def load_checkpoint(
self,
filename,
reset_optimizer=False,
reset_lr_scheduler=False,
optimizer_overrides=None,
reset_meters=False,
):
"""Load all training state from a checkpoint file."""
extra_state, self._optim_history, last_optim_state = None, [], None
bexists = PathManager.isfile(filename)
if bexists:
state = checkpoint_utils.load_checkpoint_to_cpu(filename)
# load model parameters
try:
self.get_model().load_state_dict(state["model"],
strict=True,
args=self.args)
if utils.has_parameters(self.get_criterion()):
self.get_criterion().load_state_dict(state["criterion"],
strict=True)
except Exception:
raise Exception(
"Cannot load model parameters from checkpoint {}; "
"please ensure that the architectures match.".format(
filename))
extra_state = state["extra_state"]
self._optim_history = state["optimizer_history"]
last_optim_state = state.get("last_optimizer_state", None)
if last_optim_state is not None and not reset_optimizer:
# rebuild optimizer after loading model, since params may have changed
self._build_optimizer()
# only reload optimizer and lr_scheduler if they match
last_optim = self._optim_history[-1]
assert (
last_optim["criterion_name"] ==
self.get_criterion().__class__.__name__
), "Criterion does not match; please reset the optimizer (--reset-optimizer)."
assert (
last_optim["optimizer_name"] ==
self.optimizer.__class__.__name__
), "Optimizer does not match; please reset the optimizer (--reset-optimizer)."
if not reset_lr_scheduler:
self.lr_scheduler.load_state_dict(
last_optim["lr_scheduler_state"])
self.optimizer.load_state_dict(last_optim_state,
optimizer_overrides)
self.set_num_updates(last_optim["num_updates"])
if extra_state is not None:
epoch = extra_state["train_iterator"]["epoch"]
logger.info("loaded checkpoint {} (epoch {} @ {} updates)".format(
filename, epoch, self.get_num_updates()))
self.lr_step(epoch)
if "metrics" in extra_state and not reset_meters:
metrics.load_state_dict(extra_state["metrics"])
# reset TimeMeters, since their start times don't make sense anymore
for meter in metrics.get_meters("default"):
if isinstance(meter, meters.TimeMeter):
meter.reset()
else:
logger.info("no existing checkpoint found {}".format(filename))
return extra_state
def train_step(self, samples, raise_oom=False):
"""Do forward, backward and parameter update."""
self._set_seed()
self.model.train()
self.criterion.train()
self.zero_grad()
metrics.log_start_time("train_wall", priority=800, round=0)
# forward and backward pass
logging_outputs, sample_size, ooms = [], 0, 0
for i, sample in enumerate(samples):
sample, is_dummy_batch = self._prepare_sample(sample)
def maybe_no_sync():
"""
Whenever *samples* contains more than one mini-batch, we
want to accumulate gradients locally and only call
all-reduce in the last backwards pass.
"""
if (
self.data_parallel_world_size > 1
and hasattr(self.model, "no_sync")
and i < len(samples) - 1
):
return self.model.no_sync()
else:
return contextlib.ExitStack() # dummy contextmanager
try:
with maybe_no_sync():
# forward and backward
loss, sample_size_i, logging_output = self.task.train_step(
sample=sample,
model=self.model,
criterion=self.criterion,
optimizer=self.optimizer,
update_num=self.get_num_updates(),
ignore_grad=is_dummy_batch,
)
del loss
logging_outputs.append(logging_output)
sample_size += sample_size_i
# emptying the CUDA cache after the first step can
# reduce the chance of OOM
if self.cuda and self.get_num_updates() == 0:
torch.cuda.empty_cache()
except RuntimeError as e:
if "out of memory" in str(e):
self._log_oom(e)
if raise_oom:
raise e
logger.warning(
"attempting to recover from OOM in forward/backward pass"
)
ooms += 1
self.zero_grad()
if self.cuda:
torch.cuda.empty_cache()
if self.cfg.distributed_training.distributed_world_size == 1:
return None
else:
raise e
if self.tpu and i < len(samples) - 1:
# tpu-comment: every XLA operation before marking step is
# appended to the IR graph, and processing too many batches
# before marking step can lead to OOM errors.
# To handle gradient accumulation use case, we explicitly
# mark step here for every forward pass without a backward pass
import torch_xla.core.xla_model as xm
xm.mark_step()
if is_dummy_batch:
if torch.is_tensor(sample_size):
sample_size.zero_()
else:
sample_size *= 0.0
if torch.is_tensor(sample_size):
sample_size = sample_size.float()
else:
sample_size = float(sample_size)
# gather logging outputs from all replicas
if self._sync_stats():
train_time = self._local_cumulative_training_time()
logging_outputs, (
sample_size,
ooms,
total_train_time,
) = self._aggregate_logging_outputs(
logging_outputs,
sample_size,
ooms,
train_time,
ignore=is_dummy_batch,
)
self._cumulative_training_time = (
total_train_time / self.data_parallel_world_size
)
overflow = False
try:
with torch.autograd.profiler.record_function("reduce-grads"):
self.optimizer.all_reduce_grads(self.model)
if utils.has_parameters(self.criterion):
self.optimizer.all_reduce_grads(self.criterion)
with torch.autograd.profiler.record_function("multiply-grads"):
# multiply gradients by (data_parallel_size / sample_size) since
# DDP already normalizes by the number of data parallel workers.
# Thus we get (sum_of_gradients / sample_size) at the end.
if not self.cfg.optimization.use_bmuf:
self.optimizer.multiply_grads(
self.data_parallel_world_size / sample_size
)
elif sample_size > 0: # BMUF needs to check sample size
num = self.data_parallel_world_size if self._sync_stats() else 1
self.optimizer.multiply_grads(num / sample_size)
with torch.autograd.profiler.record_function("clip-grads"):
# clip grads
grad_norm = self.clip_grad_norm(self.cfg.optimization.clip_norm)
# check that grad norms are consistent across workers
# on tpu check tensor is slow
if not self.tpu:
if (
not self.cfg.optimization.use_bmuf
and self.cfg.distributed_training.distributed_wrapper != "SlowMo"
):
self._check_grad_norms(grad_norm)
if not torch.isfinite(grad_norm).all():
# check local gradnorm single GPU case, trigger NanDetector
raise FloatingPointError("gradients are Nan/Inf")
with torch.autograd.profiler.record_function("optimizer"):
# take an optimization step
self.task.optimizer_step(
self.optimizer, model=self.model, update_num=self.get_num_updates()
)
except FloatingPointError:
# re-run the forward and backward pass with hooks attached to print
# out where it fails
self.zero_grad()
with NanDetector(self.get_model()):
for _, sample in enumerate(samples):
sample, _ = self._prepare_sample(sample)
self.task.train_step(
sample,
self.model,
self.criterion,
self.optimizer,
self.get_num_updates(),
ignore_grad=False,
)
raise
except OverflowError as e:
overflow = True
logger.info("NOTE: overflow detected, " + str(e))
grad_norm = torch.tensor(0.0).cuda()
self.zero_grad()
except RuntimeError as e:
if "out of memory" in str(e):
self._log_oom(e)
logger.error("OOM during optimization, irrecoverable")
raise e
# Some distributed wrappers (e.g., SlowMo) need access to the optimizer after the step
if hasattr(self.model, "perform_additional_optimizer_actions"):
if hasattr(self.optimizer, "fp32_params"):
self.model.perform_additional_optimizer_actions(
self.optimizer.optimizer, self.optimizer.fp32_params
)
else:
self.model.perform_additional_optimizer_actions(
self.optimizer.optimizer
)
logging_output = None
if (
not overflow
or self.cfg.distributed_training.distributed_wrapper == "SlowMo"
):
self.set_num_updates(self.get_num_updates() + 1)
if self.tpu:
# mark step on TPUs
import torch_xla.core.xla_model as xm
xm.mark_step()
# only log stats every log_interval steps
# this causes wps to be misreported when log_interval > 1
logging_output = {}
