def test_cosine_lr(self):
cosine_schedule = utils.WarmupLearningRateSchedule(
1.0, total_steps=10, lr_decay_type='cosine', warmup_epochs=None)
lr = cosine_schedule(4)
self.assertAllClose(lr, 0.654508)
lr = cosine_schedule(5)
self.assertAllClose(lr, 0.5)
lr = cosine_schedule(6)
self.assertAllClose(lr, 0.345491)
def test_linear_lr(self):
linear_schedule = utils.WarmupLearningRateSchedule(
1.0, total_steps=10, lr_decay_type='linear', warmup_epochs=None)
lr = linear_schedule(0)
self.assertAllClose(lr, 1.0)
lr = linear_schedule(5)
self.assertAllClose(lr, 0.5)
lr = linear_schedule(10)
self.assertAllClose(lr, 0.0)
def test_warmup(self):
warmup_schedule = utils.WarmupLearningRateSchedule(
1.0,
total_steps=100,
steps_per_epoch=10,
warmup_epochs=2,
lr_decay_type='constant')
lr = warmup_schedule(5)
self.assertAllClose(lr, 0.25)
lr = warmup_schedule(35)
self.assertAllClose(lr, 1.0)
def test_exponential_lr(self):
exponential_schedule = utils.WarmupLearningRateSchedule(
1.0,
total_steps=100,
steps_per_epoch=10,
decay_epochs=2,
decay_factor=0.5,
lr_decay_type='exponential',
warmup_epochs=None)
lr = exponential_schedule(5)
self.assertAllClose(lr, 1.0)
lr = exponential_schedule(25)
self.assertAllClose(lr, 0.5)
lr = exponential_schedule(70)
self.assertAllClose(lr, 0.125)
def model_fn(features, labels, mode, params):
"""The model_fn to be used with TPUEstimator.
Args:
features: A dict of `Tensor` of batched images and other features.
labels: a Tensor or a dict of Tensor representing the batched labels.
mode: one of `tf.estimator.ModeKeys.{TRAIN,EVAL,PREDICT}`
params: `dict` of parameters passed to the model from the TPUEstimator,
`params['batch_size']` is always provided and should be used as the
effective batch size.
Returns:
A `TPUEstimatorSpec` for the model
"""
logging.info('params=%s', params)
images = features['image'] if isinstance(features, dict) else features
labels = labels['label'] if isinstance(labels, dict) else labels
config = params['config']
image_size = params['image_size']
utils.scalar('model/resolution', image_size)
if config.model.data_format == 'channels_first':
images = tf.transpose(images, [0, 3, 1, 2])
is_training = (mode == tf.estimator.ModeKeys.TRAIN)
has_moving_average_decay = (config.train.ema_decay > 0)
if FLAGS.use_tpu and not config.model.bn_type:
config.model.bn_type = 'tpu_bn'
# This is essential, if using a keras-derived model.
tf.keras.backend.set_learning_phase(is_training)
def build_model(in_images):
"""Build model using the model_name given through the command line."""
config.model.num_classes = config.data.num_classes
model = effnetv2_model.EffNetV2Model(config.model.model_name,
config.model)
logits = model(in_images, training=is_training)[0]
return logits
pre_num_params, pre_num_flops = utils.num_params_flops(
readable_format=True)
if config.runtime.mixed_precision:
precision = 'mixed_bfloat16' if FLAGS.use_tpu else 'mixed_float16'
logits = utils.build_model_with_precision(precision, build_model,
images, is_training)
logits = tf.cast(logits, tf.float32)
else:
logits = build_model(images)
num_params, num_flops = utils.num_params_flops(readable_format=True)
num_params = num_params - pre_num_params
num_flops = (num_flops - pre_num_flops) / params['batch_size']
logging.info('backbone params/flops = %.4f M / %.4f B', num_params,
num_flops)
utils.scalar('model/params', num_params)
utils.scalar('model/flops', num_flops)
