feat(remote_model): support variable remote backend for model loader (#3964)

Signed-off-by: wangyu <wangyu.steph@bytedance.com>

examples/runtime/engine/save_remote_state.py

+# SPDX-License-Identifier: Apache-2.0
+"""
+Saves each worker's model state dict directly to a checkpoint, which enables a
+fast load path for large tensor-parallel models where each worker only needs to
+read its own shard rather than the entire checkpoint.
+
+Example usage:
+
+python save_remote_state.py \
+    --model-path /path/to/load \
+    --tensor-parallel-size 8 \
+    --remote-model-save-url [protocol]://[host]:[port]/[model_name] \
+
+Then, the model can be loaded with
+
+llm = Engine(
+    model_path="/path/to/save",
+    --remote-model-url [protocol]://[host]:[port]/[model_name],
+    tensor_parallel_size=8,
+)
+"""
+import dataclasses
+from argparse import ArgumentParser
+from pathlib import Path
+
+from sglang import Engine, ServerArgs
+
+parser = ArgumentParser()
+ServerArgs.add_cli_args(parser)
+
+parser.add_argument(
+    "--remote-model-save-url",
+    required=True,
+    type=str,
+    help="remote address to store model weights",
+)
+
+
+def main(args):
+    engine_args = ServerArgs.from_cli_args(args)
+    model_path = engine_args.model_path
+    if not Path(model_path).is_dir():
+        raise ValueError("model path must be a local directory")
+    # Create LLM instance from arguments
+    llm = Engine(**dataclasses.asdict(engine_args))
+    llm.save_remote_model(url=args.remote_model_save_url)
+
+
+if __name__ == "__main__":
+    args = parser.parse_args()
+    main(args)

examples/runtime/engine/save_sharded_state.py

+# SPDX-License-Identifier: Apache-2.0
+"""
+Saves each worker's model state dict directly to a checkpoint, which enables a
+fast load path for large tensor-parallel models where each worker only needs to
+read its own shard rather than the entire checkpoint.
+
+Example usage:
+
+python save_sharded_state.py \
+    --model-path /path/to/load \
+    --quantization deepspeedfp \
+    --tensor-parallel-size 8 \
+    --output /path/to/save
+
+Then, the model can be loaded with
+
+llm = Engine(
+    model_path="/path/to/save",
+    load_format="sharded_state",
+    quantization="deepspeedfp",
+    tensor_parallel_size=8,
+)
+"""
+import dataclasses
+import os
+import shutil
+from argparse import ArgumentParser
+from pathlib import Path
+
+from sglang import Engine, ServerArgs
+
+parser = ArgumentParser()
+ServerArgs.add_cli_args(parser)
+
+parser.add_argument(
+    "--output", "-o", required=True, type=str, help="path to output checkpoint"
+)
+parser.add_argument(
+    "--file-pattern", type=str, help="string pattern of saved filenames"
+)
+parser.add_argument(
+    "--max-file-size",
+    type=str,
+    default=5 * 1024**3,
+    help="max size (in bytes) of each safetensors file",
+)
+
+
+def main(args):
+    engine_args = ServerArgs.from_cli_args(args)
+    model_path = engine_args.model_path
+    if not Path(model_path).is_dir():
+        raise ValueError("model path must be a local directory")
+    # Create LLM instance from arguments
+    llm = Engine(**dataclasses.asdict(engine_args))
+    Path(args.output).mkdir(exist_ok=True)
+    llm.save_sharded_model(
+        path=args.output, pattern=args.file_pattern, max_size=args.max_file_size
+    )
+
+    # Copy metadata files to output directory
+    for file in os.listdir(model_path):
+        if os.path.splitext(file)[1] not in (".bin", ".pt", ".safetensors"):
+            if os.path.isdir(os.path.join(model_path, file)):
+                shutil.copytree(
+                    os.path.join(model_path, file), os.path.join(args.output, file)
+                )
+            else:
+                shutil.copy(os.path.join(model_path, file), args.output)
+
+
+if __name__ == "__main__":
+    args = parser.parse_args()
+    main(args)

python/sglang/__init__.py

@@ -32,6 +32,7 @@ from sglang.lang.choices import (
 )
 from sglang.utils import LazyImport
 
+ServerArgs = LazyImport("sglang.srt.server_args", "ServerArgs")
 Anthropic = LazyImport("sglang.lang.backend.anthropic", "Anthropic")
 LiteLLM = LazyImport("sglang.lang.backend.litellm", "LiteLLM")
 OpenAI = LazyImport("sglang.lang.backend.openai", "OpenAI")
@@ -67,6 +68,7 @@ __all__ = [
     "greedy_token_selection",
     "token_length_normalized",
     "unconditional_likelihood_normalized",
+    "ServerArgs",
     "Anthropic",
     "LiteLLM",
     "OpenAI",

python/sglang/srt/configs/load_config.py

@@ -22,6 +22,7 @@ class LoadFormat(str, enum.Enum):
     MISTRAL = "mistral"
     LAYERED = "layered"
     JAX = "jax"
+    REMOTE = "remote"
 
