fix(backend): Handle missing content in streaming delta #316
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sjmonson
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Signed-off-by: xinjun.jiang <[email protected]>
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sjmonson
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…#316) ## Summary This PR fixes a `KeyError: 'content'` that occurs when processing streaming chat completions. ## Details When using the `chat_completions` endpoint with `stream=True`, the final `delta` chunk sent by the server may not contain a `content` key. This is part of the standard API behavior to signal the end of the stream. The existing code in `_extract_completions_delta_content` did not account for this possibility and tried to access `delta['content']` directly, leading to a `KeyError` and causing the benchmark process to crash when the stream ended. ## Test Plan This was discovered while running `guidellm benchmark` against an OpenAI-compatible API endpoint (via `litellm`) that correctly implements the streaming protocol. guidellm benchmark \ --target "http://10.64.1.62:4000/v1" \ --model "qwen3-06b-2" \ --processor "Qwen/Qwen3-0.6B" \ --rate-type "synchronous" \ --max-requests 1 \ --data "prompt_tokens=32,output_tokens=32,samples=1" ## Related Issues vllm-project#315 - Resolves # --- - [x] "I certify that all code in this PR is my own, except as noted below." ## Use of AI - [ ] Includes AI-assisted code completion - [ ] Includes code generated by an AI application - [ ] Includes AI-generated tests (NOTE: AI written tests should have a docstring that includes `## WRITTEN BY AI ##`) Signed-off-by: xinjun.jiang <[email protected]> Co-authored-by: Samuel Monson <[email protected]>
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Summary
This PR fixes a
KeyError: 'content'that occurs when processing streaming chat completions.Details
When using the
chat_completionsendpoint withstream=True, the finaldeltachunk sent by the server may not contain acontentkey. This is part of the standard API behavior to signal the end of the stream.The existing code in
_extract_completions_delta_contentdid not account for this possibility and tried to accessdelta['content']directly, leading to aKeyErrorand causing the benchmark process to crash when the stream ended.Test Plan
This was discovered while running
guidellm benchmarkagainst an OpenAI-compatible API endpoint (vialitellm) that correctly implements the streaming protocol.guidellm benchmark
--target "http://10.64.1.62:4000/v1"
--model "qwen3-06b-2"
--processor "Qwen/Qwen3-0.6B"
--rate-type "synchronous"
--max-requests 1
--data "prompt_tokens=32,output_tokens=32,samples=1"
Related Issues
#315
Use of AI
## WRITTEN BY AI ##)