115 lines
4.7 KiB
Markdown
115 lines
4.7 KiB
Markdown
# Offline Inference
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Offline inference is possible in your own code using vLLM's [`LLM`][vllm.LLM] class.
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## Model Types
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vLLM models can be categorized into two types:
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- **[Generative Models](../models/supported_models.md)** - Models that produce text completions or chat responses (e.g., LLaMA, Qwen, DeepSeek). Use `LLM.generate()` and `LLM.chat()` for these models.
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- **[Pooling Models](../models/pooling_models/README.md)** - These models do not generate content. They are primarily used for classification and retrieval tasks, such as bge-m3 and Qwen3 Reranker.
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## Generative APIs
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For further details on generative models, please refer to [this page](../models/supported_models.md).
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- `LLM.generate` - Generates completions for the given input prompts.
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- `LLM.chat` - Generates responses for a chat conversation.
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## Asynchronous Queue APIs
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- `LLM.enqueue` - Enqueues prompts for generation without waiting for completion.
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- `LLM.enqueue_chat` - Enqueues chat conversations for generation without waiting.
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- `LLM.wait_for_completion` - Waits for all enqueued requests to complete and returns results.
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## Pooling APIs
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For further details on pooling models, please refer to [this page](../models/pooling_models/README.md).
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- `LLM.classify` - Only applicable to [classification models](../models/pooling_models/classify.md).
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- `LLM.embed` - Only applicable to [embedding models](../models/pooling_models/embed.md).
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- `LLM.score` - Applicable to [score models](../models/pooling_models/scoring.md) (cross-encoder, bi-encoder, late-interaction).
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- `LLM.encode` - Applicable to all [pooling models](../models/pooling_models/README.md).
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## Profiling APIs
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For further details on profiling, please refer to [this page](../contributing/profiling.md).
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- `LLM.start_profile` - Starts profiling with an optional custom trace prefix.
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- `LLM.stop_profile` - Stops the ongoing profiling session.
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## Sleep Mode APIs
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For further details on sleep mode, please refer to [this page](../features/sleep_mode.md).
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- `LLM.sleep` - Puts the engine into sleep mode.
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- `LLM.wake_up` - Wakes up the engine from sleep mode.
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## Cache Management APIs
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- `LLM.reset_mm_cache` - Resets the multi-modal cache.
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- `LLM.reset_prefix_cache` - Resets the prefix cache.
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## Metrics APIs
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For further details on metrics, please refer to [this page](../design/metrics.md).
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- `LLM.get_metrics` - Returns a snapshot of aggregated metrics from Prometheus.
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## Weight Transfer APIs (RL Training)
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For further details on Weight Transfer, please refer to [this page](../training/weight_transfer/README.md).
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- `LLM.init_weight_transfer_engine` - Initializes the weight transfer engine for RL training.
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- `LLM.start_weight_update` - Starts a new weight update cycle.
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- `LLM.update_weights` - Updates the model weights.
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- `LLM.finish_weight_update` - Finishes the current weight update cycle.
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## Additional APIs
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- `LLM.collective_rpc` - Executes a method or callable collectively across all workers.
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- `LLM.apply_model` - Applies a function directly to the model inside each worker.
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## API Reference
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[Offline Inference](../api/README.md#offline-inference)
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## Ray Data LLM API
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Ray Data LLM is an alternative offline inference API that uses vLLM as the underlying engine.
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This API adds several batteries-included capabilities that simplify large-scale, GPU-efficient inference:
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- Streaming execution processes datasets that exceed aggregate cluster memory.
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- Automatic sharding, load balancing, and autoscaling distribute work across a Ray cluster with built-in fault tolerance.
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- Continuous batching keeps vLLM replicas saturated and maximizes GPU utilization.
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- Transparent support for tensor and pipeline parallelism enables efficient multi-GPU inference.
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- Reading and writing to most popular file formats and cloud object storage.
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- Scaling up the workload without code changes.
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??? code
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```python
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import ray # Requires ray>=2.44.1
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from ray.data.llm import vLLMEngineProcessorConfig, build_llm_processor
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config = vLLMEngineProcessorConfig(model_source="unsloth/Llama-3.2-1B-Instruct")
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processor = build_llm_processor(
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config,
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preprocess=lambda row: {
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"messages": [
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{"role": "system", "content": "You are a bot that completes unfinished haikus."},
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{"role": "user", "content": row["item"]},
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],
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"sampling_params": {"temperature": 0.3, "max_tokens": 250},
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},
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postprocess=lambda row: {"answer": row["generated_text"]},
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)
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ds = ray.data.from_items(["An old silent pond..."])
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ds = processor(ds)
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ds.write_parquet("local:///tmp/data/")
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```
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For more information about the Ray Data LLM API, see the [Ray Data LLM documentation](https://docs.ray.io/en/latest/data/working-with-llms.html).
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