def translate_and_calculate_bleu(*, p_pred_step, p_init_cache, target,
predict_ds: tf.data.Dataset, decode_tokens,
max_predict_length: int):
"""Translates the `predict_ds` and calculates the BLEU score."""
n_devices = jax.local_device_count()
logging.info("Translating evaluation dataset.")
sources, references, predictions = [], [], []
for pred_batch in predict_ds:
pred_batch = jax.tree_map(lambda x: x._numpy(), pred_batch) # pylint: disable=protected-access
# Handle final odd-sized batch by padding instead of dropping it.
cur_pred_batch_size = pred_batch["inputs"].shape[0]
if cur_pred_batch_size % n_devices:
padded_size = int(
np.ceil(cur_pred_batch_size / n_devices) * n_devices)
pred_batch = jax.tree_map(
lambda x: pad_examples(x, padded_size), # pylint: disable=cell-var-from-loop
pred_batch)
pred_batch = common_utils.shard(pred_batch)
cache = p_init_cache(pred_batch["inputs"])
predicted = p_pred_step(pred_batch["inputs"], target, cache,
decode.EOS_ID, max_predict_length)
predicted = tohost(predicted)
inputs = tohost(pred_batch["inputs"])
targets = tohost(pred_batch["targets"])
# Iterate through non-padding examples of batch.
for i, s in enumerate(predicted[:cur_pred_batch_size]):
sources.append(decode_tokens(inputs[i]))
references.append(decode_tokens(targets[i]))
predictions.append(decode_tokens(s))
logging.info("Translation: %d predictions %d references %d sources.",
len(predictions), len(references), len(sources))
# Calculate BLEU score for translated eval corpus against reference.
bleu_matches = bleu.bleu_partial(references, predictions)
all_bleu_matches = per_host_sum_pmap(bleu_matches)
bleu_score = bleu.complete_bleu(*all_bleu_matches)
# Save translation samples for tensorboard.
exemplars = ""
for n in np.random.choice(np.arange(len(predictions)), 8):
exemplars += f"{sources[n]}\n\n{references[n]}\n\n{predictions[n]}\n\n"
return exemplars, bleu_score
def main(argv):
if len(argv) > 1:
raise app.UsageError('Too many command-line arguments.')
if FLAGS.jax_backend_target:
jax.config.FLAGS.jax_xla_backend = "tpu_driver"
jax.config.FLAGS.jax_backend_target = FLAGS.jax_backend_target
# This seems to be necessary even when importing TF2?
tf.enable_v2_behavior()
# Number of local devices for this host.
n_devices = jax.local_device_count()
if jax.host_id() == 0:
train_summary_writer = tensorboard.SummaryWriter(
os.path.join(FLAGS.model_dir, 'train'))
eval_summary_writer = tensorboard.SummaryWriter(
os.path.join(FLAGS.model_dir, 'eval'))
if FLAGS.batch_size % n_devices:
raise ValueError(
'Batch size must be divisible by the number of devices')
vocab_path = FLAGS.vocab_path
if vocab_path is None:
vocab_path = os.path.join(FLAGS.model_dir, 'sentencepiece_model')
# Load Dataset
logging.info('Initializing dataset.')
train_ds, eval_ds, predict_ds, encoder = input_pipeline.get_wmt_datasets(
n_devices=n_devices,
dataset_name=FLAGS.dataset_name,
eval_dataset_name=FLAGS.eval_dataset_name,
shard_idx=jax.host_id(),
shard_count=jax.host_count(),
data_dir=FLAGS.data_dir,
vocab_path=vocab_path,
batch_size=FLAGS.batch_size,
max_length=FLAGS.max_target_length,
max_eval_length=FLAGS.max_eval_target_length)
train_iter = iter(train_ds)
vocab_size = int(encoder.vocab_size())
eos_token = 2 # Default Sentencepiece EOS token.
def decode_tokens(toks):
valid_toks = toks[:np.argmax(toks == eos_token) + 1].astype(np.int32)
return encoder.detokenize(valid_toks).numpy().decode('utf-8')
logging.info('Initializing model, optimizer, and step functions.')
