refactor: vllm EPD refactor (#4994)

Signed-off-by: Guan Luo <gluo@nvidia.com>
Signed-off-by: Guan Luo <41310872+GuanLuo@users.noreply.github.com>

components/src/dynamo/vllm/main.py

@@ -34,7 +34,7 @@ from dynamo.vllm.multimodal_handlers import (
     EncodeWorkerHandler,
     MultimodalDecodeWorkerHandler,
     MultimodalPDWorkerHandler,
-    ProcessorHandler,
+    PreprocessedHandler,
     VLLMEncodeWorkerHandler,
 )
 from dynamo.vllm.multimodal_utils.encode_utils import create_ec_transfer_config
@@ -676,13 +676,17 @@ async def init_multimodal_processor(runtime: DistributedRuntime, config: Config)
         .client()
     )
 
-    # Get prompt template from args (must be passed via environment or command line)
-    mm_prompt_template = config.mm_prompt_template
+    pd_worker_client = (
+        await runtime.namespace(config.namespace)
+        .component("backend")
+        .endpoint("generate")
+        .client()
+    )
 
-    handler = ProcessorHandler(
+    handler = PreprocessedHandler(
         config.engine_args,
         encode_worker_client,
-        mm_prompt_template,
+        pd_worker_client,
     )
 
     logger.info("Waiting for Encoder Worker Instances ...")
@@ -690,7 +694,7 @@ async def init_multimodal_processor(runtime: DistributedRuntime, config: Config)
 
     # Register the endpoint as entrypoint to a model
     await register_llm(
-        ModelInput.Text,  # Custom processor is used and this type bypasses SDK processor
+        ModelInput.Tokens,
         ModelType.Chat,
         generate_endpoint,
         config.model,

components/src/dynamo/vllm/multimodal_handlers/__init__.py

@@ -5,10 +5,8 @@ from dynamo.vllm.multimodal_handlers.encode_worker_handler import (
     EncodeWorkerHandler,
     VLLMEncodeWorkerHandler,
 )
-from dynamo.vllm.multimodal_handlers.preprocessor_handler import (
-    ECProcessorHandler,
-    ProcessorHandler,
-)
+from dynamo.vllm.multimodal_handlers.preprocessed_handler import PreprocessedHandler
+from dynamo.vllm.multimodal_handlers.preprocessor_handler import ECProcessorHandler
 from dynamo.vllm.multimodal_handlers.worker_handler import (
     MultimodalDecodeWorkerHandler,
     MultimodalPDWorkerHandler,
@@ -17,7 +15,7 @@ from dynamo.vllm.multimodal_handlers.worker_handler import (
 __all__ = [
     "EncodeWorkerHandler",
     "VLLMEncodeWorkerHandler",
-    "ProcessorHandler",
+    "PreprocessedHandler",
     "MultimodalPDWorkerHandler",
     "MultimodalDecodeWorkerHandler",
     "ECProcessorHandler",

components/src/dynamo/vllm/multimodal_handlers/encode_worker_handler.py

@@ -2,9 +2,12 @@
 # SPDX-License-Identifier: Apache-2.0
 
 import logging
+import os
 import shutil
+import time
 from typing import AsyncGenerator, AsyncIterator
 
+import safetensors
 from transformers import AutoImageProcessor
 from vllm.engine.arg_utils import AsyncEngineArgs
 from vllm.inputs.data import TextPrompt
@@ -16,10 +19,10 @@ from dynamo.runtime import Client, DistributedRuntime
 
 from ..multimodal_utils import (
     ImageLoader,
-    MyRequestOutput,
     VLLMNativeEncoderRequest,
     VLLMNativeEncoderResponse,
     encode_image_embeddings,
+    get_embedding_hash,
     get_encoder_components,
     load_vision_model,
     vLLMMultimodalRequest,
@@ -42,6 +45,8 @@ except ImportError as e:
 
 CACHE_SIZE_MAXIMUM = 8
 
+TRANSFER_LOCAL = int(os.getenv("TRANSFER_LOCAL", 1))
+
 
 class EncodeWorkerHandler:
     def __init__(
@@ -65,6 +70,10 @@ class EncodeWorkerHandler:
             self.model, self.vision_model
         )
         self._connector = None
+        self._accumulated_time = 0.0
+        self._processed_requests = 0
+        self.readables = []
+        self.cached_embeddings = {}
 
     def cleanup(self):
         pass
@@ -101,14 +110,35 @@ class EncodeWorkerHandler:
         # 8. Yield the encode response.
 
         try:
-            if not request.multimodal_input.image_url:
+            time_start = time.perf_counter()
+            for idx in range(len(request.multimodal_inputs)):
+                if not request.multimodal_inputs[idx].multimodal_input.image_url:
                     raise ValueError("image_url is required for the encode worker.")
 
