 1:
return self._opt.apply_gradients(grads_and_vars, global_step)
global_step = global_step or py_utils.GetOrCreateGlobalStepVar()
with tf.init_scope():
self._create_slots([v for (_, v) in grads_and_vars])
accums = []
variables = []
for g, v in grads_and_vars:
accum = self.get_slot(v, 'grad_accum')
variables.append(v)
# pytype: disable=attribute-error
if isinstance(g, tf.IndexedSlices):
scaled_grad = tf.IndexedSlices(
g.values / self._num_micro_batches,
g.indices,
dense_shape=g.dense_shape)
else:
scaled_grad = g / self._num_micro_batches
accum_tensor = accum.read_value()
accums.append(accum.assign(accum_tensor + scaled_grad))
# pytype: enable=attribute-error
def _ApplyAndReset():
normalized_accums = accums
if self._apply_crs_to_grad:
normalized_accums = [
tf.tpu.cross_replica_sum(accum.read_value()) for accum in accums
]
apply_op = self._opt.apply_gradients(
list(zip(normalized_accums, variables)))
with tf.control_dependencies([apply_op]):
zero_op = [tf.assign(accum, tf.zeros_like(accum)) for accum in accums]
return tf.group(zero_op, tf.assign_add(global_step, 1))
def _Accum():
return tf.no_op()
accum_step = tf.cond(
tf.equal(
tf.math.floormod(self._counter + 1, self._num_micro_batches), 0),
_ApplyAndReset, # Apply the accumulated gradients and reset.
_Accum) # Accumulate gradients.
with tf.control_dependencies([tf.group(accums)]):
return tf.group(accum_step, tf.assign_add(self._counter, 1))
def testVariableThetaValue(self):
with self.session():
layer_p = TestLayer.Params().Set(name='test')
layer = layer_p.Instantiate()
tf.global_variables_initializer().run()
self.assertAllClose(layer.vars.w.eval(), layer.theta.w.eval())
b_eval = layer.vars.b.eval()
self.assertAllClose(b_eval, layer.theta.b.eval())
self.assertAllClose(b_eval, layer._private_theta['b'].eval())
# theta reflects the vars change.
new_b = layer.vars.b.assign(tf.ones_like(layer.vars.b) * 3.)
with tf.control_dependencies([new_b]):
self.assertAllClose(b_eval * 3., new_b.eval())
self.assertAllClose(layer.vars.b.eval(), new_b.eval())
self.assertAllClose(layer.vars.b.eval(), layer.theta.b.eval())
def IsWithinBBox(points, bbox):
"""Checks if points are within a 2-d bbox.
The function returns true if points are strictly inside the box. It also
returns true when the points are exactly on the box edges.
Args:
points: a float Tensor of shape [..., 2] of points to be tested. The last
coordinates are (x, y).
bbox: a float Tensor of shape [..., 4, 2] of bboxes. The last coordinates
are the four corners of the bbox and (x, y). The corners are assumed to be
given in counter-clockwise order.
Returns:
Tensor: If ``pshape = tf.shape(points)[:-1]`` and
``bshape = tf.shape(bbox)[:-2]``, returns a boolean tensor of shape
``tf.concat(pshape, bshape)``, where each element is true if the point is
inside to the corresponding box. If a point falls exactly on an edge of the
bbox, it is also true.
"""
bshape = py_utils.GetShape(bbox)[:-2]
pshape = py_utils.GetShape(points)[:-1]
bbox = py_utils.HasShape(bbox, bshape + [4, 2])
points = py_utils.HasShape(points, pshape + [2])
# Enumerate all 4 edges:
v1, v2, v3, v4 = (bbox[..., 0, :], bbox[..., 1, :], bbox[...,
2, :], bbox[...,
3, :])
v1v2v3_check = tf.reduce_all(_IsCounterClockwiseDirection(v1, v2, v3))
v2v3v4_check = tf.reduce_all(_IsCounterClockwiseDirection(v2, v3, v4))
v4v1v2_check = tf.reduce_all(_IsCounterClockwiseDirection(v4, v1, v2))
v3v4v1_check = tf.reduce_all(_IsCounterClockwiseDirection(v3, v4, v1))
with tf.control_dependencies([
py_utils.Assert(v1v2v3_check, [v1, v2, v3]),
py_utils.Assert(v2v3v4_check, [v3, v3, v4]),
py_utils.Assert(v4v1v2_check, [v4, v1, v2]),
py_utils.Assert(v3v4v1_check, [v3, v4, v1])
]):
is_inside = tf.math.logical_and(
tf.math.logical_and(_IsOnLeftHandSideOrOn(points, v1, v2),
_IsOnLeftHandSideOrOn(points, v2, v3)),
tf.math.logical_and(_IsOnLeftHandSideOrOn(points, v3, v4),
_IsOnLeftHandSideOrOn(points, v4, v1)))
# Swap the last two dimensions.
ndims = is_inside.shape.ndims
return tf.transpose(is_inside,
list(range(ndims - 2)) + [ndims - 1, ndims - 2])
def FProp(self, theta, inputs, paddings=None):
"""Apply batch normalization.