# Build Model and Optimizer
transformer_kwargs = {
'vocab_size': vocab_size,
'output_vocab_size': vocab_size,
'emb_dim': 1024,
'num_heads': 16,
'num_layers': 6,
'qkv_dim': 1024,
'mlp_dim': 4096,
'max_len': max(FLAGS.max_target_length, FLAGS.max_eval_target_length),
'share_embeddings': FLAGS.share_embeddings,
'logits_via_embedding': FLAGS.logits_via_embedding,
}
start_step = 0
rng = random.PRNGKey(FLAGS.random_seed)
rng, init_rng = random.split(rng)
input_shape = (FLAGS.batch_size, FLAGS.max_target_length)
target_shape = (FLAGS.batch_size, FLAGS.max_target_length)
model, cache_def = create_model(init_rng, input_shape, target_shape,
transformer_kwargs)
optimizer = create_optimizer(model, FLAGS.learning_rate,
FLAGS.weight_decay)
# We access model only from optimizer below via optimizer.target.
del model
if FLAGS.restore_checkpoints:
# Restore unreplicated optimizer + model state from last checkpoint.
optimizer = checkpoints.restore_checkpoint(FLAGS.model_dir, optimizer)
# Grab last step.
start_step = int(optimizer.state.step)
# Replicate optimizer.
optimizer = jax_utils.replicate(optimizer)
learning_rate_fn = create_learning_rate_scheduler(
base_learning_rate=FLAGS.learning_rate,
warmup_steps=FLAGS.warmup_steps)
p_train_step = jax.pmap(functools.partial(
train_step,
learning_rate_fn=learning_rate_fn,
label_smoothing=FLAGS.label_smoothing,
use_bfloat16=FLAGS.use_bfloat16),
axis_name='batch')
p_eval_step = jax.pmap(functools.partial(
eval_step,
label_smoothing=FLAGS.label_smoothing,
use_bfloat16=FLAGS.use_bfloat16),
axis_name='batch')
p_pred_step = jax.pmap(
functools.partial(predict_step, use_bfloat16=FLAGS.use_bfloat16),
axis_name='batch',
static_broadcasted_argnums=(3,
4)) # eos token, max_length are constant
# We init the first set of dropout PRNG keys, but update it afterwards inside
# the main pmap'd training update for performance.
dropout_rngs = random.split(rng, n_devices)
logging.info('Starting training loop.')
metrics_all = []
t_loop_start = time.time()
for step, batch in zip(range(start_step, FLAGS.num_train_steps),
train_iter):
# Shard data to devices and do a training step.
batch = common_utils.shard(jax.tree_map(lambda x: x._numpy(), batch)) # pylint: disable=protected-access
optimizer, metrics, dropout_rngs = p_train_step(
optimizer, batch, dropout_rng=dropout_rngs)
metrics_all.append(metrics)
# Save a checkpoint on one host after every checkpoint_freq steps.
if (FLAGS.save_checkpoints and step % FLAGS.checkpoint_freq == 0
and step > 0 and jax.host_id() == 0):
checkpoints.save_checkpoint(FLAGS.model_dir,
jax_utils.unreplicate(optimizer), step)
# Periodic metric handling.
if step % FLAGS.eval_frequency != 0:
continue
logging.info('Gathering training metrics.')
# Training Metrics
metrics_all = common_utils.get_metrics(metrics_all)
lr = metrics_all.pop('learning_rate').mean()
metrics_sums = jax.tree_map(jnp.sum, metrics_all)
denominator = metrics_sums.pop('denominator')
summary = jax.tree_map(lambda x: x / denominator, metrics_sums) # pylint: disable=cell-var-from-loop
summary['learning_rate'] = lr
steps_per_eval = FLAGS.eval_frequency if step != 0 else 1
steps_per_sec = steps_per_eval / (time.time() - t_loop_start)
t_loop_start = time.time()
if jax.host_id() == 0:
train_summary_writer.scalar('steps per second', steps_per_sec,
step)
for key, val in summary.items():
train_summary_writer.scalar(key, val, step)
train_summary_writer.flush()
metrics_all = []
logging.info('train in step: %d, loss: %.4f', step, summary['loss'])
# Eval Metrics
logging.info('Gathering evaluation metrics.')
