verl/utils/distributed.py

# Copyright 2024 Bytedance Ltd. and/or its affiliates
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
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#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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"""Utilities for distributed training."""

import ctypes
import os
import socket
from datetime import timedelta

import ray
import torch.distributed

from verl.utils.device import get_device_name, get_nccl_backend, get_torch_device, is_npu_available
from verl.utils.net_utils import is_ipv6


def set_numa_affinity():
    if is_npu_available:
        # TODO (FightingZhen) libnuma.so is not available in e2e_ascend CI image, remove this code after image update.
        return

    initialized = False
    try:
        libnuma = ctypes.CDLL("libnuma.so")
        if libnuma.numa_available() < 0:
            return

        import pynvml

        pynvml.nvmlInit()
        initialized = True
        device_name = "NPU" if is_npu_available else "GPU"
        local_rank = int(ray.get_runtime_context().get_accelerator_ids()[device_name][0])
        handle = pynvml.nvmlDeviceGetHandleByIndex(local_rank)
        pynvml.nvmlDeviceSetCpuAffinity(handle)
    except ImportError:
        print("Warning: pynvml not available, skipping NUMA affinity setup")
    except Exception as e:
        print(f"Warning: Failed to set NUMA affinity: {e}")
    finally:
        if initialized:
            pynvml.nvmlShutdown()


def initialize_global_process_group(timeout_second=36000):
    torch.distributed.init_process_group(
        get_nccl_backend(),
        timeout=timedelta(seconds=timeout_second),
        init_method=os.environ.get("DIST_INIT_METHOD", None),
    )
    local_rank = int(os.environ["LOCAL_RANK"])
    rank = int(os.environ["RANK"])
    world_size = int(os.environ["WORLD_SIZE"])

    if torch.distributed.is_initialized():
        get_torch_device().set_device(local_rank)
    return local_rank, rank, world_size


def destroy_global_process_group():
    if torch.distributed.is_initialized():
        torch.distributed.destroy_process_group()


def initialize_global_process_group_ray(timeout_second=None, backend=None):
    # in current ray environment, LOCAL_RANK is always zero.

    import torch.distributed

    timeout = timedelta(seconds=timeout_second) if timeout_second is not None else None
    backend = backend or f"cpu:gloo,{get_device_name()}:{get_nccl_backend()}"
    if not torch.distributed.is_initialized():
        rank = int(os.environ.get("RANK", 0))
        world_size = int(os.environ.get("WORLD_SIZE", 1))
        torch.distributed.init_process_group(
            backend=backend,
            rank=rank,
            world_size=world_size,
            timeout=timeout,
            init_method=os.environ.get("DIST_INIT_METHOD", None),
        )


def stateless_init_process_group(master_address, master_port, rank, world_size, device):
    """
    vLLM provides `StatelessProcessGroup` to create a process group
    without considering the global process group in torch.distributed.
    It is recommended to create `StatelessProcessGroup`, and then initialize
    the data-plane communication (NCCL) between external (train processes)
    and vLLM workers.
    """
    # NOTE: If it is necessary to support weight synchronization with the sglang backend in the future,
    # the following can be used:
    # from sglang.srt.distributed.device_communicators.pynccl import PyNcclCommunicator
    # from sglang.srt.distributed.utils import statelessprocessgroup

    from torch.distributed import TCPStore
    from vllm.distributed.utils import StatelessProcessGroup

    from verl.utils.device import is_npu_available

    if is_npu_available:
        from vllm_ascend.distributed.device_communicators.pyhccl import PyHcclCommunicator as PyNcclCommunicator
    else:
        from vllm.distributed.device_communicators.pynccl import PyNcclCommunicator

    def create_process_group(
        host: str,
        port: int,
        rank: int,
        world_size: int,
        data_expiration_seconds: int = 3600,
        store_timeout: int = 300,
    ) -> "StatelessProcessGroup":
        """
        This is copied from vllm/distributed/utils.py:StatelessProcessGroup.create
        Modified to support ipv6 stateless communication groups."""
        launch_server = rank == 0
        if launch_server:
            # listen on the specified interface (instead of 0.0.0.0)
            if is_ipv6(master_address):
                listen_socket = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
            else:
                listen_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            listen_socket.bind((host, port))
            listen_socket.listen()
            listen_fd = listen_socket.fileno()
        else:
            listen_socket = None
            listen_fd = None

        store = TCPStore(
            host_name=host,
            port=port,
            world_size=world_size,
            is_master=launch_server,
            timeout=timedelta(seconds=store_timeout),
            use_libuv=False,  # for now: github.com/pytorch/pytorch/pull/150215
            master_listen_fd=listen_fd,
        )

        return StatelessProcessGroup(
            rank=rank,
            world_size=world_size,
            store=store,
            socket=listen_socket,
            data_expiration_seconds=data_expiration_seconds,
        )

    pg = create_process_group(host=master_address, port=master_port, rank=rank, world_size=world_size)

    pynccl = PyNcclCommunicator(pg, device=device)
    return pynccl