 
 @dataclass

python/sglang/srt/configs/model_config.py

@@ -51,13 +51,14 @@ class ModelConfig:
         self.quantization = quantization
 
         # Parse args
+        self.maybe_pull_model_tokenizer_from_remote()
         self.model_override_args = json.loads(model_override_args)
         kwargs = {}
         if override_config_file and override_config_file.strip():
             kwargs["_configuration_file"] = override_config_file.strip()
 
         self.hf_config = get_config(
-            model_path,
+            self.model_path,
             trust_remote_code=trust_remote_code,
             revision=revision,
             model_override_args=self.model_override_args,
@@ -318,6 +319,29 @@ class ModelConfig:
             eos_ids = {eos_ids} if isinstance(eos_ids, int) else set(eos_ids)
         return eos_ids
 
+    def maybe_pull_model_tokenizer_from_remote(self) -> None:
+        """
+        Pull the model config files to a temporary
+        directory in case of remote.
+
+        Args:
+            model: The model name or path.
+
+        """
+        from sglang.srt.connector import create_remote_connector
+        from sglang.srt.utils import is_remote_url
+
+        if is_remote_url(self.model_path):
+            logger.info("Pulling model configs from remote...")
+            # BaseConnector implements __del__() to clean up the local dir.
+            # Since config files need to exist all the time, so we DO NOT use
+            # with statement to avoid closing the client.
+            client = create_remote_connector(self.model_path)
+            if is_remote_url(self.model_path):
+                client.pull_files(allow_pattern=["*config.json"])
+                self.model_weights = self.model_path
+                self.model_path = client.get_local_dir()
+
 
 def get_hf_text_config(config: PretrainedConfig):
     """Get the "sub" config relevant to llm for multi modal models.

python/sglang/srt/connector/__init__.py

+# SPDX-License-Identifier: Apache-2.0
+
+import enum
+import logging
+
+from sglang.srt.connector.base_connector import (
+    BaseConnector,
+    BaseFileConnector,
+    BaseKVConnector,
+)
+from sglang.srt.connector.redis import RedisConnector
+from sglang.srt.connector.s3 import S3Connector
+from sglang.srt.utils import parse_connector_type
+
+logger = logging.getLogger(__name__)
+
+
+class ConnectorType(str, enum.Enum):
+    FS = "filesystem"
+    KV = "KV"
+
+
+def create_remote_connector(url, device="cpu") -> BaseConnector:
+    connector_type = parse_connector_type(url)
+    if connector_type == "redis":
+        return RedisConnector(url)
+    elif connector_type == "s3":
+        return S3Connector(url)
+    else:
+        raise ValueError(f"Invalid connector type: {url}")
+
+
+def get_connector_type(client: BaseConnector) -> ConnectorType:
+    if isinstance(client, BaseKVConnector):
+        return ConnectorType.KV
+    if isinstance(client, BaseFileConnector):
+        return ConnectorType.FS
+
+    raise ValueError(f"Invalid connector type: {client}")
+
+
+__all__ = [
+    "BaseConnector",
+    "BaseFileConnector",
+    "BaseKVConnector",
+    "RedisConnector",
+    "S3Connector",
+    "ConnectorType",
+    "create_remote_connector",
+    "get_connector_type",
+]

python/sglang/srt/connector/base_connector.py

+# SPDX-License-Identifier: Apache-2.0
+
+import os
+import shutil
+import signal
+import tempfile
+from abc import ABC, abstractmethod
+from typing import Generator, List, Optional, Tuple
+
+import torch
+
+
+class BaseConnector(ABC):
+    """
+    For fs connector such as s3:
+    <connector_type>://<path>/<filename>
+
+    For kv connector such as redis:
+    <connector_type>://<host>:<port>/<model_name>/keys/<key>
+    <connector_type://<host>:<port>/<model_name>/files/<filename>
+    """
+
+    def __init__(self, url: str, device: torch.device = "cpu"):
+        self.url = url
+        self.device = device
+        self.closed = False
+        self.local_dir = tempfile.mkdtemp()
+        for sig in (signal.SIGINT, signal.SIGTERM):
+            existing_handler = signal.getsignal(sig)
+            signal.signal(sig, self._close_by_signal(existing_handler))
+
+    def get_local_dir(self):
+        return self.local_dir
+
+    @abstractmethod
+    def weight_iterator(
+        self, rank: int = 0
+    ) -> Generator[Tuple[str, torch.Tensor], None, None]:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def pull_files(
+        self,
+        allow_pattern: Optional[List[str]] = None,
+        ignore_pattern: Optional[List[str]] = None,
+    ) -> None:
+        raise NotImplementedError()
+
+    def close(self):
+        if self.closed:
+            return
+
+        self.closed = True
+        if os.path.exists(self.local_dir):
+            shutil.rmtree(self.local_dir)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.close()
+
+    def __del__(self):
+        self.close()
+
+    def _close_by_signal(self, existing_handler=None):
+
+        def new_handler(signum, frame):
+            self.close()
+            if existing_handler:
+                existing_handler(signum, frame)
+
+        return new_handler
+
+
+class BaseKVConnector(BaseConnector):
+
+    @abstractmethod
+    def get(self, key: str) -> Optional[torch.Tensor]:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def getstr(self, key: str) -> Optional[str]:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def set(self, key: str, obj: torch.Tensor) -> None:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def setstr(self, key: str, obj: str) -> None:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def list(self, prefix: str) -> List[str]:
+        raise NotImplementedError()
+
+
+class BaseFileConnector(BaseConnector):
+    """
+    List full file names from remote fs path and filter by allow pattern.
+
+    Args:
+        allow_pattern: A list of patterns of which files to pull.
+
+    Returns:
+        list[str]: List of full paths allowed by the pattern
+    """
+
+    @abstractmethod
+    def glob(self, allow_pattern: str) -> List[str]:
+        raise NotImplementedError()