t_eval_start = time.time()
eval_metrics = []
eval_iter = iter(eval_ds)
for _, eval_batch in zip(range(FLAGS.num_eval_steps), eval_iter):
eval_batch = jax.tree_map(lambda x: x._numpy(), eval_batch) # pylint: disable=protected-access
eval_batch = common_utils.shard(eval_batch)
metrics = p_eval_step(optimizer.target, eval_batch)
eval_metrics.append(metrics)
eval_metrics = common_utils.get_metrics(eval_metrics)
eval_metrics_sums = jax.tree_map(jnp.sum, eval_metrics)
eval_denominator = eval_metrics_sums.pop('denominator')
eval_summary = jax.tree_map(
lambda x: x / eval_denominator, # pylint: disable=cell-var-from-loop
eval_metrics_sums)
if jax.host_id() == 0:
for key, val in eval_summary.items():
eval_summary_writer.scalar(key, val, step)
eval_summary_writer.flush()
logging.info('eval in step: %d, loss: %.4f', step,
eval_summary['loss'])
logging.info('eval time: %.4f s step %d',
time.time() - t_eval_start, step)
# Translation and BLEU Score.
logging.info('Translating evaluation dataset.')
t_inference_start = time.time()
predict_iter = iter(predict_ds)
sources, references, predictions = [], [], []
for _, pred_batch in enumerate(predict_iter):
pred_batch = jax.tree_map(lambda x: x._numpy(), pred_batch) # pylint: disable=protected-access
# Handle final odd-sized batch by padding instead of dropping it.
cur_pred_batch_size = pred_batch['inputs'].shape[0]
if cur_pred_batch_size % n_devices:
padded_size = int(
np.ceil(cur_pred_batch_size / n_devices) * n_devices)
pred_batch = jax.tree_map(
lambda x: pad_examples(x, padded_size), pred_batch) # pylint: disable=cell-var-from-loop
pred_batch = common_utils.shard(pred_batch)
per_device_batchsize = pred_batch['inputs'].shape[1]
cache_dtype = jnp.bfloat16 if FLAGS.use_bfloat16 else jnp.float32
cache = jax_utils.replicate(
cache_def.initialize_cache(
(per_device_batchsize, FLAGS.max_predict_length),
dtype=cache_dtype))
predicted = p_pred_step(pred_batch['inputs'], optimizer.target,
cache, eos_token, FLAGS.max_predict_length)
predicted = tohost(predicted)
inputs = tohost(pred_batch['inputs'])
targets = tohost(pred_batch['targets'])
# Iterate through non-padding examples of batch.
for i, s in enumerate(predicted[:cur_pred_batch_size]):
sources.append(decode_tokens(inputs[i]))
references.append(decode_tokens(targets[i]))
predictions.append(decode_tokens(s))
logging.info('Translation: %d predictions %d references %d sources.',
len(predictions), len(references), len(sources))
logging.info('Translation time: %.4f s step %d.',
time.time() - t_inference_start, step)
# Calculate BLEU score for translated eval corpus against reference.
bleu_matches = bleu.bleu_partial(references, predictions)
all_bleu_matches = per_host_sum_pmap(bleu_matches)
bleu_score = bleu.complete_bleu(*all_bleu_matches)
# Save translation samples for tensorboard.
exemplars = ''
for n in np.random.choice(np.arange(len(predictions)), 8):
exemplars += f'{sources[n]}\n\n{references[n]}\n\n{predictions[n]}\n\n'
if jax.host_id() == 0:
eval_summary_writer.scalar('bleu', bleu_score, step)
eval_summary_writer.text('samples', exemplars, step)
eval_summary_writer.flush()
logging.info('Translation BLEU Score %.4f', bleu_score)
def main(argv):
if len(argv) > 1:
raise app.UsageError('Too many command-line arguments.')
