# Copyright 2023-2024 SGLang Team
# 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
#
#     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,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""ModelRunner runs the forward passes of the models."""

from __future__ import annotations

import datetime
import gc
import inspect
import json
import logging
import os
import socket
import threading
import time
from collections import defaultdict
from dataclasses import dataclass
from typing import Callable, List, Optional, Tuple, Union

import torch
import torch.distributed as dist
from torch import nn

from sglang.jit_kernel.ngram_embedding import update_token_table
from sglang.srt.configs import (
    BailingHybridConfig,
    FalconH1Config,
    GraniteMoeHybridConfig,
    JetNemotronConfig,
    JetVLMConfig,
    KimiLinearConfig,
    Lfm2Config,
    Lfm2MoeConfig,
    NemotronH_Nano_VL_V2_Config,
    NemotronHConfig,
    Qwen3_5Config,
    Qwen3_5MoeConfig,
    Qwen3NextConfig,
)
from sglang.srt.configs.device_config import DeviceConfig
from sglang.srt.configs.load_config import LoadConfig, LoadFormat
from sglang.srt.configs.model_config import AttentionArch, ModelConfig, ModelImpl
from sglang.srt.configs.update_config import adjust_config_with_unaligned_cpu_tp
from sglang.srt.constants import GPU_MEMORY_TYPE_WEIGHTS
from sglang.srt.debug_utils.dumper import dumper
from sglang.srt.debug_utils.tensor_dump_forward_hook import (
    register_forward_hook_for_model,
)
from sglang.srt.distributed import (
    get_default_distributed_backend,
    get_pp_group,
    get_tp_group,
    get_world_group,
    init_distributed_environment,
    initialize_model_parallel,
    set_custom_all_reduce,
    set_mscclpp_all_reduce,
    set_torch_symm_mem_all_reduce,
)
from sglang.srt.distributed.device_communicators.pynccl_allocator import (
    use_symmetric_memory,
)
from sglang.srt.distributed.parallel_state import monkey_patch_vllm_parallel_state
from sglang.srt.elastic_ep.elastic_ep import ElasticEPStateManager
from sglang.srt.elastic_ep.expert_backup_client import ExpertBackupClient
from sglang.srt.environ import envs
from sglang.srt.eplb.eplb_manager import EPLBManager
from sglang.srt.eplb.expert_distribution import (
    ExpertDistributionMetrics,
    ExpertDistributionRecorder,
    get_global_expert_distribution_recorder,
    set_global_expert_distribution_recorder,
)
from sglang.srt.eplb.expert_location import (
    ExpertLocationMetadata,
    compute_initial_expert_location_metadata,
    get_global_expert_location_metadata,
    set_global_expert_location_metadata,
)
from sglang.srt.eplb.expert_location_updater import ExpertLocationUpdater
from sglang.srt.hardware_backend.npu.graph_runner.npu_graph_runner import NPUGraphRunner
from sglang.srt.layers import deep_gemm_wrapper
from sglang.srt.layers.attention.attention_registry import (
    ATTENTION_BACKENDS,
    attn_backend_wrapper,
)
from sglang.srt.layers.attention.nsa.utils import is_nsa_enable_prefill_cp
from sglang.srt.layers.attention.tbo_backend import TboAttnBackend
from sglang.srt.layers.dp_attention import (
    DpPaddingMode,
    get_attention_tp_group,
    get_attention_tp_size,
    initialize_dp_attention,
    set_dp_buffer_len,
    set_is_extend_in_batch,
)
from sglang.srt.layers.logits_processor import LogitsProcessorOutput
from sglang.srt.layers.moe.routed_experts_capturer import (
    RoutedExpertsCapturer,
    get_global_experts_capturer,
    set_global_experts_capturer,
)
from sglang.srt.layers.pooler import EmbeddingPoolerOutput
from sglang.srt.layers.quantization.fp8_kernel import fp8_dtype
from sglang.srt.layers.sampler import create_sampler
from sglang.srt.layers.torchao_utils import apply_torchao_config_to_model
from sglang.srt.lora.lora_manager import LoRAManager
from sglang.srt.lora.lora_registry import LoRARef
from sglang.srt.managers.schedule_batch import sanity_check_mm_pad_shift_value
from sglang.srt.mem_cache.allocator import BaseTokenToKVPoolAllocator
from sglang.srt.mem_cache.memory_pool import ReqToTokenPool
from sglang.srt.model_executor.cpu_graph_runner import CPUGraphRunner
from sglang.srt.model_executor.cuda_graph_runner import (
    CudaGraphRunner,
    DecodeInputBuffers,
    set_torch_compile_config,
)
from sglang.srt.model_executor.forward_batch_info import (
    CaptureHiddenMode,
    ForwardBatch,
    ForwardMode,
    PPProxyTensors,
)
from sglang.srt.model_executor.hook_manager import register_forward_hooks
from sglang.srt.model_executor.model_runner_kv_cache_mixin import (
    MemoryPoolConfig,
    ModelRunnerKVCacheMixin,
)
from sglang.srt.model_executor.piecewise_cuda_graph_runner import (
    PiecewiseCudaGraphRunner,
)
from sglang.srt.model_loader.loader import DefaultModelLoader, get_model_loader
from sglang.srt.model_loader.remote_instance_weight_loader_utils import (
    RemoteInstanceWeightLoaderBackend,
    register_memory_region,
    trigger_init_weights_send_group_for_remote_instance_request,
)
from sglang.srt.model_loader.utils import set_default_torch_dtype
from sglang.srt.model_loader.weight_utils import default_weight_loader
from sglang.srt.sampling.sampling_batch_info import SamplingBatchInfo
from sglang.srt.server_args import (
    ServerArgs,
    get_global_server_args,
    set_global_server_args_for_scheduler,
)
from sglang.srt.speculative.spec_info import SpeculativeAlgorithm
from sglang.srt.utils import (
    MultiprocessingSerializer,
    cpu_has_amx_support,
    dynamic_import,
    empty_context,
    enable_show_time_cost,
    get_available_gpu_memory,
    get_cpu_ids_by_node,
    init_custom_process_group,
    is_hip,
    is_host_cpu_arm64,
    is_npu,
    log_info_on_rank0,
    monkey_patch_p2p_access_check,
    require_attn_tp_gather,
    require_gathered_buffer,
    require_mlp_tp_gather,
    reserve_rope_cache_for_long_sequences,
    set_cuda_arch,
    slow_rank_detector,
)
from sglang.srt.utils.network import NetworkAddress, get_local_ip_auto
from sglang.srt.utils.nvtx_pytorch_hooks import PytHooks
from sglang.srt.utils.offloader import (
    create_offloader_from_server_args,
    get_offloader,
    set_offloader,
)
from sglang.srt.utils.patch_torch import (
    monkey_patch_torch_reductions,
    register_sgl_tp_rank,
)
from sglang.srt.utils.torch_memory_saver_adapter import TorchMemorySaverAdapter
from sglang.srt.utils.weight_checker import WeightChecker
from sglang.srt.weight_sync.tensor_bucket import (
    FlattenedTensorBucket,
    FlattenedTensorMetadata,
)

_is_hip = is_hip()
_is_npu = is_npu()
_is_cpu_amx_available = cpu_has_amx_support()
_is_cpu_arm64 = is_host_cpu_arm64()

if _is_npu:
    from sglang.srt.hardware_backend.npu.utils import init_npu_backend

    init_npu_backend()

MLA_ATTENTION_BACKENDS = [
    "aiter",
    "flashinfer",
    "fa3",
    "fa4",
    "triton",
    "flashmla",
    "cutlass_mla",
    "trtllm_mla",
    "ascend",
    "nsa",
]

CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS = [
    "flashinfer",
    "fa3",
    "fa4",
    "flashmla",
    "cutlass_mla",
    "trtllm_mla",
]

TORCH_DTYPE_TO_KV_CACHE_STR = {
    torch.float8_e4m3fn: "fp8_e4m3",
    torch.float8_e4m3fnuz: "fp8_e4m3",
    torch.float8_e5m2: "fp8_e5m2",
    torch.bfloat16: "bf16",
}


def add_mla_attention_backend(backend_name):
    if backend_name not in MLA_ATTENTION_BACKENDS:
        MLA_ATTENTION_BACKENDS.append(backend_name)
        logger.info(f"Added {backend_name} to MLA_ATTENTION_BACKENDS.")


def add_chunked_prefix_cache_attention_backend(backend_name):
    if backend_name not in CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS:
        CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS.append(backend_name)
        logger.info(
            f"Added {backend_name} to CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS."
        )


# Detect stragger ranks in model loading
UNBALANCED_MODEL_LOADING_TIMEOUT_S = 480  # leave more time for post data processing


logger = logging.getLogger(__name__)


def resolve_language_model(model: nn.Module) -> nn.Module:
    model_cls_name = model.__class__.__name__
    if model_cls_name == "Qwen3OmniMoeForConditionalGeneration":
        return model.thinker.model
    return model.model


class RankZeroFilter(logging.Filter):
    """Filter that only allows INFO level logs from rank 0, but allows all other levels from any rank."""

    def __init__(self, is_rank_zero):
        super().__init__()
        self.is_rank_zero = is_rank_zero

    def filter(self, record):
        if record.levelno == logging.INFO:
            return self.is_rank_zero
        return True


@dataclass
class ModelRunnerOutput:
    logits_output: Union[LogitsProcessorOutput, PPProxyTensors]
    can_run_graph: bool
    expert_distribution_metrics: Optional[ExpertDistributionMetrics] = None


class ModelRunner(ModelRunnerKVCacheMixin):
    """ModelRunner runs the forward passes of the models."""

    def __init__(
        self,
        model_config: ModelConfig,
        mem_fraction_static: float,
        gpu_id: int,
        tp_rank: int,
        tp_size: int,
        moe_ep_rank: int,
        moe_ep_size: int,
        pp_rank: int,
        pp_size: int,
        nccl_port: int,
        server_args: ServerArgs,
        dp_rank: Optional[int] = None,
        attn_cp_rank: Optional[int] = None,
        moe_dp_rank: Optional[int] = None,
        is_draft_worker: bool = False,
        req_to_token_pool: Optional[ReqToTokenPool] = None,
        token_to_kv_pool_allocator: Optional[BaseTokenToKVPoolAllocator] = None,
        memory_pool_config: Optional[MemoryPoolConfig] = None,
        draft_model_idx: Optional[int] = None,
    ):
        # Parse args
        self.mem_fraction_static = mem_fraction_static
        self.device = server_args.device
        self.gpu_id = gpu_id
        self.tp_rank = tp_rank
        self.tp_size = tp_size
        self.moe_ep_rank = moe_ep_rank
        self.moe_ep_size = moe_ep_size
        self.dp_size = server_args.dp_size if server_args.enable_dp_attention else 1
        self.pp_rank = pp_rank
        self.pp_size = pp_size
        self.attn_cp_rank = attn_cp_rank
        self.attn_cp_size = server_args.attn_cp_size
        self.moe_dp_rank = moe_dp_rank
        self.moe_dp_size = server_args.moe_dp_size
        self.model_config = model_config
        self.dist_port = nccl_port
        self.server_args = server_args
        self.is_draft_worker = is_draft_worker
        self.memory_pool_config = memory_pool_config
        self.is_generation = model_config.is_generation
        self.is_multimodal = model_config.is_multimodal
        self.is_multimodal_chunked_prefill_supported = (
            model_config.is_multimodal_chunked_prefill_supported
        )
        self.spec_algorithm = SpeculativeAlgorithm.from_string(
            server_args.speculative_algorithm
        )
        self.page_size = server_args.page_size
        self.req_to_token_pool = req_to_token_pool
        self.token_to_kv_pool_allocator = token_to_kv_pool_allocator
        self.is_hybrid_swa = model_config.is_hybrid_swa
        self.is_hybrid_swa_compress = model_config.is_hybrid_swa_compress
        self.use_mla_backend = self.model_config.attention_arch == AttentionArch.MLA
        self.attention_chunk_size = model_config.attention_chunk_size
        self.forward_pass_id = 0
        self.init_new_workspace = False
        self.draft_model_idx = draft_model_idx
        self.enable_hisparse = server_args.enable_hisparse

        self.remote_instance_transfer_engine = None
        self.remote_instance_transfer_engine_session_id = ""
        self.remote_instance_transfer_engine_weight_info = None
        # auxiliary hidden capture mode. TODO: expose this to server args?
        self.eagle_use_aux_hidden_state = False
        if self.spec_algorithm.is_eagle3() and not self.is_draft_worker:
            # load draft config
            draft_model_config = ModelConfig.from_server_args(
                server_args,
                model_path=(server_args.speculative_draft_model_path),
                model_revision=server_args.speculative_draft_model_revision,
                is_draft_model=True,
            )
            self.eagle_use_aux_hidden_state = True

            try:
                # get the aux layer from draft model config
                eagle_config = getattr(
                    draft_model_config.hf_config, "eagle_config", None
                )
                self.eagle_use_aux_hidden_state = eagle_config.get(
                    "use_aux_hidden_state", True
                )
                self.eagle_aux_hidden_state_layer_ids = eagle_config[
                    "eagle_aux_hidden_state_layer_ids"
                ]
            except:
                # if there is no aux layer, set to None
                self.eagle_aux_hidden_state_layer_ids = None