python/sglang/srt/connector/redis.py

+# SPDX-License-Identifier: Apache-2.0
+
+import logging
+from typing import Generator, List, Optional, Tuple
+from urllib.parse import urlparse
+
+import torch
+
+from sglang.srt.connector import BaseKVConnector
+from sglang.srt.connector.serde import create_serde
+from sglang.srt.connector.utils import pull_files_from_db
+
+logger = logging.getLogger(__name__)
+
+
+class RedisConnector(BaseKVConnector):
+
+    def __init__(self, url: str, device: torch.device = "cpu"):
+        import redis
+
+        super().__init__(url, device)
+        parsed_url = urlparse(url)
+        self.connection = redis.Redis(host=parsed_url.hostname, port=parsed_url.port)
+        self.model_name = parsed_url.path.lstrip("/")
+        # TODO: more serde options
+        self.s, self.d = create_serde("safe")
+
+    def get(self, key: str) -> Optional[torch.Tensor]:
+        val = self.connection.get(key)
+
+        if val is None:
+            logger.error("Key %s not found", key)
+            return None
+
+        return self.d.from_bytes(val)
+
+    def getstr(self, key: str) -> Optional[str]:
+        val = self.connection.get(key)
+        if val is None:
+            logger.error("Key %s not found", key)
+            return None
+
+        return val.decode("utf-8")
+
+    def set(self, key: str, tensor: torch.Tensor) -> None:
+        assert tensor is not None
+        self.connection.set(key, self.s.to_bytes(tensor))
+
+    def setstr(self, key: str, obj: str) -> None:
+        self.connection.set(key, obj)
+
+    def list(self, prefix: str) -> List[str]:
+        cursor = 0
+        all_keys: List[bytes] = []
+
+        while True:
+            ret: Tuple[int, List[bytes]] = self.connection.scan(
+                cursor=cursor, match=f"{prefix}*"
+            )  # type: ignore
+            cursor, keys = ret
+            all_keys.extend(keys)
+            if cursor == 0:
+                break
+
+        return [key.decode("utf-8") for key in all_keys]
+
+    def weight_iterator(
+        self, rank: int = 0
+    ) -> Generator[Tuple[str, bytes], None, None]:
+        keys = self.list(f"{self.model_name}/keys/rank_{rank}/")
+        for key in keys:
+            val = self.get(key)
+            key = key.removeprefix(f"{self.model_name}/keys/rank_{rank}/")
+            yield key, val
+
+    def pull_files(
+        self,
+        allow_pattern: Optional[List[str]] = None,
+        ignore_pattern: Optional[List[str]] = None,
+    ) -> None:
+        pull_files_from_db(self, self.model_name, allow_pattern, ignore_pattern)
+
+    def close(self):
+        self.connection.close()
+        super().close()