if self.get_num_updates() % self.cfg.common.log_interval == 0:
# log memory usage
mem_info = xm.get_memory_info(self.device)
gb_free = mem_info["kb_free"] / 1024 / 1024
gb_total = mem_info["kb_total"] / 1024 / 1024
metrics.log_scalar(
"gb_free",
gb_free,
priority=1500,
round=1,
weight=0,
)
metrics.log_scalar(
"gb_total",
gb_total,
priority=1600,
round=1,
weight=0,
)
logging_output = self._reduce_and_log_stats(
logging_outputs,
sample_size,
grad_norm,
)
# log whenever there's an XLA compilation, since these
# slow down training and may indicate opportunities for
# optimization
self._check_xla_compilation()
else:
# log stats
logging_output = self._reduce_and_log_stats(
logging_outputs,
sample_size,
grad_norm,
)
# clear CUDA cache to reduce memory fragmentation
if (
self.cuda
and self.cfg.common.empty_cache_freq > 0
and (
(self.get_num_updates() + self.cfg.common.empty_cache_freq - 1)
% self.cfg.common.empty_cache_freq
)
== 0
):
torch.cuda.empty_cache()
if self.cfg.common.fp16:
metrics.log_scalar(
"loss_scale",
self.optimizer.scaler.loss_scale,
priority=700,
round=4,
weight=0,
)
metrics.log_stop_time("train_wall")
return logging_output
def load_checkpoint(
self,
filename,
reset_optimizer=False,
reset_lr_scheduler=False,
optimizer_overrides=None,
reset_meters=False,
):
"""Load all training state from a checkpoint file."""
extra_state, self._optim_history, last_optim_state = None, [], None
if os.path.exists(filename):
state = checkpoint_utils.load_checkpoint_to_cpu(filename)
# load model parameters
try:
missing_keys, _ = self.get_model().load_state_dict(
state['model'], strict=False)
if len(missing_keys) > 0:
print('Find missing keys when loading: {}'.format(
missing_keys))
if utils.has_parameters(self.get_criterion()):
self.get_criterion().load_state_dict(state['criterion'],
strict=True)
except Exception:
raise Exception(
'Cannot load model parameters from checkpoint {}; '
'please ensure that the architectures match.'.format(
filename))
extra_state = state['extra_state']
self._optim_history = state['optimizer_history']
last_optim_state = state.get('last_optimizer_state', None)
if last_optim_state is not None and not reset_optimizer:
# rebuild optimizer after loading model, since params may have changed
self._build_optimizer()
# only reload optimizer and lr_scheduler if they match
last_optim = self._optim_history[-1]
assert last_optim['criterion_name'] == self.get_criterion().__class__.__name__, \
'Criterion does not match; please reset the optimizer (--reset-optimizer).'
assert last_optim['optimizer_name'] == self.optimizer.__class__.__name__, \
'Optimizer does not match; please reset the optimizer (--reset-optimizer).'
if not reset_lr_scheduler:
self.lr_scheduler.load_state_dict(
last_optim['lr_scheduler_state'])
self.optimizer.load_state_dict(last_optim_state,
optimizer_overrides)
self.set_num_updates(last_optim['num_updates'])
if extra_state is not None:
epoch = extra_state['train_iterator']['epoch']
print('| loaded checkpoint {} (epoch {} @ {} updates)'.format(
filename, epoch, self.get_num_updates()))
self.lr_step(epoch)
if 'train_meters' in extra_state and not reset_meters:
self.meters.update(extra_state['train_meters'])
del extra_state['train_meters']
# reset TimeMeters, since their start times don't make sense anymore
for meter in self.meters.values():
if isinstance(meter, TimeMeter):
meter.reset()
else:
print('| no existing checkpoint found {}'.format(filename))
return extra_state
def load_checkpoint(
self,
filename,
reset_optimizer=False,
reset_lr_scheduler=False,
optimizer_overrides=None,
reset_meters=False,
):
"""
Load all training state from a checkpoint file.
rank = 0 will load the checkpoint, and then broadcast it to all
other ranks.