        # Apply the rank zero filter to logger
        if server_args.show_time_cost:
            enable_show_time_cost()

        # Model-specific adjustment
        self.model_specific_adjustment()

        # Set the global server_args in the scheduler process
        set_global_server_args_for_scheduler(server_args)
        global_server_args = get_global_server_args()

        # FIXME: hacky set `use_mla_backend`
        global_server_args.use_mla_backend = self.use_mla_backend

        # Init OpenMP threads binding for CPU
        if self.device == "cpu":
            self.init_threads_binding()

        # Initialize MooncakeTransferEngine
        self.init_shared_mooncake_transfer_engine()

        # Get available memory before model loading
        pre_model_load_memory = self.init_torch_distributed()

        # Init forward stream for overlap schedule
        self.forward_stream = torch.get_device_module(self.device).Stream()

        # CPU offload
        set_offloader(create_offloader_from_server_args(server_args, dp_rank=dp_rank))

        self._weight_checker = WeightChecker(model_runner=self)

        if envs.SGLANG_DETECT_SLOW_RANK.get():
            slow_rank_detector.execute()

        # Init mindspore running environment when model impl is "mindspore"
        self.init_mindspore_runner()

        # Update deep gemm configure
        if deep_gemm_wrapper.ENABLE_JIT_DEEPGEMM:
            deep_gemm_wrapper.update_deep_gemm_config(gpu_id, server_args)

        # For hisparse (must be set before initialize() so CUDA graph capture can see it)
        self.hisparse_coordinator = None

        # Initialize the model runner
        self.initialize(pre_model_load_memory)
        self.check_quantized_moe_compatibility()

        if self.is_multimodal:
            sanity_check_mm_pad_shift_value(self.model_config.vocab_size)

        # Temporary cached values
        self.support_pp = (
            "pp_proxy_tensors" in inspect.signature(self.model.forward).parameters
        )

        if self.pp_size > 1:
            assert (
                self.support_pp
            ), "Pipeline Parallel is not compatible with this model."

        # For weight updates
        self._model_update_group = {}
        self._weights_send_group = {}

    def init_mindspore_runner(self):
        # Init the mindspore runner
        # for now, there is only some communication initialization work
        if self.server_args.model_impl.lower() == ModelImpl.MINDSPORE and _is_npu:
            from sglang.srt.model_executor.mindspore_runner import init_ms_distributed

            init_ms_distributed(
                world_size=self.tp_size * self.pp_size,
                rank=self.tp_size * self.pp_rank + self.tp_rank,
                local_rank=self.gpu_id,
                server_args=self.server_args,
                port=self.dist_port,
            )

    def initialize(self, pre_model_load_memory: float):
        server_args = self.server_args

        self.memory_saver_adapter = TorchMemorySaverAdapter.create(
            enable=self.server_args.enable_memory_saver
        )

        if self.server_args.remote_instance_weight_loader_use_transfer_engine():
            self.remote_instance_init_transfer_engine()

        if not self.is_draft_worker:
            set_global_expert_location_metadata(
                compute_initial_expert_location_metadata(
                    server_args=server_args,
                    model_config=self.model_config,
                    moe_ep_rank=self.moe_ep_rank,
                )
            )
            if self.tp_rank == 0 and envs.SGLANG_LOG_EXPERT_LOCATION_METADATA.get():
                logger.info(
                    f"Initial expert_location_metadata: {get_global_expert_location_metadata()}"
                )

            set_global_expert_distribution_recorder(
                ExpertDistributionRecorder.init_new(
                    server_args,
                    get_global_expert_location_metadata(),
                    rank=self.tp_rank,
                )
            )

        # Expert parallelism
        self.eplb_manager = (
            EPLBManager(self)
            if self.server_args.enable_eplb and (not self.is_draft_worker)
            else None
        )
        self.expert_location_updater = ExpertLocationUpdater()

        (
            ElasticEPStateManager.init(self.server_args)
            if self.server_args.elastic_ep_backend
            else None
        )
        # Load the model
        self.sampler = create_sampler()
        self.load_model()

        # Load the expert backup client
        self.expert_backup_client = (
            ExpertBackupClient(self.server_args, self)
            if (
                self.server_args.enable_elastic_expert_backup
                and self.server_args.elastic_ep_backend is not None
            )
            else None
        )

        if (
            self.server_args.remote_instance_weight_loader_use_transfer_engine()
            and self.remote_instance_transfer_engine is not None
            and self.remote_instance_transfer_engine_weight_info is None
        ):
            self.remote_instance_transfer_engine_weight_info = register_memory_region(
                self.model, self.remote_instance_transfer_engine
            )

        # For MTP models like DeepSeek-V3 or GLM-4.5, the MTP layer(s) are used separately as draft
        # models for speculative decoding. In those cases, `num_nextn_predict_layers` is used to
        # determine the number of layers.
        model_has_mtp_layers = self.model_config.num_nextn_predict_layers is not None
        model_num_layers = (
            self.model_config.num_nextn_predict_layers
            if self.is_draft_worker and model_has_mtp_layers
            else max(
                self.model_config.num_hidden_layers,
                self.model_config.num_attention_layers,
            )
        )
        if self.model_config.hf_config.architectures[0] == "MiMoV2MTP":
            model_num_layers = 1
        elif self.model_config.hf_config.architectures[0] == "Step3p5MTP":
            model_num_layers = 1
        self.start_layer = getattr(self.model, "start_layer", 0)
        self.end_layer = getattr(self.model, "end_layer", model_num_layers)
        self.num_effective_layers = self.end_layer - self.start_layer

        # For LoopCoder models, each loop has its own layer_id, so we need to multiply by loop_num
        loop_num = getattr(self.model_config.hf_config, "loop_num", 1)
        if loop_num > 1:
            self.num_effective_layers = self.num_effective_layers * loop_num

        assert (
            (not model_has_mtp_layers)
            or (self.spec_algorithm.is_none())
            or (
                (not self.spec_algorithm.is_none())
                and (self.num_effective_layers == model_num_layers)
            )
        ), "PP is not compatible with MTP models."

        # Consider PP, so use start_layer and end_layer.
        full_attention_layer_ids = [
            layer_idx
            for layer_idx in range(self.start_layer, self.end_layer + 1)
            if hasattr(self.model_config, "full_attention_layer_ids")
            and layer_idx in self.model_config.full_attention_layer_ids
        ]
        swa_attention_layer_ids = [
            layer_idx
            for layer_idx in range(self.start_layer, self.end_layer + 1)
            if hasattr(self.model_config, "swa_attention_layer_ids")
            and layer_idx in self.model_config.swa_attention_layer_ids
        ]
        # Update back to model_config.
        self.model_config.swa_attention_layer_ids = swa_attention_layer_ids
        self.model_config.full_attention_layer_ids = full_attention_layer_ids

        # Apply torchao quantization
        torchao_applied = getattr(self.model, "torchao_applied", False)
        # In layered loading, torchao may have been applied
        if not torchao_applied:
            apply_torchao_config_to_model(
                self.model, get_global_server_args().torchao_config
            )

        # Apply torch TP if the model supports it
        supports_torch_tp = getattr(self.model, "supports_torch_tp", False)
        if self.tp_size > 1 and supports_torch_tp:
            self.apply_torch_tp()

        # Init lora
        if server_args.enable_lora:
            self.init_lora_manager()

        # Init Double Sparsity
        if server_args.enable_double_sparsity:
            if server_args.ds_heavy_channel_type is None:
                raise ValueError(
                    "Please specify the heavy channel type for double sparsity optimization."
                )
            self.init_double_sparsity_channel_config(server_args.ds_heavy_channel_type)

        # Enable batch invariant mode
        if server_args.enable_deterministic_inference:
            from sglang.srt.batch_invariant_ops import enable_batch_invariant_mode

            enable_batch_invariant_mode()

        # Deduce KV cache dtype
        self.configure_kv_cache_dtype()

        # Init memory pool and attention backends
        self.init_memory_pool(pre_model_load_memory)

        # Init ngram embedding token table
        self.maybe_init_ngram_embedding()

        # Init hisparse coordinator (must happen before CUDA graph capture)
        if self.enable_hisparse:
            from sglang.srt.managers.hisparse_coordinator import HiSparseCoordinator
            from sglang.srt.mem_cache.sparsity import parse_hisparse_config

            hisparse_cfg = parse_hisparse_config(self.server_args)
            self.hisparse_coordinator = HiSparseCoordinator(
                req_to_token_pool=self.req_to_token_pool,
                token_to_kv_pool_allocator=self.token_to_kv_pool_allocator,
                top_k=hisparse_cfg.top_k,
                device_buffer_size=hisparse_cfg.device_buffer_size,
                device=self.device,
                tp_group=(
                    self.attention_tp_group.cpu_group
                    if self.server_args.enable_dp_attention
                    else self.tp_group.cpu_group
                ),
                host_to_device_ratio=hisparse_cfg.host_to_device_ratio,
            )

        # Init routed experts capturer
        self.init_routed_experts_capturer()

        if self.device == "cuda" or self.device == "musa":
            self.init_cublas()
            self.init_attention_backend()
            self.kernel_warmup()
            self.init_device_graphs()
        elif self.device in ["npu", "cpu"]:
            self.init_attention_backend()
            self.init_device_graphs()
        else:
            self.graph_runner = None
            self.graph_mem_usage = 0
            self.init_attention_backend()

        if server_args.forward_hooks:
            register_forward_hooks(self.model, server_args.forward_hooks)

        if self.eagle_use_aux_hidden_state:
            self.model.set_eagle3_layers_to_capture(
                self.eagle_aux_hidden_state_layer_ids
            )

        # Initialize piecewise CUDA graph
        self.init_piecewise_cuda_graphs()

        self.prealloc_symmetric_memory_pool()

    def init_routed_experts_capturer(self):
        if not self.server_args.disable_shared_experts_fusion and hasattr(
            self.model, "num_fused_shared_experts"
        ):
            num_fused_shared_experts = self.model.num_fused_shared_experts
        else:
            num_fused_shared_experts = 0

        set_global_experts_capturer(
            RoutedExpertsCapturer.create(
                enable=get_global_server_args().enable_return_routed_experts,
                model_config=self.model_config,
                num_fused_shared_experts=num_fused_shared_experts,
                num_tokens=self.max_total_num_tokens + self.page_size,
                max_running_requests=self.max_running_requests,
                device=self.device,
            )
        )

    def remote_instance_init_transfer_engine(self):
        try:
            from mooncake.engine import TransferEngine
        except ImportError as e:
            logger.warning(
                "Please install mooncake for using remote instance transfer engine: pip install mooncake"
            )
            return
        self.remote_instance_transfer_engine = TransferEngine()
        local_ip = get_local_ip_auto()
        self.remote_instance_transfer_engine.initialize(
            local_ip, "P2PHANDSHAKE", "rdma", envs.MOONCAKE_DEVICE.get()
        )
        self.remote_instance_transfer_engine_session_id = NetworkAddress(
            local_ip, self.remote_instance_transfer_engine.get_rpc_port()
        ).to_host_port_str()

    def _publish_modelexpress_metadata(self):
        """Publish TransferEngine metadata to ModelExpress server (seed mode)."""
        try:
            from modelexpress import p2p_pb2
            from modelexpress.client import MxClient
        except ImportError as exc:
            raise ImportError(
                "ModelExpress support requires the 'modelexpress' package. "
                "Install it with: pip install modelexpress"
            ) from exc

        model_name = (
            self.server_args.modelexpress_model_name or self.server_args.model_path
        )
        mx_url = self.server_args.modelexpress_url
        session_id = self.remote_instance_transfer_engine_session_id
        weight_info = self.remote_instance_transfer_engine_weight_info

        if not session_id or weight_info is None:
            logger.warning(
                "ModelExpress source: skipping publish -- "
                "TransferEngine not initialized or no weight info"
            )
            return

        # Build tensor descriptors from weight_info dict
        tensors = []
        for name, (addr, numel, element_size) in weight_info.items():
            tensors.append(
                p2p_pb2.TensorDescriptor(
                    name=name,
                    addr=addr,
                    size=numel * element_size,
                    device_id=self.gpu_id,
                )
            )

        worker = p2p_pb2.WorkerMetadata(
            worker_rank=self.tp_rank,
            transfer_engine_session_id=session_id,
            tensors=tensors,
        )

        mx_client = MxClient(server_url=mx_url)
        try:
            logger.info(
                "ModelExpress source: publishing metadata for model=%s, "
                "tp_rank=%d, session=%s, %d tensors",
                model_name,
                self.tp_rank,
                session_id,
                len(tensors),
            )
            mx_client.publish_metadata(model_name, [worker])
            mx_client.publish_ready(
                model_name,
                worker_id=self.tp_rank,
                session_id=mx_client.session_id,
                metadata_hash="",
            )
            logger.info(
                "ModelExpress source: published ready for model=%s, tp_rank=%d",
                model_name,
                self.tp_rank,
            )
        finally:
            mx_client.close()

    def model_specific_adjustment(self):
        server_args = self.server_args

        if server_args.enable_double_sparsity:
            logger.info(
                "Double sparsity optimization is turned on. Use triton backend without CUDA graph."
            )
            server_args.attention_backend = "triton"
            server_args.disable_cuda_graph = True

        if self.is_multimodal:
            if not self.is_multimodal_chunked_prefill_supported:
                server_args.chunked_prefill_size = -1
                logger.info(
                    f"Automatically turn off --chunked-prefill-size as it is not supported for "
                    f"{self.model_config.hf_config.model_type}"
                )

        if (
            not self.use_mla_backend
            or server_args.attention_backend
            not in CHUNKED_PREFIX_CACHE_SUPPORTED_ATTENTION_BACKENDS
        ):
            server_args.disable_chunked_prefix_cache = True

        if not server_args.disable_chunked_prefix_cache:
            log_info_on_rank0(logger, "Chunked prefix cache is turned on.")