python/sglang/srt/connector/s3.py

+# SPDX-License-Identifier: Apache-2.0
+
+import fnmatch
+import os
+from pathlib import Path
+from typing import Generator, Optional, Tuple
+
+import torch
+
+from sglang.srt.connector import BaseFileConnector
+
+
+def _filter_allow(paths: list[str], patterns: list[str]) -> list[str]:
+    return [
+        path
+        for path in paths
+        if any(fnmatch.fnmatch(path, pattern) for pattern in patterns)
+    ]
+
+
+def _filter_ignore(paths: list[str], patterns: list[str]) -> list[str]:
+    return [
+        path
+        for path in paths
+        if not any(fnmatch.fnmatch(path, pattern) for pattern in patterns)
+    ]
+
+
+def list_files(
+    s3,
+    path: str,
+    allow_pattern: Optional[list[str]] = None,
+    ignore_pattern: Optional[list[str]] = None,
+) -> tuple[str, str, list[str]]:
+    """
+    List files from S3 path and filter by pattern.
+
+    Args:
+        s3: S3 client to use.
+        path: The S3 path to list from.
+        allow_pattern: A list of patterns of which files to pull.
+        ignore_pattern: A list of patterns of which files not to pull.
+
+    Returns:
+        tuple[str, str, list[str]]: A tuple where:
+            - The first element is the bucket name
+            - The second element is string represent the bucket
+              and the prefix as a dir like string
+            - The third element is a list of files allowed or
+              disallowed by pattern
+    """
+    parts = path.removeprefix("s3://").split("/")
+    prefix = "/".join(parts[1:])
+    bucket_name = parts[0]
+
+    objects = s3.list_objects_v2(Bucket=bucket_name, Prefix=prefix)
+    paths = [obj["Key"] for obj in objects.get("Contents", [])]
+
+    paths = _filter_ignore(paths, ["*/"])
+    if allow_pattern is not None:
+        paths = _filter_allow(paths, allow_pattern)
+
+    if ignore_pattern is not None:
+        paths = _filter_ignore(paths, ignore_pattern)
+
+    return bucket_name, prefix, paths
+
+
+class S3Connector(BaseFileConnector):
+
+    def __init__(self, url: str) -> None:
+        import boto3
+
+        super().__init__(url)
+        self.client = boto3.client("s3")
+
+    def glob(self, allow_pattern: Optional[list[str]] = None) -> list[str]:
+        bucket_name, _, paths = list_files(
+            self.client, path=self.url, allow_pattern=allow_pattern
+        )
+        return [f"s3://{bucket_name}/{path}" for path in paths]
+
+    def pull_files(
+        self,
+        allow_pattern: Optional[list[str]] = None,
+        ignore_pattern: Optional[list[str]] = None,
+    ) -> None:
+        """
+        Pull files from S3 storage into the temporary directory.
+
+        Args:
+            s3_model_path: The S3 path of the model.
+            allow_pattern: A list of patterns of which files to pull.
+            ignore_pattern: A list of patterns of which files not to pull.
+
+        """
+        bucket_name, base_dir, files = list_files(
+            self.client, self.url, allow_pattern, ignore_pattern
+        )
+        if len(files) == 0:
+            return
+
+        for file in files:
+            destination_file = os.path.join(self.local_dir, file.removeprefix(base_dir))
+            local_dir = Path(destination_file).parent
+            os.makedirs(local_dir, exist_ok=True)
+            self.client.download_file(bucket_name, file, destination_file)
+
+    def weight_iterator(
+        self, rank: int = 0
+    ) -> Generator[Tuple[str, torch.Tensor], None, None]:
+        from sglang.srt.model_loader.weight_utils import (
+            runai_safetensors_weights_iterator,
+        )
+
+        # only support safetensor files now
+        hf_weights_files = self.glob(allow_pattern=["*.safetensors"])
+        return runai_safetensors_weights_iterator(hf_weights_files)
+
+    def close(self):
+        self.client.close()
+        super().close()

python/sglang/srt/connector/serde/__init__.py

+# SPDX-License-Identifier: Apache-2.0
+
+# inspired by LMCache
+from typing import Optional, Tuple
+
+import torch
+
+from sglang.srt.connector.serde.safe_serde import SafeDeserializer, SafeSerializer
+from sglang.srt.connector.serde.serde import Deserializer, Serializer
+
+
+def create_serde(serde_type: str) -> Tuple[Serializer, Deserializer]:
+    s: Optional[Serializer] = None
+    d: Optional[Deserializer] = None
+
+    if serde_type == "safe":
+        s = SafeSerializer()
+        d = SafeDeserializer(torch.uint8)
+    else:
+        raise ValueError(f"Unknown serde type: {serde_type}")
+
+    return s, d
+
+
+__all__ = [
+    "Serializer",
+    "Deserializer",
+    "SafeSerializer",
+    "SafeDeserializer",
+    "create_serde",
+]

python/sglang/srt/connector/serde/safe_serde.py

+# SPDX-License-Identifier: Apache-2.0
+
+from typing import Union
+
+import torch
+from safetensors.torch import load, save
+
+from sglang.srt.connector.serde.serde import Deserializer, Serializer
+
+
+class SafeSerializer(Serializer):
+
+    def __init__(self):
+        super().__init__()
+
+    def to_bytes(self, t: torch.Tensor) -> bytes:
+        return save({"tensor_bytes": t.cpu().contiguous()})
+
+
+class SafeDeserializer(Deserializer):
+
+    def __init__(self, dtype):
+        super().__init__(dtype)
+
+    def from_bytes_normal(self, b: Union[bytearray, bytes]) -> torch.Tensor:
+        return load(bytes(b))["tensor_bytes"].to(dtype=self.dtype)
+
+    def from_bytes(self, b: Union[bytearray, bytes]) -> torch.Tensor:
+        return self.from_bytes_normal(b)

python/sglang/srt/connector/serde/serde.py

+# SPDX-License-Identifier: Apache-2.0
+
+import abc
+from abc import ABC, abstractmethod
+
+import torch
+
+
+class Serializer(ABC):
+
+    @abstractmethod
+    def to_bytes(self, t: torch.Tensor) -> bytes:
+        """
+        Serialize a pytorch tensor to bytes. The serialized bytes should contain
+        both the data and the metadata (shape, dtype, etc.) of the tensor.
+
+        Input:
+            t: the input pytorch tensor, can be on any device, in any shape,
+               with any dtype
+
+        Returns:
+            bytes: the serialized bytes
+        """
+        raise NotImplementedError
+
+
+class Deserializer(metaclass=abc.ABCMeta):
+
+    def __init__(self, dtype):
+        self.dtype = dtype
+
+    @abstractmethod
+    def from_bytes(self, bs: bytes) -> torch.Tensor:
+        """
+        Deserialize a pytorch tensor from bytes.
+
+        Input:
+            bytes: a stream of bytes
+
+        Output:
+            torch.Tensor: the deserialized pytorch tensor
+        """
+        raise NotImplementedError

