DDP2Plugin

class pytorch_lightning.plugins.training_type.DDP2Plugin(parallel_devices=None, num_nodes=1, cluster_environment=None, sync_batchnorm=False, ddp_comm_state=None, ddp_comm_hook=None, ddp_comm_wrapper=None, **kwargs)

Bases: pytorch_lightning.plugins.training_type.ddp.DDPPlugin

DDP2 behaves like DP in one node, but synchronization across nodes behaves like in DDP.

model_to_device()

Moves the model to the correct device

reduce(tensor, *args, **kwargs)

Reduces a tensor from all processes to one aggregated tensor. In DDP2, the reduction here is only across local devices within the node.

Parameters

• tensor – the tensor to sync and reduce

• *args – ignored for DDP2

• **kwargs – ignored for DDP2

Returns

reduced value, except when the input was not a tensor the output remains is unchanged

setup(model)

Called by the accelerator to finish setup.

property root_device

Returns the root device