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Add materialisation of new modules before loading checkpoint #1030

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e0a3731
Add materialisation of new modules before loading checkpoint
kacpnowak Oct 5, 2025
f423b8f
Initialize new modules in load_model
kacpnowak Oct 7, 2025
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48 changes: 35 additions & 13 deletions src/weathergen/train/trainer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -216,12 +216,14 @@ def run(self, cf, devices, run_id_contd=None, epoch_contd=None):

if cf.with_ddp and cf.with_fsdp:
fsdp_kwargs = {
"mp_policy": MixedPrecisionPolicy(
param_dtype=self.mixed_precision_dtype,
reduce_dtype=torch.float32,
)
if cf.with_mixed_precision
else None,
"mp_policy": (
MixedPrecisionPolicy(
param_dtype=self.mixed_precision_dtype,
reduce_dtype=torch.float32,
)
if cf.with_mixed_precision
else None
),
}
modules_to_shard = (
MLP,
Expand Down Expand Up @@ -252,12 +254,14 @@ def run(self, cf, devices, run_id_contd=None, epoch_contd=None):
fully_shard(module, **fsdp_kwargs)

full_precision_fsdp_kwargs = {
"mp_policy": MixedPrecisionPolicy(
param_dtype=torch.float32,
reduce_dtype=torch.float32,
)
if cf.with_mixed_precision
else None,
"mp_policy": (
MixedPrecisionPolicy(
param_dtype=torch.float32,
reduce_dtype=torch.float32,
)
if cf.with_mixed_precision
else None
),
}
for module in self.model.pred_adapter_kv.modules():
if isinstance(module, modules_to_shard):
Expand All @@ -274,7 +278,6 @@ def run(self, cf, devices, run_id_contd=None, epoch_contd=None):
for tensor in itertools.chain(self.model.parameters(), self.model.buffers()):
assert tensor.device == torch.device("meta")

# load model if specified
if run_id_contd is None:
self.model.to_empty(device="cuda")
self.model.reset_parameters()
Expand Down Expand Up @@ -714,6 +717,25 @@ def load_model(self, run_id: str, epoch=-1):
# choose `assign=True` for sharded model since we cannot call `copy_` on meta tensor
mkeys, ukeys = self.model.load_state_dict(maybe_sharded_sd, strict=False, assign=True)

if mkeys:
# Get the unique parent modules for the missing parameters
new_modules_to_init = {key.rsplit(".", 1)[0] for key in mkeys}

# Find the highest-level "root" new modules to avoid redundant initializations
root_new_modules = set()
for path in sorted(list(new_modules_to_init)):
if not any(path.startswith(root + ".") for root in root_new_modules):
root_new_modules.add(path)

# Get all modules for quick lookup and initialize the new ones
all_modules = dict(self.model.named_modules())
for path in root_new_modules:
if is_root():
logger.info(f"Initializing new module not found in checkpoint: {path}")
module_to_init = all_modules[path]
module_to_init.to_empty(device="cuda")
module_to_init.reset_parameters()

if not is_model_sharded:
self.model = self.model.to(self.device)

Expand Down
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