-            image = await self.image_loader.load_image(
-                request.multimodal_input.image_url
+                image_url = request.multimodal_inputs[idx].multimodal_input.image_url
+                # see if we have local cache
+                if image_url in self.cached_embeddings:
+                    (
+                        embedding_key,
+                        image_grid_thw,
+                        embeddings_shape,
+                    ) = self.cached_embeddings[image_url]
+                    # [gluo FIXME] need mechanism to clean up local files
+                    request.multimodal_inputs[
+                        idx
+                    ].serialized_request = (
+                        f"/tmp/encoder_cache.{embedding_key}.safetensors"
                     )
+                    request.multimodal_inputs[idx].multimodal_input.image_url = None
+                    request.multimodal_inputs[idx].image_grid_thw = image_grid_thw
+                    request.multimodal_inputs[idx].embeddings_shape = embeddings_shape
+                    continue
 
-            logger.debug(f"Processing image for request: {{ id: {request_id} }}")
+                image = await self.image_loader.load_image(image_url)
+
+                logger.debug(
+                    f"Processing image {image_url} for request: {{ id: {request_id} }}"
+                )
                 image_embeds = self.image_processor(images=image, return_tensors="pt")
 
                 # Encode the image embeddings using model-specific encoder
@@ -131,33 +161,56 @@ class EncodeWorkerHandler:
                 # Move embeddings to CPU for NIXL transfer to avoid UCX/InfiniBand issues
                 embeddings_cpu = embeddings.cpu()
 
-            request.image_grid_thw = image_grid_thw
-            request.embeddings_shape = tuple(embeddings.shape)
+                request.multimodal_inputs[idx].image_grid_thw = image_grid_thw
+                request.multimodal_inputs[idx].embeddings_shape = tuple(
+                    embeddings.shape
+                )
+
+                if TRANSFER_LOCAL:
+                    embedding_key = get_embedding_hash(image_url)
+                    logger.debug(
+                        f"ENCODER: saving local safetensors file with key {embedding_key}, {embeddings_cpu.numel()} * {embeddings_cpu.element_size()} bytes"
+                    )
+                    tensors = {"ec_cache": embeddings_cpu}
+                    safetensors.torch.save_file(
+                        tensors, f"/tmp/encoder_cache.{embedding_key}.safetensors"
+                    )
+                    # [gluo FIXME] need mechanism to clean up local files
+                    request.multimodal_inputs[
+                        idx
+                    ].serialized_request = (
+                        f"/tmp/encoder_cache.{embedding_key}.safetensors"
+                    )
+                    self.cached_embeddings[image_url] = (
+                        embedding_key,
+                        request.multimodal_inputs[idx].image_grid_thw,
+                        request.multimodal_inputs[idx].embeddings_shape,
+                    )
+                else:
+                    # [gluo FIXME] nixl_connector path needs to be update to handle multiple embeddings
                     descriptor = connect.Descriptor(embeddings_cpu)
+                    self.readables.append(
+                        await self._connector.create_readable(descriptor)
+                    )
+                    request.multimodal_inputs[idx].serialized_request = self.readables[
+                        -1
+                    ].metadata()
 
-            with await self._connector.create_readable(descriptor) as readable:
-                request.serialized_request = readable.metadata()
                 # Clear the image URL as hint that the image is passed as embeddings.
-                request.multimodal_input.image_url = None
+                request.multimodal_inputs[idx].multimodal_input.image_url = None
 
             logger.debug(f"Request: {request.model_dump_json()}")
 
-                # Get the response generator
-                response_generator = await self.pd_worker_client.round_robin(
-                    request.model_dump_json(), context=context
+            time_end = time.perf_counter()
+            self._accumulated_time += time_end - time_start
+            self._processed_requests += 1
+            logger.debug(
+                f"Encoded image(s) for request {{ id: {request_id} }} in {time_end - time_start:.4f} seconds. "
+                f"Average encoding time: {self._accumulated_time / self._processed_requests:.4f} seconds over {self._processed_requests} requests."
             )
-                await readable.wait_for_completion()
-
-                async for response in response_generator:
-                    output = MyRequestOutput.model_validate_json(response.data())
-                    yield MyRequestOutput(
-                        request_id=output.request_id,
-                        prompt=output.prompt,
-                        prompt_token_ids=output.prompt_token_ids,
-                        prompt_logprobs=output.prompt_logprobs,
-                        outputs=output.outputs,
-                        finished=output.finished,
-                    ).model_dump_json()
+
+            # Yield transformed request back
+            yield request.model_dump_json()
 
         except Exception as e:
             logger.error(f"Error processing request {request_id}: {e}")
@@ -240,7 +293,7 @@ class VLLMEncodeWorkerHandler:
         try:
             # Prompt can be a random string as the encoder is only interested in the multimodal data
             prompt_dict = TextPrompt(
-                prompt="<image>", multi_modal_data={media_key: media}
+                prompt=request.prompt, multi_modal_data={media_key: media}
             )
 