# Make sure tf does not allocate gpu memory.
tf.config.experimental.set_visible_devices([], 'GPU')
if FLAGS.jax_backend_target:
jax.config.FLAGS.jax_xla_backend = 'tpu_driver'
jax.config.FLAGS.jax_backend_target = FLAGS.jax_backend_target
# Number of local devices for this host.
n_devices = jax.local_device_count()
if jax.host_id() == 0:
tf.io.gfile.makedirs(FLAGS.model_dir)
train_summary_writer = tensorboard.SummaryWriter(
os.path.join(FLAGS.model_dir, 'train'))
eval_summary_writer = tensorboard.SummaryWriter(
os.path.join(FLAGS.model_dir, 'eval'))
if FLAGS.batch_size % n_devices:
raise ValueError(
'Batch size must be divisible by the number of devices')
vocab_path = FLAGS.vocab_path
if vocab_path is None:
vocab_path = os.path.join(FLAGS.model_dir, 'sentencepiece_model')
tf.io.gfile.makedirs(os.path.split(vocab_path)[0])
# Load Dataset
# ---------------------------------------------------------------------------
logging.info('Initializing dataset.')
train_ds, eval_ds, predict_ds, encoder = input_pipeline.get_wmt_datasets(
n_devices=n_devices,
dataset_name=FLAGS.dataset_name,
eval_dataset_name=FLAGS.eval_dataset_name,
shard_idx=jax.host_id(),
shard_count=jax.host_count(),
data_dir=FLAGS.data_dir,
vocab_path=vocab_path,
target_vocab_size=FLAGS.vocab_size,
batch_size=FLAGS.batch_size,
max_length=FLAGS.max_target_length,
max_eval_length=FLAGS.max_eval_target_length)
train_iter = iter(train_ds)
vocab_size = int(encoder.vocab_size())
eos_id = decode.EOS_ID # Default Sentencepiece EOS token.
def decode_tokens(toks):
valid_toks = toks[:np.argmax(toks == eos_id) + 1].astype(np.int32)
return encoder.detokenize(valid_toks).numpy().decode('utf-8')
logging.info('Initializing model, optimizer, and step functions.')
# Build Model and Optimizer
# ---------------------------------------------------------------------------
train_config = models.TransformerConfig(
vocab_size=vocab_size,
output_vocab_size=vocab_size,
share_embeddings=FLAGS.share_embeddings,
logits_via_embedding=FLAGS.logits_via_embedding,
dtype=jnp.bfloat16 if FLAGS.use_bfloat16 else jnp.float32,
emb_dim=FLAGS.emb_dim,
num_heads=FLAGS.num_heads,
num_layers=FLAGS.num_layers,
qkv_dim=FLAGS.qkv_dim,
mlp_dim=FLAGS.mlp_dim,
max_len=max(FLAGS.max_target_length, FLAGS.max_eval_target_length),
dropout_rate=FLAGS.dropout_rate,
attention_dropout_rate=FLAGS.attention_dropout_rate,
deterministic=False,
decode=False,
kernel_init=nn.initializers.xavier_uniform(),
bias_init=nn.initializers.normal(stddev=1e-6))
eval_config = train_config.replace(deterministic=True)
predict_config = train_config.replace(deterministic=True, decode=True)
start_step = 0
rng = random.PRNGKey(FLAGS.random_seed)
rng, init_rng = random.split(rng)
input_shape = (FLAGS.batch_size, FLAGS.max_target_length)
target_shape = (FLAGS.batch_size, FLAGS.max_target_length)
# call a jitted initialization function to get the initial parameter tree
@jax.jit
def initialize_variables(rng):
return models.Transformer(eval_config).init(
rng, jnp.ones(input_shape, jnp.float32),
jnp.ones(target_shape, jnp.float32))
initial_variables = initialize_variables(init_rng)
# apply an optimizer to this tree
optimizer_def = optim.Adam(FLAGS.learning_rate,
beta1=0.9,
beta2=0.98,
eps=1e-9,
weight_decay=FLAGS.weight_decay)
optimizer = optimizer_def.create(initial_variables['params'])
# We access model params only from optimizer below via optimizer.target.
del initial_variables
if FLAGS.restore_checkpoints:
# Restore unreplicated optimizer + model state from last checkpoint.
optimizer = checkpoints.restore_checkpoint(FLAGS.model_dir, optimizer)
# Grab last step.
start_step = int(optimizer.state.step)
# Replicate optimizer.
optimizer = jax_utils.replicate(optimizer)
learning_rate_fn = create_learning_rate_scheduler(
base_learning_rate=FLAGS.learning_rate,
warmup_steps=FLAGS.warmup_steps)