# Calculate loss, which includes softmax cross entropy and L2 regularization.
if config.train.loss_type == 'sigmoid':
cross_entropy = tf.losses.sigmoid_cross_entropy(
multi_class_labels=tf.cast(labels, dtype=logits.dtype),
logits=logits,
label_smoothing=config.train.label_smoothing)
elif config.train.loss_type == 'custom':
xent = tf.nn.sigmoid_cross_entropy_with_logits(labels=tf.cast(
labels, dtype=logits.dtype),
logits=logits)
cross_entropy = tf.reduce_mean(tf.reduce_sum(xent, axis=-1))
else:
if config.data.multiclass:
logging.info('use multi-class loss: %s', config.data.multiclass)
labels /= tf.reshape(tf.reduce_sum(labels, axis=1), (-1, 1))
cross_entropy = tf.losses.softmax_cross_entropy(
onehot_labels=labels,
logits=logits,
label_smoothing=config.train.label_smoothing)
train_steps = max(config.train.min_steps,
config.train.epochs * params['steps_per_epoch'])
global_step = tf.train.get_global_step()
weight_decay_inc = config.train.weight_decay_inc * (
tf.cast(global_step, tf.float32) / tf.cast(train_steps, tf.float32))
weight_decay = (1 + weight_decay_inc) * config.train.weight_decay
utils.scalar('train/weight_decay', weight_decay)
# Add weight decay to the loss for non-batch-normalization variables.
matcher = re.compile(config.train.weight_decay_exclude)
l2loss = weight_decay * tf.add_n([
tf.nn.l2_loss(v)
for v in tf.trainable_variables() if not matcher.match(v.name)
])
loss = cross_entropy + l2loss
utils.scalar('loss/l2reg', l2loss)
utils.scalar('loss/xent', cross_entropy)
if has_moving_average_decay:
ema = tf.train.ExponentialMovingAverage(decay=config.train.ema_decay,
num_updates=global_step)
ema_vars = utils.get_ema_vars()
host_call = None
restore_vars_dict = None
if is_training:
# Compute the current epoch and associated learning rate from global_step.
current_epoch = (tf.cast(global_step, tf.float32) /
params['steps_per_epoch'])
utils.scalar('train/epoch', current_epoch)
scaled_lr = config.train.lr_base * (config.train.batch_size / 256.0)
scaled_lr_min = config.train.lr_min * (config.train.batch_size / 256.0)
learning_rate = utils.WarmupLearningRateSchedule(
scaled_lr,
steps_per_epoch=params['steps_per_epoch'],
decay_epochs=config.train.lr_decay_epoch,
warmup_epochs=config.train.lr_warmup_epoch,
decay_factor=config.train.lr_decay_factor,
lr_decay_type=config.train.lr_sched,
total_steps=train_steps,
minimal_lr=scaled_lr_min)(global_step)
utils.scalar('train/lr', learning_rate)
optimizer = utils.build_optimizer(
learning_rate, optimizer_name=config.train.optimizer)
if FLAGS.use_tpu:
# When using TPU, wrap the optimizer with CrossShardOptimizer which
# handles synchronization details between different TPU cores. To the
# user, this should look like regular synchronous training.
optimizer = tf.tpu.CrossShardOptimizer(optimizer)
# filter trainable variables if needed.
var_list = tf.trainable_variables()
if config.train.varsexp:
vars2 = [
v for v in var_list if re.match(config.train.varsexp, v.name)
]
if len(vars2) == len(var_list):
logging.warning('%s has no match.', config.train.freeze)
logging.info('Filter variables: orig=%d, final=%d, delta=%d',
len(var_list), len(vars2),
len(var_list) - len(vars2))
var_list = vars2
# Batch norm requires update_ops to be added as a train_op dependency.
update_ops = tf.get_collection(tf.GraphKeys.UPDATE_OPS)
if config.train.gclip and is_training:
logging.info('clip gradients norm by %f', config.train.gclip)
grads_and_vars = optimizer.compute_gradients(loss, var_list)
with tf.name_scope('gclip'):
grads = [gv[0] for gv in grads_and_vars]
tvars = [gv[1] for gv in grads_and_vars]
utils.scalar('train/gnorm', tf.linalg.global_norm(grads))
utils.scalar('train/gnormmax',
tf.math.reduce_max([tf.norm(g) for g in grads]))
