on_llm_start() — langchain Function Reference

Architecture documentation for the on_llm_start() function in base.py from the langchain codebase.

Function python Observability Tracers calls 3 called by 1

Entity Profile

Observability→ Tracers→ on_llm_start() — langchain Function Reference

Dependency Diagram

graph TD
  250dea62_af5d_b691_60f6_419e79310ae9["on_llm_start()"]
  b3ab8001_c14c_4191_ca53_2dbabc99917f["AsyncBaseTracer"]
  250dea62_af5d_b691_60f6_419e79310ae9 -->|defined in| b3ab8001_c14c_4191_ca53_2dbabc99917f
  d89ecf66_57c7_5671_97a2_4cb2416c215f["on_llm_start()"]
  d89ecf66_57c7_5671_97a2_4cb2416c215f -->|calls| 250dea62_af5d_b691_60f6_419e79310ae9
  6f36dacc_adf3_1223_4aff_3ae256a05ed8["_start_trace()"]
  250dea62_af5d_b691_60f6_419e79310ae9 -->|calls| 6f36dacc_adf3_1223_4aff_3ae256a05ed8
  b4438399_97b7_d6fc_517e_dee981c4ae5e["_on_llm_start()"]
  250dea62_af5d_b691_60f6_419e79310ae9 -->|calls| b4438399_97b7_d6fc_517e_dee981c4ae5e
  d89ecf66_57c7_5671_97a2_4cb2416c215f["on_llm_start()"]
  250dea62_af5d_b691_60f6_419e79310ae9 -->|calls| d89ecf66_57c7_5671_97a2_4cb2416c215f
  style 250dea62_af5d_b691_60f6_419e79310ae9 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/tracers/base.py lines 593–614

    async def on_llm_start(
        self,
        serialized: dict[str, Any],
        prompts: list[str],
        *,
        run_id: UUID,
        parent_run_id: UUID | None = None,
        tags: list[str] | None = None,
        metadata: dict[str, Any] | None = None,
        **kwargs: Any,
    ) -> None:
        llm_run = self._create_llm_run(
            serialized=serialized,
            prompts=prompts,
            run_id=run_id,
            parent_run_id=parent_run_id,
            tags=tags,
            metadata=metadata,
            **kwargs,
        )
        tasks = [self._start_trace(llm_run), self._on_llm_start(llm_run)]
        await asyncio.gather(*tasks)