# compile multidevice versions of train/eval/predict step and cache init fn.
p_train_step = jax.pmap(functools.partial(
train_step,
config=train_config,
learning_rate_fn=learning_rate_fn,
label_smoothing=FLAGS.label_smoothing),
axis_name='batch',
donate_argnums=(0, ))
p_eval_step = jax.pmap(functools.partial(
eval_step, config=eval_config, label_smoothing=FLAGS.label_smoothing),
axis_name='batch')
p_init_cache = jax.pmap(functools.partial(
initialize_cache,
max_decode_len=FLAGS.max_predict_length,
config=predict_config),
axis_name='batch')
p_pred_step = jax.pmap(
functools.partial(predict_step,
config=predict_config,
beam_size=FLAGS.beam_size),
axis_name='batch',
static_broadcasted_argnums=(3,
4)) # eos token, max_length are constant
# Main Train Loop
# ---------------------------------------------------------------------------
# We init the first set of dropout PRNG keys, but update it afterwards inside
# the main pmap'd training update for performance.
dropout_rngs = random.split(rng, n_devices)
logging.info('Starting training loop.')
metrics_all = []
t_loop_start = time.time()
for step, batch in zip(range(start_step, FLAGS.num_train_steps),
train_iter):
# Shard data to devices and do a training step.
batch = common_utils.shard(jax.tree_map(lambda x: x._numpy(), batch)) # pylint: disable=protected-access
optimizer, metrics, dropout_rngs = p_train_step(
optimizer, batch, dropout_rng=dropout_rngs)
metrics_all.append(metrics)
# Save a checkpoint on one host after every checkpoint_freq steps.
if (FLAGS.save_checkpoints and step % FLAGS.checkpoint_freq == 0
and step > 0 and jax.host_id() == 0):
checkpoints.save_checkpoint(FLAGS.model_dir,
jax_utils.unreplicate(optimizer), step)
# Periodic metric handling.
if step % FLAGS.eval_frequency != 0 and step > 0:
continue
# Training Metrics
logging.info('Gathering training metrics.')
metrics_all = common_utils.get_metrics(metrics_all)
lr = metrics_all.pop('learning_rate').mean()
metrics_sums = jax.tree_map(jnp.sum, metrics_all)
denominator = metrics_sums.pop('denominator')
summary = jax.tree_map(lambda x: x / denominator, metrics_sums) # pylint: disable=cell-var-from-loop
summary['learning_rate'] = lr
steps_per_eval = FLAGS.eval_frequency if step != 0 else 1
steps_per_sec = steps_per_eval / (time.time() - t_loop_start)
t_loop_start = time.time()
if jax.host_id() == 0:
train_summary_writer.scalar('steps per second', steps_per_sec,
step)
for key, val in summary.items():
train_summary_writer.scalar(key, val, step)
train_summary_writer.flush()
metrics_all = []
logging.info('train in step: %d, loss: %.4f', step, summary['loss'])
# Eval Metrics
logging.info('Gathering evaluation metrics.')
t_eval_start = time.time()
eval_metrics = []
eval_iter = iter(eval_ds)
for _, eval_batch in zip(range(FLAGS.num_eval_steps), eval_iter):
eval_batch = jax.tree_map(lambda x: x._numpy(), eval_batch) # pylint: disable=protected-access
eval_batch = common_utils.shard(eval_batch)
metrics = p_eval_step(optimizer.target, eval_batch)
eval_metrics.append(metrics)
eval_metrics = common_utils.get_metrics(eval_metrics)
eval_metrics_sums = jax.tree_map(jnp.sum, eval_metrics)
eval_denominator = eval_metrics_sums.pop('denominator')
eval_summary = jax.tree_map(
lambda x: x / eval_denominator, # pylint: disable=cell-var-from-loop
eval_metrics_sums)
if jax.host_id() == 0:
for key, val in eval_summary.items():
eval_summary_writer.scalar(key, val, step)
eval_summary_writer.flush()
logging.info('eval in step: %d, loss: %.4f', step,
eval_summary['loss'])
logging.info('eval time: %.4f s step %d',
time.time() - t_eval_start, step)
# Translation and BLEU Score.
logging.info('Translating evaluation dataset.')
