Support precomputed multimodal features for Qwen-VL and Gemma3 models. (#6136)

Co-authored-by: Yury Sulsky <ysulsky@tesla.com>

docs/backend/vlm_query.ipynb

+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "0",
+   "metadata": {},
+   "source": [
+    "# Querying Qwen-VL"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "1",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import nest_asyncio\n",
+    "\n",
+    "nest_asyncio.apply()  # Run this first.\n",
+    "\n",
+    "model_path = \"Qwen/Qwen2.5-VL-3B-Instruct\"\n",
+    "chat_template = \"qwen2-vl\""
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "2",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Lets create a prompt.\n",
+    "\n",
+    "from io import BytesIO\n",
+    "import requests\n",
+    "from PIL import Image\n",
+    "\n",
+    "from sglang.srt.openai_api.protocol import ChatCompletionRequest\n",
+    "from sglang.srt.conversation import chat_templates\n",
+    "\n",
+    "image = Image.open(\n",
+    "    BytesIO(\n",
+    "        requests.get(\n",
+    "            \"https://github.com/sgl-project/sglang/blob/main/test/lang/example_image.png?raw=true\"\n",
+    "        ).content\n",
+    "    )\n",
+    ")\n",
+    "\n",
+    "conv = chat_templates[chat_template].copy()\n",
+    "conv.append_message(conv.roles[0], f\"What's shown here: {conv.image_token}?\")\n",
+    "conv.append_message(conv.roles[1], \"\")\n",
+    "conv.image_data = [image]\n",
+    "\n",
+    "print(conv.get_prompt())\n",
+    "image"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "3",
+   "metadata": {},
+   "source": [
+    "## Query via the offline Engine API"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "4",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from sglang import Engine\n",
+    "\n",
+    "llm = Engine(\n",
+    "    model_path=model_path, chat_template=chat_template, mem_fraction_static=0.8\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "5",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "out = llm.generate(prompt=conv.get_prompt(), image_data=[image])\n",
+    "print(out[\"text\"])"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "6",
+   "metadata": {},
+   "source": [
+    "## Query via the offline Engine API, but send precomputed embeddings"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "7",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Compute the image embeddings using Huggingface.\n",
+    "\n",
+    "from transformers import AutoProcessor\n",
+    "from transformers import Qwen2_5_VLForConditionalGeneration\n",
+    "\n",
+    "processor = AutoProcessor.from_pretrained(model_path, use_fast=True)\n",
+    "vision = (\n",
+    "    Qwen2_5_VLForConditionalGeneration.from_pretrained(model_path).eval().visual.cuda()\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "8",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "processed_prompt = processor(\n",
+    "    images=[image], text=conv.get_prompt(), return_tensors=\"pt\"\n",
+    ")\n",
+    "input_ids = processed_prompt[\"input_ids\"][0].detach().cpu().tolist()\n",
+    "precomputed_features = vision(\n",
+    "    processed_prompt[\"pixel_values\"].cuda(), processed_prompt[\"image_grid_thw\"].cuda()\n",
+    ")\n",
+    "\n",
+    "mm_item = dict(\n",
+    "    modality=\"IMAGE\",\n",
+    "    image_grid_thws=processed_prompt[\"image_grid_thw\"],\n",
+    "    precomputed_features=precomputed_features,\n",
+    ")\n",
+    "out = llm.generate(input_ids=input_ids, image_data=[mm_item])\n",
+    "print(out[\"text\"])"
+   ]
+  }
+ ],
+ "metadata": {
+  "jupytext": {
+   "cell_metadata_filter": "-all",
+   "custom_cell_magics": "kql",
+   "encoding": "# -*- coding: utf-8 -*-"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

python/sglang/srt/entrypoints/engine.py

@@ -47,6 +47,7 @@ from sglang.srt.managers.io_struct import (
     EmbeddingReqInput,
     GenerateReqInput,
     GetWeightsByNameReqInput,
+    ImageDataItem,
     InitWeightsUpdateGroupReqInput,
     ReleaseMemoryOccupationReqInput,
     ResumeMemoryOccupationReqInput,
@@ -150,9 +151,9 @@ class Engine(EngineBase):
         # See also python/sglang/srt/utils.py:load_image for more details.
         image_data: Optional[
             Union[
-                List[List[Union[Image, str]]],
-                List[Union[Image, str]],
-                Union[Image, str],
+                List[List[ImageDataItem]],
+                List[ImageDataItem],
+                ImageDataItem,
             ]
         ] = None,
         return_logprob: Optional[Union[List[bool], bool]] = False,
@@ -221,9 +222,9 @@ class Engine(EngineBase):
         # See also python/sglang/srt/utils.py:load_image for more details.
         image_data: Optional[
             Union[
-                List[List[Union[Image, str]]],
-                List[Union[Image, str]],
-                Union[Image, str],
+                List[List[ImageDataItem]],
+                List[ImageDataItem],
+                ImageDataItem,
             ]
         ] = None,
         return_logprob: Optional[Union[List[bool], bool]] = False,