Args:
theta: A `.NestedMap` object containing weights' values of this layer and
its children layers.
inputs: The inputs tensor. Shaped [..., dim].
paddings: The paddings tensor. Shaped [..., 1], with the same rank as the
input tensor.
Returns:
Output after applying batch normalization, with the same shape as
'inputs'.
"""
p = self.params
if paddings is None:
paddings = self._GetDefaultPaddings(inputs)
with tf.name_scope(p.name):
norm_mean, norm_variance, beta, gamma = self.ComputeAndUpdateMoments(
theta, inputs, paddings)
with tf.control_dependencies([
py_utils.assert_greater_equal(
norm_variance, tf.zeros_like(norm_variance)),
py_utils.assert_shape_match([tf.shape(inputs)[-1]],
tf.shape(norm_mean)),
py_utils.assert_shape_match([tf.shape(inputs)[-1]],
tf.shape(norm_variance)),
]):
if p.use_fused_batch_norm_for_eval and self.do_eval:
bn_output, _, _ = nn.fused_batch_norm(inputs,
gamma,
beta,
norm_mean,
norm_variance,
self._epsilon,
is_training=False)
else:
bn_output = tf.nn.batch_normalization(
inputs, norm_mean, norm_variance, beta, gamma,
self._epsilon)
if p.set_padded_output_to_zero:
bn_output *= 1.0 - paddings
return bn_output
def Value(self):
p = self.params
with tf.name_scope(p.name):
steps = self._best_step
best_step = steps[0]
last_step = steps[1]
ref_step = tf.maximum(self.theta.ref_step, best_step)
f = self.theta.cur_factor
# Decay if no improvement within window.
new_factor = tf.where(last_step - ref_step < p.window, f,
tf.maximum(p.min_factor, f * p.decay))
# Update ref_step if we decayed.
new_step = tf.where(tf.equal(new_factor, f), ref_step, last_step)
update_step = tf.assign(self.vars.ref_step, new_step)
with tf.control_dependencies([update_step]):
return tf.assign(self.vars.cur_factor, new_factor)
def ExtractLogMelFeatures(wav_bytes_t):
"""Create Log-Mel Filterbank Features from raw bytes.
Args:
wav_bytes_t: Tensor representing raw wav file as a string of bytes. It is
currently assumed that the wav file is encoded at 16KHz (see DecodeWav,
below).
Returns:
A Tensor representing three stacked log-Mel filterbank energies, sub-sampled
every three frames.
"""
# We want to use these parameters exactly.
def _CreateAsrFrontend():
"""Parameters corresponding to default ASR frontend."""
p = asr_frontend.MelAsrFrontend.Params()
p.sample_rate = 16000.
p.frame_size_ms = 25.
p.frame_step_ms = 10.
p.num_bins = 80
p.lower_edge_hertz = 125.
p.upper_edge_hertz = 7600.
p.preemph = 0.97
p.noise_scale = 0.
p.pad_end = False
return p.Instantiate()
sample_rate, audio = DecodeWav(wav_bytes_t)
audio *= 32768
# Remove channel dimension, since we have a single channel.
audio = tf.squeeze(audio, axis=1)
# TODO(drpng): make batches.
audio = tf.expand_dims(audio, axis=0)
static_sample_rate = 16000
mel_frontend = _CreateAsrFrontend()
with tf.control_dependencies(
[tf.assert_equal(sample_rate, static_sample_rate)]):
outputs = mel_frontend.FPropDefaultTheta(
py_utils.NestedMap(src_inputs=audio,
paddings=tf.zeros_like(audio)))
log_mel = outputs.src_inputs
return log_mel
def GetNext(self):
"""Override of the root's GetNext to support checking repeat sentinel."""
self._InitIterator()
if py_utils.GetUnitTestSession():
self.Initialize(py_utils.GetUnitTestSession())
batch = self._iterator[self.host_id].get_next()
# Sentinel check.
if self._repeat_with_sentinel and not self._repeat_steps:
assert_op = tf.debugging.assert_none_equal(
batch[self.params.sentinel_key],
tf.constant(self.params.sentinel_value),
summarize=1,
message='REPEAT_SENTINEL_')
tf.logging.info('sentinel constant dtype %r',
tf.constant(self.params.sentinel_value))
with tf.control_dependencies([assert_op]):
# This identity transform will throw tf.errors.InvalidArgumentError
# if assert_op fails (sentinel_key takes on sentinel_value).
batch = batch.Transform(tf.identity)
return batch
def TpuTrainStep(*args):
"""Train a shard of a batch on a single TPU core.
Args:
*args: metrics values from previous steps.
Returns:
New summed metrics values and a train_op.
"""
self._model = self._task_params.Instantiate()
self._model.ConstructFPropBPropGraph()
per_step_eval_metrics = self._eval_metrics.SetMetrics(
self._model.GetTask().eval_metrics, args)
outfeed_op = self._OutfeedEnqueue(
self._model.GetTask().per_example_tensors)
summed_metrics = []
assert len(per_step_eval_metrics) == len(args)
with tf.control_dependencies([outfeed_op]):
for x, y in zip(per_step_eval_metrics, args):
summed_metrics.append(x + y)
return summed_metrics + [self._model.GetTask().train_op]
def TpuTrainStep(*args):
"""Train a shard of a batch on a single TPU core.