t_inference_start = time.time()
predict_iter = iter(predict_ds)
sources, references, predictions = [], [], []
for _, pred_batch in enumerate(predict_iter):
pred_batch = jax.tree_map(lambda x: x._numpy(), pred_batch) # pylint: disable=protected-access
# Handle final odd-sized batch by padding instead of dropping it.
cur_pred_batch_size = pred_batch['inputs'].shape[0]
if cur_pred_batch_size % n_devices:
padded_size = int(
np.ceil(cur_pred_batch_size / n_devices) * n_devices)
pred_batch = jax.tree_map(
lambda x: pad_examples(x, padded_size), pred_batch) # pylint: disable=cell-var-from-loop
pred_batch = common_utils.shard(pred_batch)
cache = p_init_cache(pred_batch['inputs'])
predicted = p_pred_step(pred_batch['inputs'], optimizer.target,
cache, eos_id, FLAGS.max_predict_length)
predicted = tohost(predicted)
inputs = tohost(pred_batch['inputs'])
targets = tohost(pred_batch['targets'])
# Iterate through non-padding examples of batch.
for i, s in enumerate(predicted[:cur_pred_batch_size]):
sources.append(decode_tokens(inputs[i]))
references.append(decode_tokens(targets[i]))
predictions.append(decode_tokens(s))
logging.info('Translation: %d predictions %d references %d sources.',
len(predictions), len(references), len(sources))
logging.info('Translation time: %.4f s step %d.',
time.time() - t_inference_start, step)
# Calculate BLEU score for translated eval corpus against reference.
bleu_matches = bleu.bleu_partial(references, predictions)
all_bleu_matches = per_host_sum_pmap(bleu_matches)
bleu_score = bleu.complete_bleu(*all_bleu_matches)
# Save translation samples for tensorboard.
exemplars = ''
for n in np.random.choice(np.arange(len(predictions)), 8):
exemplars += f'{sources[n]}\n\n{references[n]}\n\n{predictions[n]}\n\n'
if jax.host_id() == 0:
eval_summary_writer.scalar('bleu', bleu_score, step)
eval_summary_writer.text('samples', exemplars, step)
eval_summary_writer.flush()
logging.info('Translation BLEU Score %.4f', bleu_score)
def train_and_evaluate(config: ml_collections.ConfigDict, workdir: str):
"""Runs a training and evaluation loop.
Args:
config: Configuration to use.
workdir: Working directory for checkpoints and TF summaries. If this
contains checkpoint training will be resumed from the latest checkpoint.
"""
tf.io.gfile.makedirs(workdir)
# Number of local devices for this host.
n_devices = jax.local_device_count()
if jax.host_id() == 0:
tf.io.gfile.makedirs(workdir)
train_summary_writer = tensorboard.SummaryWriter(
os.path.join(workdir, "train"))
eval_summary_writer = tensorboard.SummaryWriter(
os.path.join(workdir, "eval"))
if config.batch_size % n_devices:
raise ValueError("Batch size must be divisible by the number of devices")
vocab_path = config.vocab_path
if vocab_path is None:
vocab_path = os.path.join(workdir, "sentencepiece_model")
tf.io.gfile.makedirs(os.path.split(vocab_path)[0])
# Load Dataset
# ---------------------------------------------------------------------------
logging.info("Initializing dataset.")
train_ds, eval_ds, predict_ds, encoder = input_pipeline.get_wmt_datasets(
n_devices=n_devices,
dataset_name=config.dataset_name,
eval_dataset_name=config.eval_dataset_name,
shard_idx=jax.host_id(),
shard_count=jax.host_count(),
vocab_path=vocab_path,
target_vocab_size=config.vocab_size,
batch_size=config.batch_size,
max_corpus_chars=config.max_corpus_chars,
max_length=config.max_target_length,
max_eval_length=config.max_eval_target_length)
train_iter = iter(train_ds)
vocab_size = int(encoder.vocab_size())
eos_id = decode.EOS_ID # Default Sentencepiece EOS token.
def decode_tokens(toks):
valid_toks = toks[:np.argmax(toks == eos_id) + 1].astype(np.int32)
return encoder.detokenize(valid_toks).numpy().decode("utf-8")
if config.num_predict_steps > 0:
predict_ds = predict_ds.take(config.num_predict_steps)
logging.info("Initializing model, optimizer, and step functions.")