python/sglang/srt/connector/utils.py

+# SPDX-License-Identifier: Apache-2.0
+
+import os
+from pathlib import Path
+from typing import Optional
+from urllib.parse import urlparse
+
+from sglang.srt.connector import BaseConnector
+
+
+def parse_model_name(url: str) -> str:
+    """
+    Parse the model name from the url.
+    Only used for db connector
+    """
+    parsed_url = urlparse(url)
+    return parsed_url.path.lstrip("/")
+
+
+def pull_files_from_db(
+    connector: BaseConnector,
+    model_name: str,
+    allow_pattern: Optional[list[str]] = None,
+    ignore_pattern: Optional[list[str]] = None,
+) -> None:
+    prefix = f"{model_name}/files/"
+    local_dir = connector.get_local_dir()
+    files = connector.list(prefix)
+
+    for file in files:
+        destination_file = os.path.join(local_dir, file.removeprefix(prefix))
+        local_dir = Path(destination_file).parent
+        os.makedirs(local_dir, exist_ok=True)
+        with open(destination_file, "wb") as f:
+            f.write(connector.getstr(file).encode("utf-8"))

python/sglang/srt/entrypoints/engine.py

@@ -27,6 +27,9 @@ import signal
 import threading
 from typing import AsyncIterator, Dict, Iterator, List, Optional, Tuple, Union
 
+import zmq
+import zmq.asyncio
+
 # Fix a bug of Python threading
 setattr(threading, "_register_atexit", lambda *args, **kwargs: None)
 
@@ -44,6 +47,8 @@ from sglang.srt.managers.io_struct import (
     InitWeightsUpdateGroupReqInput,
     ReleaseMemoryOccupationReqInput,
     ResumeMemoryOccupationReqInput,
+    RpcReqInput,
+    RpcReqOutput,
     UpdateWeightFromDiskReqInput,
     UpdateWeightsFromDistributedReqInput,
     UpdateWeightsFromTensorReqInput,
@@ -57,6 +62,7 @@ from sglang.srt.utils import (
     MultiprocessingSerializer,
     assert_pkg_version,
     configure_logger,
+    get_zmq_socket,
     kill_process_tree,
     launch_dummy_health_check_server,
     maybe_set_triton_cache_manager,
@@ -102,15 +108,25 @@ class Engine:
         # Shutdown the subprocesses automatically when the program exits
         atexit.register(self.shutdown)
 
+        # Allocate ports for inter-process communications
+        port_args = PortArgs.init_new(server_args)
+        logger.info(f"{server_args=}")
+
         # Launch subprocesses
         tokenizer_manager, scheduler_info = _launch_subprocesses(
-            server_args=server_args
+            server_args=server_args,
+            port_args=port_args,
         )
 
         self.server_args = server_args
         self.tokenizer_manager = tokenizer_manager
         self.scheduler_info = scheduler_info
 
+        context = zmq.Context(2)
+        self.send_to_rpc = get_zmq_socket(
+            context, zmq.DEALER, port_args.rpc_ipc_name, True
+        )
+
     def generate(
         self,
         # The input prompt. It can be a single prompt or a batch of prompts.
@@ -350,6 +366,23 @@ class Engine:
             self.tokenizer_manager.resume_memory_occupation(obj, None)
         )
 
+    """
+    Execute an RPC call on all scheduler processes.
+    """
+
+    def collective_rpc(self, method: str, **kwargs):
+        obj = RpcReqInput(method=method, parameters=kwargs)
+        self.send_to_rpc.send_pyobj(obj)
+        recv_req = self.send_to_rpc.recv_pyobj(zmq.BLOCKY)
+        assert isinstance(recv_req, RpcReqOutput)
+        assert recv_req.success, recv_req.message
+
+    def save_remote_model(self, **kwargs):
+        self.collective_rpc("save_remote_model", **kwargs)
+
+    def save_sharded_model(self, **kwargs):
+        self.collective_rpc("save_sharded_model", **kwargs)
+
 
 def _set_envs_and_config(server_args: ServerArgs):
     # Set global environments
@@ -408,7 +441,9 @@ def _set_envs_and_config(server_args: ServerArgs):
     mp.set_start_method("spawn", force=True)
 
 
-def _launch_subprocesses(server_args: ServerArgs) -> Tuple[TokenizerManager, Dict]:
+def _launch_subprocesses(
+    server_args: ServerArgs, port_args: Optional[PortArgs] = None
+) -> Tuple[TokenizerManager, Dict]:
     """
     Launch the TokenizerManager in the main process, the Scheduler in a subprocess, and the DetokenizerManager in another subprocess.
     """
@@ -418,6 +453,7 @@ def _launch_subprocesses(server_args: ServerArgs) -> Tuple[TokenizerManager, Dic
     _set_envs_and_config(server_args)
 
     # Allocate ports for inter-process communications
+    if port_args is None:
         port_args = PortArgs.init_new(server_args)
         logger.info(f"{server_args=}")
 

python/sglang/srt/hf_transformers_utils.py

@@ -37,6 +37,8 @@ from sglang.srt.configs import (
     MultiModalityConfig,
     Qwen2_5_VLConfig,
 )
+from sglang.srt.connector import create_remote_connector
+from sglang.srt.utils import is_remote_url
 