    def check_quantized_moe_compatibility(self):
        if (
            quantization_config := getattr(
                self.model_config.hf_config, "quantization_config", None
            )
        ) is not None and (
            weight_block_size := quantization_config.get("weight_block_size", None)
        ) is not None:
            weight_block_size_n = weight_block_size[0]

            if self.tp_size % self.moe_ep_size != 0:
                raise ValueError(
                    f"tp_size {self.tp_size} must be divisible by ep_size {self.moe_ep_size}"
                )
            moe_tp_size = self.tp_size // self.moe_ep_size // self.moe_dp_size

            moe_intermediate_size = getattr(
                self.model_config.hf_text_config, "moe_intermediate_size", None
            )
            if moe_intermediate_size is None:
                return

            if moe_intermediate_size % moe_tp_size != 0:
                raise ValueError(
                    f"moe_intermediate_size {moe_intermediate_size} must be divisible by moe_tp_size ({moe_tp_size}) which is tp_size ({self.tp_size}) divided by moe_ep_size ({self.moe_ep_size})."
                )

            if (moe_intermediate_size // moe_tp_size) % weight_block_size_n != 0:
                raise ValueError(
                    f"For quantized MoE models, please make sure ({moe_intermediate_size=} / {moe_tp_size=}) % {weight_block_size_n=} == 0 "
                    f"where moe_tp_size is equal to tp_size ({self.tp_size}) divided by ep_size ({self.moe_ep_size}). "
                    f"You can fix this by setting arguments `--tp` and `--ep` correctly."
                )

    def init_torch_distributed(self):
        tic = time.perf_counter()
        logger.info("Init torch distributed begin.")

        try:
            torch.get_device_module(self.device).set_device(self.gpu_id)
        except Exception:
            logger.warning(
                f"Context: {self.device=} {self.gpu_id=} {os.environ.get('CUDA_VISIBLE_DEVICES')=} {self.tp_rank=} {self.tp_size=}"
            )
            raise

        backend = get_default_distributed_backend(self.device)
        if self.device == "cuda" and self.server_args.elastic_ep_backend == "mooncake":
            backend = "mooncake"
            if self.server_args.mooncake_ib_device:
                mooncake_ib_device = self.server_args.mooncake_ib_device.split(",")
                try:
                    from mooncake import ep as mooncake_ep

                    mooncake_ep.set_device_filter(mooncake_ib_device)
                except:
                    pass  # A warning will be raised in `init_distributed_environment`

        before_avail_memory = get_available_gpu_memory(self.device, self.gpu_id)
        if not self.server_args.enable_p2p_check:
            monkey_patch_p2p_access_check()

        # Allow external orchestrators (e.g. trainpi) to override the distributed
        # init method.  When set to "env://", torch uses MASTER_ADDR/MASTER_PORT
        # env-vars and an externally-created TCPStore, completely avoiding port
        # conflicts with intra-host collocation.
        dist_init_method_override = envs.SGLANG_DISTRIBUTED_INIT_METHOD_OVERRIDE.get()
        if dist_init_method_override:
            dist_init_method = dist_init_method_override
        elif self.server_args.dist_init_addr:
            na = NetworkAddress.parse(self.server_args.dist_init_addr)
            dist_init_method = na.to_tcp()
        else:
            dist_init_method = NetworkAddress(
                self.server_args.host or "127.0.0.1", self.dist_port
            ).to_tcp()
        set_custom_all_reduce(not self.server_args.disable_custom_all_reduce)
        set_mscclpp_all_reduce(self.server_args.enable_mscclpp)
        set_torch_symm_mem_all_reduce(self.server_args.enable_torch_symm_mem)

        if not self.is_draft_worker:
            if self.device == "cpu":
                if _is_cpu_amx_available or _is_cpu_arm64:
                    # Bind OpenMP threads to CPU cores
                    torch.ops.sgl_kernel.init_cpu_threads_env(self.local_omp_cpuid)

                    # Set local size to hint SGLang to use shared memory based AllReduce
                    os.environ["LOCAL_SIZE"] = str(self.tp_size)
                    torch.ops.sgl_kernel.initialize(self.tp_size, self.tp_rank)

                    @torch.library.register_fake("sgl_kernel::shm_allgather")
                    def _(data, dim):
                        return torch.cat([data] * self.tp_size, dim=dim)

                else:
                    logger.warning(
                        "init_cpu_threads_env and shared memory based AllReduce is disabled, only intel amx backend and arm64 are supported"
                    )

            # Only initialize the distributed environment on the target model worker.
            init_distributed_environment(
                backend=backend,
                world_size=self.tp_size * self.pp_size,
                rank=self.tp_size * self.pp_rank + self.tp_rank,
                local_rank=self.gpu_id,
                distributed_init_method=dist_init_method,
                timeout=self.server_args.dist_timeout,
                moe_a2a_backend=self.server_args.moe_a2a_backend,
            )
            initialize_model_parallel(
                tensor_model_parallel_size=self.tp_size,
                attention_data_parallel_size=self.dp_size,
                pipeline_model_parallel_size=self.pp_size,
                expert_model_parallel_size=self.moe_ep_size,
                attention_context_model_parallel_size=self.attn_cp_size,
                moe_data_model_parallel_size=self.moe_dp_size,
                duplicate_tp_group=self.server_args.enable_pdmux,
            )
            initialize_dp_attention(
                server_args=self.server_args,
                model_config=self.model_config,
            )
            if is_npu():
                register_sgl_tp_rank(self.gpu_id)

            # Pre-warm NCCL/RCCL to eliminate cold-start latency in first request
            # Controlled by --pre-warm-nccl flag (default: enabled on AMD GPUs)
            if self.server_args.pre_warm_nccl and (
                self.tp_size > 1 or self.pp_size > 1 or self.moe_ep_size > 1
            ):
                warmup_start = time.perf_counter()
                tp_group_handle = get_tp_group().device_group

                # Single warmup all_reduce to initialize NCCL/RCCL communicator
                warmup_tensor = torch.zeros(1, device=torch.cuda.current_device())
                dist.all_reduce(warmup_tensor, group=tp_group_handle)
                torch.cuda.synchronize()

                warmup_elapsed = time.perf_counter() - warmup_start
                logger.info(
                    f"NCCL/RCCL warmup completed in {warmup_elapsed:.3f}s "
                    f"(tp_size={self.tp_size}, pp_size={self.pp_size}, ep_size={self.moe_ep_size})"
                )

        pre_model_load_memory = get_available_gpu_memory(
            self.device,
            self.gpu_id,
            distributed=get_world_group().world_size > 1,
            cpu_group=get_world_group().cpu_group,
        )
        self.tp_group = get_tp_group()
        self.pp_group = get_pp_group()
        self.attention_tp_group = get_attention_tp_group()

        # Check memory for tensor parallelism
        local_gpu_memory = get_available_gpu_memory(self.device, self.gpu_id)
        if self.tp_size > 1 and not self.is_draft_worker:
            if pre_model_load_memory < local_gpu_memory * 0.9:
                msg = "The memory capacity is unbalanced. Some GPUs may be occupied by other processes. "
                msg += f"{pre_model_load_memory=}, {local_gpu_memory=}, {local_gpu_memory * 0.9=}"
                if envs.SGLANG_ENABLE_TP_MEMORY_INBALANCE_CHECK.get():
                    raise RuntimeError(msg)
                else:
                    logger.warning(msg)

        logger.info(
            f"Init torch distributed ends. elapsed={time.perf_counter() - tic:.2f} s, "
            f"mem usage={(before_avail_memory - local_gpu_memory):.2f} GB"
        )
        return pre_model_load_memory

    def init_shared_mooncake_transfer_engine(self):
        """
        Need MooncakeTransferEngine when:
        1) PD disaggregation uses mooncake for KV transfer (prefill/decode)
        2) HiCache uses mooncake storage backend
        3) Encoder disaggregation uses mooncake
        """
        use_mooncake_te = (
            (
                self.server_args.disaggregation_mode != "null"
                and self.server_args.disaggregation_transfer_backend == "mooncake"
            )
            or (
                self.server_args.enable_hierarchical_cache
                and self.server_args.hicache_storage_backend == "mooncake"
                and envs.SGLANG_HICACHE_MOONCAKE_REUSE_TE.get()
            )
            or (
                self.server_args.encoder_only
                and self.server_args.encoder_transfer_backend == "mooncake"
            )
            or (
                self.server_args.language_only
                and self.server_args.encoder_transfer_backend == "mooncake"
            )
            or (
                self.server_args.enable_elastic_expert_backup
                and self.server_args.elastic_ep_backend is not None
            )
        )

        if use_mooncake_te:
            from sglang.srt.distributed.device_communicators.mooncake_transfer_engine import (
                init_mooncake_transfer_engine,
            )

            init_mooncake_transfer_engine(
                hostname=get_local_ip_auto(),
                gpu_id=self.gpu_id,
                ib_device=(
                    self.server_args.disaggregation_ib_device
                    or self.server_args.mooncake_ib_device
                ),
            )

    def load_model(self):
        tic_total = time.perf_counter()
        before_avail_memory = get_available_gpu_memory(self.device, self.gpu_id)
        logger.info(
            f"Load weight begin. avail mem={get_available_gpu_memory(self.device, self.gpu_id):.2f} GB"
        )

        # This can reduce thread conflicts and speed up weight loading.
        if self.device != "cpu":
            torch.set_num_threads(1)
        if self.device == "cuda":
            if torch.cuda.get_device_capability()[0] < 8:
                logger.info(
                    "Compute capability below sm80. Use float16 due to lack of bfloat16 support."
                )
                self.server_args.dtype = "float16"
                self.model_config.dtype = torch.float16
                if torch.cuda.get_device_capability()[1] < 5:
                    raise RuntimeError("SGLang only supports sm75 and above.")

        set_cuda_arch()

        # Prepare the model config
        from sglang.srt.configs.modelopt_config import ModelOptConfig

        modelopt_config = ModelOptConfig(
            quant=self.server_args.modelopt_quant,
            checkpoint_restore_path=self.server_args.modelopt_checkpoint_restore_path,
            checkpoint_save_path=self.server_args.modelopt_checkpoint_save_path,
            export_path=self.server_args.modelopt_export_path,
            quantize_and_serve=self.server_args.quantize_and_serve,
        )

        self.load_config = LoadConfig(
            load_format=self.server_args.load_format,
            download_dir=self.server_args.download_dir,
            model_loader_extra_config=self.server_args.model_loader_extra_config,
            tp_rank=self.tp_rank,
            remote_instance_weight_loader_seed_instance_ip=self.server_args.remote_instance_weight_loader_seed_instance_ip,
            remote_instance_weight_loader_seed_instance_service_port=self.server_args.remote_instance_weight_loader_seed_instance_service_port,
            remote_instance_weight_loader_send_weights_group_ports=self.server_args.remote_instance_weight_loader_send_weights_group_ports,
            remote_instance_weight_loader_backend=self.server_args.remote_instance_weight_loader_backend,
            remote_instance_weight_loader_transfer_engine=self.remote_instance_transfer_engine,
            modelexpress_url=self.server_args.modelexpress_url,
            modelexpress_model_name=self.server_args.modelexpress_model_name
            or self.server_args.model_path,
            modelopt_config=modelopt_config,
            rl_quant_profile=self.server_args.rl_quant_profile,
            draft_model_idx=self.draft_model_idx,
        )
        if self.device == "cpu":
            self.model_config = adjust_config_with_unaligned_cpu_tp(
                self.model_config, self.load_config, self.tp_size
            )

        if (
            self.server_args.load_format == LoadFormat.REMOTE_INSTANCE
            and self.server_args.remote_instance_weight_loader_backend
            == RemoteInstanceWeightLoaderBackend.NCCL
        ):
            if self.tp_rank == 0:
                instance_ip = NetworkAddress.resolve_host(socket.gethostname())
                t = threading.Thread(
                    target=trigger_init_weights_send_group_for_remote_instance_request,
                    args=(
                        self.server_args.remote_instance_weight_loader_seed_instance_ip,
                        self.server_args.remote_instance_weight_loader_seed_instance_service_port,
                        self.server_args.remote_instance_weight_loader_send_weights_group_ports,
                        instance_ip,
                    ),
                )
                t.start()