Args:
*args: metrics values from previous steps.
Returns:
New summed metrics values and a train_op.
"""
with py_utils.OpportunisticVariableReuseScope(True):
self._model.InstantiateVariables()
self._model.ConstructFPropBPropGraph()
per_step_eval_metrics = self._eval_metrics.SetMetrics(
self._task.eval_metrics, args)
outfeed_op = self._OutfeedEnqueue(self._task.per_example_tensors)
summed_metrics = []
assert len(per_step_eval_metrics) == len(args)
with tf.control_dependencies([outfeed_op]):
for x, y in zip(per_step_eval_metrics, args):
summed_metrics.append(x + y)
return summed_metrics + [self._task.train_op]
def Finalize(self):
"""Finishes creation of the overall figure, returning the image summary."""
subplot_grid_shape = self._subplot_grid_shape
if subplot_grid_shape is None:
subplot_grid_shape = (len(self._subplots), 1)
# AddMatplotlibFigureSummary (due to restrictions of py_func) only supports
# flattened list of tensors so we must do some bookkeeping to maintain a
# mapping from _SubplotMetadata object to flattened_tensors.
subplot_slices = []
flattened_tensors = []
for subplot in self._subplots:
start = len(flattened_tensors)
subplot_slices.append((start, start + len(subplot.tensor_list)))
flattened_tensors.extend(subplot.tensor_list)
def PlotFunc(fig, *numpy_data_list):
gs = gridspec.GridSpec(*subplot_grid_shape,
**self._gridspec_kwargs)
for n, subplot in enumerate(self._subplots):
axes = fig.add_subplot(gs[n])
start, end = subplot_slices[n]
subplot_data = numpy_data_list[start:end]
subplot.plot_func(fig, axes, *subplot_data)
func = functools.partial(_RenderMatplotlibFigures, self._figsize,
self._max_outputs, PlotFunc)
batch_sizes = [tf.shape(t)[0] for t in flattened_tensors]
num_tensors = len(flattened_tensors)
with tf.control_dependencies([
tf.assert_equal(batch_sizes, [batch_sizes[0]] * num_tensors,
summarize=num_tensors)
]):
rendered = tf.py_func(func,
flattened_tensors,
tf.uint8,
name='RenderMatplotlibFigures')
return tf.summary.image(self._name,
rendered,
max_outputs=self._max_outputs)
def DecodeWithTheta(self, theta, input_batch):
"""Constructs the inference graph."""
p = self.params
# from IPython import embed; embed()
with tf.name_scope('decode'), tf.name_scope(p.name):
with tf.name_scope('encoder'):
encoder_outputs = self._FrontendAndEncoderFProp(
theta, input_batch.src)
if p.inference_compute_only_log_softmax:
global_step = tf.train.get_global_step()
increment_global_step = tf.assign(global_step, global_step + 1)
with tf.control_dependencies([increment_global_step]):
log_probabilities = tf.transpose(tf.nn.log_softmax(
encoder_outputs.encoded, axis=2),
perm=(1, 0, 2))
with tf.name_scope('decoder'):
decoder_outs = self._DecodeCTC(encoder_outputs)
# encoder_outputs's shape is [T,B,F]
return {
'log_probabilities':
log_probabilities,
'log_probabilities_lengths':
py_utils.LengthsFromBitMask(encoder_outputs.padding, 0),
'int64_uttid':
input_batch.sample_ids,
'int64_audio_document_id':
input_batch.audio_document_ids,
'num_utterances_in_audio_document':
input_batch.num_utterances_in_audio_document,
'transcripts':
decoder_outs.transcripts,
}
with tf.name_scope('decoder'):
decoder_outs = self._DecodeCTC(encoder_outputs)
decoder_metrics = py_utils.RunOnTpuHost(self._CalculateErrorRates,
decoder_outs, input_batch)
return decoder_metrics
def GetNext(self):
"""Override of the root's GetNext to support checking repeat sentinel."""
# Use `init_scope()` to ensure that the datasets and iterators are created
# outside of the function-building graph. This ensures that these creation
# operations are not repeated in subsequent `tf.function` calls.
with tf.init_scope():
self._InitIterator()
if py_utils.GetUnitTestSession():
self.Initialize(py_utils.GetUnitTestSession())
batch = self._iterator[self.host_id].get_next()
# Sentinel check.
if self._repeat_with_sentinel and not self._repeat_steps:
assert_op = tf.debugging.assert_none_equal(
batch[self.params.sentinel_key],
tf.constant(self.params.sentinel_value),
summarize=1,
message='REPEAT_SENTINEL_')
tf.logging.info('sentinel constant dtype %r',
tf.constant(self.params.sentinel_value))
with tf.control_dependencies([assert_op]):
# This identity transform will throw tf.errors.InvalidArgumentError
# if assert_op fails (sentinel_key takes on sentinel_value).
batch = batch.Transform(tf.identity)
return batch
def _BPropGenTrainOps(self, vmap, metrics=None, add_summary=True):
"""Populates the train_ops dictionary in a backwards pass."""
