def _get_grads(self, process_group, hook_type=None):
device_id = gpus_for_rank(self.world_size)[self.rank][0]
gpu_model = DistributedDataParallel(
TestDdpCommHook().to(device_id),
device_ids=[device_id],
process_group=process_group,
)
# Register DDP Communication Hook if defined
if hook_type is not None:
register_ddp_comm_hook(
comm_hook_type=hook_type, model=gpu_model, state=process_group
)
return self._run_and_get_grads(gpu_model)
def DistributedFairseqModel(args, model, process_group, device):
"""
Wrap a *model* to support distributed data parallel training.
This is similar to the built-in DistributedDataParallel, but allows
additional configuration of the DistributedDataParallel class to
use, and also provides easier access to the wrapped model by
forwarding requests for missing attributes to the wrapped model.
Args:
args (argparse.Namespace): fairseq args
model (BaseFairseqModel): model to wrap
process_group: the c10d process group to be used for distributed data
parallel all-reduction.
device: device to move model to
"""
assert isinstance(model, nn.Module)
if args.tpu:
wrapped_model = TPUDistributedDataParallel(
module=model.to(device),
process_group=process_group,
)
# forward missing getattr and state_dict/load_state_dict to orig model
wrapped_model = ModuleProxyWrapper(wrapped_model)
elif args.ddp_backend in {"c10d", "pytorch_ddp"}:
wrapped_model = DistributedDataParallel(
module=model.to(device),
device_ids=[args.device_id],
output_device=args.device_id,
broadcast_buffers=args.broadcast_buffers,
bucket_cap_mb=args.bucket_cap_mb,
process_group=process_group,
find_unused_parameters=args.find_unused_parameters,
gradient_as_bucket_view=args.gradient_as_bucket_view,
)
if args.ddp_comm_hook == "fp16":
logger.info("enable fp16 communication hook in DDP")
try:
from torch.distributed.algorithms.ddp_comm_hooks import (
register_ddp_comm_hook,
DDPCommHookType,
)
except:
logger.error(
"Could not import from torch.distributed.algorithms.ddp_comm_hooks; you may need to update your pytorch version"
)
raise
register_ddp_comm_hook(DDPCommHookType.FP16_COMPRESS, wrapped_model)
# forward missing getattr and state_dict/load_state_dict to orig model
wrapped_model = ModuleProxyWrapper(wrapped_model)
elif args.ddp_backend in {"no_c10d", "legacy_ddp"}:
wrapped_model = LegacyDistributedDataParallel(
module=model.to(device),
buffer_size=2 ** 28,
process_group=process_group,
)
# forward missing getattr and state_dict/load_state_dict to orig model
wrapped_model = ModuleProxyWrapper(wrapped_model)
elif args.ddp_backend == "slowmo":
if _SLOWMO_DDP_DISABLED:
raise ImportError(
"Cannot find SlowMoDistributedDataParallel. "
"Please install fairscale with: pip install fairscale"
)
# The values of slowmo_momentum below were obtained by tuning on the
# En-De 16 dataset by training the transformer_wmt_en_de_large model
if args.slowmo_momentum is None:
if args.distributed_world_size <= 16:
args.slowmo_momentum = 0.0
elif args.distributed_world_size <= 32:
args.slowmo_momentum = 0.2
elif args.distributed_world_size <= 64:
args.slowmo_momentum = 0.5
else:
args.slowmo_momentum = 0.6
slowmo_base_algorithm = SlowMoBaseAlgorithm[args.slowmo_base_algorithm.upper()]
wrapped_model = SlowMoDistributedDataParallel(
module=model.to(device),
broadcast_buffers=args.broadcast_buffers,
nprocs_per_node=args.nprocs_per_node,
slowmo_momentum=args.slowmo_momentum,
slowmo_base_algorithm=slowmo_base_algorithm,
localsgd_frequency=args.localsgd_frequency,
)
# forward missing getattr and state_dict/load_state_dict to orig model
wrapped_model = ModuleProxyWrapper(wrapped_model)
elif args.ddp_backend == "fully_sharded":
try:
from fairscale.nn.data_parallel import FullyShardedDataParallel as FSDP
except ImportError:
raise ImportError(
"Cannot find FullyShardedDataParallel. "
"Please install fairscale with: pip install fairscale"
)
assert isinstance(model, FSDP), "expected model to already be wrapped in FSDP"
wrapped_model = model
if args.memory_efficient_fp16:
wrapped_model = wrapped_model.half()
if not args.cpu_offload:
wrapped_model = wrapped_model.to(device=device)
else:
raise ValueError("Unknown --ddp-backend: " + args.ddp_backend)
# kill hung distributed jobs after a timeout
if getattr(args, "heartbeat_timeout", -1) > 0:
wrapped_model = DistributedTimeoutWrapper(
wrapped_model, timeout=getattr(args, "heartbeat_timeout", -1)
)
return wrapped_model
