[Frontend] Support OpenAI batch file format

[wuisawesome]

This PR adds basic support for the OpenAI batch file format (for chat endpoints).

The following help page summarizes the usage options:

# python -m vllm.entrypoints.openai.run_batch --help
usage: run_batch.py [-h] -i INPUT_FILE -o OUTPUT_FILE [--response-role RESPONSE_ROLE] [--model MODEL] [--tokenizer TOKENIZER] [--skip-tokenizer-init] [--revision REVISION]
                    [--code-revision CODE_REVISION] [--tokenizer-revision TOKENIZER_REVISION] [--tokenizer-mode {auto,slow}] [--trust-remote-code] [--download-dir DOWNLOAD_DIR]
                    [--load-format {auto,pt,safetensors,npcache,dummy,tensorizer}] [--dtype {auto,half,float16,bfloat16,float,float32}] [--kv-cache-dtype {auto,fp8}]
                    [--quantization-param-path QUANTIZATION_PARAM_PATH] [--max-model-len MAX_MODEL_LEN] [--guided-decoding-backend {outlines,lm-format-enforcer}] [--worker-use-ray]
                    [--pipeline-parallel-size PIPELINE_PARALLEL_SIZE] [--tensor-parallel-size TENSOR_PARALLEL_SIZE] [--max-parallel-loading-workers MAX_PARALLEL_LOADING_WORKERS]
                    [--ray-workers-use-nsight] [--block-size {8,16,32}] [--enable-prefix-caching] [--use-v2-block-manager] [--num-lookahead-slots NUM_LOOKAHEAD_SLOTS] [--seed SEED]
                    [--swap-space SWAP_SPACE] [--gpu-memory-utilization GPU_MEMORY_UTILIZATION] [--num-gpu-blocks-override NUM_GPU_BLOCKS_OVERRIDE]
                    [--max-num-batched-tokens MAX_NUM_BATCHED_TOKENS] [--max-num-seqs MAX_NUM_SEQS] [--max-logprobs MAX_LOGPROBS] [--disable-log-stats]
                    [--quantization {aqlm,awq,fp8,gptq,squeezellm,gptq_marlin,marlin,deepspeedfp,None}] [--enforce-eager] [--max-context-len-to-capture MAX_CONTEXT_LEN_TO_CAPTURE]
                    [--max-seq_len-to-capture MAX_SEQ_LEN_TO_CAPTURE] [--disable-custom-all-reduce] [--tokenizer-pool-size TOKENIZER_POOL_SIZE]
                    [--tokenizer-pool-type TOKENIZER_POOL_TYPE] [--tokenizer-pool-extra-config TOKENIZER_POOL_EXTRA_CONFIG] [--enable-lora] [--max-loras MAX_LORAS]
                    [--max-lora-rank MAX_LORA_RANK] [--lora-extra-vocab-size LORA_EXTRA_VOCAB_SIZE] [--lora-dtype {auto,float16,bfloat16,float32}] [--max-cpu-loras MAX_CPU_LORAS]
                    [--fully-sharded-loras] [--device {auto,cuda,neuron,cpu}] [--image-input-type {pixel_values,image_features}] [--image-token-id IMAGE_TOKEN_ID]
                    [--image-input-shape IMAGE_INPUT_SHAPE] [--image-feature-size IMAGE_FEATURE_SIZE] [--scheduler-delay-factor SCHEDULER_DELAY_FACTOR] [--enable-chunked-prefill]
                    [--speculative-model SPECULATIVE_MODEL] [--num-speculative-tokens NUM_SPECULATIVE_TOKENS] [--speculative-max-model-len SPECULATIVE_MAX_MODEL_LEN]
                    [--speculative-disable-by-batch-size SPECULATIVE_DISABLE_BY_BATCH_SIZE] [--ngram-prompt-lookup-max NGRAM_PROMPT_LOOKUP_MAX]
                    [--ngram-prompt-lookup-min NGRAM_PROMPT_LOOKUP_MIN] [--model-loader-extra-config MODEL_LOADER_EXTRA_CONFIG]
                    [--served-model-name SERVED_MODEL_NAME [SERVED_MODEL_NAME ...]] [--engine-use-ray] [--disable-log-requests] [--max-log-len MAX_LOG_LEN]

vLLM OpenAI-Compatible batch runner.

options:
  -h, --help            show this help message and exit
  -i INPUT_FILE, --input-file INPUT_FILE
                        The path or url to a single input file. Currently supports local file paths, or the http protocol (http or https). If a URL is specified, the file should be
                        available via HTTP GET.
  -o OUTPUT_FILE, --output-file OUTPUT_FILE
                        The path or url to a single output file. Currently supports local file paths, or web (http or https) urls. If a URL is specified, the file should be
                        available via HTTP PUT.
  --response-role RESPONSE_ROLE
                        The role name to return if `request.add_generation_prompt=true`.
  --model MODEL         Name or path of the huggingface model to use.
...