metrics = metrics or self._metrics
bprop_variable_filters = self.input_generator.GetBpropVariableFilters()
# Only compute the mask if the variable filters are not empty.
if bprop_variable_filters != [''] * len(bprop_variable_filters):
self._ComputeGradientMask(bprop_variable_filters)
train_ops = {} # mapping from op name to op.
gradient_mask = None
if self._per_input_gradient_mask:
# TODO(neerajgaur): Change this to use source_selected from input_batch.
onehot = self.input_generator.GetInputSourceOneHot()
gradient_mask = {
k: tf.tensordot(v, onehot, 1)
for k, v in self._per_input_gradient_mask.items()
}
all_losses = []
for optimization in self.learners:
learner_name = optimization.params.name
loss_name = optimization.params.loss_name or learner_name
metric = metrics.get(loss_name, None)
if metric is None:
raise ValueError('Loss %s not found in metrics %s' %
(loss_name, list(metrics.keys())))
loss = metric[0]
all_losses.append(loss)
train_ops['train/%s' % learner_name], eval_metrics = optimization.Apply(
loss,
vmap,
gradient_mask=gradient_mask,
gradient_adjuster=self.AdjustGradients)
if add_summary:
for key, (value, weight) in eval_metrics.items():
self.AddEvalMetric(key + '/' + learner_name, value, weight)
relevant_bn_updates, _ = py_utils.FindRelevantBatchNormUpdates(
all_losses, tf.get_collection(py_utils.BATCH_NORM_UPDATES))
train_ops['bn_updates'] = relevant_bn_updates
var_update_ops = [
tf.group(*tf.nest.flatten(train_ops), name='var_update_ops')
]
# Post training step update.
with tf.control_dependencies(var_update_ops):
post_step_op = self.PostTrainingStepUpdate(self.global_step)
train_ops = {}
with tf.control_dependencies([post_step_op]):
# Get the op to update the weight masks and thresholds
mask_update_op = self._GetMaskUpdateOp()
train_ops['mask_updates'] = mask_update_op
with tf.control_dependencies([mask_update_op]):
true_global_step = py_utils.GetOrCreateGlobalStepVar()
with tf.ops.colocate_with(true_global_step):
increment_global_steps = tf.assign_add(true_global_step, 1)
if self._global_step_var != true_global_step:
with tf.ops.colocate_with(self._global_step_var):
increment_global_steps = tf.group(
increment_global_steps, tf.assign_add(self._global_step_var, 1))
train_ops['global_step'] = increment_global_steps
# If we are using Tpu Embeddings, generate the monolithic send
# gradient op.
tpu_embedding_activations = tf.get_collection(
py_utils.TPU_EMBEDDING_ACTIVATIONS)
if tpu_embedding_activations:
tpu_embedding_activations_dict = tpu_embedding_activations[0]
tpu_embedding = tf.get_collection(py_utils.TPU_EMBEDDING)[0]
tpu_embedding_send_gradient_op = py_utils.ComputeTpuEmbeddingGradients(
self.loss, tpu_embedding_activations_dict, tpu_embedding)
train_ops['tpu_embedding'] = tpu_embedding_send_gradient_op
for op_name, op in train_ops.items():
assert op is not None, op_name
return train_ops
def testAccumulator(self):
# testAccumulator compares
# - explicit averaging of independently computed var_grads1 and
# var_grads2,
# - Accumulator(SGD) optimizer effectively doing this over 2 steps.
np.random.seed(12345)
np_input1 = np.random.normal(0.1, 0.5, [2, 4, 3])
np.random.seed(12346)
np_input2 = np.random.normal(0.1, 0.5, [2, 4, 3])
with self.session(use_gpu=True, graph=tf.Graph()) as sess:
tf.random.set_seed(123456)
params = layers.ProjectionLayer.Params()
params.name = 'proj'
params.dtype = tf.float64
params.input_dim = 3
params.output_dim = 2
params.params_init = py_utils.WeightInit.Gaussian(0.01, 123456)
params.batch_norm = False
proj_layer = layers.ProjectionLayer(params)
inputs1 = tf.placeholder(shape=[2, 4, 3], dtype=tf.float64)
in_padding1 = tf.zeros([2, 4, 1], dtype=tf.float64)
inputs2 = tf.placeholder(shape=[2, 4, 3], dtype=tf.float64)
in_padding2 = tf.zeros([2, 4, 1], dtype=tf.float64)
output1 = proj_layer.FPropDefaultTheta(inputs1, in_padding1)
output2 = proj_layer.FPropDefaultTheta(inputs2, in_padding2)
loss1 = tf.reduce_sum(output1)
loss2 = tf.reduce_sum(output2)
var_grads1 = py_utils.ComputeGradients(loss1, proj_layer.vars)
var_grads2 = py_utils.ComputeGradients(loss2, proj_layer.vars)
op = optimizer.SGD.Params()
opt = op.Instantiate()
lr = 1e-1
with tf.control_dependencies([loss1, loss2]):
var_update_op1 = opt.Apply(
lr, py_utils.ApplyGradMultiplier(var_grads1, 1. / 2.))