python/sglang/srt/managers/io_struct.py

@@ -40,6 +40,10 @@ class SessionParams:
     replace: Optional[bool] = None
 
 
+AudioDataItem = Union[str, Dict]
+ImageDataItem = Union[Image, str, Dict]
+
+
 @dataclass
 class GenerateReqInput:
     # The input prompt. It can be a single prompt or a batch of prompts.
@@ -55,10 +59,10 @@ class GenerateReqInput:
     # - List of lists of images (multiple images per request)
     # See also python/sglang/srt/utils.py:load_image for more details.
     image_data: Optional[
-        Union[List[List[Union[Image, str]]], List[Union[Image, str]], Union[Image, str]]
+        Union[List[List[ImageDataItem]], List[ImageDataItem], ImageDataItem]
     ] = None
     # The audio input. Like image data, it can be a file name, a url, or base64 encoded string.
-    audio_data: Optional[Union[List[str], str]] = None
+    audio_data: Optional[Union[List[AudioDataItem], AudioDataItem]] = None
     # The sampling_params. See descriptions below.
     sampling_params: Optional[Union[List[Dict], Dict]] = None
     # The request id.

python/sglang/srt/managers/mm_utils.py

@@ -368,13 +368,13 @@ def general_mm_embed_routine(
     input_ids: torch.Tensor,
     forward_batch: ForwardBatch,
     language_model: nn.Module,
-    image_data_embedding_func: Callable[
-        [List[MultimodalDataItem]], torch.Tensor
+    image_data_embedding_func: Optional[
+        Callable[[List[MultimodalDataItem]], torch.Tensor]
     ] = None,
-    audio_data_embedding_func: Callable[
-        [List[MultimodalDataItem]], torch.Tensor
+    audio_data_embedding_func: Optional[
+        Callable[[List[MultimodalDataItem]], torch.Tensor]
     ] = None,
-    placeholder_tokens: dict[Modality, List[int]] = None,
+    placeholder_tokens: Optional[dict[Modality, List[int]]] = None,
     **kwargs,
 ) -> torch.Tensor:
     """
@@ -389,7 +389,6 @@ def general_mm_embed_routine(
             forwarded hidden states
 
     """
-
     assert hasattr(language_model, "get_input_embeddings")
     embed_tokens = language_model.get_input_embeddings()
     if (

python/sglang/srt/managers/multimodal_processors/base_processor.py

@@ -3,16 +3,16 @@ import concurrent.futures
 import dataclasses
 import multiprocessing as mp
 import os
+import re
 from abc import ABC, abstractmethod
-from typing import List, Optional
+from typing import List, Optional, Union
 
 import numpy as np
-import PIL
 import torch
 from PIL import Image
 from transformers import BaseImageProcessorFast
 
-from sglang.srt.managers.schedule_batch import Modality
+from sglang.srt.managers.schedule_batch import Modality, MultimodalDataItem
 from sglang.srt.utils import encode_video, load_audio, load_image
 
 
@@ -22,13 +22,13 @@ class BaseMultiModalProcessorOutput:
     input_text: str
 
     # frames loaded from image and video, in given order
-    images: Optional[list[PIL.Image]] = None
+    images: Optional[list[Union[Image.Image, MultimodalDataItem]]] = None
 
     # audios
-    audios: Optional[list[np.ndarray]] = None
+    audios: Optional[list[Union[np.ndarray, MultimodalDataItem]]] = None
 
     def normalize(self):
-        for field_name in ["image_sizes", "images", "audios"]:
+        for field_name in ["images", "audios"]:
             field = getattr(self, field_name, None)
             if field is not None and isinstance(field, list) and len(field) == 0:
                 setattr(self, field_name, None)
@@ -40,12 +40,32 @@ class MultimodalSpecialTokens:
     video_token: Optional[str] = None
     audio_token: Optional[str] = None
 
-    def collect(self) -> list[str]:
-        return [
-            token
-            for token in [self.image_token, self.video_token, self.audio_token]
-            if token
+    image_token_regex: Optional[re.Pattern] = None
+    video_token_regex: Optional[re.Pattern] = None
+    audio_token_regex: Optional[re.Pattern] = None
+
+    def __post_init__(self):
+        if self.image_token_regex is None and self.image_token is not None:
+            self.image_token_regex = re.compile(re.escape(self.image_token))
+        if self.video_token_regex is None and self.video_token is not None:
+            self.video_token_regex = re.compile(re.escape(self.video_token))
+        if self.audio_token_regex is None and self.audio_token is not None:
+            self.audio_token_regex = re.compile(re.escape(self.audio_token))
+
+    def collect(self) -> re.Pattern:
+        tokens = [
+            self.image_token_regex,
+            self.video_token_regex,
+            self.audio_token_regex,
         ]
+        patterns = []
+        flags = 0
+        for t in tokens:
+            if t is not None:
+                patterns.append(t.pattern)
+                flags |= t.flags
+        combined = "(" + "|".join(f"(?:{p})" for p in patterns) + ")"
+        return re.compile(combined, flags)
 