Assuming the following file exists:

# cat ../batch.jsonl 
{"custom_id": "request-1", "method": "POST", "url": "/v1/chat/completions", "body": {"model": "meta-llama/Meta-Llama-3-8B-Instruct", "messages": [{"role": "system", "content": "You are a helpful assistant."},{"role": "user", "content": "Hello world!"}],"max_tokens": 1000}}
{"custom_id": "request-2", "method": "POST", "url": "/v1/chat/completions", "body": {"model": "meta-llama/Meta-Llama-3-8B-Instruct", "messages": [{"role": "system", "content": "You are an unhelpful assistant."},{"role": "user", "content": "Hello world!"}],"max_tokens": 1000}}

The program is run as python -m vllm.entrypoints.openai.run_batch -i ../batch.jsonl -o ../results.jsonl --model meta-llama/Meta-Llama-3-8B-Instruct (this produces the typical logging from the async engine, which I've omitted).

Finally, the resulting file produced is:

# cat ../results.jsonl
{"id":"vllm-383d1c59835645aeb2e07d004d62a826","custom_id":"request-1","response":{"id":"cmpl-61c020e54b964d5a98fa7527bfcdd378","object":"chat.completion","created":1715633336,"model":"meta-llama/Meta-Llama-3-8B-Instruct","choices":[{"index":0,"message":{"role":"assistant","content":"Hello! It's great to meet you! I'm here to help with any questions or tasks you may have. What's on your mind today?"},"logprobs":null,"finish_reason":"stop","stop_reason":null}],"usage":{"prompt_tokens":25,"total_tokens":56,"completion_tokens":31}},"error":null}
{"id":"vllm-42e3d09b14b04568afa3f1797751a267","custom_id":"request-2","response":{"id":"cmpl-f44d049f6b3a42d4b2d7850bb1e31bcc","object":"chat.completion","created":1715633336,"model":"meta-llama/Meta-Llama-3-8B-Instruct","choices":[{"index":0,"message":{"role":"assistant","content":"*silence*"},"logprobs":null,"finish_reason":"stop","stop_reason":null}],"usage":{"prompt_tokens":27,"total_tokens":32,"completion_tokens":5}},"error":null}

FIX #4777

BEFORE SUBMITTING, PLEASE READ THE CHECKLIST BELOW AND FILL IN THE DESCRIPTION ABOVE

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[robertgshaw2-neuralmagic]

I would prefer if this PR did not touch this file

[robertgshaw2-neuralmagic]

Is there a reason we cannot support /v1/embeddings?

https://platform.openai.com/docs/guides/batch

[robertgshaw2-neuralmagic]

[ This could be done in a follow up PR ]

[wuisawesome]

Yes, we can support the other 2 endpoints in follow ups.

[wuisawesome]

My only concern is that this is not really an OpenAI-compatible API - but rather an OpenAI-compatible file format. I think this is fine, but perhaps we should make this explicit in the documentation ...

Yes I agree, I tried to use the wording "batch file format" everywhere but when writing the documentation I can be even more explicit. I alluded to it in the ticket (and I think you noticed it too on slack), but the actual openai api is tightly coupled to its file concept and opens up a whole can of worms around life cycle management/long lived state.

See comments in code - my biggest feedback is around the is_aborted - I would rather this PR not touch that function signature.

Updated to maintain backwards compatibility in the signature, but let me know if you have something specific in mind.

We should add embedding models as a follow up

Yup, agreed

[robertgshaw2-neuralmagic]

This looks great.

Can you just add a short example of run_batch.py in /examples

[wuisawesome]

These examples links point to master, so they don't work now, but should work once merged.

[wuisawesome]

Example/docs are in. Let me know what you think.

[robertgshaw2-neuralmagic]

LGTM. Waiting for the CI to pass

[robertgshaw2-neuralmagic]

Thanks for the good work here

[AllenDou]

openi_example_batch.jsonl -> openai_example_batch.jsonl ?

[wuisawesome]

🤦yes, thanks for catching that.

[robertgshaw2-neuralmagic]

@wuisawesome ping me on slack and ill merge it

[wuisawesome]

I think we're good here, Sang merged it already