             gen = self.engine_client.generate(

components/src/dynamo/vllm/multimodal_handlers/preprocessed_handler.py

+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+import asyncio
+import logging
+import uuid
+from collections import defaultdict
+from enum import Enum
+from typing import AsyncIterator, Final
+
+from vllm.engine.arg_utils import AsyncEngineArgs
+from vllm.outputs import RequestOutput
+from vllm.sampling_params import SamplingParams as VllmSamplingParams
+
+from dynamo.runtime import Client
+
+from ..handlers import BaseWorkerHandler, build_sampling_params
+from ..multimodal_utils import (
+    MultiModalGroup,
+    MultiModalInput,
+    MyRequestOutput,
+    PatchedTokensPrompt,
+    ProcessMixIn,
+    vLLMMultimodalRequest,
+)
+
+logger = logging.getLogger(__name__)
+
+# Multimodal data dictionary keys
+IMAGE_URL_KEY: Final = "image_url"
+VIDEO_URL_KEY: Final = "video_url"
+URL_VARIANT_KEY: Final = "Url"
+DECODED_VARIANT_KEY: Final = "Decoded"
+
+
+class RequestType(Enum):
+    CHAT = "chat"
+    COMPLETION = "completion"
+
+
+class PreprocessedHandler(ProcessMixIn):
+    """
+    vLLM pre and post processing for multimodal requests
+    """
+
+    def __init__(
+        self,
+        engine_args: AsyncEngineArgs,
+        encode_worker_client: Client,
+        pd_worker_client: Client,
+    ):
+        self.encode_worker_client = encode_worker_client
+        self.pd_worker_client = pd_worker_client
+        self.engine_args = engine_args
+        self.model_config = self.engine_args.create_model_config()
+        self.default_sampling_params = self.model_config.get_diff_sampling_param()
+
+    def cleanup(self):
+        pass
+
+    # Main method to parse the request and send the request to the vllm worker.
+    async def _generate(
+        self,
+        raw_request,
+        multimodal_inputs,
+        context,
+    ):
+        # [gluo NOTE] panic for now as encoder here is for image only
+        if VIDEO_URL_KEY in multimodal_inputs or multimodal_inputs[VIDEO_URL_KEY]:
+            raise ValueError("Video URL not supported in encode worker yet")
+
+        request_id = str(uuid.uuid4().hex)
+
+        # Build sampling params from request using shared utility
+        sampling_params = build_sampling_params(
+            raw_request, self.default_sampling_params
+        )
+
+        # [gluo WIP] encoder doesn't really need any of this
+        encode_request = vLLMMultimodalRequest(
+            engine_prompt=PatchedTokensPrompt(prompt_token_ids=[]),
+            sampling_params=VllmSamplingParams(),
+            request_id=request_id,
+            multimodal_inputs=[],
+        )
+
+        # [gluo WIP] experiment with batching..
+        ENCODE_BATCH_SIZE = 1
+        encode_res_gen = []
+        for mm_type, urls in multimodal_inputs.items():
+            for url in urls:
+                multimodal_input = MultiModalInput()
+                if mm_type == IMAGE_URL_KEY:
+                    multimodal_input.image_url = url
+                elif mm_type == VIDEO_URL_KEY:
+                    multimodal_input.video_url = url
+                    # [gluo NOTE] should not reach here due to earlier check
+                    continue
+                encode_request.multimodal_inputs.append(
+                    MultiModalGroup(multimodal_input=multimodal_input)
+                )
+
+                if len(encode_request.multimodal_inputs) >= ENCODE_BATCH_SIZE:
+                    # model_dump_json() serializes the request to JSON string
+                    # This API could accept Pydantic class, but SamplingParams
+                    # in vLLMMultimodalRequest is not a Pydantic class and will
+                    # cause TypeError: unsupported type SamplingParams
+                    encode_res_gen.append(
+                        await self.encode_worker_client.round_robin(
+                            encode_request.model_dump_json()
+                        )
+                    )
+                    encode_request.multimodal_inputs = []
+        if encode_request.multimodal_inputs:
+            encode_res_gen.append(
+                await self.encode_worker_client.round_robin(
+                    encode_request.model_dump_json()
+                )
+            )
+        # Gather transformed requests
+        worker_request = vLLMMultimodalRequest(
+            engine_prompt=PatchedTokensPrompt(
+                prompt_token_ids=raw_request["token_ids"]
+            ),
+            sampling_params=sampling_params,
+            request_id=request_id,
+            multimodal_inputs=[],  # will be filled in next
+        )
+        for encode_res in encode_res_gen:
+            async for response in encode_res:
+                logger.debug(f"Received response from encode worker: {response}")
+                output = vLLMMultimodalRequest.model_validate_json(response.data())
+                worker_request.multimodal_inputs.extend(output.multimodal_inputs)
+
+        response_generator = await self.pd_worker_client.round_robin(
+            worker_request.model_dump_json(), context=context
+        )
+
+        # [gluo FIXME] <im_end> being returned
+        async for output in self._generate_responses(response_generator):
+            yield output
+
+    # This method is used to process the responses from the engine generator.
+    async def _generate_responses(
+        self,
+        response_generator: AsyncIterator[RequestOutput],
+    ):
+        # [gluo WIP] modified from handler.py (BaseWorkerHandler.generate_tokens)
+        num_output_tokens_so_far = 0
+        try:
+            async for resp in response_generator:
+                # Deserialize the response from the engine
+                # Creates correct vLLM objects for each field
+                output = MyRequestOutput.model_validate_json(resp.data())
+
+                # OpenAIServingChat.chat_completion_stream_generator() method expects a RequestOutput object
+                res = RequestOutput(
+                    request_id=output.request_id,
+                    prompt=output.prompt,
+                    prompt_token_ids=output.prompt_token_ids,
+                    prompt_logprobs=output.prompt_logprobs,
+                    outputs=output.outputs,
+                    finished=output.finished,
+                    metrics=output.metrics,
+                )
+
+                if not res.outputs:
+                    continue
+                output = res.outputs[0]
+                next_total_toks = len(output.token_ids)
+                out = {"token_ids": output.token_ids[num_output_tokens_so_far:]}
+
+                # Extract logprobs for new tokens if available
+                log_probs, top_logprobs = BaseWorkerHandler._extract_logprobs(
+                    output, num_output_tokens_so_far
+                )
+                if log_probs is not None:
+                    out["log_probs"] = log_probs
+                if top_logprobs is not None:
+                    out["top_logprobs"] = top_logprobs
+
+                if output.finish_reason:
+                    out["finish_reason"] = output.finish_reason
+                    out["completion_usage"] = BaseWorkerHandler._build_completion_usage(
+                        request_output=res
+                    )
+                if output.stop_reason:
+                    out["stop_reason"] = output.stop_reason
+                yield out
+                num_output_tokens_so_far = next_total_toks
+        except asyncio.CancelledError:
+            # raise EngineShGeneratorExit when engine exits so that frontend can migrate the request
+            raise GeneratorExit(
+                "Decode engine was shut down during token generation"
+            ) from None
+
+    def _extract_multimodal_data(self, request):
+        """
+        Extract and decode multimodal data from PreprocessedRequest.
+        """
+        # [gluo NOTE] modified from components/src/dynamo/vllm/handlers.py
+        if "multi_modal_data" not in request or request["multi_modal_data"] is None:
+            return {}
+
+        # [gluo FIXME] add this security option
+        # Security check: reject multimodal data if not explicitly enabled
+        # if not self.enable_multimodal:
+        #     raise ValueError(
+        #         "Received multimodal data but multimodal processing is not enabled. "
+        #         "Use --enable-multimodal flag to enable multimodal processing."
+        #     )
+
+        mm_map = request["multi_modal_data"]
+        multimodal_inputs = defaultdict(list)
+
+        for mm_type in [IMAGE_URL_KEY, VIDEO_URL_KEY]:
+            for item in mm_map.get(mm_type, []):
+                if isinstance(item, dict) and URL_VARIANT_KEY in item:
+                    multimodal_inputs[mm_type].append(item[URL_VARIANT_KEY])
+                elif isinstance(item, dict) and DECODED_VARIANT_KEY in item:
+                    # Decoded support from PRs #3971/#3988 (frontend decoding + NIXL transfer)
+                    # Will contain NIXL metadata for direct memory access
+                    # TODO: Implement NIXL read when PRs merge
+                    logger.warning(
+                        "Decoded multimodal data not yet supported in standard worker"
+                    )
+
+        return multimodal_inputs
+
+    # The generate endpoint will be used by the frontend to handle incoming requests.
+    async def generate(self, request, context):
+        logger.debug(f"Got preprocessed request: {request}")
+
+        # Extract multimodal inputs for dispatching to encode worker
+        multimodal_inputs = self._extract_multimodal_data(request)
+
+        if not multimodal_inputs:
+            raise ValueError("Either image URL or video URL is required")
+        elif len(multimodal_inputs) > 1:
+            raise ValueError(
+                "Only one of image URL or video URL is supported per request"
+            )
+
+        async for response in self._generate(request, multimodal_inputs, context):
+            yield response