"""
extra_state, self._optim_history, last_optim_state = None, [], None
logger.info(f"Preparing to load checkpoint {filename}")
bexists = PathManager.isfile(filename)
if bexists:
load_on_all_ranks = (
self.cfg.checkpoint.load_checkpoint_on_all_dp_ranks
# TPUs don't support broadcast yet, so load checkpoints
# on every worker for now
or self.tpu
)
if load_on_all_ranks or self.data_parallel_rank == 0:
state = checkpoint_utils.load_checkpoint_to_cpu(filename)
last_optim_state = state.get("last_optimizer_state", None)
# If doing zero_sharding, do not broadcast global optimizer
# state. Later we will broadcast sharded states to each rank
# to avoid memory from exploding.
if (
not load_on_all_ranks
and self.cfg.distributed_training.zero_sharding == "os"
and "last_optimizer_state" in state
and self.data_parallel_world_size > 1
):
state["last_optimizer_state"] = "SHARDED"
else:
last_optim_state = None
state = None
if self.data_parallel_world_size > 1 and not load_on_all_ranks:
state = distributed_utils.broadcast_object(
state,
src_rank=0,
group=self.data_parallel_process_group,
dist_device=self.device,
)
if self.data_parallel_rank > 0:
last_optim_state = state.get("last_optimizer_state", None)
# load model parameters
try:
self.get_model().load_state_dict(
state["model"], strict=True, model_cfg=self.cfg.model
)
if utils.has_parameters(self.get_criterion()):
self.get_criterion().load_state_dict(
state["criterion"], strict=True
)
except Exception:
raise Exception(
"Cannot load model parameters from checkpoint {}; "
"please ensure that the architectures match.".format(filename)
)
extra_state = state["extra_state"]
self._optim_history = state["optimizer_history"]
if last_optim_state is not None and not reset_optimizer:
# rebuild optimizer after loading model, since params may have changed
self._build_optimizer()
# only reload optimizer and lr_scheduler if they match
last_optim = self._optim_history[-1]
assert (
last_optim["criterion_name"] == self.get_criterion().__class__.__name__
), "Criterion does not match; please reset the optimizer (--reset-optimizer)."
assert (
last_optim["optimizer_name"] == self.optimizer.__class__.__name__
), "Optimizer does not match; please reset the optimizer (--reset-optimizer)."
if not reset_lr_scheduler:
self.lr_scheduler.load_state_dict(last_optim["lr_scheduler_state"])
if not load_on_all_ranks and self.data_parallel_world_size > 1:
last_optim_state = self.optimizer.broadcast_global_state_dict(
last_optim_state
)
self.optimizer.load_state_dict(last_optim_state, optimizer_overrides)
self.set_num_updates(last_optim["num_updates"])
if extra_state is not None:
epoch = extra_state["train_iterator"]["epoch"]
if "previous_training_time" in extra_state:
self._previous_training_time = extra_state["previous_training_time"]
self._start_time = time.time()
self.lr_step(epoch)
if "metrics" in extra_state and not reset_meters:
metrics.load_state_dict(extra_state["metrics"])
# reset TimeMeters, since their start times don't make sense anymore
for meter in metrics.get_meters("default"):
if isinstance(meter, meters.TimeMeter):
meter.reset()
logger.info(
"Loaded checkpoint {} (epoch {} @ {} updates)".format(
filename, epoch, self.get_num_updates()
)
)
else:
logger.info("No existing checkpoint found {}".format(filename))
return extra_state