        # Load the model
        # Remove monkey_patch when linear.py quant remove dependencies with vllm
        monkey_patch_vllm_parallel_state()

        enable_cpu_backup = self.server_args.enable_weights_cpu_backup or (
            self.is_draft_worker and self.server_args.enable_draft_weights_cpu_backup
        )
        with self.memory_saver_adapter.region(
            GPU_MEMORY_TYPE_WEIGHTS,
            enable_cpu_backup=enable_cpu_backup,
        ):
            self.loader = get_model_loader(
                load_config=self.load_config,
                model_config=self.model_config,
            )
            self.model = self.loader.load_model(
                model_config=self.model_config,
                device_config=DeviceConfig(self.device, self.gpu_id),
            )
            if hasattr(self.loader, "remote_instance_transfer_engine_weight_info"):
                self.remote_instance_transfer_engine_weight_info = (
                    self.loader.remote_instance_transfer_engine_weight_info
                )
        monkey_patch_vllm_parallel_state(reverse=True)

        # Publish metadata to ModelExpress if running as seed source
        if self.server_args.modelexpress_source:
            # Seed loads via DefaultModelLoader (load_format=auto), which doesn't
            # call register_memory_region(). Do it here so weight_info is populated.
            if (
                self.remote_instance_transfer_engine_weight_info is None
                and self.remote_instance_transfer_engine is not None
            ):
                from sglang.srt.model_loader.remote_instance_weight_loader_utils import (
                    register_memory_region,
                )

                self.remote_instance_transfer_engine_weight_info = (
                    register_memory_region(
                        self.model, self.remote_instance_transfer_engine
                    )
                )
            self._publish_modelexpress_metadata()

        get_offloader().post_init()

        # Register model for layerwise NVTX profiling if enabled
        if self.server_args.enable_layerwise_nvtx_marker:
            self.pyt_hooks = PytHooks()
            self.pyt_hooks.register_hooks(self.model, module_prefix="model")

        if self.server_args.kv_cache_dtype == "fp8_e4m3":
            if self.server_args.quantization_param_path is not None:
                if callable(getattr(self.model, "load_kv_cache_scales", None)):
                    self.model.load_kv_cache_scales(
                        self.server_args.quantization_param_path
                    )
                    logger.info(
                        "Loaded KV cache scaling factors from %s",
                        self.server_args.quantization_param_path,
                    )
                else:
                    raise RuntimeError(
                        "Using FP8 KV cache and scaling factors provided but "
                        "model %s does not support loading scaling factors.",
                        self.model.__class__,
                    )
            else:
                logger.warning(
                    "Using FP8 KV cache but no scaling factors "
                    "provided. Defaulting to scaling factors of 1.0. "
                    "This may lead to less accurate results!"
                )

        # Parse other args
        self.sliding_window_size = None
        if hasattr(self.model, "get_attention_sliding_window_size"):
            self.sliding_window_size = self.model.get_attention_sliding_window_size()
        elif (
            self.model_config.is_hybrid_swa
            and self.model_config.sliding_window_size is not None
        ):
            # sliding window field in model config may have different meaning for different kinds of models (e.g., dllm), here we only consider the sliding window in SWA model
            self.sliding_window_size = self.model_config.sliding_window_size
        elif self.model_config.attention_chunk_size is not None:
            self.sliding_window_size = self.model_config.attention_chunk_size
            logger.info(
                f"Setting sliding_window_size to be attention_chunk_size: {self.sliding_window_size}"
            )

        self.dtype = self.model_config.dtype

        after_avail_memory = get_available_gpu_memory(self.device, self.gpu_id)
        self.weight_load_mem_usage = before_avail_memory - after_avail_memory
        # Get quantization config from ModelConfig
        # This handles both config.json (standard) and hf_quant_config.json (ModelOpt)
        quant_str = self.model_config.get_quantization_config_log_str()

        logger.info(
            f"Load weight end. "
            f"elapsed={time.perf_counter() - tic_total:.2f} s, "
            f"type={type(self.model).__name__}, "
            f"{quant_str + ', ' if quant_str else ''}"
            f"avail mem={after_avail_memory:.2f} GB, "
            f"mem usage={self.weight_load_mem_usage:.2f} GB."
        )
        if self.server_args.debug_tensor_dump_output_folder is not None:
            register_forward_hook_for_model(
                self.model,
                self.server_args.debug_tensor_dump_output_folder,
                self.server_args.debug_tensor_dump_layers,
                self.tp_size,
                self.tp_rank,
                self.pp_rank,
            )

        if dumper.may_enable:
            dumper.apply_source_patches()
            dumper.register_non_intrusive_dumper(self.model)

        # Pre-expand RoPE cache before CUDA Graph capture
        reserve_rope_cache_for_long_sequences(
            self.model,
            self.server_args,
            self.model_config,
            logger,
        )

        if self.server_args.elastic_ep_backend == "mooncake":
            # Mooncake does not support `monitored_barrier`
            dist.barrier(group=get_tp_group().cpu_group)
        else:
            # Handle the case where some ranks do not finish loading.
            try:
                dist.monitored_barrier(
                    group=get_tp_group().cpu_group,
                    timeout=datetime.timedelta(
                        seconds=UNBALANCED_MODEL_LOADING_TIMEOUT_S
                    ),
                    wait_all_ranks=True,
                )
            except RuntimeError:
                raise ValueError(
                    f"TP rank {self.tp_rank} could finish the model loading, but there are other ranks that didn't finish loading. It is likely due to unexpected failures (e.g., OOM) or a slow node."
                ) from None

    def update_expert_location(
        self,
        new_expert_location_metadata: ExpertLocationMetadata,
        update_layer_ids: List[int],
    ):
        p2p_missing_logical_experts = self.expert_location_updater.update(
            self.model.routed_experts_weights_of_layer,
            new_expert_location_metadata,
            update_layer_ids=update_layer_ids,
            nnodes=self.server_args.nnodes,
            rank=self.tp_rank,
        )

        if len(p2p_missing_logical_experts) > 0:
            # Load the missing expert weights from disk
            if callable(getattr(self.model, "generate_weight_name_filter", None)):
                # Filter and load only missing expert weights
                weight_name_filter = self.model.generate_weight_name_filter(
                    p2p_missing_logical_experts
                )
            else:
                # Do a full reload from disk/DRAM
                logger.info(
                    "[Elastic EP] Model does not implement generate_weight_name_filter. "
                    "Performing full weight reload."
                )
                weight_name_filter = None

            if (
                self.expert_backup_client is not None
                and self.expert_backup_client.use_backup
            ):
                # Load the missing weights from the DRAM backup
                self.expert_backup_client.update_weights(weight_name_filter)
            else:
                # Load the missing weights from disk
                self.update_weights_from_disk(
                    get_global_server_args().model_path,
                    get_global_server_args().load_format,
                    weight_name_filter=weight_name_filter,
                )

    def update_weights_from_disk(
        self,
        model_path: str,
        load_format: str,
        weight_name_filter: Optional[Callable[[str], bool]] = None,
        recapture_cuda_graph: bool = False,
    ) -> tuple[bool, str]:
        """Update engine weights in-place from the disk."""
        logger.info(
            f"Update engine weights online from disk begin. "
            f"avail mem={get_available_gpu_memory(self.device, self.gpu_id, empty_cache=False):.2f} GB"
        )

        target_device = torch.device(self.device)
        self.model_config.model_path = model_path
        load_config = LoadConfig(load_format=load_format)

        # Only support DefaultModelLoader for now
        loader = get_model_loader(load_config, self.model_config)
        if not isinstance(loader, DefaultModelLoader):
            message = f"Failed to get model loader: {loader}."
            return False, message

        def get_weight_iter(config):
            iter = loader._get_weights_iterator(
                DefaultModelLoader.Source.init_new(config, self.model)
            )
            if weight_name_filter is not None:
                iter = (
                    (name, weight) for name, weight in iter if weight_name_filter(name)
                )

            return iter

        def model_load_weights(model, iter):
            loader.load_weights_and_postprocess(model, iter, target_device)
            return model

        with set_default_torch_dtype(self.model_config.dtype):
            try:
                iter = get_weight_iter(self.model_config)
            except Exception as e:
                message = f"Failed to get weights iterator: {e}."
                return False, message
            try:
                model = model_load_weights(self.model, iter)
            except Exception as e:
                message = (
                    f"Failed to update weights: {e}.\nRolling back to original weights."
                )
                del iter
                gc.collect()
                iter = get_weight_iter(self.model_config)
                self.model = model_load_weights(self.model, iter)
                return False, message

        self.model = model
        self.server_args.model_path = model_path
        self.server_args.load_format = load_format
        self.load_config = load_config

        if recapture_cuda_graph and (self.device == "cuda" or self.device == "musa"):
            self.init_device_graphs()

        logger.info("Update weights end.")
        return True, "Succeeded to update model weights."

    def init_weights_send_group_for_remote_instance(
        self,
        master_address,
        ports,
        group_rank,
        world_size,
        group_name,
        backend="nccl",
    ):
        assert (
            torch.distributed.is_initialized()
        ), "Default torch process group must be initialized"
        assert group_name != "", "Group name cannot be empty"

        ports_list = ports.split(",")
        assert (
            len(ports_list) == self.tp_size
        ), f"Expected {self.tp_size} ports, but got {len(ports_list)} ports."
        group_port = ports_list[self.tp_rank]
        group_name = f"{group_name}_{group_port}_{self.tp_rank}"

        logger.info(
            f"init custom process group: tp_rank={self.tp_rank}, gpu_id={self.gpu_id}, master_address={master_address}, master_port={group_port}, "
            f"group_rank={group_rank}, world_size={world_size}, group_name={group_name}, backend={backend}"
        )

        torch.cuda.empty_cache()
        success = False
        message = ""
        try:
            na = NetworkAddress(master_address, group_port)
            self._weights_send_group[group_name] = init_custom_process_group(
                backend=backend,
                init_method=na.to_tcp(),
                world_size=world_size,
                rank=group_rank,
                group_name=group_name,
                device_id=torch.device("cuda", self.gpu_id),
            )
            dist.barrier(group=self._weights_send_group[group_name])
            success = True
            message = f"Succeeded to init group through {na.to_host_port_str()} group."
        except Exception as e:
            message = f"Failed to init group: {e}."
            logger.error(message)

        torch.cuda.empty_cache()
        return success, message

    def send_weights_to_remote_instance(
        self,
        master_address,
        ports,
        group_name,
    ):
        assert (
            torch.distributed.is_initialized()
        ), "Default torch process group must be initialized"
        assert group_name != "", "Group name cannot be empty"

        ports_list = ports.split(",")
        assert (
            len(ports_list) == self.tp_size
        ), f"Expected {self.tp_size} ports, but got {len(ports_list)} ports."
        group_port = ports_list[self.tp_rank]
        group_name = f"{group_name}_{group_port}_{self.tp_rank}"

        if self._weights_send_group[group_name] is not None:
            send_group = self._weights_send_group[group_name]
        else:
            message = f"Group {group_name} not in _weights_send_group list. Please call `init_weights_send_group_for_remote_instance` first."
            logger.error(message)
            return False, message

        torch.cuda.empty_cache()
        success = False
        na = NetworkAddress(master_address, group_port)
        message = ""
        try:
            for _, weights in self.model.named_parameters():
                torch.distributed.broadcast(
                    weights,
                    src=0,
                    group=send_group,
                )
            success = True
            message = f"Succeeded to send weights through {na.to_host_port_str()} {group_name}."
        except Exception as e:
            message = f"Failed to send weights: {e}."
            logger.error(message)

        # destroy the process group after sending weights
        del self._weights_send_group[group_name]
        torch.distributed.distributed_c10d.destroy_process_group(send_group)
        torch.cuda.empty_cache()
        return success, message

    def init_weights_update_group(
        self,
        master_address,
        master_port,
        rank_offset,
        world_size,
        group_name,
        backend="nccl",
    ):
        """Initialize the Torch process group for model parameter updates.

        `_model_update_group` is used in the RLHF workflow, where rank
        0 is the actor model in the training engine, and the other ranks are
        the inference engine, which is used for rollout.

        In the RLHF workflow, the training engine updates the model
        weights/parameters online, and broadcasts them to the inference
        engine through the `_model_update_group` process group.
        """
        assert (
            torch.distributed.is_initialized()
        ), "Default torch process group must be initialized"
        assert group_name != "", "Group name cannot be empty"

        rank = rank_offset + self.tp_rank

        logger.info(
            f"init custom process group: master_address={master_address}, master_port={master_port}, "
            f"rank_offset={rank_offset}, rank={rank}, world_size={world_size}, group_name={group_name}, backend={backend}"
        )

        try:
            na = NetworkAddress(master_address, master_port)
            self._model_update_group[group_name] = init_custom_process_group(
                backend=backend,
                init_method=na.to_tcp(),
                world_size=world_size,
                rank=rank,
                group_name=group_name,
            )
            return True, "Succeeded to initialize custom process group."
        except Exception as e:
            message = f"Failed to initialize custom process group: {e}."
            logger.error(message)
            return False, message

    def destroy_weights_update_group(self, group_name):
        try:
            if group_name in self._model_update_group:
                pg = self._model_update_group.pop(group_name)
                torch.distributed.destroy_process_group(pg)
                return True, "Succeeded to destroy custom process group."
            else:
                return False, "The group to be destroyed does not exist."
        except Exception as e:
            message = f"Failed to destroy custom process group: {e}."
            logger.error(message)
            return False, message

    def update_weights_from_distributed(
        self,
        names,
        dtypes,
        shapes,
        group_name,
        load_format: Optional[str] = None,
    ):
        """
        Update specific parameter in the model weights online
        through `_model_update_group` process group.