# First clip each variable's norm, then clip global norm.
clip_norm = abs(config.train.gclip)
clipped_grads = [
tf.clip_by_norm(g, clip_norm) if g is not None else None
for g in grads
]
clipped_grads, _ = tf.clip_by_global_norm(
clipped_grads, clip_norm)
grads_and_vars = list(zip(clipped_grads, tvars))
with tf.control_dependencies(update_ops):
train_op = optimizer.apply_gradients(grads_and_vars,
global_step)
else:
with tf.control_dependencies(update_ops):
train_op = optimizer.minimize(loss,
global_step,
var_list=var_list)
if has_moving_average_decay:
with tf.control_dependencies([train_op]):
train_op = ema.apply(ema_vars)
if not config.runtime.skip_host_call:
host_call = utils.get_tpu_host_call(
global_step, FLAGS.model_dir,
config.runtime.iterations_per_loop)
else:
train_op = None
if has_moving_average_decay:
# Load moving average variables for eval.
restore_vars_dict = ema.variables_to_restore(ema_vars)
eval_metrics = None
if mode == tf.estimator.ModeKeys.EVAL:
def metric_fn(labels, logits):
"""Evaluation metric function.
Evaluates accuracy.
This function is executed on the CPU and should not directly reference
any Tensors in the rest of the `model_fn`. To pass Tensors from the model
to the `metric_fn`, provide as part of the `eval_metrics`. See
https://www.tensorflow.org/api_docs/python/tf/estimator/tpu/TPUEstimatorSpec
for more information.
Arguments should match the list of `Tensor` objects passed as the second
element in the tuple passed to `eval_metrics`.
Args:
labels: `Tensor` with shape `[batch, num_classes]`.
logits: `Tensor` with shape `[batch, num_classes]`.
Returns:
A dict of the metrics to return from evaluation.
"""
metrics = {}
if config.data.multiclass:
metrics['eval/global_ap'] = tf.metrics.auc(
labels,
tf.nn.sigmoid(logits),
curve='PR',
num_thresholds=200,
summation_method='careful_interpolation',
name='global_ap')
# Convert labels to set: be careful, tf.metrics.xx_at_k are horrible.
labels = tf.cast(labels, dtype=tf.int64)
label_to_repeat = tf.expand_dims(tf.argmax(labels, axis=-1),
axis=-1)
all_labels_set = tf.range(0, labels.shape[-1], dtype=tf.int64)
all_labels_set = tf.expand_dims(all_labels_set, axis=0)
labels_set = labels * all_labels_set + (
1 - labels) * label_to_repeat
metrics['eval/precision@1'] = tf.metrics.precision_at_k(
labels_set, logits, k=1)
metrics['eval/recall@1'] = tf.metrics.recall_at_k(labels_set,
logits,
k=1)
metrics['eval/precision@5'] = tf.metrics.precision_at_k(
labels_set, logits, k=5)
metrics['eval/recall@5'] = tf.metrics.recall_at_k(labels_set,
logits,
k=5)
# always add accuracy.
labels = tf.argmax(labels, axis=1)
predictions = tf.argmax(logits, axis=1)
metrics['eval/acc_top1'] = tf.metrics.accuracy(labels, predictions)
in_top_5 = tf.cast(tf.nn.in_top_k(logits, labels, 5), tf.float32)
metrics['eval/acc_top5'] = tf.metrics.mean(in_top_5)
metrics['model/resolution'] = tf.metrics.mean(image_size)
metrics['model/flops'] = tf.metrics.mean(num_flops)
metrics['model/params'] = tf.metrics.mean(num_params)
return metrics
eval_metrics = (metric_fn, [labels, logits])
if has_moving_average_decay and not is_training:
def scaffold_fn(): # read ema for eval jobs.
saver = tf.train.Saver(restore_vars_dict)
return tf.train.Scaffold(saver=saver)
elif config.train.ft_init_ckpt and is_training:
def scaffold_fn():
logging.info('restore variables from %s',
config.train.ft_init_ckpt)
var_map = utils.get_ckpt_var_map(
ckpt_path=config.train.ft_init_ckpt,
skip_mismatch=True,
init_ema=config.train.ft_init_ema)
tf.train.init_from_checkpoint(config.train.ft_init_ckpt, var_map)
return tf.train.Scaffold()
else:
scaffold_fn = None
return tf.estimator.tpu.TPUEstimatorSpec(mode=mode,
loss=loss,
train_op=train_op,
host_call=host_call,
eval_metrics=eval_metrics,
scaffold_fn=scaffold_fn)
def test_constant_lr(self):
constant_schedule = utils.WarmupLearningRateSchedule(
1.0, lr_decay_type='constant', warmup_epochs=None)
lr = constant_schedule(10)
self.assertAllClose(lr, 1.0)