on_llm_start() — langchain Function Reference

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

Function python Observability CallbackManager calls 2 called by 1

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Observability→ CallbackManager→ on_llm_start() — langchain Function Reference

Dependency Diagram

graph TD
  082e343b_042a_f645_ef5e_35d66aa78bc3["on_llm_start()"]
  f2c19eb2_a092_16e7_b693_b7ae35a0bc8c["CallbackManager"]
  082e343b_042a_f645_ef5e_35d66aa78bc3 -->|defined in| f2c19eb2_a092_16e7_b693_b7ae35a0bc8c
  aff29c00_eb3e_fd6a_1d26_af2c7296121e["on_llm_start()"]
  aff29c00_eb3e_fd6a_1d26_af2c7296121e -->|calls| 082e343b_042a_f645_ef5e_35d66aa78bc3
  aff29c00_eb3e_fd6a_1d26_af2c7296121e["on_llm_start()"]
  082e343b_042a_f645_ef5e_35d66aa78bc3 -->|calls| aff29c00_eb3e_fd6a_1d26_af2c7296121e
  8964b4e9_440e_18a7_2a15_a54a0b2b733c["handle_event()"]
  082e343b_042a_f645_ef5e_35d66aa78bc3 -->|calls| 8964b4e9_440e_18a7_2a15_a54a0b2b733c
  style 082e343b_042a_f645_ef5e_35d66aa78bc3 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/callbacks/manager.py lines 1307–1356

    def on_llm_start(
        self,
        serialized: dict[str, Any],
        prompts: list[str],
        run_id: UUID | None = None,
        **kwargs: Any,
    ) -> list[CallbackManagerForLLMRun]:
        """Run when LLM starts running.

        Args:
            serialized: The serialized LLM.
            prompts: The list of prompts.
            run_id: The ID of the run.
            **kwargs: Additional keyword arguments.

        Returns:
            A callback manager for each prompt as an LLM run.

        """
        managers = []
        for i, prompt in enumerate(prompts):
            # Can't have duplicate runs with the same run ID (if provided)
            run_id_ = run_id if i == 0 and run_id is not None else uuid7()
            handle_event(
                self.handlers,
                "on_llm_start",
                "ignore_llm",
                serialized,
                [prompt],
                run_id=run_id_,
                parent_run_id=self.parent_run_id,
                tags=self.tags,
                metadata=self.metadata,
                **kwargs,
            )

            managers.append(
                CallbackManagerForLLMRun(
                    run_id=run_id_,
                    handlers=self.handlers,
                    inheritable_handlers=self.inheritable_handlers,
                    parent_run_id=self.parent_run_id,
                    tags=self.tags,
                    inheritable_tags=self.inheritable_tags,
                    metadata=self.metadata,
                    inheritable_metadata=self.inheritable_metadata,
                )
            )

        return managers