 
 class BaseMultimodalProcessor(ABC):
@@ -136,6 +156,10 @@ class BaseMultimodalProcessor(ABC):
         data, is_video, is_audio, frame_count_limit=None, discard_alpha_channel=True
     ):
         """Static method that can be pickled for multiprocessing"""
+        if isinstance(data, dict):
+            return MultimodalDataItem.from_dict(data)
+        if isinstance(data, MultimodalDataItem):
+            return data
         try:
             if is_audio:
                 return load_audio(data)
@@ -175,7 +199,10 @@ class BaseMultimodalProcessor(ABC):
         image_index, audio_index = 0, 0
 
         for text_part in text_parts:
-            if text_part == multimodal_tokens.image_token:
+            if (
+                multimodal_tokens.image_token_regex
+                and multimodal_tokens.image_token_regex.match(text_part)
+            ):
                 data = image_data[image_index]
                 is_video = isinstance(data, str) and data.startswith("video:")
                 estimated_frames = estimated_frames_list[image_index]
@@ -192,7 +219,10 @@ class BaseMultimodalProcessor(ABC):
                 )
                 task_info.append((Modality.IMAGE, data, frame_count_limit))
                 image_index += 1
-            elif text_part == multimodal_tokens.audio_token:
+            elif (
+                multimodal_tokens.audio_token_regex
+                and multimodal_tokens.audio_token_regex.match(text_part)
+            ):
                 data = audio_data[audio_index]
                 futures.append(
                     self.io_executor.submit(
@@ -228,17 +258,22 @@ class BaseMultimodalProcessor(ABC):
             discard_alpha_channel: if True, discards the alpha channel in the returned images
 
         """
+        if not return_text:
+            raise NotImplementedError()
 
         if image_data is None:
             image_data = []
         if isinstance(multimodal_tokens.image_token, int):
-            multimodal_tokens.image_token = (
+            multimodal_tokens.image_token = re.compile(
+                re.escape(
                     self._processor.tokenizer.convert_ids_to_tokens(
                         multimodal_tokens.image_token
                     )
                 )
+            )
         else:
             multimodal_tokens.image_token = multimodal_tokens.image_token
+        multimodal_tokens_pattern = multimodal_tokens.collect()
 
         if isinstance(prompt, list) and return_text:
             assert len(prompt) and isinstance(prompt[0], int)
@@ -247,16 +282,8 @@ class BaseMultimodalProcessor(ABC):
             prompt = prompt
 
         assert isinstance(prompt, str)
-        if return_text:
-            import re
-
-            pattern = (
-                "("
-                + "|".join(re.escape(sep) for sep in multimodal_tokens.collect())
-                + ")"
-            )
         # split text into list of normal text and special tokens
-            text_parts = re.split(pattern, prompt)
+        text_parts = re.split(multimodal_tokens_pattern, prompt)
 
         futures, task_info = self.submit_data_loading_tasks(
             text_parts=text_parts,
@@ -266,26 +293,40 @@ class BaseMultimodalProcessor(ABC):
             discard_alpha_channel=discard_alpha_channel,
         )
         # Process results
-        image_sizes, images, audios = [], [], []
+        images, audios = [], []
         new_text = ""
         task_ptr = 0
 
         for text_part in text_parts:
-            if text_part in multimodal_tokens.collect():
+            if multimodal_tokens_pattern.match(text_part):
                 task_type, data, frame_limit = task_info[task_ptr]
                 result = futures[task_ptr].result()
                 task_ptr += 1
 
                 if task_type == Modality.IMAGE:
+                    # If data is already processed it will be a
+                    # dictionary. In this case we want to keep the
+                    # expanded tokens in text_part. Otherwise, we will
+                    # call the processor code, so keep only a single image
+                    # token.
+                    mm_tokens = (
+                        text_part
+                        if isinstance(data, dict)
+                        else multimodal_tokens.image_token
+                    )
                     frames = [result] if not isinstance(result, list) else result
                     if frames:
-                        image_sizes += frames[0].size * len(frames)
                         images += frames
-                        new_text += multimodal_tokens.image_token * len(frames)
+                        new_text += mm_tokens * len(frames)
                 elif task_type == Modality.AUDIO:
                     # audio
+                    mm_tokens = (
+                        text_part
+                        if isinstance(data, dict)
+                        else multimodal_tokens.audio_token
+                    )
                     audios.append(result)
-                    new_text += multimodal_tokens.audio_token
+                    new_text += mm_tokens
                 # TODO: handle video
             else:
                 new_text += text_part
@@ -297,3 +338,16 @@ class BaseMultimodalProcessor(ABC):
         )
         out.normalize()
         return out
+
+    def mm_inputs_are_preprocessed(self, mm_inputs: Optional[list]):
+        """Returns true if all images are preprocessed, false if all are not, and error otherwise."""
+        if not mm_inputs:
+            return True
+        ret = any(isinstance(mm_input, MultimodalDataItem) for mm_input in mm_inputs)
+        if ret and not all(
+            isinstance(mm_input, MultimodalDataItem) for mm_input in mm_inputs
+        ):
+            raise ValueError(
+                "Unsupported: mixture of multimodal inputs where some but not all are preprocessed."
+            )
+        return ret