        Args:
            name: the name of the parameter to be updated.
            dtype: the data type of the parameter to be updated.
            shape: the shape of the parameter to be updated.
        """

        assert group_name in self._model_update_group, (
            f"Group {group_name} not in {list(self._model_update_group.keys())}. "
            "Please call `init_weights_update_group` first."
        )

        if load_format == "flattened_bucket":
            return self._update_bucketed_weights_from_distributed(
                names, dtypes, shapes, group_name
            )
        try:
            weights = []
            handles = []
            for name, dtype, shape in zip(names, dtypes, shapes):
                target_dtype = (
                    dtype if isinstance(dtype, torch.dtype) else getattr(torch, dtype)
                )
                weight = torch.empty(shape, dtype=target_dtype, device=self.device)
                handles.append(
                    torch.distributed.broadcast(
                        weight,
                        src=0,
                        group=self._model_update_group[group_name],
                        async_op=True,
                    )
                )
                weights.append((name, weight))
            for handle in handles:
                handle.wait()

            self.model.load_weights(weights)
            return True, "Succeeded to update parameter online."

        except Exception as e:
            error_msg = (
                f"Failed to update parameter online: {e}. "
                f"The full weights of the ModelRunner are partially updated. "
                f"Please discard the whole weights."
            )
            logger.error(error_msg)
            return False, error_msg

    def _update_bucketed_weights_from_distributed(
        self, names, dtypes, shapes, group_name
    ):
        try:
            named_tensors = []
            for name, dtype, shape in zip(names, dtypes, shapes):
                target_dtype = (
                    dtype if isinstance(dtype, torch.dtype) else getattr(torch, dtype)
                )
                named_tensors.append(
                    (name, torch.empty(shape, dtype=target_dtype, device=self.device))
                )
            bucket = FlattenedTensorBucket(named_tensors=named_tensors)
            flattened_tensor = bucket.get_flattened_tensor()
            torch.distributed.broadcast(
                flattened_tensor,
                src=0,
                group=self._model_update_group[group_name],
            )
            reconstructed_tensors = bucket.reconstruct_tensors()
            self.model.load_weights(reconstructed_tensors)
            return True, f"Succeeded to update parameter online."
        except Exception as e:
            error_msg = (
                f"Failed to update parameter online: {e}. "
                f"The full weights of the ModelRunner are partially updated. "
                f"Please discard the whole weights."
            )
            logger.error(error_msg)
            return False, error_msg

    def update_weights_from_tensor(
        self,
        named_tensors: List[Tuple[str, Union[torch.Tensor, "LocalSerializedTensor"]]],
        load_format: Optional[str] = None,
    ):
        monkey_patch_torch_reductions()
        if load_format == "flattened_bucket":
            # Handle flattened bucket format
            return self._update_weights_from_flattened_bucket(
                flattened_tensor_bucket_dict=named_tensors
            )

        # We need to get device after patch otherwise the device would be wrong
        self.device_module = torch.get_device_module(self.device)
        infered_device = self.device_module.current_device()

        named_tensors = [
            (name, _unwrap_tensor(tensor, tp_rank=self.tp_rank, device=infered_device))
            for name, tensor in named_tensors
        ]
        if load_format == "direct":
            _model_load_weights_direct(self.model, named_tensors)
        elif load_format in self.server_args.custom_weight_loader:
            custom_loader = dynamic_import(load_format)
            custom_loader(self.model, named_tensors)
        elif load_format is None:
            self.model.load_weights(named_tensors)
        else:
            raise NotImplementedError(f"Unknown load_format={load_format}")
        return True, "Success"

    def _update_weights_from_flattened_bucket(
        self,
        flattened_tensor_bucket_dict,
    ):
        """Handle flattened bucket format for weight updates"""
        flattened_tensor = flattened_tensor_bucket_dict["flattened_tensor"]
        metadata = flattened_tensor_bucket_dict["metadata"]

        # Convert metadata dict to our format
        converted_metadata = []
        for meta in metadata:
            converted_meta = FlattenedTensorMetadata(
                name=meta.name,
                shape=meta.shape,
                dtype=meta.dtype,
                start_idx=meta.start_idx,
                end_idx=meta.end_idx,
                numel=meta.numel,
            )
            converted_metadata.append(converted_meta)

        # Create bucket and reconstruct tensors
        bucket = FlattenedTensorBucket(
            flattened_tensor=flattened_tensor, metadata=converted_metadata
        )
        reconstructed_tensors = bucket.reconstruct_tensors()

        # Load the reconstructed tensors using the standard method
        self.model.load_weights(reconstructed_tensors)

        return True, "Success"

    def get_weights_by_name(
        self, name: str, truncate_size: int = 100
    ) -> Optional[torch.Tensor]:
        """Get the weights of the parameter by its name. Similar to `get_parameter` in Hugging Face.

        Only used for unit test with an unoptimized performance.
        For optimized performance, please use torch.save and torch.load.
        """
        # TODO: (chenyang) Add support for Qwen models.
        try:
            return self.model.get_weights_by_name(
                name, truncate_size, tp_size=self.tp_size
            )
        except Exception as e:
            logger.error(f"Error when getting parameter {name}: {e}")
            return None

    def init_lora_manager(self):
        self.lora_manager = LoRAManager(
            base_model=self.model,
            base_hf_config=self.model_config.hf_config,
            max_loras_per_batch=self.server_args.max_loras_per_batch,
            load_config=self.load_config,
            dtype=self.dtype,
            server_args=self.server_args,
            lora_backend=self.server_args.lora_backend,
            tp_size=self.tp_size,
            tp_rank=self.tp_rank,
            max_lora_rank=self.server_args.max_lora_rank,
            target_modules=self.server_args.lora_target_modules,
            lora_paths=self.server_args.lora_paths,
        )

    def load_lora_adapter(self, lora_ref: LoRARef):
        """Load a new lora adapter from disk or huggingface."""

        logger.info(
            f"LoRA adapter loading starts: {lora_ref}. "
            f"avail mem={get_available_gpu_memory(self.device, self.gpu_id):.2f} GB"
        )

        result = self.lora_manager.load_lora_adapter(lora_ref)

        logger.info(
            f"LoRA adapter loading completes: {lora_ref}. "
            f"avail mem={get_available_gpu_memory(self.device, self.gpu_id):.2f} GB"
        )

        return result

    def load_lora_adapter_from_tensors(
        self, lora_ref: LoRARef, tensors, config_dict, added_tokens_config=None
    ):
        logger.info(f"LoRA adapter loading from tensors starts: {lora_ref}.")
        result = self.lora_manager.load_lora_adapter_from_tensors(
            lora_ref, tensors, config_dict, added_tokens_config
        )
        logger.info(f"LoRA adapter loading from tensors completes: {lora_ref}.")
        return result

    def unload_lora_adapter(self, lora_ref: LoRARef):
        """Unload a lora adapter that was previously loaded during initialization or dynamic loading."""

        logger.info(
            f"LoRA adapter unloading starts: {lora_ref}. "
            f"avail mem={get_available_gpu_memory(self.device, self.gpu_id):.2f} GB"
        )

        result = self.lora_manager.unload_lora_adapter(lora_ref)

        logger.info(
            f"LoRA adapter unloading completes: {lora_ref}. "
            f"avail mem={get_available_gpu_memory(self.device, self.gpu_id):.2f} GB"
        )

        return result

    @property
    def qwen3_next_config(self):
        config = self.model_config.hf_config
        if isinstance(config, Qwen3NextConfig):
            return config
        return None

    @property
    def hybrid_lightning_config(self):
        config = self.model_config.hf_config
        if isinstance(config, BailingHybridConfig):
            return config
        return None

    @property
    def hybrid_gdn_config(self):
        config = self.model_config.hf_config.get_text_config()
        if isinstance(
            config,
            Qwen3NextConfig
            | Qwen3_5Config
            | Qwen3_5MoeConfig
            | JetNemotronConfig
            | JetVLMConfig,
        ):
            return config
        return None

    @property
    def mamba2_config(self):
        config = self.model_config.hf_config
        if isinstance(config, NemotronHConfig) and self.is_draft_worker:
            # NemotronH MTP draft models have no Mamba layers (pattern like "*E")
            # so they shouldn't use HybridLinearAttnBackend
            pattern = getattr(config, "mtp_hybrid_override_pattern", None)
            if pattern is not None and "M" not in pattern:
                return None
        if isinstance(
            config, FalconH1Config | NemotronHConfig | Lfm2Config | Lfm2MoeConfig
        ):
            return config
        if isinstance(config, NemotronH_Nano_VL_V2_Config):
            return config.llm_config

        if isinstance(config, GraniteMoeHybridConfig):
            has_mamba = any(
                layer_type == "mamba"
                for layer_type in getattr(config, "layer_types", [])
            )
            if not has_mamba:
                return None
            else:
                return config

        return None

    @property
    def max_token_pool_size(self):
        """Return the max token pool size considering hybrid swa settings."""
        if self.is_hybrid_swa:
            return min(self.swa_max_total_num_tokens, self.max_total_num_tokens)
        else:
            return self.max_total_num_tokens

    @property
    def kimi_linear_config(self):
        config = self.model_config.hf_config
        if isinstance(config, KimiLinearConfig):
            return config
        return None

    @property
    def mambaish_config(self):
        return (
            self.mamba2_config
            or self.hybrid_gdn_config
            or self.kimi_linear_config
            or self.hybrid_lightning_config
        )

    def configure_kv_cache_dtype(self):
        if self.server_args.kv_cache_dtype == "auto":
            quant_config = getattr(self.model, "quant_config", None)
            kv_cache_quant_algo = getattr(quant_config, "kv_cache_quant_algo", None)
            if (
                isinstance(kv_cache_quant_algo, str)
                and kv_cache_quant_algo.upper() == "FP8"
            ):
                if _is_hip:
                    self.kv_cache_dtype = fp8_dtype
                    self.server_args.kv_cache_dtype = TORCH_DTYPE_TO_KV_CACHE_STR[
                        self.kv_cache_dtype
                    ]
                else:
                    self.kv_cache_dtype = torch.float8_e4m3fn
                    self.server_args.kv_cache_dtype = TORCH_DTYPE_TO_KV_CACHE_STR[
                        self.kv_cache_dtype
                    ]
            else:
                self.kv_cache_dtype = self.dtype
        elif self.server_args.kv_cache_dtype == "fp8_e5m2":
            if _is_hip:  # Using natively supported format
                self.kv_cache_dtype = fp8_dtype
            else:
                self.kv_cache_dtype = torch.float8_e5m2
        elif self.server_args.kv_cache_dtype == "fp8_e4m3":
            if _is_hip:  # Using natively supported format
                self.kv_cache_dtype = fp8_dtype
            else:
                self.kv_cache_dtype = torch.float8_e4m3fn
        elif self.server_args.kv_cache_dtype in ("bf16", "bfloat16"):
            self.kv_cache_dtype = torch.bfloat16
        elif self.server_args.kv_cache_dtype == "fp4_e2m1":
            if hasattr(torch, "float4_e2m1fn_x2"):
                self.kv_cache_dtype = torch.float4_e2m1fn_x2
                logger.warning(f"FP4 (E2M1) KV Cache might lead to a accuracy drop!")
            else:
                logger.warning(
                    f"--kv-cache-dtype falls back to 'auto' because this torch version does not support torch.float4_e2m1fn_x2"
                )
                self.kv_cache_dtype = self.dtype
        else:
            raise ValueError(
                f"Unsupported kv_cache_dtype: {self.server_args.kv_cache_dtype}."
            )

        log_info_on_rank0(logger, f"Using KV cache dtype: {self.kv_cache_dtype}")

    def init_cublas(self):
        """We need to run a small matmul to init cublas. Otherwise, it will raise some errors later."""
        dtype = torch.float16
        device = "cuda"
        a = torch.ones((16, 16), dtype=dtype, device=device)
        b = torch.ones((16, 16), dtype=dtype, device=device)
        c = a @ b
        return c

    def init_attention_backend(self):
        """Init attention kernel backend."""
        if self.server_args.enable_pdmux:
            self.attn_backend = self._get_attention_backend(init_new_workspace=True)
            self.decode_attn_backend_group = []
            for _ in range(self.server_args.sm_group_num):
                self.decode_attn_backend_group.append(self._get_attention_backend())
            self.decode_attn_backend = self.decode_attn_backend_group[0]
        elif self.server_args.enable_two_batch_overlap and not self.is_draft_worker:
            self.attn_backend = TboAttnBackend.init_new(self._get_attention_backend)
        else:
            self.attn_backend = self._get_attention_backend()

    def _get_attention_backend(self, init_new_workspace: bool = False):
        """Init attention kernel backend."""
        draft_attn_backend = self.server_args.speculative_draft_attention_backend
        if self.is_draft_worker and draft_attn_backend:
            logger.warning(
                f"Overriding draft attention backend to {draft_attn_backend}."
            )
            return self._get_attention_backend_from_str(
                draft_attn_backend,
                init_new_workspace=init_new_workspace,
            )

