on_llm_start() — langchain Function Reference

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

Function python Observability TelemetryUtilities calls 1 called by 1

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Observability→ TelemetryUtilities→ on_llm_start() — langchain Function Reference

Dependency Diagram

graph TD
  d132e733_724f_f8b9_75ac_1de3b10fd868["on_llm_start()"]
  64513429_d001_87b1_5f19_cc17a3f3577b["AsyncCallbackHandler"]
  d132e733_724f_f8b9_75ac_1de3b10fd868 -->|defined in| 64513429_d001_87b1_5f19_cc17a3f3577b
  2982d426_3118_c144_0d4b_d101dba16236["on_llm_start()"]
  2982d426_3118_c144_0d4b_d101dba16236 -->|calls| d132e733_724f_f8b9_75ac_1de3b10fd868
  2982d426_3118_c144_0d4b_d101dba16236["on_llm_start()"]
  d132e733_724f_f8b9_75ac_1de3b10fd868 -->|calls| 2982d426_3118_c144_0d4b_d101dba16236
  style d132e733_724f_f8b9_75ac_1de3b10fd868 fill:#6366f1,stroke:#818cf8,color:#fff

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Source Code

libs/core/langchain_core/callbacks/base.py lines 490–517

    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:
        """Run when the model starts running.

        !!! warning

            This method is called for non-chat models (regular text completion LLMs). If
            you're implementing a handler for a chat model, you should use
            `on_chat_model_start` instead.

        Args:
            serialized: The serialized LLM.
            prompts: The prompts.
            run_id: The ID of the current run.
            parent_run_id: The ID of the parent run.
            tags: The tags.
            metadata: The metadata.
            **kwargs: Additional keyword arguments.
        """