components/src/dynamo/vllm/multimodal_handlers/preprocessor_handler.py

@@ -19,6 +19,7 @@ from dynamo.runtime import Client
 from ..multimodal_utils import (
     ChatProcessor,
     CompletionsProcessor,
+    MultiModalGroup,
     MultiModalInput,
     MultiModalRequest,
     MyRequestOutput,
@@ -264,6 +265,7 @@ class ECProcessorHandler(ProcessorHandler):
 
     @staticmethod
     def _create_encoder_request(
+        prompt: str,
         mm_item: Dict[str, Any],
         model: str,
         request_id: str,
@@ -282,6 +284,7 @@ class ECProcessorHandler(ProcessorHandler):
             raise ValueError(f"Unsupported multimodal type: {mm_item.get('type')}")
 
         return {
+            "prompt": prompt,
             "request_id": request_id,
             "multimodal_input": multimodal_input,
             "modality": modality,
@@ -289,6 +292,7 @@ class ECProcessorHandler(ProcessorHandler):
 
     async def _encode_multimodal_items(
         self,
+        prompt: str,
         mm_items: List[Dict[str, Any]],
         model: str,
         request_id: str,
@@ -312,6 +316,7 @@ class ECProcessorHandler(ProcessorHandler):
 
             # Build encoder request
             encoder_request = self._create_encoder_request(
+                prompt=prompt,
                 mm_item=mm_item,
                 model=model,
                 request_id=item_request_id,
@@ -421,6 +426,7 @@ class ECProcessorHandler(ProcessorHandler):
             )
             try:
                 await self._encode_multimodal_items(
+                    prompt=prompt,
                     mm_items=mm_items,
                     model=raw_request.model,
                     request_id=request_id,
@@ -453,7 +459,9 @@ class ECProcessorHandler(ProcessorHandler):
             engine_prompt=engine_prompt,
             sampling_params=sampling_params,
             request_id=request_id,
-            multimodal_input=multimodal_input,  # ✓ Keep this so vLLM can generate mm_hash
+            multimodal_inputs=[
+                MultiModalGroup(multimodal_input=multimodal_input)
+            ],  # ✓ Keep this so vLLM can generate mm_hash
         )
 
         logger.debug(

components/src/dynamo/vllm/multimodal_handlers/worker_handler.py

@@ -3,7 +3,10 @@
 
 import copy
 import logging
+import os
+from collections import defaultdict
 
+import safetensors
 import torch
 from vllm.inputs.data import TokensPrompt
 from vllm.v1.engine.async_llm import AsyncLLM
@@ -22,6 +25,8 @@ from ..multimodal_utils.model import construct_qwen_decode_mm_data, is_qwen_vl_m
 
 logger = logging.getLogger(__name__)
 