with tf.control_dependencies([var_update_op1]):
var_update_op2 = opt.Apply(
lr, py_utils.ApplyGradMultiplier(var_grads2, 1. / 2.))
self.evaluate(tf.global_variables_initializer())
vars1 = self.evaluate(proj_layer.vars.Flatten())
loss1_1, grads1_1, loss1_2, grads1_2 = sess.run(
[
loss1,
var_grads1.Transform(tuple), loss2,
var_grads2.Transform(tuple)
],
feed_dict={
inputs1: np_input1,
inputs2: np_input2,
},
)
sess.run([var_update_op2],
feed_dict={
inputs1: np_input1,
inputs2: np_input2,
})
vars1_1 = self.evaluate(proj_layer.vars.Flatten())
with self.session(use_gpu=True, graph=tf.Graph()) as sess:
tf.random.set_seed(123456)
params = layers.ProjectionLayer.Params()
params.name = 'proj'
params.dtype = tf.float64
params.input_dim = 3
params.output_dim = 2
params.params_init = py_utils.WeightInit.Gaussian(0.01, 123456)
params.batch_norm = False
proj_layer = layers.ProjectionLayer(params)
in_padding1 = tf.zeros([2, 4, 1], dtype=tf.float64)
inputs1 = tf.placeholder(shape=[2, 4, 3], dtype=tf.float64)
output1 = proj_layer.FPropDefaultTheta(inputs1, in_padding1)
loss = tf.reduce_sum(output1)
var_grads = py_utils.ComputeGradients(loss, proj_layer.vars)
op = optimizer.Accumulator.Params().Set(
accum_steps=2,
dtype=tf.float64,
optimizer_tpl=optimizer.SGD.Params())
opt = op.Instantiate()
lr = 1e-1
with cluster_factory.ForTestingWorker(add_summary=True):
var_update_op = opt.Apply(lr, var_grads)
increment_global_step_op = tf.assign_add(
py_utils.GetOrCreateGlobalStepVar(), 1)
self.evaluate(tf.global_variables_initializer())
vars2 = self.evaluate(proj_layer.vars.Flatten())
loss2_1, grads2_1 = sess.run(
[loss, var_grads.Transform(tuple)],
feed_dict={
inputs1: np_input1,
})
loss2_2, grads2_2 = sess.run(
[loss, var_grads.Transform(tuple)],
feed_dict={
inputs1: np_input2,
})
acc_0 = self.evaluate([
v for v in tf.global_variables()
if 'grad_accumulator' in v.name
])[0]
sess.run([var_update_op], feed_dict={
inputs1: np_input1,
})
acc_1 = self.evaluate([
v for v in tf.global_variables()
if 'grad_accumulator' in v.name
])[0]
vars2_intermediate = self.evaluate(proj_layer.vars.Flatten())
self.evaluate(increment_global_step_op)
sess.run([var_update_op], feed_dict={
inputs1: np_input2,
})
acc_2 = self.evaluate([
v for v in tf.global_variables()
if 'grad_accumulator' in v.name
])[0]
vars2_1 = self.evaluate(proj_layer.vars.Flatten())
summary = tf.Summary.FromString(
self.evaluate(tf.summary.merge_all()))
tf.logging.info(f'summary: {summary}')
self.assertEqual(summary.value[0].tag, 'sgd_lr')
self.assertAllClose(vars1, vars2)
self.assertAllClose(acc_0, np.zeros_like(acc_0))
self.assertAllClose(acc_1, grads2_1['w'][1])
self.assertAllClose(acc_2, np.zeros_like(acc_0))
self.assertAllClose(loss1_1, loss2_1)
self.assertAllClose(loss1_2, loss2_2)
self.assertAllClose(grads1_1, grads2_1)
self.assertAllClose(grads1_2, grads2_2)
self.assertAllClose(vars1, vars2_intermediate)
self.assertAllClose(vars2[0], grads2_1['w'][0])
self.assertAllClose(vars2[0], grads2_2['w'][0])
self.assertAllClose(
vars1[0] - 0.5 * lr * (grads1_1['w'][1] + grads1_2['w'][1]),
vars1_1[0])
self.assertAllClose(
vars2[0] - 0.5 * lr * (grads2_1['w'][1] + grads2_2['w'][1]),
vars2_1[0])
self.assertAllClose(vars2, vars2_intermediate)
self.assertAllClose(vars1_1, vars2_1)
def TrainAndDecode():
with tf.control_dependencies([TpuTrain()]):
return _DecodeFn()
def _internal_apply_dense(self, grad, var, magnitude_optimizer_apply_fn,
direction_optimizer_apply_fn): # pylint: disable=g-doc-args
"""Main optimization logic of AdaGraft, which calls the child optimizers.