python/sglang/srt/managers/multimodal_processors/gemma3.py

-from typing import List, Union
+import re
+from typing import Dict, List, Union
 
 from sglang.srt.managers.multimodal_processor import (
     BaseMultimodalProcessor as SGLangBaseProcessor,
@@ -18,13 +19,18 @@ class Gemma3SGLangImageProcessor(SGLangBaseProcessor):
 
     def __init__(self, hf_config, server_args, _processor):
         super().__init__(hf_config, server_args, _processor)
+        # The single, pre-expanded image token.
         self.IMAGE_TOKEN = "<start_of_image>"
+        # The regex that matches expanded image tokens.
+        self.IMAGE_TOKEN_REGEX = re.compile(
+            r"<start_of_image>(?:(?:<image_soft_token>)*<end_of_image>)?"
+        )
         self.IM_START_TOKEN_ID = hf_config.boi_token_index
         self.IM_END_TOKEN_ID = hf_config.eoi_token_index
 
     async def process_mm_data_async(
         self,
-        image_data: List[Union[str, bytes]],
+        image_data: List[Union[str, bytes, Dict]],
         input_text,
         request_obj,
         max_req_input_len,
@@ -37,22 +43,35 @@ class Gemma3SGLangImageProcessor(SGLangBaseProcessor):
             image_data = [image_data]
 
         image_token = self.IMAGE_TOKEN
+        image_token_regex = self.IMAGE_TOKEN_REGEX
         base_output = self.load_mm_data(
             prompt=input_text,
             image_data=image_data,
-            multimodal_tokens=MultimodalSpecialTokens(image_token=image_token),
+            multimodal_tokens=MultimodalSpecialTokens(
+                image_token=image_token, image_token_regex=image_token_regex
+            ),
             max_req_input_len=max_req_input_len,
             discard_alpha_channel=True,
         )
 
+        images_are_preprocessed = self.mm_inputs_are_preprocessed(base_output.images)
         ret = self.process_mm_data(
-            input_text=base_output.input_text, images=base_output.images
+            input_text=base_output.input_text,
+            images=None if images_are_preprocessed else base_output.images,
         )
 
         items = []
         for i, image in enumerate(base_output.images):
+            if images_are_preprocessed:
+                pixel_values = image.pixel_values
+                precomputed_features = image.precomputed_features
+            else:
+                pixel_values = ret["pixel_values"][i]
+                precomputed_features = None
+
             item = MultimodalDataItem(
-                pixel_values=ret["pixel_values"][i],
+                pixel_values=pixel_values,
+                precomputed_features=precomputed_features,
                 modality=Modality.IMAGE,
             )
             items += [item]

python/sglang/srt/managers/multimodal_processors/qwen_vl.py

 import asyncio
 import math
-from typing import List, Union
+import re
+from typing import Dict, List, Union
 
 import torch
 from PIL import Image
@@ -23,7 +24,12 @@ class Qwen2_5VLImageProcessor(SGLangBaseProcessor):
 
     def __init__(self, hf_config, server_args, _processor):
         super().__init__(hf_config, server_args, _processor)
+        # The single, pre-expanded image token.
         self.IMAGE_TOKEN = "<|vision_start|><|image_pad|><|vision_end|>"
+        # The regex that matches expanded image tokens.
+        self.IMAGE_TOKEN_REGEX = re.compile(
+            r"<\|vision_start\|>(?:<\|image_pad\|>)+<\|vision_end\|>"
+        )
         self.IM_START_TOKEN_ID = hf_config.vision_start_token_id
         self.IM_END_TOKEN_ID = hf_config.vision_end_token_id
         self.image_token_id = hf_config.image_token_id
@@ -38,7 +44,7 @@ class Qwen2_5VLImageProcessor(SGLangBaseProcessor):
 
     async def process_mm_data_async(
         self,
-        image_data: List[Union[str, bytes]],
+        image_data: List[Union[str, bytes, Dict]],
         input_text,
         request_obj,
         max_req_input_len,
@@ -48,11 +54,13 @@ class Qwen2_5VLImageProcessor(SGLangBaseProcessor):
         if isinstance(image_data, str):
             image_data = [image_data]
 
-        image_token = self.IMAGE_TOKEN
         base_output = self.load_mm_data(
             prompt=input_text,
             image_data=image_data,
-            multimodal_tokens=MultimodalSpecialTokens(image_token=image_token),
+            multimodal_tokens=MultimodalSpecialTokens(
+                image_token=self.IMAGE_TOKEN,
+                image_token_regex=self.IMAGE_TOKEN_REGEX,
+            ),
             max_req_input_len=max_req_input_len,
         )
 
@@ -117,26 +125,56 @@ class Qwen2_5VLImageProcessor(SGLangBaseProcessor):
         async def resize_image_async(image):
             return resize_image(image)
 