+TRANSFER_LOCAL = int(os.getenv("TRANSFER_LOCAL", 1))
+
 
 class MultimodalDecodeWorkerHandler(BaseWorkerHandler):
     """Decode worker for disaggregated multimodal serving"""
@@ -164,6 +169,8 @@ class MultimodalPDWorkerHandler(BaseWorkerHandler):
                 request = vLLMMultimodalRequest.model_validate(request)
         logger.debug(f"Received PD request: {{ id: {request.request_id} }}.")
 
+        multi_modal_data = defaultdict(list)
+        for mi in request.multimodal_inputs:
             # ECConnector consumer mode: vLLM loads embeddings automatically from disk
             # We need to pass multimodal_input so vLLM can generate mm_hash and look up cache
             if self.config.ec_consumer_mode:
@@ -173,32 +180,37 @@ class MultimodalPDWorkerHandler(BaseWorkerHandler):
                 )
                 # Use PIL image loading - vLLM will detect it's already in EC cache
                 # and load from disk instead of reprocessing
-            if request.multimodal_input and request.multimodal_input.image_url:
-                multi_modal_data = {
-                    "image": await self.image_loader.load_image(
-                        request.multimodal_input.image_url
+                if mi.multimodal_input.image_url:
+                    multi_modal_data["image"].append(
+                        await self.image_loader.load_image(
+                            mi.multimodal_input.image_url
                         )
-                }
-            elif request.multimodal_input and request.multimodal_input.video_url:
+                    )
+                elif mi.multimodal_input.video_url:
                     # For video, load as image placeholder (vLLM will use EC cache)
-                multi_modal_data = {
-                    "image": await self.image_loader.load_image(
+                    multi_modal_data["image"].append(
+                        await self.image_loader.load_image(
                             request.multimodal_input.video_url
                         )
-                }
+                    )
                 else:
                     raise ValueError(
                         "ECConnector mode requires multimodal_input with image/video URL"
                     )
             elif (
-            request.multimodal_input is not None
-            and request.multimodal_input.image_url is None
-            and request.multimodal_input.video_url is None
+                mi.multimodal_input.image_url is None
+                and mi.multimodal_input.video_url is None
             ):
-            # Network transfer mode: receive embeddings via connector from encoder worker
+                # Process embeddings using the connector
                 # Create a descriptor based on the embedding shape.
+                if TRANSFER_LOCAL:
+                    logger.info("PD: Loading local safetensors file")
+                    embeddings = safetensors.torch.load_file(mi.serialized_request)[
+                        "ec_cache"
+                    ]
+                else:
                     embeddings = torch.empty(
-                request.embeddings_shape,
+                        mi.embeddings_shape,
                         dtype=self.EMBEDDINGS_DTYPE,
                         device=self.EMBEDDINGS_DEVICE,
                     )
@@ -210,40 +222,65 @@ class MultimodalPDWorkerHandler(BaseWorkerHandler):
                         )
 
                     read_op = await self._connector.begin_read(
-                request.serialized_request, descriptor
+                        mi.serialized_request, descriptor
                     )
                     await read_op.wait_for_completion()
                 if "video" in self.config.model.lower():
                     video_numpy = embeddings.numpy()
-                multi_modal_data = construct_mm_data(
+                    mm_data = construct_mm_data(
                         self.config.model,
                         self.EMBEDDINGS_DTYPE,
                         video_numpy=video_numpy,
                     )
+                    multi_modal_data["video"].append(mm_data["video"])
                 else:
-                multi_modal_data = construct_mm_data(
+                    mm_data = construct_mm_data(
                         self.config.model,
                         self.EMBEDDINGS_DTYPE,
                         image_embeds=embeddings,
-                    image_grid_thw=request.image_grid_thw,
+                        image_grid_thw=mi.image_grid_thw,
+                    )
+                    if isinstance(mm_data["image"], dict):
+                        if multi_modal_data["image"] == []:
+                            multi_modal_data["image"] = mm_data["image"]
+                        else:
+                            # [gluo FIXME] need to understand how Qwen consumes multi-image embeddings
+                            # Merging tensors
+                            multi_modal_data["image"]["image_embeds"] = torch.cat(
+                                (
+                                    multi_modal_data["image"]["image_embeds"],
+                                    mm_data["image"]["image_embeds"],
+                                )
+                            )
+                            multi_modal_data["image"]["image_grid_thw"] = torch.cat(
+                                (
+                                    multi_modal_data["image"]["image_grid_thw"],
+                                    mm_data["image"]["image_grid_thw"],
                                 )
-        elif request.multimodal_input is not None:
-            # Native mode: Use PIL image instead of image embeddings
-            multi_modal_data = {
-                "image": await self.image_loader.load_image(
-                    request.multimodal_input.image_url
                             )
-            }
                     else:
-            raise ValueError(
-                "Invalid request: multimodal_input is None but not in ec_consumer_mode"
+                        logger.info(f"Get embedding of shape {mm_data['image'].shape}")
+                        # [gluo FIXME] embedding with multiple images?
+                        if multi_modal_data["image"] == []:
+                            multi_modal_data["image"] = mm_data["image"]
+                        else:
+                            multi_modal_data["image"] = torch.cat(
+                                (multi_modal_data["image"], mm_data["image"])
+                            )
+            else:
+                # Use PIL image instead of image embeddings
+                multi_modal_data["image"].append(
+                    await self.image_loader.load_image(mi.multimodal_input.image_url)
                 )
 
