# Copied and adapted from: https://github.com/hao-ai-lab/FastVideo # SPDX-License-Identifier: Apache-2.0 # Adapted from https://github.com/vllm-project/vllm/blob/v0.7.3/vllm/distributed/utils.py # Copyright 2023 The vLLM team. # Adapted from # https://github.com/NVIDIA/Megatron-LM/blob/main/megatron/core/tensor_parallel/utils.py # Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved. import dataclasses import pickle import time from collections import deque from collections.abc import Sequence from typing import Any import torch from torch.distributed import TCPStore from sglang.multimodal_gen.runtime.utils.logging_utils import init_logger logger = init_logger(__name__) def ensure_divisibility(numerator, denominator) -> None: """Ensure that numerator is divisible by the denominator.""" assert numerator % denominator == 0, "{} is not divisible by {}".format( numerator, denominator ) def divide(numerator: int, denominator: int) -> int: """Ensure that numerator is divisible by the denominator and return the division value.""" ensure_divisibility(numerator, denominator) return numerator // denominator def split_tensor_along_last_dim( tensor: torch.Tensor, num_partitions: int, contiguous_split_chunks: bool = False, ) -> Sequence[torch.Tensor]: """Split a tensor along its last dimension. Arguments: tensor: input tensor. num_partitions: number of partitions to split the tensor contiguous_split_chunks: If True, make each chunk contiguous in memory. Returns: A list of Tensors """ # Get the size and dimension. last_dim = tensor.dim() - 1 last_dim_size = divide(tensor.size()[last_dim], num_partitions) # Split. tensor_list = torch.split(tensor, last_dim_size, dim=last_dim) # NOTE: torch.split does not create contiguous tensors by default. if contiguous_split_chunks: return tuple(chunk.contiguous() for chunk in tensor_list) return tuple(tensor_list) @dataclasses.dataclass class StatelessProcessGroup: """A dataclass to hold a metadata store, and the rank, world_size of the group. Only use it to communicate metadata between processes. For data-plane communication, create NCCL-related objects. """ rank: int world_size: int store: torch._C._distributed_c10d.Store data_expiration_seconds: int = 3600 # 1 hour # dst rank -> counter send_dst_counter: dict[int, int] = dataclasses.field(default_factory=dict) # src rank -> counter recv_src_counter: dict[int, int] = dataclasses.field(default_factory=dict) broadcast_send_counter: int = 0 broadcast_recv_src_counter: dict[int, int] = dataclasses.field(default_factory=dict) # A deque to store the data entries, with key and timestamp. entries: deque[tuple[str, float]] = dataclasses.field(default_factory=deque) def __post_init__(self): assert self.rank < self.world_size self.send_dst_counter = {i: 0 for i in range(self.world_size)} self.recv_src_counter = {i: 0 for i in range(self.world_size)} self.broadcast_recv_src_counter = {i: 0 for i in range(self.world_size)} def send_obj(self, obj: Any, dst: int): """Send an object to a destination rank.""" self.expire_data() key = f"send_to/{dst}/{self.send_dst_counter[dst]}" self.store.set(key, pickle.dumps(obj)) self.send_dst_counter[dst] += 1 self.entries.append((key, time.perf_counter())) def expire_data(self) -> None: """Expire data that is older than `data_expiration_seconds` seconds.""" while self.entries: # check the oldest entry key, timestamp = self.entries[0] if time.perf_counter() - timestamp > self.data_expiration_seconds: self.store.delete_key(key) self.entries.popleft() else: break def recv_obj(self, src: int) -> Any: """Receive an object from a source rank.""" obj = pickle.loads( self.store.get(f"send_to/{self.rank}/{self.recv_src_counter[src]}") ) self.recv_src_counter[src] += 1 return obj def broadcast_obj(self, obj: Any | None, src: int) -> Any: """Broadcast an object from a source rank to all other ranks. It does not clean up after all ranks have received the object. Use it for limited times, e.g., for initialization. """ if self.rank == src: self.expire_data() key = f"broadcast_from/{src}/" f"{self.broadcast_send_counter}" self.store.set(key, pickle.dumps(obj)) self.broadcast_send_counter += 1 self.entries.append((key, time.perf_counter())) return obj else: key = f"broadcast_from/{src}/" f"{self.broadcast_recv_src_counter[src]}" recv_obj = pickle.loads(self.store.get(key)) self.broadcast_recv_src_counter[src] += 1 return recv_obj def all_gather_obj(self, obj: Any) -> list[Any]: """All gather an object from all ranks.""" gathered_objs = [] for i in range(self.world_size): if i == self.rank: gathered_objs.append(obj) self.broadcast_obj(obj, src=self.rank) else: recv_obj = self.broadcast_obj(None, src=i) gathered_objs.append(recv_obj) return gathered_objs def barrier(self): """A barrier to synchronize all ranks.""" for i in range(self.world_size): if i == self.rank: self.broadcast_obj(None, src=self.rank) else: self.broadcast_obj(None, src=i) @staticmethod def create( host: str, port: int, rank: int, world_size: int, data_expiration_seconds: int = 3600, ) -> "StatelessProcessGroup": """A replacement for `torch.distributed.init_process_group` that does not pollute the global state. If we have process A and process B called `torch.distributed.init_process_group` to form a group, and then we want to form another group with process A, B, C, D, it is not possible in PyTorch, because process A and process B have already formed a group, and process C and process D cannot join that group. This function is a workaround for this issue. `torch.distributed.init_process_group` is a global call, while this function is a stateless call. It will return a `StatelessProcessGroup` object that can be used for exchanging metadata. With this function, process A and process B can call `StatelessProcessGroup.create` to form a group, and then process A, B, C, and D can call `StatelessProcessGroup.create` to form another group. """ # noqa store = TCPStore( host_name=host, port=port, world_size=world_size, is_master=(rank == 0), ) return StatelessProcessGroup( rank=rank, world_size=world_size, store=store, data_expiration_seconds=data_expiration_seconds, )