        (
            self.prefill_attention_backend_str,
            self.decode_attention_backend_str,
        ) = self.server_args.get_attention_backends()

        if self.decode_attention_backend_str != self.prefill_attention_backend_str:
            from sglang.srt.layers.attention.hybrid_attn_backend import (
                HybridAttnBackend,
            )

            attn_backend = HybridAttnBackend(
                self,
                decode_backend=self._get_attention_backend_from_str(
                    self.decode_attention_backend_str,
                    init_new_workspace=init_new_workspace,
                ),
                prefill_backend=self._get_attention_backend_from_str(
                    self.prefill_attention_backend_str,
                    init_new_workspace=init_new_workspace,
                ),
            )
            logger.info(
                f"Using hybrid attention backend for decode and prefill: "
                f"decode_backend={self.decode_attention_backend_str}, "
                f"prefill_backend={self.prefill_attention_backend_str}."
            )
            logger.warning(
                "Warning: Attention backend specified by --attention-backend or default backend might be overridden."
                "The feature of hybrid attention backend is experimental and unstable. Please raise an issue if you encounter any problem."
            )
        else:
            attn_backend = self._get_attention_backend_from_str(
                self.server_args.attention_backend,
                init_new_workspace=init_new_workspace,
            )

        (
            get_global_server_args().prefill_attention_backend,
            get_global_server_args().decode_attention_backend,
        ) = (self.prefill_attention_backend_str, self.decode_attention_backend_str)
        return attn_backend

    def _get_attention_backend_from_str(
        self, backend_str: str, init_new_workspace: bool = False
    ):
        if backend_str not in ATTENTION_BACKENDS:
            raise ValueError(f"Invalid attention backend: {backend_str}")
        self.init_new_workspace = init_new_workspace
        full_attention_backend = ATTENTION_BACKENDS[backend_str](self)
        return attn_backend_wrapper(self, full_attention_backend)

    def init_double_sparsity_channel_config(self, selected_channel):
        selected_channel = "." + selected_channel + "_proj"
        self.sorted_channels = []
        # load channel config
        with open(self.server_args.ds_channel_config_path, "r") as f:
            channel_config = json.load(f)

        for i in range(self.start_layer, self.end_layer):
            key = "model.layers." + str(i) + ".self_attn" + selected_channel
            self.sorted_channels.append(
                torch.tensor(channel_config[key])[
                    :, : self.server_args.ds_heavy_channel_num
                ]
                .contiguous()
                .cuda()
            )

    def kernel_warmup(self):
        """
        Warmup and tune kernels before cuda graph capture.
        Currently only doing FlashInfer autotune.
        """
        if self.device != "cuda":
            return

        if self._should_run_flashinfer_autotune():
            self._flashinfer_autotune()

    def _should_run_flashinfer_autotune(self) -> bool:
        """Check if flashinfer autotune should be run."""
        if self.server_args.disable_flashinfer_autotune:
            return False

        backend_str = self.server_args.moe_runner_backend

        # TODO smor- support other cases for flashinfer autotune, such as, mamba backend

        if backend_str not in [
            "flashinfer_trtllm",
            "flashinfer_mxfp4",
            # TODO: flashinfer_cutlass will cause some flashinfer compilation errors. To be fixed.
            # "flashinfer_cutlass",
        ]:
            return False

        major, _ = torch.cuda.get_device_capability()
        if major < 9:
            return False

        if (
            self.spec_algorithm.is_eagle()
            or self.spec_algorithm.is_standalone()
            or self.spec_algorithm.is_ngram()
        ):
            return not self.is_draft_worker

        return True

    def _flashinfer_autotune(self):
        """Run flashinfer autotune."""
        from flashinfer.autotuner import autotune

        logger.info("Running FlashInfer autotune...")

        # Run warmup on the non-default stream to avoid NCCL 2.29+ cudaMemcpyBatchAsync
        # calls on default stream (unsupported by CUDA) when --enable-symm-mem is used.
        self.forward_stream.wait_stream(torch.cuda.current_stream())
        with torch.get_device_module(self.device).stream(self.forward_stream):
            with torch.inference_mode(), autotune():
                self._dummy_run(
                    batch_size=self.req_to_token_pool.size, run_ctx=autotune()
                )
        torch.cuda.current_stream().wait_stream(self.forward_stream)
        logger.info("FlashInfer autotune completed.")

    def _dummy_run(self, batch_size: int, run_ctx=None):
        """Run a dummy forward pass for warmup/profiling."""
        if self.is_generation:
            capture_forward_mode = ForwardMode.DECODE
        else:
            capture_forward_mode = ForwardMode.EXTEND
        capture_hidden_mode = CaptureHiddenMode.NULL
        num_tokens_per_bs = 1
        if (
            self.spec_algorithm.is_eagle()
            or self.spec_algorithm.is_standalone()
            or self.spec_algorithm.is_ngram()
        ):
            if self.is_draft_worker:
                raise RuntimeError("This should not happen")
            else:
                capture_forward_mode = ForwardMode.TARGET_VERIFY
                num_tokens_per_bs = self.server_args.speculative_num_draft_tokens

        if self.server_args.enable_return_hidden_states:
            capture_hidden_mode = CaptureHiddenMode.FULL

        num_tokens = batch_size * num_tokens_per_bs

        if require_gathered_buffer(self.server_args):
            attn_tp_size = get_attention_tp_size()
            if attn_tp_size > 1 and num_tokens % attn_tp_size != 0:
                num_tokens = num_tokens // attn_tp_size * attn_tp_size
                batch_size = num_tokens // num_tokens_per_bs

        seq_len_fill_value = self.attn_backend.get_cuda_graph_seq_len_fill_value()

        if self.server_args.enable_torch_compile:
            set_torch_compile_config()

        if self.eagle_use_aux_hidden_state:
            self.model.set_eagle3_layers_to_capture()

        require_mlp_tp_gather_ = require_mlp_tp_gather(self.server_args)
        if require_gathered_buffer(self.server_args):
            assert require_mlp_tp_gather_ or require_attn_tp_gather(self.server_args)

        buffers: DecodeInputBuffers = DecodeInputBuffers.create(
            device=self.device,
            max_bs=batch_size,
            max_num_token=num_tokens,
            hidden_size=self.model_config.hidden_size,
            vocab_size=self.model_config.vocab_size,
            dtype=self.model_config.dtype,
            dp_size=self.server_args.dp_size,
            pp_size=self.server_args.pp_size,
            is_encoder_decoder=self.model_config.is_encoder_decoder,
            require_mlp_tp_gather=require_mlp_tp_gather_,
            seq_len_fill_value=seq_len_fill_value,
            encoder_len_fill_value=(
                getattr(self.model_config.hf_config, "max_source_positions", 0)
                if self.model_config.is_encoder_decoder
                else 0
            ),
            num_tokens_per_bs=num_tokens_per_bs,
            cache_loc_dtype=torch.int64,
            enable_mamba_track=False,
        )
        buffers.num_token_non_padded[...] = num_tokens

        # For extend mode
        if not self.is_generation:
            extend_prefix_lens_cpu = [0] * batch_size
            extend_seq_lens_cpu = [seq_len_fill_value] * batch_size
            extend_num_tokens = num_tokens
            extend_seq_lens = torch.full(
                (batch_size,), seq_len_fill_value, dtype=torch.int32, device=self.device
            )
            extend_prefix_lens = torch.zeros(
                (batch_size,), dtype=torch.int32, device=self.device
            )
            extend_start_loc = torch.arange(
                0, num_tokens, num_tokens_per_bs, dtype=torch.int32, device=self.device
            )
        else:
            extend_prefix_lens_cpu = None
            extend_seq_lens_cpu = None
            extend_num_tokens = None
            extend_seq_lens = None
            extend_prefix_lens = None
            extend_start_loc = None

        if self.server_args.pp_size > 1:
            pp_proxy_tensors = PPProxyTensors(
                {k: v[:num_tokens] for k, v in buffers.pp_proxy_tensors.items()}
            )

        if require_mlp_tp_gather_:
            buffers.global_num_tokens_gpu.copy_(
                torch.tensor(
                    [num_tokens] * self.server_args.dp_size,
                    dtype=torch.int32,
                    device=self.device,
                )
            )
            buffers.global_num_tokens_for_logprob_gpu.copy_(
                torch.tensor(
                    [num_tokens] * self.server_args.dp_size,
                    dtype=torch.int32,
                    device=self.device,
                )
            )
            global_dp_buffer_len = num_tokens * self.server_args.dp_size
        elif require_attn_tp_gather(self.server_args):
            buffers.global_num_tokens_gpu.copy_(
                torch.tensor(
                    [num_tokens],
                    dtype=torch.int32,
                    device=self.device,
                )
            )
            buffers.global_num_tokens_for_logprob_gpu.copy_(
                torch.tensor(
                    [num_tokens],
                    dtype=torch.int32,
                    device=self.device,
                )
            )
            global_dp_buffer_len = num_tokens
        else:
            global_dp_buffer_len = None

        def get_spec_info():
            spec_info = None
            if self.spec_algorithm.is_eagle() or self.spec_algorithm.is_standalone():
                from sglang.srt.speculative.eagle_info import EagleVerifyInput

                if self.is_draft_worker:
                    raise RuntimeError("This should not happen.")
                else:
                    spec_info = EagleVerifyInput(
                        draft_token=None,
                        custom_mask=buffers.custom_mask,
                        positions=None,
                        retrive_index=None,
                        retrive_next_token=None,
                        retrive_next_sibling=None,
                        retrive_cum_len=None,
                        spec_steps=self.server_args.speculative_num_steps,
                        topk=self.server_args.speculative_eagle_topk,
                        draft_token_num=self.server_args.speculative_num_draft_tokens,
                        capture_hidden_mode=CaptureHiddenMode.FULL,
                        seq_lens_sum=None,
                        seq_lens_cpu=None,
                    )

            elif self.spec_algorithm.is_ngram():
                from sglang.srt.speculative.ngram_info import NgramVerifyInput

                spec_info = NgramVerifyInput(
                    draft_token=None,
                    tree_mask=buffers.custom_mask,
                    positions=None,
                    retrive_index=None,
                    retrive_next_token=None,
                    retrive_next_sibling=None,
                    draft_token_num=num_tokens_per_bs,
                )
                spec_info.capture_hidden_mode = CaptureHiddenMode.NULL

            return spec_info

        spec_info = get_spec_info()
        if capture_hidden_mode != CaptureHiddenMode.FULL:
            capture_hidden_mode = (
                spec_info.capture_hidden_mode if spec_info else CaptureHiddenMode.NULL
            )

        if self.server_args.enable_lora:
            lora_ids = [None] * batch_size
        else:
            lora_ids = None

        forward_batch = ForwardBatch(
            forward_mode=capture_forward_mode,
            batch_size=batch_size,
            input_ids=buffers.input_ids,
            req_pool_indices=buffers.req_pool_indices,
            seq_lens=buffers.seq_lens,
            seq_lens_cpu=buffers.seq_lens_cpu,
            next_token_logits_buffer=buffers.next_token_logits_buffer,
            orig_seq_lens=buffers.seq_lens,
            req_to_token_pool=self.req_to_token_pool,
            token_to_kv_pool=self.token_to_kv_pool,
            attn_backend=self.attn_backend,
            out_cache_loc=buffers.out_cache_loc,
            seq_lens_sum=buffers.seq_lens.sum().item(),
            encoder_lens=buffers.encoder_lens,
            return_logprob=False,
            positions=buffers.positions,
            extend_num_tokens=extend_num_tokens,
            extend_seq_lens=extend_seq_lens,
            extend_prefix_lens=extend_prefix_lens,
            extend_start_loc=extend_start_loc,
            extend_prefix_lens_cpu=extend_prefix_lens_cpu,
            extend_seq_lens_cpu=extend_seq_lens_cpu,
            global_num_tokens_gpu=buffers.global_num_tokens_gpu,
            global_num_tokens_for_logprob_gpu=buffers.global_num_tokens_for_logprob_gpu,
            dp_padding_mode=DpPaddingMode.get_default_mode_in_cuda_graph(),
            global_dp_buffer_len=global_dp_buffer_len,
            mrope_positions=buffers.mrope_positions,
            spec_algorithm=self.spec_algorithm,
            spec_info=spec_info,
            capture_hidden_mode=capture_hidden_mode,
            num_token_non_padded=buffers.num_token_non_padded,
            global_forward_mode=capture_forward_mode,
            lora_ids=lora_ids,
        )