Args:
grad: Tensor containing gradients.
var: Tensor containing parameter values.
magnitude_optimizer_apply_fn: Apply magnitude optimizer.
direction_optimizer_apply_fn: Apply direction optimizer.
Returns:
The final update op, which increments var by the grafted step.
Pseudocode:
- Copy weights into scratch space 'scratch_copy'.
- Run magnitude_optimizer in-place.
- Use scratch copy to figure out how far we moved ('magnitude_step').
- Copy weights back.
- Run direction_optimizer in-place.
- Move weights along the line segment with scratch_copy.
"""
if self.use_global_norm:
self._variables.append(var)
# Slot with current parameter values
scratch_slot = self.get_slot(var, "scratch_copy")
old_var = tf.assign(scratch_slot, var)
with tf.control_dependencies([old_var]):
m_updated_var = magnitude_optimizer_apply_fn(grad, var) # pylint: disable=protected-access
# Run magnitude optimizer and compute the norm of the update.
with tf.control_dependencies([m_updated_var]):
m_step = var - old_var
m_step_norm = tf.norm(m_step)
if self.diagnostic or self.use_global_norm:
m_step_norm = tf.assign(self.get_slot(var, "m_step_norm"),
m_step_norm)
# Run direction optimizer and compute its norm, and the direction.
with tf.control_dependencies([m_step_norm]):
flushed_var = tf.assign(var, old_var)
with tf.control_dependencies([flushed_var]):
d_updated_var = direction_optimizer_apply_fn(grad, var) # pylint: disable=protected-access
# Run an update of the direction optimizer with magnitude optimizer norm.
with tf.control_dependencies([d_updated_var]):
d_step = var - old_var
d_step_norm = tf.norm(d_step)
if self.diagnostic or self.use_global_norm:
d_step_norm = tf.assign(self.get_slot(var, "d_step_norm"),
d_step_norm)
if self.use_global_norm:
flushed_var = tf.assign(var, old_var)
with tf.control_dependencies([d_step_norm, flushed_var]):
return tf.assign(scratch_slot, d_step)
step = tf.where(tf.greater(d_step_norm, 0),
(m_step_norm / tf.maximum(d_step_norm, 1e-30)) *
d_step, tf.zeros_like(d_step))
return tf.assign(var, old_var + self._learning_rate_tensor * step)
def FProp(self, theta, inputs, paddings=None):
"""Apply group normalization.
Args:
theta: A NestedMap object containing weights' values of this layer and its
children layers.
inputs: The inputs tensor with shape [batch_size, height, width, channel].
paddings: The paddings tensor with shape [batch_size, height]. Intended to
be used for sequence processing where `height` is `time`.
Returns:
A single tensor as the output after applying group normalization, with
the same shape as 'inputs'. Or a output, output_paddings pair if input
paddings is not None.
"""
p = self.params
n, h, w, c = tf.unstack(tf.shape(inputs), axis=0, num=4)
group_size = p.dim // p.num_groups
num_groups = p.num_groups
min_group_size = p.min_group_size if p.dim > p.min_group_size else p.dim
if group_size <= min_group_size:
group_size = min_group_size
num_groups = p.dim // group_size
with tf.name_scope(p.name):
x = tf.reshape(inputs, [n, h, w, num_groups, group_size])
if paddings is None:
counts, means_ss, variance_ss, _, = tf.nn.sufficient_statistics(
x, axes=[1, 2, 4], keepdims=True)
norm_mean, norm_variance = tf.nn.normalize_moments(
counts, means_ss, variance_ss, None)
else:
expanded_paddings = tf.reshape(paddings, [n, h, 1, 1, 1])
if p.cumulative:
norm_mean, norm_variance = ComputeMomentsWithPadding(
x,
expanded_paddings,
reduce_over_dims=[2, 4],
cumulative_axis=1,
keepdims=True)
else:
norm_mean, norm_variance = ComputeMomentsWithPadding(
x, expanded_paddings, [1, 2, 4], keepdims=True)
norm_mean = py_utils.CheckNumerics(
norm_mean, 'mean of %s failed numeric check' % p.name)
norm_variance = py_utils.CheckNumerics(
norm_variance, 'variance of %s failed numeric check' % p.name)
beta = theta.beta
gamma = theta.gamma
t = h if p.cumulative else 1
with tf.control_dependencies([
py_utils.assert_greater_equal(
norm_variance, tf.cast(0., norm_variance.dtype)),
py_utils.assert_shape_match([n, t, 1, num_groups, 1],
tf.shape(norm_mean)),
py_utils.assert_shape_match([n, t, 1, num_groups, 1],
tf.shape(norm_variance)),
]):
x = (x - norm_mean) / tf.sqrt(norm_variance + self._epsilon)
x = tf.reshape(x, [n, h, w, c])
gn_output = x * gamma + beta
gn_output = tf.reshape(gn_output, [n, h, w, c])
if paddings is None:
return gn_output
else:
return gn_output, paddings
def _BPropForVariables(self, vmap):
"""Constructs the backward graph."""