 _CONFIG_REGISTRY: Dict[str, Type[PretrainedConfig]] = {
     ChatGLMConfig.model_type: ChatGLMConfig,
@@ -155,6 +157,14 @@ def get_tokenizer(
         kwargs["gguf_file"] = tokenizer_name
         tokenizer_name = Path(tokenizer_name).parent
 
+    if is_remote_url(tokenizer_name):
+        # BaseConnector implements __del__() to clean up the local dir.
+        # Since config files need to exist all the time, so we DO NOT use
+        # with statement to avoid closing the client.
+        client = create_remote_connector(tokenizer_name)
+        client.pull_files(ignore_pattern=["*.pt", "*.safetensors", "*.bin"])
+        tokenizer_name = client.get_local_dir()
+
     try:
         tokenizer = AutoTokenizer.from_pretrained(
             tokenizer_name,

python/sglang/srt/managers/io_struct.py

@@ -723,3 +723,15 @@ class SeparateReasoningReqInput:
 class VertexGenerateReqInput:
     instances: List[dict]
     parameters: Optional[dict] = None
+
+
+@dataclass
+class RpcReqInput:
+    method: str
+    parameters: Optional[Dict] = None
+
+
+@dataclass
+class RpcReqOutput:
+    success: bool
+    message: str

python/sglang/srt/managers/scheduler.py

@@ -32,6 +32,7 @@ import psutil
 import setproctitle
 import torch
 import zmq
+from torch.distributed import barrier
 
 from sglang.global_config import global_config
 from sglang.srt.configs.model_config import ModelConfig
@@ -59,6 +60,8 @@ from sglang.srt.managers.io_struct import (
     ReleaseMemoryOccupationReqOutput,
     ResumeMemoryOccupationReqInput,
     ResumeMemoryOccupationReqOutput,
+    RpcReqInput,
+    RpcReqOutput,
     SetInternalStateReq,
     SetInternalStateReqOutput,
     TokenizedEmbeddingReqInput,
@@ -193,8 +196,13 @@ class Scheduler(SchedulerOutputProcessorMixin):
                 self.send_to_detokenizer = get_zmq_socket(
                     context, zmq.PUSH, port_args.detokenizer_ipc_name, False
                 )
+
+            self.recv_from_rpc = get_zmq_socket(
+                context, zmq.DEALER, port_args.rpc_ipc_name, False
+            )
         else:
             self.recv_from_tokenizer = None
+            self.recv_from_rpc = None
             self.send_to_tokenizer = SimpleNamespace(send_pyobj=lambda x: None)
             self.send_to_detokenizer = SimpleNamespace(send_pyobj=lambda x: None)
 
@@ -376,6 +384,7 @@ class Scheduler(SchedulerOutputProcessorMixin):
                 (ProfileReq, self.profile),
                 (GetInternalStateReq, self.get_internal_state),
                 (SetInternalStateReq, self.set_internal_state),
+                (RpcReqInput, self.handle_rpc_request),
             ]
         )
 
@@ -549,6 +558,13 @@ class Scheduler(SchedulerOutputProcessorMixin):
                 except zmq.ZMQError:
                     break
                 recv_reqs.append(recv_req)
+
+            while True:
+                try:
+                    recv_rpc = self.recv_from_rpc.recv_pyobj(zmq.NOBLOCK)
+                except zmq.ZMQError:
+                    break
+                recv_reqs.append(recv_rpc)
         else:
             recv_reqs = None
 
@@ -600,6 +616,10 @@ class Scheduler(SchedulerOutputProcessorMixin):
 
             output = self._request_dispatcher(recv_req)
             if output is not None:
+                if isinstance(output, RpcReqOutput):
+                    if self.recv_from_rpc is not None:
+                        self.recv_from_rpc.send_pyobj(output)
+                else:
                     self.send_to_tokenizer.send_pyobj(output)
 
     def handle_generate_request(
@@ -1492,6 +1512,47 @@ class Scheduler(SchedulerOutputProcessorMixin):
             server_args=global_server_args_dict,
         )
 
+    def handle_rpc_request(self, recv_req: RpcReqInput):
+        # Handle RPC requests
+        logger.info(
+            f"handle_rpc_request: {recv_req.method}, param: {recv_req.parameters}"
+        )
+
+        success = True
+        exec = None
+        try:
+            func = getattr(self, recv_req.method)
+            func(recv_req.parameters)
+        except Exception as e:
+            success = False
+            exec = e
+            logger.error(f"Failed to call rpc {recv_req.method}: {str(e)}")
+
+        barrier()
+        return RpcReqOutput(success, "" if not exec else str(exec))
+
+    def save_remote_model(self, params):
+        url = params["url"]
+
+        if isinstance(self.tp_worker, TpModelWorkerClient):
+            worker = self.tp_worker.worker
+        else:
+            worker = self.tp_worker
+
+        worker.model_runner.save_remote_model(url)
+
+    def save_sharded_model(self, params):
+        if isinstance(self.tp_worker, TpModelWorkerClient):
+            worker = self.tp_worker.worker
+        else:
+            worker = self.tp_worker
+
+        worker.model_runner.save_sharded_model(
+            path=params["path"],
+            pattern=params["pattern"],
+            max_size=params["max_size"],
+        )
+
     def abort_request(self, recv_req: AbortReq):
         # Delete requests in the waiting queue
         to_del = []

python/sglang/srt/model_executor/model_runner.py

@@ -1009,6 +1009,22 @@ class ModelRunner:
             return False
         return rope_scaling.get("type", None) == "mrope"
 
