def initialize_apex(model, optimizer=None, **distributed_params):
"""
Prepares model and optimizer for work with Nvidia Apex.
Args:
model: torch model
optimizer: torch optimizer
**distributed_params: extra params for ``apex.amp.initialize``
Returns:
model and optimiezer, wrapped with Nvidia Apex initialization
"""
import apex
amp_params = get_fn_default_params(apex.amp.initialize,
["models", "optimizers"])
amp_params["opt_level"] = "O0"
for dp in distributed_params:
if dp in amp_params:
amp_params[dp] = distributed_params[dp]
# NVIDIA apex support only:
# model: nn.Module or list of modules
# optimizer: None, torch.Optimizer or list of optimizers
# while key-value is preferred in the `catalyst`.
# So if model/optimizer is a dict, convert it to lists of keys
# and values first, and then cast it back after apex initialization
model_keys, optimizer_keys = None, None
if isinstance(model, dict):
model_keys, model = list(model.keys()), list(model.values())
if isinstance(optimizer, dict):
optimizer_keys = list(optimizer.keys())
optimizer = list(optimizer.values())
amp_result = apex.amp.initialize(model, optimizer, **amp_params)
if optimizer is not None:
model, optimizer = amp_result
else:
model = amp_result
# convert model/optimizer back to dict if it needed
if model_keys is not None:
model = OrderedDict([(k, v) for k, v in zip(model_keys, model)])
if optimizer_keys is not None:
optimizers = [(k, v) for k, v in zip(optimizer_keys, optimizer)]
optimizer = OrderedDict(optimizers)
return model, optimizer
def initialize_apex(model, optimizer=None, **distributed_params):
"""@TODO: Docs. Contribution is welcome."""
import apex
amp_params = get_fn_default_params(
apex.amp.initialize, ["models", "optimizers"]
)
amp_params["opt_level"] = "O0"
for dp in distributed_params:
if dp in amp_params:
amp_params[dp] = distributed_params[dp]
amp_result = apex.amp.initialize(model, optimizer, **amp_params)
if optimizer is not None:
model, optimizer = amp_result
else:
model = amp_result
return model, optimizer
