|
| 1 | +import logging |
| 2 | +import pickle |
| 3 | + |
| 4 | +import torch |
| 5 | + |
| 6 | +from pytorch_lightning.utilities.imports import _TORCH_GREATER_EQUAL_1_8 |
| 7 | + |
| 8 | +log = logging.getLogger(__name__) |
| 9 | + |
| 10 | +if torch.distributed.is_available(): |
| 11 | + from torch.distributed import Backend, broadcast, get_backend, get_rank, GroupMember |
| 12 | + |
| 13 | +# The code underneath is taken from PyTorch `torch/distributed/distributed_c10d.py` |
| 14 | +# and enable broadcasting for PyTorch 1.6 and lower. |
| 15 | + |
| 16 | + |
| 17 | +# https://github.com/pytorch/pytorch/blob/1.7/torch/distributed/distributed_c10d.py#L160 |
| 18 | +def _rank_not_in_group(group): |
| 19 | + """Helper that checks if the current process's rank is not in a given group.""" |
| 20 | + if group is None: |
| 21 | + return False |
| 22 | + return group == GroupMember.NON_GROUP_MEMBER |
| 23 | + |
| 24 | + |
| 25 | +# Taken from https://github.com/pytorch/pytorch/blob/1.7/torch/distributed/distributed_c10d.py#L1164 |
| 26 | +def _object_to_tensor(obj): |
| 27 | + buffer = pickle.dumps(obj) |
| 28 | + byte_storage = torch.ByteStorage.from_buffer(buffer) # type: ignore[attr-defined] |
| 29 | + byte_tensor = torch.ByteTensor(byte_storage) |
| 30 | + local_size = torch.LongTensor([byte_tensor.numel()]) |
| 31 | + return byte_tensor, local_size |
| 32 | + |
| 33 | + |
| 34 | +# Taken from https://github.com/pytorch/pytorch/blob/1.7/torch/distributed/distributed_c10d.py |
| 35 | +def _tensor_to_object(tensor, tensor_size): |
| 36 | + buf = tensor.numpy().tobytes()[:tensor_size] |
| 37 | + out = pickle.loads(buf) |
| 38 | + return out |
| 39 | + |
| 40 | + |
| 41 | +# Taken from https://github.com/pytorch/pytorch/blob/1.7/torch/distributed/distributed_c10d.py#L1327 |
| 42 | +def _broadcast_object_list(object_list, src=0, group=None): |
| 43 | + if _rank_not_in_group(group): |
| 44 | + return |
| 45 | + |
| 46 | + my_rank = get_rank() |
| 47 | + # Serialize object_list elements to tensors on src rank. |
| 48 | + if my_rank == src: |
| 49 | + tensor_list, size_list = zip(*(_object_to_tensor(obj) for obj in object_list)) |
| 50 | + object_sizes_tensor = torch.cat(size_list) |
| 51 | + else: |
| 52 | + object_sizes_tensor = torch.LongTensor(len(object_list)) |
| 53 | + |
| 54 | + group_backend = get_backend(group) |
| 55 | + is_nccl_backend = group_backend == Backend.NCCL |
| 56 | + current_device = torch.device("cpu") |
| 57 | + if is_nccl_backend: |
| 58 | + # See note about using torch.cuda.current_device() here in docstring. |
| 59 | + # We cannot simply use my_rank since rank == device is not necessarily |
| 60 | + # true. |
| 61 | + current_device = torch.device("cuda", torch.cuda.current_device()) |
| 62 | + object_sizes_tensor = object_sizes_tensor.to(current_device) |
| 63 | + object_sizes_tensor = object_sizes_tensor.to(current_device) |
| 64 | + |
| 65 | + # Broadcast object sizes |
| 66 | + broadcast(object_sizes_tensor, src=src, group=group) |
| 67 | + |
| 68 | + # Concatenate and broadcast serialized object tensors |
| 69 | + if my_rank == src: |
| 70 | + object_tensor = torch.cat(tensor_list) |
| 71 | + else: |
| 72 | + object_tensor = torch.ByteTensor(torch.sum(object_sizes_tensor).item()) |
| 73 | + |
| 74 | + if is_nccl_backend: |
| 75 | + object_tensor = object_tensor.to(current_device) |
| 76 | + |
| 77 | + broadcast(object_tensor, src=src, group=group) |
| 78 | + |
| 79 | + # Deserialize objects using their stored sizes. |
| 80 | + offset = 0 |
| 81 | + if my_rank != src: |
| 82 | + for i, obj_size in enumerate(object_sizes_tensor): |
| 83 | + obj_view = object_tensor[offset : offset + obj_size] |
| 84 | + obj_view = obj_view.type(torch.ByteTensor) # type: ignore[call-overload] |
| 85 | + offset += obj_size |
| 86 | + object_list[i] = _tensor_to_object(obj_view, obj_size) |
| 87 | + |
| 88 | + |
| 89 | +if not torch.distributed.is_available(): |
| 90 | + # avoid failures on early PyTorch versions for Windows where |
| 91 | + # not all functions used in `broadcast_object_list` are available. |
| 92 | + def _broadcast_noop(obj, *_, **__): |
| 93 | + return obj |
| 94 | + |
| 95 | + broadcast_object_list = _broadcast_noop |
| 96 | +elif _TORCH_GREATER_EQUAL_1_8: |
| 97 | + from torch.distributed.distributed_c10d import broadcast_object_list |
| 98 | +else: |
| 99 | + broadcast_object_list = _broadcast_object_list |
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