bprop_variable_filters = self.input_generator.GetBpropVariableFilters()
# Only compute the mask if the variable filters are not empty.
if bprop_variable_filters != [''] * len(bprop_variable_filters):
self._ComputeGradientMask(bprop_variable_filters)
train_ops = {} # mapping from op name to op.
gradient_mask = None
if self._per_input_gradient_mask:
# TODO(neerajgaur): Change this to use source_selected from input_batch.
onehot = self.input_generator.GetInputSourceOneHot()
gradient_mask = {
k: tf.tensordot(v, onehot, 1)
for k, v in six.iteritems(self._per_input_gradient_mask)
}
all_losses = []
for optimization in self.learners:
loss_name = optimization.params.name
metric = self._metrics.get(loss_name, None)
if metric is None:
raise ValueError('Loss %s not found in metrics %s' %
(loss_name, list(self._metrics.keys())))
loss = metric[0]
all_losses.append(loss)
train_ops['train/%s' % loss_name], eval_metrics = optimization.Apply(
loss,
vmap,
gradient_mask=gradient_mask,
gradient_adjuster=self.AdjustGradients)
for key, (value, weight) in six.iteritems(eval_metrics):
self.AddEvalMetric(key + '/' + loss_name, value, weight)
relevant_bn_updates, _ = py_utils.FindRelevantBatchNormUpdates(
all_losses, tf.get_collection(py_utils.BATCH_NORM_UPDATES))
train_ops['bn_updates'] = relevant_bn_updates
# Get the op to update the weight masks and thresholds
train_ops['mask_updates'] = self._GetMaskUpdateOp()
# Post training step update.
train_ops['post_step'] = self.PostTrainingStepUpdate(self.global_step)
with tf.control_dependencies(tf.nest.flatten(train_ops)):
true_global_step = py_utils.GetOrCreateGlobalStepVar()
with tf.colocate_with(true_global_step):
increment_global_steps = tf.assign_add(true_global_step, 1)
if self._global_step_var != true_global_step:
with tf.colocate_with(self._global_step_var):
increment_global_steps = tf.group(
increment_global_steps, tf.assign_add(self._global_step_var, 1))
train_ops['global_step'] = increment_global_steps
# If we are using Tpu Embeddings, generate the monolithic send
# gradient op.
tpu_embedding_activations = tf.get_collection(
py_utils.TPU_EMBEDDING_ACTIVATIONS)
if tpu_embedding_activations:
tpu_embedding_activations_dict = tpu_embedding_activations[0]
tpu_embedding = tf.get_collection(py_utils.TPU_EMBEDDING)[0]
tpu_embedding_send_gradient_op = py_utils.ComputeTpuEmbeddingGradients(
self.loss, tpu_embedding_activations_dict, tpu_embedding)
train_ops['tpu_embedding'] = tpu_embedding_send_gradient_op
for op_name, op in six.iteritems(train_ops):
assert op is not None, op_name
# TODO(rpang): try to structure _train_op as:
# tf.cond(skip_step, <only update skip stats>, <all updates>)
# so that we skip all other updates when a step is skipped.
self._train_op = tf.group(*tf.nest.flatten(train_ops), name='bprop')
def FProp(self, theta, inputs, paddings=None):
"""Apply group normalization.
Args:
theta: A NestedMap object containing weights' values of this layer and its
children layers.
inputs: The inputs tensor with shape [batch_size, height, width, channel].
paddings: The paddings tensor with shape [batch_size, height]. Intended to
be used for sequence processing where `height` is `time`.
Returns:
A single tensor as the output after applying group normalization, with
the same shape as 'inputs'. Or a output, output_paddings pair if input
paddings is not None.
"""
p = self.params
inputs = py_utils.with_dependencies([
py_utils.assert_greater_equal(py_utils.GetRank(inputs),
p.input_rank)
], inputs)
min_group_size = min(p.min_group_size, p.dim)
group_size = max(p.dim // p.num_groups, min_group_size)
num_groups = p.dim // group_size
input_shape = py_utils.GetShape(inputs)
with tf.name_scope(p.name):
x = tf.reshape(inputs, input_shape[:-1] + [num_groups, group_size])
expanded_rank = p.input_rank + 1
all_dims = list(range(expanded_rank))
if paddings is None:
# Skip d0, d[-2]
axes = all_dims[1:-2] + all_dims[-1:]
counts, means_ss, variance_ss, _, = tf.nn.sufficient_statistics(
x, axes=axes, keepdims=True)
norm_mean, norm_variance = tf.nn.normalize_moments(
counts, means_ss, variance_ss, None)
else:
expanded_paddings = tf.reshape(
paddings, input_shape[:2] + [1] * (expanded_rank - 2))
# skip the batching and group dim
if p.cumulative:
# Skip d0, d1 and d[-2]
reduce_over_dims = all_dims[2:-2] + all_dims[-1:]
norm_mean, norm_variance = ComputeMomentsWithPadding(
x,
expanded_paddings,
reduce_over_dims=reduce_over_dims,
cumulative_axis=1,
keepdims=True)
else:
# Skip d0, d[-2]
reduce_over_dims = all_dims[1:-2] + all_dims[-1:]
norm_mean, norm_variance = ComputeMomentsWithPadding(
x, expanded_paddings, reduce_over_dims, keepdims=True)
norm_mean = py_utils.CheckNumerics(
norm_mean, 'mean of %s failed numeric check' % p.name)
norm_variance = py_utils.CheckNumerics(
norm_variance, 'variance of %s failed numeric check' % p.name)
beta = theta.beta
gamma = theta.gamma
n = input_shape[0]
t = input_shape[1] if p.cumulative else 1
norm_shape = [n, t, 1, num_groups, 1
] if p.input_rank == 4 else [n, t, num_groups, 1]
with tf.control_dependencies([
py_utils.assert_greater_equal(
norm_variance, tf.cast(0., norm_variance.dtype)),
py_utils.assert_shape_match(norm_shape,
tf.shape(norm_mean)),
py_utils.assert_shape_match(norm_shape,
tf.shape(norm_variance)),
]):
x = (x - norm_mean) / tf.sqrt(norm_variance + self._epsilon)
x = tf.reshape(x, input_shape)
gn_output = x * gamma + beta
gn_output = tf.reshape(gn_output, input_shape)
if paddings is None:
return gn_output
else:
return gn_output, paddings
def GuaranteeConstGetter(next_creator, **kwargs):
if _CONST_GUARANTEE:
with tf.control_dependencies(None):
name = kwargs['var_name'] + '/GuaranteeConst'
return tf.guarantee_const(next_creator(**kwargs), name=name)
return next_creator(**kwargs)
def _BPropGenTrainOps(self, vmap, metrics=None, add_summary=True):
"""Populates the train_ops dictionary in a backwards pass."""
metrics = metrics or self._metrics
bprop_variable_filters = self.input_generator.GetBpropVariableFilters()
# Only compute the mask if the variable filters are not empty.
if bprop_variable_filters != [''] * len(bprop_variable_filters):
self._ComputeGradientMask(bprop_variable_filters)
train_ops = {} # mapping from op name to op.
gradient_mask = None
if self._per_input_gradient_mask:
# TODO(neerajgaur): Change this to use source_selected from input_batch.
onehot = self.input_generator.GetInputSourceOneHot()
gradient_mask = {
k: tf.tensordot(v, onehot, 1)
for k, v in self._per_input_gradient_mask.items()
}
all_losses = []
for optimization in self.learners:
learner_name = optimization.params.name
(losses, train_ops['train/%s' % learner_name],
eval_metrics) = optimization.Apply(
metrics,
vmap,
gradient_mask=gradient_mask,
gradient_adjuster=self.AdjustGradients)
all_losses.extend(losses)
if add_summary:
for key, (value, weight) in eval_metrics.items():
self.AddEvalMetric(key + '/' + learner_name, value, weight)
relevant_bn_updates, _ = py_utils.FindRelevantBatchNormUpdates(
all_losses, tf.get_collection(py_utils.BATCH_NORM_UPDATES))
train_ops['bn_updates'] = relevant_bn_updates
var_update_ops = [
tf.group(*tf.nest.flatten(train_ops), name='var_update_ops')
]
# Post training step update.
with tf.control_dependencies(var_update_ops):
post_step_op = self.PostTrainingStepUpdate()
train_ops = {}
with tf.control_dependencies([post_step_op]):
# Get the op to update the weight masks and thresholds
mask_update_op = self._GetMaskUpdateOp()
train_ops['mask_updates'] = mask_update_op
with tf.control_dependencies([mask_update_op]):
true_global_step = py_utils.GetOrCreateGlobalStepVar()
with tf.ops.colocate_with(true_global_step):
if self.params.defer_global_step_update:
increment_global_steps = true_global_step
else:
increment_global_steps = tf.assign_add(true_global_step, 1)
if self._global_step_var != true_global_step:
with tf.ops.colocate_with(self._global_step_var):
increment_global_steps = tf.group(
increment_global_steps, tf.assign_add(self._global_step_var, 1))
train_ops['global_step'] = increment_global_steps
# If we are using Tpu Embeddings, generate the monolithic send
# gradient op.
if tf.get_collection(py_utils.TPU_EMBEDDING):
tpu_embedding = tf.get_collection(py_utils.TPU_EMBEDDING)[0]
sparse_grads = (
tpu_embedding_gradient.get_gradients_through_dummy_table_variables(
tpu_embedding))
tpu_embedding_send_gradient_op = tpu_embedding.generate_send_gradients_op(
sparse_grads, py_utils.GetGlobalStep())
train_ops['tpu_embedding'] = tpu_embedding_send_gradient_op
tpu_embedding_summary_tensors = tf.get_collection(
py_utils.TPU_EMBEDDING_SUMMARY_TENSORS)
if add_summary:
for name, value, weight in tpu_embedding_summary_tensors:
self.AddEvalMetric(name, value, weight, raise_if_already_added=False)
for op_name, op in train_ops.items():
assert op is not None, op_name
return train_ops
def control_after_assigns(self):
if not self._assign_ops:
return tf.no_op()
with tf.control_dependencies(self._assign_ops):
return tf.no_op()