+    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 _model_load_weights_direct(model, named_tensors: List[Tuple[str, torch.Tensor]]):
     params_dict = dict(model.named_parameters())

python/sglang/srt/model_loader/loader.py

@@ -9,6 +9,7 @@ import json
 import logging
 import math
 import os
+import time
 from abc import ABC, abstractmethod
 from contextlib import contextmanager
 from typing import Any, Dict, Generator, Iterable, List, Optional, Tuple, cast
@@ -25,6 +26,12 @@ from transformers.utils import SAFE_WEIGHTS_INDEX_NAME
 from sglang.srt.configs.device_config import DeviceConfig
 from sglang.srt.configs.load_config import LoadConfig, LoadFormat
 from sglang.srt.configs.model_config import ModelConfig
+from sglang.srt.connector import (
+    ConnectorType,
+    create_remote_connector,
+    get_connector_type,
+)
+from sglang.srt.connector.utils import parse_model_name
 from sglang.srt.distributed import (
     get_tensor_model_parallel_rank,
     get_tensor_model_parallel_world_size,
@@ -46,6 +53,7 @@ from sglang.srt.model_loader.weight_utils import (
     np_cache_weights_iterator,
     pt_weights_iterator,
     safetensors_weights_iterator,
+    set_runai_streamer_env,
 )
 from sglang.srt.utils import (
     get_bool_env_var,
@@ -490,7 +498,7 @@ class ShardedStateLoader(BaseModelLoader):
     Model loader that directly loads each worker's model state dict, which
     enables a fast load path for large tensor-parallel models where each worker
     only needs to read its own shard rather than the entire checkpoint. See
-    `examples/save_sharded_state.py` for creating a sharded checkpoint.
+    `examples/runtime/engine/save_sharded_state.py` for creating a sharded checkpoint.
     """
 
     DEFAULT_PATTERN = "model-rank-{rank}-part-{part}.safetensors"
@@ -1204,6 +1212,153 @@ class GGUFModelLoader(BaseModelLoader):
         return model
 
 
+class RemoteModelLoader(BaseModelLoader):
+    """Model loader that can load Tensors from remote database."""
+
+    def __init__(self, load_config: LoadConfig):
+        super().__init__(load_config)
+        # TODO @DellCurry: move to s3 connector only
+        set_runai_streamer_env(load_config)
+
+    def _get_weights_iterator_kv(
+        self,
+        client,
+    ) -> Generator[Tuple[str, torch.Tensor], None, None]:
+        """Get an iterator for the model weights from remote storage."""
+        assert get_connector_type(client) == ConnectorType.KV
+        rank = get_tensor_model_parallel_rank()
+        return client.weight_iterator(rank)
+
+    def _get_weights_iterator_fs(
+        self,
+        client,
+    ) -> Generator[Tuple[str, torch.Tensor], None, None]:
+        """Get an iterator for the model weights from remote storage."""
+        assert get_connector_type(client) == ConnectorType.FS
+        return client.weight_iterator()
+
+    def download_model(self, model_config: ModelConfig) -> None:
+        pass
+
+    @staticmethod
+    def save_model(
+        model: torch.nn.Module,
+        model_path: str,
+        url: str,
+    ) -> None:
+        with create_remote_connector(url) as client:
+            assert get_connector_type(client) == ConnectorType.KV
+            model_name = parse_model_name(url)
+            rank = get_tensor_model_parallel_rank()
+            state_dict = ShardedStateLoader._filter_subtensors(model.state_dict())
+            for key, tensor in state_dict.items():
+                r_key = f"{model_name}/keys/rank_{rank}/{key}"
+                client.set(r_key, tensor)
+
+            for root, _, files in os.walk(model_path):
+                for file_name in files:
+                    # ignore hidden files
+                    if file_name.startswith("."):
+                        continue
+                    if os.path.splitext(file_name)[1] not in (
+                        ".bin",
+                        ".pt",
+                        ".safetensors",
+                    ):
+                        file_path = os.path.join(root, file_name)
+                        with open(file_path, encoding="utf-8") as file:
+                            file_content = file.read()
+                            f_key = f"{model_name}/files/{file_name}"
+                            client.setstr(f_key, file_content)
+
+    def _load_model_from_remote_kv(self, model: nn.Module, client):
+        for _, module in model.named_modules():
+            quant_method = getattr(module, "quant_method", None)
+            if quant_method is not None:
+                quant_method.process_weights_after_loading(module)
+        weights_iterator = self._get_weights_iterator_kv(client)
+        state_dict = ShardedStateLoader._filter_subtensors(model.state_dict())
+        for key, tensor in weights_iterator:
+            # If loading with LoRA enabled, additional padding may
+            # be added to certain parameters. We only load into a
+            # narrowed view of the parameter data.
+            param_data = state_dict[key].data
+            param_shape = state_dict[key].shape
+            for dim, size in enumerate(tensor.shape):
+                if size < param_shape[dim]:
+                    param_data = param_data.narrow(dim, 0, size)
+            if tensor.shape != param_shape:
+                logger.warning(
+                    "loading tensor of shape %s into " "parameter '%s' of shape %s",
+                    tensor.shape,
+                    key,
+                    param_shape,
+                )
+            param_data.copy_(tensor)
+            state_dict.pop(key)
+        if state_dict:
+            raise ValueError(f"Missing keys {tuple(state_dict)} in loaded state!")
+
+    def _load_model_from_remote_fs(
+        self, model, client, model_config: ModelConfig, device_config: DeviceConfig
+    ) -> nn.Module:
+
+        target_device = torch.device(device_config.device)
+        with set_default_torch_dtype(model_config.dtype):
+            model.load_weights(self._get_weights_iterator_fs(client))
+
+            for _, module in model.named_modules():
+                quant_method = getattr(module, "quant_method", None)
+                if quant_method is not None:
+                    # When quant methods need to process weights after loading
+                    # (for repacking, quantizing, etc), they expect parameters
+                    # to be on the global target device. This scope is for the
+                    # case where cpu offloading is used, where we will move the
+                    # parameters onto device for processing and back off after.
+                    with device_loading_context(module, target_device):
+                        quant_method.process_weights_after_loading(module)
+
+    def load_model(
+        self,
+        *,
+        model_config: ModelConfig,
+        device_config: DeviceConfig,
+    ) -> nn.Module:
+        logger.info("Loading weights from remote storage ...")
+        start = time.perf_counter()
+        load_config = self.load_config
+
+        assert load_config.load_format == LoadFormat.REMOTE, (
+            f"Model loader {self.load_config.load_format} is not supported for "
+            f"load format {load_config.load_format}"
+        )
+
+        model_weights = model_config.model_path
+        if hasattr(model_config, "model_weights"):
+            model_weights = model_config.model_weights
+
+        with set_default_torch_dtype(model_config.dtype):
+            with torch.device(device_config.device):
+                model = _initialize_model(model_config, self.load_config)
+                for _, module in model.named_modules():
+                    quant_method = getattr(module, "quant_method", None)
+                    if quant_method is not None:
+                        quant_method.process_weights_after_loading(module)
+
+            with create_remote_connector(model_weights, device_config.device) as client:
+                connector_type = get_connector_type(client)
+                if connector_type == ConnectorType.KV:
+                    self._load_model_from_remote_kv(model, client)
+                elif connector_type == ConnectorType.FS:
+                    self._load_model_from_remote_fs(
+                        model, client, model_config, device_config
+                    )
+
+        end = time.perf_counter()
+        logger.info("Loaded weights from remote storage in %.2f seconds.", end - start)
+        return model.eval()
+
+
 def get_model_loader(load_config: LoadConfig) -> BaseModelLoader:
     """Get a model loader based on the load format."""
 
