[Feature] Add API lifecycle events and request attributes (PR #8)#16
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[Feature] Add API lifecycle events and request attributes (PR #8)#16
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Implements journey tracing PR #8: - Add EVENT_TS_MONOTONIC attribute for API event timestamps - Emit HANDOFF_TO_CORE event after engine.generate() - Emit FIRST_RESPONSE_FROM_CORE event on first response (streaming and non-streaming) - Set request attributes on API spans (model, prompt tokens, sampling params) - Add _update_first_response_time() helper to track first response timing - All span operations wrapped defensively (G7 compliance) - Zero overhead when span not recording (G6 compliance) - 12 behavioral tests covering G1, G3-G7 (G2 verified by code inspection) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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Summary
Implements journey tracing PR #8, adding API lifecycle events and request attributes to span instrumentation.
Changes
New Events:
HANDOFF_TO_CORE: Emitted after submitting request to engine (engine.generate())FIRST_RESPONSE_FROM_CORE: Emitted when engine first responds (both streaming and non-streaming paths)Request Attributes:
gen_ai.response.model)gen_ai.usage.prompt_tokens)temperature,top_p,max_tokens,n(when non-None)Infrastructure:
EVENT_TS_MONOTONICattribute for monotonic timestamps on API events_update_first_response_time()helper to track first response timing in_api_spanstupleGuarantees
✅ G1: EVENT_TS_MONOTONIC attribute defined
✅ G2: HANDOFF_TO_CORE emitted after engine.generate() (verified by code inspection)
✅ G3: FIRST_RESPONSE_FROM_CORE emitted exactly once per request
✅ G4: First response time persisted in _api_spans tuple
✅ G5: Request attributes set on API span (conditionally for non-None values)
✅ G6: Early exit when span not recording (zero overhead)
✅ G7: All span operations wrapped defensively (failures never break requests)
Testing
test_api_additional_events.pyFiles Changed
vllm/tracing.py: Added EVENT_TS_MONOTONIC attributevllm/entrypoints/openai/engine/serving.py: Added _update_first_response_time() helpervllm/entrypoints/openai/chat_completion/serving.py: Event emissions and attribute settingtests/entrypoints/openai/test_api_additional_events.py: Test coverage (new file)🤖 Generated with Claude Code