-        if base_output.images:
+        images_are_preprocessed = self.mm_inputs_are_preprocessed(base_output.images)
+        if base_output.images and not images_are_preprocessed:
             resize_tasks = [resize_image_async(image) for image in base_output.images]
             base_output.images = await asyncio.gather(*resize_tasks)
 
         ret = self.process_mm_data(
             input_text=base_output.input_text,
-            images=base_output.images,
+            images=None if images_are_preprocessed else base_output.images,
         )
-
+        input_ids = ret["input_ids"].flatten().tolist()
+        image_grid_thw = None
+        video_grid_thw = None  # TODO
         items = []
 
-        input_ids = ret["input_ids"].flatten().tolist()
-        if "pixel_values" in ret:
+        if base_output.images:
+            if images_are_preprocessed:
+                image_grid_thw = torch.concat(
+                    [
+                        torch.as_tensor(item.image_grid_thws)
+                        for item in base_output.images
+                    ]
+                )
+                all_pixel_values = [
+                    item.pixel_values
+                    for item in base_output.images
+                    if item.pixel_values is not None
+                ]
+                all_precomputed_features = [
+                    item.precomputed_features
+                    for item in base_output.images
+                    if item.precomputed_features is not None
+                ]
+                pixel_values = (
+                    torch.concat(all_pixel_values) if all_pixel_values else None
+                )
+                precomputed_features = (
+                    torch.concat(all_precomputed_features)
+                    if all_precomputed_features
+                    else None
+                )
+            else:
+                image_grid_thw = ret["image_grid_thw"]
+                pixel_values = ret["pixel_values"]
+                precomputed_features = None
             items += [
                 MultimodalDataItem(
-                    pixel_values=ret["pixel_values"],
-                    image_grid_thws=torch.concat([ret["image_grid_thw"]]),
-                    # TODO
-                    video_grid_thws=None,
-                    second_per_grid_ts=ret.get("second_per_grid_ts", None),
+                    pixel_values=pixel_values,
+                    image_grid_thws=image_grid_thw,
+                    video_grid_thws=video_grid_thw,
+                    precomputed_features=precomputed_features,
                     modality=Modality.IMAGE,
                 )
             ]
@@ -151,8 +189,8 @@ class Qwen2_5VLImageProcessor(SGLangBaseProcessor):
                 self.hf_config.vision_config, "tokens_per_second", None
             ),
             input_ids=torch.tensor(input_ids).unsqueeze(0),
-            image_grid_thw=ret.get("image_grid_thw", None),
-            video_grid_thw=ret.get("video_grid_thw", None),
+            image_grid_thw=image_grid_thw,
+            video_grid_thw=video_grid_thw,
             second_per_grid_ts=ret.get("second_per_grid_ts", None),
         )
         mrope_positions = mrope_positions.squeeze(1)

python/sglang/srt/managers/schedule_batch.py

@@ -177,10 +177,10 @@ class MultimodalDataItem:
     image_offsets: Optional[list] = None
 
     # the real data, pixel_values or audio_features
-    # data: Union[List[torch.Tensor], List[np.array]]
-    pixel_values: Union[torch.Tensor, np.array] = None
-    image_grid_thws: Union[torch.Tensor, np.array] = None
-    video_grid_thws: Union[torch.Tensor, np.array] = None
+    # data: Union[List[torch.Tensor], List[np.ndarray]]
+    pixel_values: Union[torch.Tensor, np.ndarray] = None
+    image_grid_thws: Union[torch.Tensor, np.ndarray] = None
+    video_grid_thws: Union[torch.Tensor, np.ndarray] = None
 
     image_emb_mask: Optional[torch.Tensor] = None
     image_spatial_crop: Optional[torch.Tensor] = None
@@ -189,9 +189,11 @@ class MultimodalDataItem:
     # [num_images, (n, w, h)]
     tgt_size: Tuple[int, int] = None
 
-    audio_features: Union[torch.Tensor, np.array] = None
+    audio_features: Union[torch.Tensor, np.ndarray] = None
     audio_feature_lens: Optional[List[torch.Tensor]] = None
 
+    precomputed_features: Optional[Union[torch.Tensor, np.ndarray]] = None
+
     @staticmethod
     def is_empty_list(l):
         if l is None:
@@ -249,7 +251,9 @@ class MultimodalDataItem:
                 return tensor_hash([f])
             return data_hash(f)
 