@@ -1225,4 +1380,7 @@ def get_model_loader(load_config: LoadConfig) -> BaseModelLoader:
     if load_config.load_format == LoadFormat.LAYERED:
         return LayeredModelLoader(load_config)
 
+    if load_config.load_format == LoadFormat.REMOTE:
+        return RemoteModelLoader(load_config)
+
     return DefaultModelLoader(load_config)

python/sglang/srt/model_loader/weight_utils.py

@@ -585,6 +585,51 @@ def composed_weight_loader(
     return composed_loader
 
 
+def runai_safetensors_weights_iterator(
+    hf_weights_files: List[str],
+) -> Generator[Tuple[str, torch.Tensor], None, None]:
+    """Iterate over the weights in the model safetensor files."""
+    from runai_model_streamer import SafetensorsStreamer
+
+    enable_tqdm = (
+        not torch.distributed.is_initialized() or torch.distributed.get_rank() == 0
+    )
+
+    with SafetensorsStreamer() as streamer:
+        for st_file in tqdm(
+            hf_weights_files,
+            desc="Loading safetensors using Runai Model Streamer",
+            disable=not enable_tqdm,
+            bar_format=_BAR_FORMAT,
+        ):
+            streamer.stream_file(st_file)
+            yield from streamer.get_tensors()
+
+
+def set_runai_streamer_env(load_config: LoadConfig):
+    if load_config.model_loader_extra_config:
+        extra_config = load_config.model_loader_extra_config
+
+        if "concurrency" in extra_config and isinstance(
+            extra_config.get("concurrency"), int
+        ):
+            os.environ["RUNAI_STREAMER_CONCURRENCY"] = str(
+                extra_config.get("concurrency")
+            )
+
+        if "memory_limit" in extra_config and isinstance(
+            extra_config.get("memory_limit"), int
+        ):
+            os.environ["RUNAI_STREAMER_MEMORY_LIMIT"] = str(
+                extra_config.get("memory_limit")
+            )
+
+    runai_streamer_s3_endpoint = os.getenv("RUNAI_STREAMER_S3_ENDPOINT")
+    aws_endpoint_url = os.getenv("AWS_ENDPOINT_URL")
+    if runai_streamer_s3_endpoint is None and aws_endpoint_url is not None:
+        os.environ["RUNAI_STREAMER_S3_ENDPOINT"] = aws_endpoint_url
+
+
 def initialize_dummy_weights(
     model: torch.nn.Module,
     low: float = -1e-3,