tokenizer

Token Producer Plugin

Type: token-producer

DataProducer plugin that tokenizes the request prompt and publishes TokenIDs (and a flat sorted MultiModalFeatures list) on InferenceRequestBody.TokenizedPrompt for downstream consumers (scorers, filters, other data producers).

Implements requestcontrol.DataProducer and runs in the PrepareRequestData phase, before filters and scorers. The plugin is idempotent: if InferenceRequestBody.TokenizedPrompt is already populated by an earlier producer, tokenization is skipped. Multi-modal features are flattened into the upstream list shape, sorted by placeholder offset.

[!NOTE] Legacy alias tokenizer is still accepted but logs a deprecation warning at instantiation. Prefer token-producer in new configs.

Backend

Backend selection:

• estimate (default): tokenizer-free byte-packing — no model, no service. Selected when no backend is set, and auto-created by the framework for any config whose plugins consume TokenizedPrompt (prefix cache, context-length, P/D routing) without declaring a token-producer.
• vllm (or modelName): calls vLLM's /v1/completions/render and /v1/chat/completions/render over plain HTTP (TLS is not supported). Future protocol fields (e.g. grpc) can be added alongside url under the same vllm block.
• udsTokenizerConfig: deprecated gRPC-over-UDS sidecar (see warning below).

[!WARNING] The estimate backend approximates token boundaries (≈4 bytes/token); its token IDs do not correspond to engine tokens. The precise prefix-cache scorer requires real tokens — configure a vllm token-producer explicitly for it. If omitted, the auto-created estimate producer satisfies the dependency but silently degrades precise cache correlation.

[!WARNING] The udsTokenizerConfig backend (gRPC-over-UDS sidecar) is deprecated and will be removed in a future release. Existing configs continue to work but emit a deprecation warning at startup. Migrate to vllm.url. See Migration below.

Config

The estimate backend tunes multimodal image placeholder estimation (empty uses the defaults below):

Failure mode

Per-request errors are returned to the Director, which currently logs and continues; downstream scorers fall back to their own paths.

Deployment

The plugin calls POST {http}/v1/completions/render and POST {http}/v1/chat/completions/render, both of which are exposed by vllm serve <model> and by the GPU-less vllm launch render <model>. Any reachable HTTP endpoint serving the same model the scheduler tokenizes for will work — sidecar in the EPP pod (loopback) or a dedicated Service shared by multiple EPP replicas.

# EPP pod spec
containers:
- name: vllm-render
  image: vllm/vllm-openai:latest          # any image shipping `vllm launch render`
  command: ["vllm", "launch", "render"]
  args: ["${MODEL_NAME}", "--port=8000"]
  ports: [{name: render-http, containerPort: 8000}]
  readinessProbe: {httpGet: {path: /health, port: 8000}, periodSeconds: 5}

Plugin config — sidecar (loopback):

- type: token-producer
  parameters:
    modelName: "${MODEL_NAME}"
    vllm:
      url: "http://localhost:8000"       # optional; this is the default

Plugin config — dedicated render Service:

- type: token-producer
  parameters:
    modelName: "${MODEL_NAME}"
    vllm:
      url: "http://vllm-render.default.svc.cluster.local:8000"

A complete sample config that pairs this with precise-prefix-cache-producer and prefix-cache-scorer is at deploy/config/sim-epp-tokenizer-vllm-http-config.yaml.

Migration from udsTokenizerConfig

The legacy UDS backend ran a per-pod tokenizer sidecar and connected over a shared Unix domain socket. Replace it with the vLLM HTTP /render backend, which calls the same model-serving pods (or a co-located vllm launch render sidecar) and removes the dedicated tokenizer image.

Before:

- type: token-producer
  parameters:
    modelName: "${MODEL_NAME}"
    udsTokenizerConfig:
      socketFile: /tmp/tokenizer/tokenizer-uds.socket

After:

- type: token-producer
  parameters:
    modelName: "${MODEL_NAME}"
    vllm:
      url: "http://localhost:8000"   # or a shared render Service

See the Deployment section above for sidecar vs shared-Service options.

Related Documentation

• Precise Prefix Cache Scorer
• Context Length Aware Scorer