# Build Model and Optimizer
# ---------------------------------------------------------------------------
train_config = models.TransformerConfig(
vocab_size=vocab_size,
output_vocab_size=vocab_size,
share_embeddings=config.share_embeddings,
logits_via_embedding=config.logits_via_embedding,
dtype=jnp.bfloat16 if config.use_bfloat16 else jnp.float32,
emb_dim=config.emb_dim,
num_heads=config.num_heads,
num_layers=config.num_layers,
qkv_dim=config.qkv_dim,
mlp_dim=config.mlp_dim,
max_len=max(config.max_target_length, config.max_eval_target_length),
dropout_rate=config.dropout_rate,
attention_dropout_rate=config.attention_dropout_rate,
deterministic=False,
decode=False,
kernel_init=nn.initializers.xavier_uniform(),
bias_init=nn.initializers.normal(stddev=1e-6))
eval_config = train_config.replace(deterministic=True)
predict_config = train_config.replace(deterministic=True, decode=True)
start_step = 0
rng = random.PRNGKey(config.seed)
rng, init_rng = random.split(rng)
input_shape = (config.batch_size, config.max_target_length)
target_shape = (config.batch_size, config.max_target_length)
m = models.Transformer(eval_config)
initial_variables = jax.jit(m.init)(init_rng, jnp.ones(input_shape, jnp.float32),
jnp.ones(target_shape, jnp.float32))
# apply an optimizer to this tree
optimizer_def = optim.Adam(
config.learning_rate,
beta1=0.9,
beta2=0.98,
eps=1e-9,
weight_decay=config.weight_decay)
optimizer = optimizer_def.create(initial_variables["params"])
# We access model params only from optimizer below via optimizer.target.
del initial_variables
if config.restore_checkpoints:
# Restore unreplicated optimizer + model state from last checkpoint.
optimizer = checkpoints.restore_checkpoint(workdir, optimizer)
# Grab last step.
start_step = int(optimizer.state.step)
# Replicate optimizer.
optimizer = jax_utils.replicate(optimizer)
learning_rate_fn = create_learning_rate_scheduler(
base_learning_rate=config.learning_rate, warmup_steps=config.warmup_steps)
# compile multidevice versions of train/eval/predict step and cache init fn.
p_train_step = jax.pmap(
functools.partial(
train_step,
config=train_config,
learning_rate_fn=learning_rate_fn,
label_smoothing=config.label_smoothing),
axis_name="batch",
donate_argnums=(0,)) # pytype: disable=wrong-arg-types
p_eval_step = jax.pmap(
functools.partial(
eval_step, config=eval_config,
label_smoothing=config.label_smoothing),
axis_name="batch")
p_init_cache = jax.pmap(
functools.partial(
initialize_cache,
max_decode_len=config.max_predict_length,
config=predict_config),
axis_name="batch")
p_pred_step = jax.pmap(
functools.partial(
predict_step, config=predict_config, beam_size=config.beam_size),
axis_name="batch",
static_broadcasted_argnums=(3, 4)) # eos token, max_length are constant
# Main Train Loop
# ---------------------------------------------------------------------------
# We init the first set of dropout PRNG keys, but update it afterwards inside
# the main pmap"d training update for performance.
dropout_rngs = random.split(rng, n_devices)
logging.info("Starting training loop.")
metrics_all = []
t_loop_start = time.time()
for step, batch in zip(range(start_step, config.num_train_steps), train_iter):
# Shard data to devices and do a training step.
batch = common_utils.shard(jax.tree_map(lambda x: x._numpy(), batch)) # pylint: disable=protected-access
optimizer, metrics, dropout_rngs = p_train_step(
optimizer, batch, dropout_rng=dropout_rngs)
metrics_all.append(metrics)
# Quick indication that training is happening.
logging.log_first_n(logging.INFO, "Finished training step %d.", 5, step)
# Save a checkpoint on one host after every checkpoint_freq steps.
if (config.save_checkpoints and step % config.checkpoint_freq == 0 and
step > 0 and jax.host_id() == 0):
checkpoints.save_checkpoint(workdir, jax_utils.unreplicate(optimizer),
step)
# Periodic metric handling.
if step % config.eval_frequency != 0 and step > 0:
continue
# Training Metrics
logging.info("Gathering training metrics.")