-        # Clear multimodal_input fields if present (not needed for engine)
-        if request.multimodal_input is not None:
-            request.multimodal_input.image_url = None
-            request.multimodal_input.video_url = None
-        request.serialized_request = None
+        # Remove the image features from the request as they are not required
+        request.multimodal_inputs = None
+
+        logger.info(f"Prepared multimodal data size: {len(multi_modal_data['image'])}")
+        logger.info(f"{multi_modal_data}")
+
+        # Deepcopy the request to avoid modifying the original
+        # when we adjust sampling params for prefill
 
         pd_request = copy.deepcopy(request)
         # Do prefill and remote decode if enable_disagg is true
@@ -311,6 +348,10 @@ class MultimodalPDWorkerHandler(BaseWorkerHandler):
                 logger.debug(
                     f"Response kv_transfer_params: {response.kv_transfer_params}"
                 )
+                logger.debug(
+                    f"length of expanded prompt ids: {len(response.prompt_token_ids)}"
+                )
+                # logger.info(f"Response outputs: {response.outputs}")
                 yield MyRequestOutput(
                     request_id=response.request_id,
                     prompt=response.prompt,

components/src/dynamo/vllm/multimodal_utils/__init__.py

@@ -8,6 +8,7 @@ from dynamo.vllm.multimodal_utils.chat_processor import (
 )
 from dynamo.vllm.multimodal_utils.encode_utils import (
     encode_image_embeddings,
+    get_embedding_hash,
     get_encoder_components,
 )
 from dynamo.vllm.multimodal_utils.http_client import get_http_client
@@ -18,9 +19,11 @@ from dynamo.vllm.multimodal_utils.model import (
     load_vision_model,
 )
 from dynamo.vllm.multimodal_utils.protocol import (
+    MultiModalGroup,
     MultiModalInput,
     MultiModalRequest,
     MyRequestOutput,
+    PatchedTokensPrompt,
     VLLMNativeEncoderRequest,
     VLLMNativeEncoderResponse,
     vLLMMultimodalRequest,
@@ -38,6 +41,9 @@ __all__ = [
     "construct_mm_data",
     "load_vision_model",
     "MultiModalInput",
+    "MultiModalGroup",
+    "PatchedTokensPrompt",
+    "get_embedding_hash",
     "MultiModalRequest",
     "MyRequestOutput",
     "vLLMMultimodalRequest",

components/src/dynamo/vllm/multimodal_utils/encode_utils.py

@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import hashlib
 import json
 import logging
 from typing import Any, Dict, Optional
@@ -25,6 +26,18 @@ from .model import SupportedModels, is_model_supported, is_qwen_vl_model
 logger = logging.getLogger(__name__)
 
 
+def get_embedding_hash(key: str) -> str:
+    """
+    Generate a unique hash key for storing/retrieving image embeddings.
+
+    Args:
+        key: The base key string (e.g., image URL or identifier)
+    Returns:
+        A unique hash string for the given key.
+    """
+    return hashlib.sha256(key.encode()).hexdigest()
+
+
 def get_qwen_image_features(
     vision_encoder: torch.nn.Module, image_embeds: Dict[str, Any]
 ) -> torch.Tensor:

components/src/dynamo/vllm/multimodal_utils/model.py

@@ -29,6 +29,7 @@ class SupportedModels:
     LLAVA_1_5_7B = "llava-hf/llava-1.5-7b-hf"
     QWEN_2_VL_2B = "Qwen/Qwen2-VL-2B-Instruct"
     QWEN_2_5_VL_7B = "Qwen/Qwen2.5-VL-7B-Instruct"
+    QWEN_2_5_VL_3B = "Qwen/Qwen2.5-VL-3B-Instruct"
     LLAVA_NEXT_VIDEO_7B = "llava-hf/LLaVA-NeXT-Video-7B-hf"
 
 
@@ -105,6 +106,7 @@ def is_model_supported(model_name: str, supported_model: str) -> bool:
 QWEN_VL_MODELS = [
     SupportedModels.QWEN_2_VL_2B,
     SupportedModels.QWEN_2_5_VL_7B,
+    SupportedModels.QWEN_2_5_VL_3B,
 ]
 
 

components/src/dynamo/vllm/multimodal_utils/protocol.py

@@ -140,20 +140,26 @@ class MultiModalInput(BaseModel):
     video_url: Optional[str] = None
 
