on_chain_start() — langchain Function Reference

Architecture documentation for the on_chain_start() function in streaming_stdout.py from the langchain codebase.

Function python Observability TelemetryUtilities

Entity Profile

Observability→ TelemetryUtilities→ on_chain_start() — langchain Function Reference

Dependency Diagram

graph TD
  9d64e139_6985_ab2b_466f_1646821cef65["on_chain_start()"]
  6b65bf57_0fa9_b411_5886_294d6dbe5842["StreamingStdOutCallbackHandler"]
  9d64e139_6985_ab2b_466f_1646821cef65 -->|defined in| 6b65bf57_0fa9_b411_5886_294d6dbe5842
  style 9d64e139_6985_ab2b_466f_1646821cef65 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/callbacks/streaming_stdout.py lines 76–85

    def on_chain_start(
        self, serialized: dict[str, Any], inputs: dict[str, Any], **kwargs: Any
    ) -> None:
        """Run when a chain starts running.

        Args:
            serialized: The serialized chain.
            inputs: The inputs to the chain.
            **kwargs: Additional keyword arguments.
        """