metrics_all = common_utils.get_metrics(metrics_all)
lr = metrics_all.pop("learning_rate").mean()
metrics_sums = jax.tree_map(jnp.sum, metrics_all)
denominator = metrics_sums.pop("denominator")
summary = jax.tree_map(lambda x: x / denominator, metrics_sums) # pylint: disable=cell-var-from-loop
summary["learning_rate"] = lr
steps_per_eval = config.eval_frequency if step != 0 else 1
steps_per_sec = steps_per_eval / (time.time() - t_loop_start)
t_loop_start = time.time()
if jax.host_id() == 0:
train_summary_writer.scalar("steps per second", steps_per_sec, step)
for key, val in summary.items():
train_summary_writer.scalar(key, val, step)
train_summary_writer.flush()
metrics_all = []
logging.info("train in step: %d, loss: %.4f", step, summary["loss"])
# Eval Metrics
logging.info("Gathering evaluation metrics.")
t_eval_start = time.time()
eval_metrics = []
eval_iter = iter(eval_ds)
for _, eval_batch in zip(range(config.num_eval_steps), eval_iter):
eval_batch = jax.tree_map(lambda x: x._numpy(), eval_batch) # pylint: disable=protected-access
eval_batch = common_utils.shard(eval_batch)
metrics = p_eval_step(optimizer.target, eval_batch)
eval_metrics.append(metrics)
eval_metrics = common_utils.get_metrics(eval_metrics)
eval_metrics_sums = jax.tree_map(jnp.sum, eval_metrics)
eval_denominator = eval_metrics_sums.pop("denominator")
eval_summary = jax.tree_map(
lambda x: x / eval_denominator, # pylint: disable=cell-var-from-loop
eval_metrics_sums)
if jax.host_id() == 0:
for key, val in eval_summary.items():
eval_summary_writer.scalar(key, val, step)
eval_summary_writer.flush()
logging.info("eval in step: %d, loss: %.4f", step, eval_summary["loss"])
logging.info("eval time: %.4f s step %d", time.time() - t_eval_start, step)
# Translation and BLEU Score.
logging.info("Translating evaluation dataset.")
t_inference_start = time.time()
sources, references, predictions = [], [], []
for pred_batch in predict_ds:
pred_batch = jax.tree_map(lambda x: x._numpy(), pred_batch) # pylint: disable=protected-access
# Handle final odd-sized batch by padding instead of dropping it.
cur_pred_batch_size = pred_batch["inputs"].shape[0]
if cur_pred_batch_size % n_devices:
padded_size = int(
np.ceil(cur_pred_batch_size / n_devices) * n_devices)
pred_batch = jax.tree_map(
lambda x: pad_examples(x, padded_size), pred_batch) # pylint: disable=cell-var-from-loop
pred_batch = common_utils.shard(pred_batch)
cache = p_init_cache(pred_batch["inputs"])
predicted = p_pred_step(pred_batch["inputs"], optimizer.target, cache,
eos_id, config.max_predict_length)
predicted = tohost(predicted)
inputs = tohost(pred_batch["inputs"])
targets = tohost(pred_batch["targets"])
# Iterate through non-padding examples of batch.
for i, s in enumerate(predicted[:cur_pred_batch_size]):
sources.append(decode_tokens(inputs[i]))
references.append(decode_tokens(targets[i]))
predictions.append(decode_tokens(s))
logging.info("Translation: %d predictions %d references %d sources.",
len(predictions), len(references), len(sources))
logging.info("Translation time: %.4f s step %d.",
time.time() - t_inference_start, step)
# Calculate BLEU score for translated eval corpus against reference.
bleu_matches = bleu.bleu_partial(references, predictions)
all_bleu_matches = per_host_sum_pmap(bleu_matches)
bleu_score = bleu.complete_bleu(*all_bleu_matches)
# Save translation samples for tensorboard.
exemplars = ""
for n in np.random.choice(np.arange(len(predictions)), 8):
exemplars += f"{sources[n]}\n\n{references[n]}\n\n{predictions[n]}\n\n"
if jax.host_id() == 0:
eval_summary_writer.scalar("bleu", bleu_score, step)
eval_summary_writer.text("samples", exemplars, step)
eval_summary_writer.flush()
logging.info("Translation BLEU Score %.4f", bleu_score)