 
-class vLLMMultimodalRequest(vLLMGenerateRequest):
+class MultiModalGroup(BaseModel):
     model_config = ConfigDict(arbitrary_types_allowed=True)
     multimodal_input: Optional[MultiModalInput] = Field(default_factory=MultiModalInput)
     image_grid_thw: Optional[List[Any]] = None
     embeddings_shape: Optional[
         Union[Tuple[int, int, int], Tuple[int, int, int, int]]
     ] = None
-    serialized_request: Optional[connect.RdmaMetadata] = None
+    serialized_request: Optional[connect.RdmaMetadata | str] = None
+
+
+class vLLMMultimodalRequest(vLLMGenerateRequest):
+    model_config = ConfigDict(arbitrary_types_allowed=True)
+    multimodal_inputs: List[MultiModalGroup] = Field(default_factory=list)
 
 
 class VLLMNativeEncoderRequest(BaseModel):
     """Request for vLLM-native encoder worker using ECConnector"""
 
     request_id: str
+    prompt: str
     multimodal_input: MultiModalInput
     modality: Literal["image", "video", "audio"]
     batch_items: Optional[List[MultiModalInput]] = None  # For future batch processing

examples/backends/vllm/launch/agg_multimodal_epd.sh

@@ -16,9 +16,7 @@ set -e
 trap 'echo Cleaning up...; kill 0' EXIT
 
 # Default values
-MODEL_NAME="llava-hf/llava-1.5-7b-hf"
-PROMPT_TEMPLATE="USER: <image>\n<prompt> ASSISTANT:"
-PROVIDED_PROMPT_TEMPLATE=""
+MODEL_NAME="Qwen/Qwen2.5-VL-7B-Instruct"
 SINGLE_GPU=false
 
 # Parse command line arguments
@@ -28,10 +26,6 @@ while [[ $# -gt 0 ]]; do
             MODEL_NAME=$2
             shift 2
             ;;
-        --prompt-template)
-            PROVIDED_PROMPT_TEMPLATE=$2
-            shift 2
-            ;;
         --single-gpu)
             SINGLE_GPU=true
             shift
@@ -40,7 +34,6 @@ while [[ $# -gt 0 ]]; do
             echo "Usage: $0 [OPTIONS]"
             echo "Options:"
             echo "  --model <model_name> Specify the model to use (default: $MODEL_NAME)"
-            echo "  --prompt-template <template> Specify the multi-modal prompt template to use. LLaVA 1.5 7B, Qwen2.5-VL, and Phi3V models have predefined templates."
             echo "  --single-gpu         Run both encode and PD workers on GPU 0 (for pre-merge CI)"
             echo "  -h, --help           Show this help message"
             exit 0
@@ -53,22 +46,6 @@ while [[ $# -gt 0 ]]; do
     esac
 done
 
-# Set PROMPT_TEMPLATE based on the MODEL_NAME
-if [[ -n "$PROVIDED_PROMPT_TEMPLATE" ]]; then
-    PROMPT_TEMPLATE="$PROVIDED_PROMPT_TEMPLATE"
-elif [[ "$MODEL_NAME" == "llava-hf/llava-1.5-7b-hf" ]]; then
-    PROMPT_TEMPLATE="USER: <image>\n<prompt> ASSISTANT:"
-elif [[ "$MODEL_NAME" == "microsoft/Phi-3.5-vision-instruct" ]]; then
-    PROMPT_TEMPLATE="<|user|>\n<|image_1|>\n<prompt><|end|>\n<|assistant|>\n"
-elif [[ "$MODEL_NAME" == "Qwen/Qwen2.5-VL-7B-Instruct" ]] || [[ "$MODEL_NAME" == "Qwen/Qwen2-VL-2B-Instruct" ]]; then
-    PROMPT_TEMPLATE="<|im_start|>system\nYou are a helpful assistant.<|im_end|>\n<|im_start|>user\n<|vision_start|><|image_pad|><|vision_end|><prompt><|im_end|>\n<|im_start|>assistant\n"
-else
-    echo "No multi-modal prompt template is defined for the model: $MODEL_NAME"
-    echo "Please provide a prompt template using --prompt-template option."
-    echo "Example: --prompt-template 'USER: <image>\n<prompt> ASSISTANT:'"
-    exit 1
-fi
-
 # Start frontend (HTTP endpoint)
 # dynamo.frontend accepts either --http-port flag or DYN_HTTP_PORT env var (defaults to 8000)
 python -m dynamo.frontend &
@@ -78,14 +55,14 @@ python -m dynamo.frontend &
 # Multi-GPU mode: Each worker gets its own GPU, so use higher memory settings
 EXTRA_ARGS=""
 if [[ "$SINGLE_GPU" == "true" ]]; then
-    EXTRA_ARGS="--gpu-memory-utilization 0.3 --max-model-len 3072 --enforce-eager"
+    EXTRA_ARGS="--gpu-memory-utilization 0.5 --enforce-eager --max-model-len 30426"
 else
     # Multi-GPU mode: standard memory settings
-    EXTRA_ARGS="--gpu-memory-utilization 0.85 --max-model-len 4096"
+    EXTRA_ARGS="--gpu-memory-utilization 0.85 --max-model-len 34096"
 fi
 