        if lora_ids is not None:
            self.lora_manager.prepare_lora_batch(forward_batch)

        self.attn_backend.init_forward_metadata(forward_batch)

        def run_once():
            forward_batch.dp_local_start_pos = forward_batch.dp_local_num_tokens = None
            set_dp_buffer_len(
                global_dp_buffer_len,
                num_tokens,
                forward_batch.dp_padding_mode.is_max_len(),
            )
            set_is_extend_in_batch(False)

            kwargs = {}
            if (
                self.server_args.pp_size > 1
                and "pp_proxy_tensors"
                in inspect.signature(self.model.forward).parameters
            ):
                kwargs["pp_proxy_tensors"] = PPProxyTensors(
                    {k: v.clone() for k, v in pp_proxy_tensors.tensors.items()}
                )
            if not self.is_generation:
                kwargs["get_embedding"] = True

            logits_output_or_pp_proxy_tensors = self.model.forward(
                buffers.input_ids,
                forward_batch.positions,
                forward_batch,
                **kwargs,
            )
            return logits_output_or_pp_proxy_tensors

        torch.get_device_module(self.device).synchronize()
        self.tp_group.barrier()
        with torch.inference_mode(), run_ctx or empty_context():
            run_once()

    def maybe_init_ngram_embedding(self):
        self.use_ngram_embedding = self.model_config.use_ngram_embedding
        if self.use_ngram_embedding:
            from sglang.srt.layers.n_gram_embedding import NgramEmbedding

            self.token_table = torch.empty(
                self.req_to_token_pool.size,
                self.model_config.context_len,
                dtype=torch.int32,
                device=self.device,
            )
            chunked_prefill_size = self.server_args.chunked_prefill_size
            assert (
                chunked_prefill_size is not None and chunked_prefill_size > 0
            ), "Ngram embedding requires chunked prefill to be enabled (chunked_prefill_size > 0)"
            for module in self.model.modules():
                if isinstance(module, NgramEmbedding):
                    module.init_buffers(
                        self.max_running_requests, chunked_prefill_size, self.device
                    )

    def maybe_update_ngram_token_table(
        self,
        next_token_ids: torch.Tensor,
        forward_batch: "ForwardBatch",
    ):
        """Update the ngram embedding token table after sampling."""
        ngram_embedding_info = forward_batch.ngram_embedding_info
        if ngram_embedding_info is None:
            return
        ngram_embedding_info.out_column_starts[: forward_batch.batch_size] = (
            forward_batch.seq_lens
        )
        ngram_embedding_info.out_req_lens[: forward_batch.batch_size] = 1
        update_token_table(
            ne_token_table=ngram_embedding_info.token_table,
            tokens=next_token_ids.to(torch.int32),
            row_indices=forward_batch.req_pool_indices,
            column_starts=ngram_embedding_info.out_column_starts,
            req_lens=torch.ones_like(ngram_embedding_info.out_column_starts),
            ignore_tokens=None,
        )

    def init_device_graphs(self):
        """Capture device graphs."""
        self.graph_runner = None
        self.graph_mem_usage = 0

        if not self.is_generation:
            # TODO: Currently, cuda graph only captures decode steps, which only exists for generation models
            return

        if self.server_args.model_impl.lower() == ModelImpl.MINDSPORE:
            return

        if self.device != "cpu" and self.server_args.disable_cuda_graph:
            return

        if self.device == "cpu" and not self.server_args.enable_torch_compile:
            return

        tic = time.perf_counter()
        before_mem = get_available_gpu_memory(self.device, self.gpu_id)
        graph_backend = defaultdict(
            lambda: "cuda graph",
            {
                "cpu": "cpu graph",
                "npu": "npu graph",
            },
        )
        logger.info(
            f"Capture {graph_backend[self.device]} begin. This can take up to several minutes. avail mem={before_mem:.2f} GB"
        )
        graph_runners = defaultdict(
            lambda: CudaGraphRunner,
            {
                "cpu": CPUGraphRunner,
                "npu": NPUGraphRunner,
            },
        )
        self.graph_runner = graph_runners[self.device](self)

        after_mem = get_available_gpu_memory(self.device, self.gpu_id)
        self.graph_mem_usage = before_mem - after_mem
        logger.info(
            f"Capture {graph_backend[self.device]} end. Time elapsed: {time.perf_counter() - tic:.2f} s. "
            f"mem usage={self.graph_mem_usage:.2f} GB. avail mem={after_mem:.2f} GB."
        )

    def init_piecewise_cuda_graphs(self):
        """Initialize piecewise CUDA graph runner."""
        self.piecewise_cuda_graph_runner = None

        if self.server_args.disable_piecewise_cuda_graph:
            logger.info(
                "Disable piecewise CUDA graph because --disable-piecewise-cuda-graph is set"
            )
            return

        # Disable piecewise CUDA graph for non-language models
        if not hasattr(self.model, "model"):
            logger.warning(
                "Disable piecewise CUDA graph because the model is not a language model"
            )
            return

        # Disable piecewise CUDA graph for non capture size
        if not self.server_args.piecewise_cuda_graph_tokens:
            logger.warning(
                "Disable piecewise CUDA graph because the capture size is not set"
            )
            return

        # Collect attention layers and moe layers from the model
        self.model.model = resolve_language_model(self.model)
        language_model = getattr(self.model, "language_model", self.model)
        self.attention_layers = []
        self.moe_layers = []
        self.moe_fusions = []
        for layer in language_model.model.layers:
            attn_layer = None
            if hasattr(layer, "self_attn"):
                if hasattr(layer.self_attn, "attn"):
                    attn_layer = layer.self_attn.attn
                elif hasattr(layer.self_attn, "attn_mqa"):
                    # For DeepSeek model
                    attn_layer = layer.self_attn.attn_mqa
            # For hybrid model
            elif hasattr(layer, "attn"):
                attn_layer = layer.attn
            elif hasattr(layer, "linear_attn"):
                if hasattr(layer.linear_attn, "attn"):
                    attn_layer = layer.linear_attn.attn
                else:
                    attn_layer = layer.linear_attn
            # For InternVL model
            elif hasattr(layer, "attention"):
                if hasattr(layer.attention, "attn"):
                    attn_layer = layer.attention.attn
            # For NemotronH and similar hybrid models using 'mixer' attribute
            elif hasattr(layer, "mixer"):
                if hasattr(layer.mixer, "attn"):
                    attn_layer = layer.mixer.attn
                elif hasattr(layer, "_forward_mamba"):
                    # Mamba layer with split op support - store the layer itself
                    attn_layer = layer

            if attn_layer is not None:
                self.attention_layers.append(attn_layer)

            moe_block = None
            moe_fusion = None
            if hasattr(layer, "mlp") and hasattr(layer.mlp, "experts"):
                moe_block = layer.mlp.experts
                moe_fusion = layer.mlp
            if hasattr(layer, "block_sparse_moe") and hasattr(
                layer.block_sparse_moe, "experts"
            ):
                moe_block = layer.block_sparse_moe.experts
                moe_fusion = layer.block_sparse_moe
            if hasattr(layer, "moe") and hasattr(layer.moe, "experts"):
                moe_block = layer.moe.experts
                moe_fusion = layer.moe
            # For NemotronH MoE layers using 'mixer' attribute
            if hasattr(layer, "mixer") and hasattr(layer.mixer, "experts"):
                moe_block = layer.mixer.experts
                moe_fusion = layer.mixer
            self.moe_layers.append(moe_block)
            self.moe_fusions.append(moe_fusion)

        if len(self.attention_layers) < self.model_config.num_hidden_layers:
            # TODO(yuwei): support Non-Standard GQA
            log_info_on_rank0(
                logger,
                "Disable piecewise CUDA graph because some layers do not apply Standard GQA",
            )
            return

        tic = time.perf_counter()
        before_mem = get_available_gpu_memory(self.device, self.gpu_id)
        logger.info(
            f"Capture piecewise CUDA graph begin. avail mem={before_mem:.2f} GB"
        )

        self.piecewise_cuda_graph_runner = PiecewiseCudaGraphRunner(self)

        after_mem = get_available_gpu_memory(self.device, self.gpu_id)
        mem_usage = before_mem - after_mem
        logger.info(
            f"Capture piecewise CUDA graph end. Time elapsed: {time.perf_counter() - tic:.2f} s. "
            f"mem usage={mem_usage:.2f} GB. avail mem={after_mem:.2f} GB."
        )

    def init_threads_binding(self):
        omp_cpuids = os.environ.get("SGLANG_CPU_OMP_THREADS_BIND", "all")
        cpu_ids_by_node = get_cpu_ids_by_node()
        n_numa_node = len(cpu_ids_by_node)
        if omp_cpuids == "all":
            assert self.tp_size <= n_numa_node, (
                f"SGLANG_CPU_OMP_THREADS_BIND is not set, in this case, "
                f"tp_size {self.tp_size} should be smaller than or equal to number of numa node on the machine {n_numa_node}. "
                f"If you need tp_size to be larger than number of numa node, please set the CPU cores for each tp rank via SGLANG_CPU_OMP_THREADS_BIND explicitly. "
                f"For example, on a machine with 2 numa nodes, where core 0-31 are on numa node 0 and core 32-63 are on numa node 1, "
                f"it is suggested to use -tp 2 and bind tp rank 0 to core 0-31 and tp rank 1 to core 32-63. "
                f"This is the default behavior if SGLANG_CPU_OMP_THREADS_BIND is not set and it is the same as setting SGLANG_CPU_OMP_THREADS_BIND=0-31|32-63. "
                f"If you do need tp_size to be larger than the number of numa nodes, you could set SGLANG_CPU_OMP_THREADS_BIND explicitly for example SGLANG_CPU_OMP_THREADS_BIND=0-15|16-31|32-47|48-63 and run with -tp 4. "
                f"If you don't want each tp rank to use all the cores on one numa node, you could set for example SGLANG_CPU_OMP_THREADS_BIND=0-15|32-47 and run with -tp 2."
            )
            if self.tp_size < n_numa_node:
                logger.warning(
                    f"Detected the current machine has {n_numa_node} numa nodes available, but tp_size is set to {self.tp_size}, so only {self.tp_size} numa nodes are used."
                )
            self.local_omp_cpuid = cpu_ids_by_node[self.tp_rank]
        else:
            threads_bind_list = omp_cpuids.split("|")
            assert self.tp_size == len(threads_bind_list), (
                f"SGLANG_CPU_OMP_THREADS_BIND setting must be aligned with TP size parameter ({self.tp_size}). "
                f"Please double check your settings."
            )
            self.local_omp_cpuid = threads_bind_list[self.tp_rank]
            if self.tp_size > n_numa_node:
                logger.warning(
                    f"TP size ({self.tp_size})is larger than numa node number ({n_numa_node}), "
                    f"in this case the available memory amount of each rank cannot be determined in prior. "
                    f"Please set proper `--max-total-tokens` to avoid the out-of-memory error."
                )

    def apply_torch_tp(self):
        logger.info(f"Enabling torch tensor parallelism on {self.tp_size} devices.")
        from sglang.srt.layers.model_parallel import tensor_parallel

        device_mesh = torch.distributed.init_device_mesh(self.device, (self.tp_size,))
        tensor_parallel(self.model, device_mesh)

    def update_decode_attn_backend(self, stream_idx: int):
        self.decode_attn_backend = self.decode_attn_backend_group[stream_idx]

    def forward_decode(
        self,
        forward_batch: ForwardBatch,
        skip_attn_backend_init: bool = False,
        pp_proxy_tensors=None,
    ) -> Union[LogitsProcessorOutput, PPProxyTensors]:
        if not skip_attn_backend_init:
            if self.server_args.enable_pdmux:
                self.decode_attn_backend.init_forward_metadata(forward_batch)
                forward_batch.attn_backend = self.decode_attn_backend
            else:
                self.attn_backend.init_forward_metadata(forward_batch)
        # FIXME: add pp_proxy_tensors arg to all models
        kwargs = {}
        if self.support_pp:
            kwargs["pp_proxy_tensors"] = pp_proxy_tensors
        return self.model.forward(
            forward_batch.input_ids,
            forward_batch.positions,
            forward_batch,
            **kwargs,
        )

    def forward_extend(
        self,
        forward_batch: ForwardBatch,
        skip_attn_backend_init: bool = False,
        pp_proxy_tensors=None,
    ) -> Tuple[
        Union[LogitsProcessorOutput, PPProxyTensors, EmbeddingPoolerOutput], bool
    ]:
        kwargs = {}
        if self.support_pp:
            kwargs["pp_proxy_tensors"] = pp_proxy_tensors
        if forward_batch.input_embeds is not None:
            kwargs["input_embeds"] = forward_batch.input_embeds.bfloat16()
        if not self.is_generation:
            kwargs["get_embedding"] = True

        can_run_graph = (
            self.piecewise_cuda_graph_runner is not None
            and self.piecewise_cuda_graph_runner.can_run(forward_batch)
        )