-        if self.is_audio():
+        if self.precomputed_features is not None:
+            self.hash = hash_feature(self.precomputed_features)
+        elif self.is_audio():
             self.hash = hash_feature(self.audio_features)
         else:
             self.hash = hash_feature(self.pixel_values)
@@ -258,19 +262,24 @@ class MultimodalDataItem:
         self.pad_value = self.hash % (1 << 30)
 
     def is_audio(self):
-        return (
-            self.modality == Modality.AUDIO
-        ) and not MultimodalDataItem.is_empty_list(self.audio_features)
+        return (self.modality == Modality.AUDIO) and (
+            self.precomputed_features is not None
+            or not MultimodalDataItem.is_empty_list(self.audio_features)
+        )
 
     def is_image(self):
         return (
             self.modality == Modality.IMAGE or self.modality == Modality.MULTI_IMAGES
-        ) and not MultimodalDataItem.is_empty_list(self.pixel_values)
+        ) and (
+            self.precomputed_features is not None
+            or not MultimodalDataItem.is_empty_list(self.pixel_values)
+        )
 
     def is_video(self):
-        return (
-            self.modality == Modality.VIDEO
-        ) and not MultimodalDataItem.is_empty_list(self.pixel_values)
+        return (self.modality == Modality.VIDEO) and (
+            self.precomputed_features is not None
+            or not MultimodalDataItem.is_empty_list(self.pixel_values)
+        )
 
     def is_valid(self) -> bool:
         return self.is_image() or self.is_video() or self.is_audio()
@@ -279,6 +288,16 @@ class MultimodalDataItem:
         ...
         # TODO
 
+    @staticmethod
+    def from_dict(obj: dict):
+        kwargs = dict(obj)
+        modality = kwargs.pop("modality")
+        if isinstance(modality, str):
+            modality = Modality[modality]
+        ret = MultimodalDataItem(modality=modality, **kwargs)
+        ret.validate()
+        return ret
+
 
 @dataclasses.dataclass
 class MultimodalInputs:

python/sglang/srt/managers/session_controller.py

@@ -54,7 +54,7 @@ class SessionReqNode:
             prefix += " -- " + self.childs[0].req.rid
             ret = self.childs[0]._str_helper(prefix)
             for child in self.childs[1:]:
-                prefix = " " * len(origin_prefix) + " \- " + child.req.rid
+                prefix = " " * len(origin_prefix) + r" \- " + child.req.rid
                 ret += child._str_helper(prefix)
             return ret
 

python/sglang/srt/models/gemma3_mm.py

@@ -278,6 +278,12 @@ class Gemma3ForConditionalGeneration(PreTrainedModel):
         Returns:
             image_features (`torch.Tensor`): Image feature tensor of shape `(num_images, image_length, embed_dim)`).
         """
+        if any(item.precomputed_features is not None for item in items):
+            if not all(item.precomputed_features is not None for item in items):
+                raise NotImplementedError(
+                    "MM inputs where only some items are precomputed."
+                )
+            return torch.concat([item.precomputed_features for item in items])
         pixel_values = torch.stack(
             flatten_nested_list([item.pixel_values for item in items]), dim=0
         )

python/sglang/srt/models/qwen2_5_vl.py

@@ -497,6 +497,12 @@ class Qwen2_5_VLForConditionalGeneration(nn.Module):
         return pattern.pad_input_tokens(input_ids, mm_inputs)
 
     def get_image_feature(self, items: List[MultimodalDataItem]) -> torch.Tensor:
+        if any(item.precomputed_features is not None for item in items):
+            if not all(item.precomputed_features is not None for item in items):
+                raise NotImplementedError(
+                    "MM inputs where only some items are precomputed."
+                )
+            return torch.concat([item.precomputed_features for item in items])
         # in qwen-vl, last dim is the same
         pixel_values = torch.cat([item.pixel_values for item in items], dim=0).type(
             self.visual.dtype

python/sglang/srt/models/qwen2_vl.py

@@ -486,6 +486,12 @@ class Qwen2VLForConditionalGeneration(nn.Module):
         return pattern.pad_input_tokens(input_ids, mm_inputs)
 
     def get_image_feature(self, items: List[MultimodalDataItem]) -> torch.Tensor:
+        if any(item.precomputed_features is not None for item in items):
+            if not all(item.precomputed_features is not None for item in items):
+                raise NotImplementedError(
+                    "MM inputs where only some items are precomputed."
+                )
+            return torch.concat([item.precomputed_features for item in items])
         # in qwen-vl, last dim is the same
         pixel_values = torch.cat([item.pixel_values for item in items], dim=0).type(
             self.visual.dtype

test/srt/test_skip_tokenizer_init.py

@@ -54,21 +54,17 @@ class TestSkipTokenizerInit(CustomTestCase):
     ):
         input_ids = self.get_input_ids(prompt_text)
 
+        request = self.get_request_json(
+            input_ids=input_ids,
+            return_logprob=return_logprob,
+            top_logprobs_num=top_logprobs_num,
+            max_new_tokens=max_new_tokens,
+            stream=False,
+            n=n,
+        )
         response = requests.post(
             self.base_url + "/generate",
-            json={
-                "input_ids": input_ids,
-                "sampling_params": {
-                    "temperature": 0 if n == 1 else 0.5,
-                    "max_new_tokens": max_new_tokens,
-                    "n": n,
-                    "stop_token_ids": [self.tokenizer.eos_token_id],
-                },
-                "stream": False,
-                "return_logprob": return_logprob,
-                "top_logprobs_num": top_logprobs_num,
-                "logprob_start_len": 0,
-            },
+            json=request,
         )
         ret = response.json()
         print(json.dumps(ret, indent=2))
@@ -87,9 +83,12 @@ class TestSkipTokenizerInit(CustomTestCase):
                 self.assertEqual(item["meta_info"]["prompt_tokens"], len(input_ids))
 