 # Start processor (Python-based preprocessing, handles prompt templating)
-python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME --mm-prompt-template "$PROMPT_TEMPLATE" &
+python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME &
 
 # run E/P/D workers
 # Use single GPU (GPU 0) for pre-merge CI, otherwise use GPU 0 for encode and GPU 1 for PD

examples/backends/vllm/launch/agg_multimodal_llama.sh

@@ -12,7 +12,7 @@ MODEL_NAME="meta-llama/Llama-4-Maverick-17B-128E-Instruct-FP8"
 python -m dynamo.frontend &
 
 # run processor
-python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME --mm-prompt-template "<|image|>\n<prompt>" &
+python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME &
 # Llama 4 doesn't support image embedding input, so use encode+prefill worker
 # that handles image encoding inline
 python -m dynamo.vllm --multimodal-encode-prefill-worker --enable-multimodal --model $MODEL_NAME --tensor-parallel-size=8 --max-model-len=208960 --gpu-memory-utilization 0.80 &

examples/backends/vllm/launch/disagg_multimodal_epd.sh

@@ -6,8 +6,6 @@ trap 'echo Cleaning up...; kill 0' EXIT
 
 # Default values
 MODEL_NAME="llava-hf/llava-1.5-7b-hf"
-PROMPT_TEMPLATE="USER: <image>\n<prompt> ASSISTANT:"
-PROVIDED_PROMPT_TEMPLATE=""
 
 # Parse command line arguments
 while [[ $# -gt 0 ]]; do
@@ -16,10 +14,6 @@ while [[ $# -gt 0 ]]; do
             MODEL_NAME=$2
             shift 2
             ;;
-        --prompt-template)
-            PROVIDED_PROMPT_TEMPLATE=$2
-            shift 2
-            ;;
         -h|--help)
             echo "Usage: $0 [OPTIONS]"
             echo ""
@@ -27,7 +21,6 @@ while [[ $# -gt 0 ]]; do
             echo ""
             echo "Options:"
             echo "  --model <model_name>          Specify the VLM model to use (default: $MODEL_NAME)"
-            echo "  --prompt-template <template>  Specify the multi-modal prompt template to use"
             echo "                                LLaVA 1.5 7B, Qwen2.5-VL, and Phi3V models have predefined templates"
             echo "  -h, --help                    Show this help message"
             echo ""
@@ -46,27 +39,11 @@ while [[ $# -gt 0 ]]; do
     esac
 done
 
-# Set PROMPT_TEMPLATE based on the MODEL_NAME
-if [[ -n "$PROVIDED_PROMPT_TEMPLATE" ]]; then
-    PROMPT_TEMPLATE="$PROVIDED_PROMPT_TEMPLATE"
-elif [[ "$MODEL_NAME" == "llava-hf/llava-1.5-7b-hf" ]]; then
-    PROMPT_TEMPLATE="USER: <image>\n<prompt> ASSISTANT:"
-elif [[ "$MODEL_NAME" == "microsoft/Phi-3.5-vision-instruct" ]]; then
-    PROMPT_TEMPLATE="<|user|>\n<|image_1|>\n<prompt><|end|>\n<|assistant|>\n"
-elif [[ "$MODEL_NAME" == "Qwen/Qwen2.5-VL-7B-Instruct" ]]; then
-    PROMPT_TEMPLATE="<|im_start|>system\nYou are a helpful assistant.<|im_end|>\n<|im_start|>user\n<|vision_start|><|image_pad|><|vision_end|><prompt><|im_end|>\n<|im_start|>assistant\n"
-else
-    echo "No multi-modal prompt template is defined for the model: $MODEL_NAME"
-    echo "Please provide a prompt template using --prompt-template option."
-    echo "Example: --prompt-template 'USER: <image>\n<prompt> ASSISTANT:'"
-    exit 1
-fi
 
 echo "=================================================="
 echo "Disaggregated Multimodal Serving"
 echo "=================================================="
 echo "Model: $MODEL_NAME"
-echo "Prompt Template: $PROMPT_TEMPLATE"
 echo "=================================================="
 
 
@@ -77,7 +54,7 @@ python -m dynamo.frontend &
 
 # Start processor
 echo "Starting processor..."
-python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME --mm-prompt-template "$PROMPT_TEMPLATE" &
+python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME &
 
 EXTRA_ARGS=""
 

examples/backends/vllm/launch/disagg_multimodal_llama.sh

@@ -49,7 +49,7 @@ if [[ $HEAD_NODE -eq 1 ]]; then
     python -m dynamo.frontend &
 
     # run processor
-    python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME --mm-prompt-template "<|image|>\n<prompt>" &
+    python -m dynamo.vllm --multimodal-processor --enable-multimodal --model $MODEL_NAME &
 
     # Llama 4 doesn't support image embedding input, so the prefill worker will also
     # handle image encoding inline.

tests/serve/test_vllm.py

@@ -296,7 +296,9 @@ vllm_configs = {
                     },
                 ],
                 repeat_count=1,
-                expected_response=["purple"],
+                # With proper prompt templating, the model actually only returns "green",
+                # verified behavior with native vLLM.
+                expected_response=["green"],
                 temperature=0.0,
                 max_tokens=100,
             )