        if can_run_graph:
            return (
                self.piecewise_cuda_graph_runner.replay(forward_batch, **kwargs),
                can_run_graph,
            )

        if not skip_attn_backend_init:
            self.attn_backend.init_forward_metadata(forward_batch)

        return (
            self.model.forward(
                forward_batch.input_ids,
                forward_batch.positions,
                forward_batch,
                **kwargs,
            ),
            can_run_graph,
        )

    def forward_idle(
        self, forward_batch: ForwardBatch, pp_proxy_tensors=None
    ) -> Union[LogitsProcessorOutput, PPProxyTensors]:
        # In DP Attention, IDLE batches are padded (batch_size > 0) for MLP sync.
        # in this case, we need to reinit the forward metadata, otherwise the stale
        # metadata causes batch_size mismatch in attention kernel(e.g. NSA Indexer).
        if forward_batch.batch_size > 0:
            self.attn_backend.init_forward_metadata(forward_batch)

        kwargs = {}
        if self.support_pp:
            kwargs["pp_proxy_tensors"] = pp_proxy_tensors
        return self.model.forward(
            forward_batch.input_ids,
            forward_batch.positions,
            forward_batch,
            **kwargs,
        )

    def forward_split_prefill(
        self,
        forward_batch: ForwardBatch,
        reinit_attn_backend: bool = False,
        forward_count: int = 1,
    ) -> LogitsProcessorOutput:
        if forward_batch.split_index == 0 or reinit_attn_backend:
            self.attn_backend.init_forward_metadata(forward_batch)
        next_split_index = min(
            forward_batch.split_index + forward_count,
            self.model_config.num_hidden_layers,
        )
        ret = self.model.forward_split_prefill(
            forward_batch.input_ids,
            forward_batch.positions,
            forward_batch,
            (forward_batch.split_index, next_split_index),
        )
        forward_batch.split_index = next_split_index
        return ret

    def forward(
        self,
        forward_batch: ForwardBatch,
        skip_attn_backend_init: bool = False,
        pp_proxy_tensors: Optional[PPProxyTensors] = None,
        reinit_attn_backend: bool = False,
        split_forward_count: int = 1,
    ) -> ModelRunnerOutput:
        self.forward_pass_id += 1

        with get_global_expert_distribution_recorder().with_forward_pass(
            self.forward_pass_id,
            forward_batch,
        ) as recorder_outputs:
            output = self._forward_raw(
                forward_batch,
                skip_attn_backend_init,
                pp_proxy_tensors,
                reinit_attn_backend,
                split_forward_count,
            )
            elastic_ep_state = ElasticEPStateManager.instance()
            if (
                elastic_ep_state is not None
                and not elastic_ep_state.is_active_equal_last()
            ):
                elastic_ep_state.snapshot_active_to_last()
                elastic_ep_state.sync_active_to_cpu()
                logging.info("EPLB due to rank faults")
                gen = self.eplb_manager.rebalance()
                while True:
                    try:
                        next(gen)
                    except StopIteration:
                        break
                output = self._forward_raw(
                    forward_batch,
                    skip_attn_backend_init,
                    pp_proxy_tensors,
                    reinit_attn_backend,
                    split_forward_count,
                )
        output.expert_distribution_metrics = recorder_outputs.get("metrics")

        # Copy cached routing experts' buffers back to CPU cache
        get_global_experts_capturer().on_forward_end(
            forward_batch=forward_batch,
            can_run_graph=output.can_run_graph,
            cuda_graph_batch=getattr(self.graph_runner, "bs", None),
        )

        if self.eplb_manager is not None:
            self.eplb_manager.on_forward_pass_end()

        if dumper.may_enable:
            dumper.step()

        return output

    def _forward_raw(
        self,
        forward_batch: ForwardBatch,
        skip_attn_backend_init: bool,
        pp_proxy_tensors: Optional[PPProxyTensors],
        reinit_attn_backend: bool = False,
        split_forward_count: int = 1,
    ) -> ModelRunnerOutput:
        mode_check = (
            forward_batch.forward_mode.is_cpu_graph
            if self.device == "cpu"
            else forward_batch.forward_mode.is_cuda_graph
        )
        can_run_graph = bool(
            mode_check()
            and self.graph_runner
            and self.graph_runner.can_run(forward_batch)
        )

        if can_run_graph:
            ret = self.graph_runner.replay(
                forward_batch,
                skip_attn_backend_init=skip_attn_backend_init,
                pp_proxy_tensors=pp_proxy_tensors,
            )
            return ModelRunnerOutput(logits_output=ret, can_run_graph=can_run_graph)

        # For MLP sync
        if forward_batch.global_num_tokens_cpu is not None:
            forward_batch.prepare_mlp_sync_batch(self)
        else:
            forward_batch.prepare_attn_tp_scatter_input(self)

        # Normalize num_token_non_padded to be local to this attention TP rank if needed.
        if (
            forward_batch.num_token_non_padded is not None
            and forward_batch.global_num_tokens_gpu is not None
            and require_gathered_buffer(self.server_args)
            and not is_nsa_enable_prefill_cp()
        ):
            forward_batch.adjust_num_token_non_padded_for_attn_tp(
                server_args=self.server_args,
            )

        # Use precomputed SWA cache location
        if forward_batch.out_cache_loc_swa is not None:
            self.token_to_kv_pool.set_swa_loc(forward_batch.out_cache_loc_swa)

        forward_batch.hisparse_coordinator = self.hisparse_coordinator
        if self.hisparse_coordinator is not None:
            self.hisparse_coordinator.num_real_reqs.fill_(forward_batch.batch_size)

        if forward_batch.forward_mode.is_decode():
            ret = self.forward_decode(
                forward_batch,
                skip_attn_backend_init=skip_attn_backend_init,
                pp_proxy_tensors=pp_proxy_tensors,
            )
        elif forward_batch.forward_mode.is_split_prefill():
            ret = self.forward_split_prefill(
                forward_batch,
                reinit_attn_backend=reinit_attn_backend,
                forward_count=split_forward_count,
            )
        elif forward_batch.forward_mode.is_extend(include_draft_extend_v2=True):
            ret, can_run_graph = self.forward_extend(
                forward_batch,
                skip_attn_backend_init=skip_attn_backend_init,
                pp_proxy_tensors=pp_proxy_tensors,
            )
        elif forward_batch.forward_mode.is_idle():
            ret = self.forward_idle(forward_batch, pp_proxy_tensors=pp_proxy_tensors)
        else:
            raise ValueError(f"Invalid forward mode: {forward_batch.forward_mode}")

        if (
            forward_batch.global_num_tokens_cpu is not None
            and self.pp_group.is_last_rank
        ):
            forward_batch.post_forward_mlp_sync_batch(ret)

        return ModelRunnerOutput(logits_output=ret, can_run_graph=can_run_graph)

    def _preprocess_logits(
        self, logits_output: LogitsProcessorOutput, sampling_info: SamplingBatchInfo
    ):
        # NOTE: In overlap mode, the function update_regex_vocab_mask (in sample)
        #       was executed after we processed last batch's results.

        # Calculate logits bias and apply it to next_token_logits.
        sampling_info.update_regex_vocab_mask()
        sampling_info.apply_logits_bias(logits_output.next_token_logits)

        # Release the vocab_mask GPU tensor immediately after it has been applied
        # to the logits. In overlap scheduling, the sampling_info (and its
        # vocab_mask) can be kept alive by the delay_sample_func closure and
        # batch_record_buf until the next iteration, causing a steady VRAM leak
        # when structured output (grammar) is used.
        sampling_info.vocab_mask = None

    def sample(
        self,
        logits_output: LogitsProcessorOutput,
        forward_batch: ForwardBatch,
    ) -> torch.Tensor:
        """Sample and compute logprobs and update logits_output.

        Args:
            logits_output: The logits output from the model forward
            forward_batch: The forward batch that generates logits_output

        Returns:
            A list of next_token_ids
        """
        # For duplex models with multiple output streams.
        if isinstance(logits_output, tuple):
            return torch.stack(
                [self.sample(values, forward_batch) for values in logits_output],
                axis=-1,
            )

        self._preprocess_logits(logits_output, forward_batch.sampling_info)
        # Sample the next tokens
        next_token_ids = self.sampler(
            logits_output,
            forward_batch.sampling_info,
            forward_batch.return_logprob,
            forward_batch.top_logprobs_nums,
            forward_batch.token_ids_logprobs,
            # For prefill, we only use the position of the last token.
            (
                forward_batch.positions
                if forward_batch.forward_mode.is_decode()
                else forward_batch.seq_lens - 1
            ),
        )
        self.maybe_update_ngram_token_table(next_token_ids, forward_batch)
        return next_token_ids

    def compute_logprobs_only(
        self,
        logits_output: LogitsProcessorOutput,
        forward_batch: ForwardBatch,
    ) -> None:
        """
        Compute token_ids_logprobs without performing sampling.

        Optimized path for prefill-only requests that need token_ids_logprobs but don't
        require next token generation. Skips expensive sampling operations
        while still providing requested probability information.

        Args:
            logits_output: The logits output from the model forward
            forward_batch: The forward batch that generates logits_output
        """
        if not forward_batch.token_ids_logprobs:
            return

        # Preprocess logits (same as in sample method)
        self._preprocess_logits(logits_output, forward_batch.sampling_info)

        # Delegate to sampler for logprob-only computation
        # This populates logits_output with requested token probabilities
        self.sampler.compute_logprobs_only(
            logits_output,
            forward_batch.sampling_info,
            forward_batch.return_logprob,
            forward_batch.top_logprobs_nums,
            forward_batch.token_ids_logprobs,
        )

    @property
    def model_is_mrope(self) -> bool:
        """Detect if the model has "mrope" rope_scaling type.
        mrope requires keep "rope_deltas" between prompt and decoding phases."""
        rope_scaling = getattr(
            self.model_config.hf_text_config, "rope_parameters", None
        ) or getattr(self.model_config.hf_text_config, "rope_scaling", {})
        if rope_scaling is None:
            return False
        is_mrope_enabled = "mrope_section" in rope_scaling
        return is_mrope_enabled

    def save_remote_model(self, url: str):
        from sglang.srt.model_loader.loader import RemoteModelLoader

        logger.info(f"Saving model to {url}")
        RemoteModelLoader.save_model(self.model, self.model_config.model_path, url)

    def save_sharded_model(
        self, path: str, pattern: Optional[str] = None, max_size: Optional[int] = None
    ):
        from sglang.srt.model_loader.loader import ShardedStateLoader

        logger.info(
            f"Save sharded model to {path} with pattern {pattern} and max_size {max_size}"
        )
        ShardedStateLoader.save_model(self.model, path, pattern, max_size)

    def check_weights(self, action: str):
        self._weight_checker.handle(action=action)

    def update_weights_from_ipc(self, recv_req):
        """Update weights from IPC for checkpoint-engine integration."""
        try:
            from sglang.srt.checkpoint_engine.checkpoint_engine_worker import (
                SGLangCheckpointEngineWorkerExtensionImpl,
            )

            # Create a worker extension that integrates with SGLang's model
            worker = SGLangCheckpointEngineWorkerExtensionImpl(self)
            worker.update_weights_from_ipc(recv_req.zmq_handles)
            return True, "IPC weight update completed successfully"
        except ImportError as e:
            return False, f"IPC weight update failed: ImportError {e}"
        except Exception as e:
            logger.error(f"IPC weight update failed: {e}")
            return False, str(e)

    def prealloc_symmetric_memory_pool(self):
        # PyTorch mempools never de-fragment memory in OOM scenarios, so we need to pre-allocate a large chunk of memory to limit fragmentation.
        if (
            self.is_draft_worker
            or not self.server_args.enable_symm_mem
            or envs.SGLANG_SYMM_MEM_PREALLOC_GB_SIZE.get() <= 0
        ):
            return

        # Memory allocation is tied to a cuda stream, use the forward stream
        with torch.get_device_module(self.device).stream(self.forward_stream):
            logger.info(
                f"Pre-allocating symmetric memory pool with {envs.SGLANG_SYMM_MEM_PREALLOC_GB_SIZE.get()} GiB"
            )
            with use_symmetric_memory(get_tp_group()):
                torch.empty(
                    (envs.SGLANG_SYMM_MEM_PREALLOC_GB_SIZE.get() * 1024 * 1024 * 1024,),
                    dtype=torch.uint8,
                    device=self.device,
                )


def _model_load_weights_direct(model, named_tensors: List[Tuple[str, torch.Tensor]]):
    params_dict = dict(model.named_parameters())
    for name, tensor in named_tensors:
        default_weight_loader(params_dict[name], tensor)


def _unwrap_tensor(tensor, tp_rank, device):
    if isinstance(tensor, LocalSerializedTensor):
        tensor = tensor.get(tp_rank)
    return tensor.to(device)


@dataclass
class LocalSerializedTensor:
    """torch.Tensor that gets serialized by MultiprocessingSerializer (which only serializes a pointer and not the data).
    The i-th element in the list corresponds to i-th rank's GPU."""

    values: List[bytes]

    def get(self, rank: int):
        return MultiprocessingSerializer.deserialize(self.values[rank])