                 if return_logprob:
+                    num_input_logprobs = len(input_ids) - request["logprob_start_len"]
+                    if num_input_logprobs > len(input_ids):
+                        num_input_logprobs -= len(input_ids)
                     self.assertEqual(
                         len(item["meta_info"]["input_token_logprobs"]),
-                        len(input_ids),
+                        num_input_logprobs,
                         f'{len(item["meta_info"]["input_token_logprobs"])} mismatch with {len(input_ids)}',
                     )
                     self.assertEqual(
@@ -113,19 +112,14 @@ class TestSkipTokenizerInit(CustomTestCase):
         requests.post(self.base_url + "/flush_cache")
         response = requests.post(
             self.base_url + "/generate",
-            json={
-                "input_ids": input_ids,
-                "sampling_params": {
-                    "temperature": 0 if n == 1 else 0.5,
-                    "max_new_tokens": max_new_tokens,
-                    "n": n,
-                    "stop_token_ids": self.eos_token_id,
-                },
-                "stream": False,
-                "return_logprob": return_logprob,
-                "top_logprobs_num": top_logprobs_num,
-                "logprob_start_len": 0,
-            },
+            json=self.get_request_json(
+                input_ids=input_ids,
+                max_new_tokens=max_new_tokens,
+                return_logprob=return_logprob,
+                top_logprobs_num=top_logprobs_num,
+                stream=False,
+                n=n,
+            ),
         )
         ret = response.json()
         print(json.dumps(ret))
@@ -137,19 +131,13 @@ class TestSkipTokenizerInit(CustomTestCase):
         requests.post(self.base_url + "/flush_cache")
         response_stream = requests.post(
             self.base_url + "/generate",
-            json={
-                "input_ids": input_ids,
-                "sampling_params": {
-                    "temperature": 0 if n == 1 else 0.5,
-                    "max_new_tokens": max_new_tokens,
-                    "n": n,
-                    "stop_token_ids": self.eos_token_id,
-                },
-                "stream": True,
-                "return_logprob": return_logprob,
-                "top_logprobs_num": top_logprobs_num,
-                "logprob_start_len": 0,
-            },
+            json=self.get_request_json(
+                input_ids=input_ids,
+                return_logprob=return_logprob,
+                top_logprobs_num=top_logprobs_num,
+                stream=True,
+                n=n,
+            ),
         )
 
         response_stream_json = []
@@ -188,6 +176,29 @@ class TestSkipTokenizerInit(CustomTestCase):
         ].tolist()
         return input_ids
 
+    def get_request_json(
+        self,
+        input_ids,
+        max_new_tokens=32,
+        return_logprob=False,
+        top_logprobs_num=0,
+        stream=False,
+        n=1,
+    ):
+        return {
+            "input_ids": input_ids,
+            "sampling_params": {
+                "temperature": 0 if n == 1 else 0.5,
+                "max_new_tokens": max_new_tokens,
+                "n": n,
+                "stop_token_ids": self.eos_token_id,
+            },
+            "stream": stream,
+            "return_logprob": return_logprob,
+            "top_logprobs_num": top_logprobs_num,
+            "logprob_start_len": 0,
+        }
+
 
 class TestSkipTokenizerInitVLM(TestSkipTokenizerInit):
     @classmethod
@@ -218,6 +229,14 @@ class TestSkipTokenizerInitVLM(TestSkipTokenizerInit):
 
         return inputs.input_ids[0].tolist()
 
+    def get_request_json(self, *args, **kwargs):
+        ret = super().get_request_json(*args, **kwargs)
+        ret["image_data"] = [self.image_url]
+        ret["logprob_start_len"] = (
+            -1
+        )  # Do not try to calculate logprobs of image embeddings.
+        return ret
+
     def test_simple_decode_stream(self):
         # TODO mick
         pass

test/srt/test_vlm_accuracy.py

@@ -3,15 +3,22 @@
 
 import unittest
 from io import BytesIO
-from typing import List
+from typing import List, Optional
 
 import numpy as np
 import requests
 import torch
 import torch.nn.functional as F
 from PIL import Image
-from transformers import AutoModel, AutoProcessor, AutoTokenizer
+from transformers import (
+    AutoModel,
+    AutoProcessor,
+    AutoTokenizer,
+    Gemma3ForConditionalGeneration,
+    Qwen2_5_VLForConditionalGeneration,
+)
 
+from sglang import Engine
 from sglang.srt.configs.model_config import ModelConfig
 from sglang.srt.conversation import generate_chat_conv
 from sglang.srt.managers.mm_utils import embed_mm_inputs
@@ -100,7 +107,7 @@ class VisionLLMLogitsBase(unittest.IsolatedAsyncioTestCase):
 
         np.testing.assert_allclose(hf_np, sg_np)
 
-    def get_processor_output(self):
+    def get_completion_request(self) -> ChatCompletionRequest:
         json_str = f"""
         {{
   "model": "{self.model_path}",
@@ -124,10 +131,12 @@ class VisionLLMLogitsBase(unittest.IsolatedAsyncioTestCase):
 }}
         """
 
-        req = ChatCompletionRequest.model_validate_json(json_str)
+        return ChatCompletionRequest.model_validate_json(json_str)
 
+    def get_processor_output(self, req: Optional[ChatCompletionRequest] = None):
+        if req is None:
+            req = self.get_completion_request()
         conv = generate_chat_conv(req, template_name=self.chat_template)
-
         text = conv.get_prompt()
 
         # Process inputs using processor
@@ -239,5 +248,129 @@ class TestMiniCPMVLogits(VisionLLMLogitsBase):
         self.compare_outputs(sglang_output, hf_output)
 
 
+class TestQwenVLUnderstandsImage(VisionLLMLogitsBase):
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.model_path = "Qwen/Qwen2.5-VL-3B-Instruct"
+        cls.chat_template = "qwen2-vl"
+        cls.processor = AutoProcessor.from_pretrained(
+            cls.model_path, trust_remote_code=True, use_fast=True
+        )
+        cls.visual = (
+            Qwen2_5_VLForConditionalGeneration.from_pretrained(
+                cls.model_path, torch_dtype=torch.bfloat16
+            )
+            .eval()
+            .visual.to(cls.device)
+        )
+
+    def setUp(self):
+        self.engine = Engine(
+            model_path=self.model_path,
+            chat_template=self.chat_template,
+            device=self.device.type,
+            mem_fraction_static=0.8,
+        )
+
+    def tearDown(self):
+        self.engine.shutdown()
+
+    async def test_qwen_vl_understands_image(self):
+        req = self.get_completion_request()
+        conv = generate_chat_conv(req, template_name=self.chat_template)
+        text = conv.get_prompt()
+        output = await self.engine.async_generate(
+            prompt=text,
+            image_data=[self.main_image],
+            sampling_params=dict(temperature=0.0),
+        )
+        self.assertIn("taxi", output["text"].lower())
+
+    async def test_qwen_vl_understands_precomputed_features(self):
+        req = self.get_completion_request()
+        processor_output = self.get_processor_output(req=req)
+        with torch.inference_mode():
+            precomputed_features = self.visual(
+                processor_output["pixel_values"], processor_output["image_grid_thw"]
+            )
+        output = await self.engine.async_generate(
+            input_ids=processor_output["input_ids"][0].detach().cpu().tolist(),
+            image_data=[
+                dict(
+                    modality="IMAGE",
+                    image_grid_thws=processor_output["image_grid_thw"],
+                    precomputed_features=precomputed_features,
+                )
+            ],
+            sampling_params=dict(temperature=0.0),
+        )
+        self.assertIn("taxi", output["text"].lower())
+
+
+class TestGemmaUnderstandsImage(VisionLLMLogitsBase):
+
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.model_path = "google/gemma-3-4b-it"
+        cls.chat_template = "gemma-it"
+        cls.processor = AutoProcessor.from_pretrained(
+            cls.model_path, trust_remote_code=True, use_fast=True
+        )
+        model = Gemma3ForConditionalGeneration.from_pretrained(
+            cls.model_path, torch_dtype=torch.bfloat16
+        )
+        cls.vision_tower = model.vision_tower.eval().to(cls.device)
+        cls.mm_projector = model.multi_modal_projector.eval().to(cls.device)
+
+    @classmethod
+    def visual(cls, pixel_values):
+        vision_outputs = cls.vision_tower(pixel_values=pixel_values).last_hidden_state
+        image_features = cls.mm_projector(vision_outputs)
+        return image_features
+
+    def setUp(self):
+        self.engine = Engine(
+            model_path=self.model_path,
+            chat_template=self.chat_template,
+            device=self.device.type,
+            mem_fraction_static=0.5,
+            enable_multimodal=True,
+        )
+
+    def tearDown(self):
+        self.engine.shutdown()
+
+    async def test_gemma_understands_image(self):
+        req = self.get_completion_request()
+        conv = generate_chat_conv(req, template_name=self.chat_template)
+        text = conv.get_prompt()
+        output = await self.engine.async_generate(
+            prompt=text,
+            image_data=[self.main_image],
+            sampling_params=dict(temperature=0.0),
+        )
+        self.assertIn("taxi", output["text"].lower())
+
+    async def test_gemma_understands_precomputed_features(self):
+        req = self.get_completion_request()
+        processor_output = self.get_processor_output(req=req)
+        with torch.inference_mode():
+            precomputed_features = self.visual(processor_output["pixel_values"])
+        output = await self.engine.async_generate(
+            input_ids=processor_output["input_ids"][0].detach().cpu().tolist(),
+            image_data=[
+                dict(
+                    modality="IMAGE",
+                    precomputed_features=precomputed_features,
+                )
+            ],
+            sampling_params=dict(temperature=0.0),
+        )
+        self.assertIn("taxi", output["text"].lower())
+
+
 if __name__ == "__main__":
     unittest.main()