Question

A Generative AI Engineer is building a LangChain LCEL chain for a customer support assistant. For each incoming ticket, the chain must simultaneously (1) classify the ticket priority and (2) extract the product name, then feed both results into a final prompt that drafts a response. Both the classification and extraction steps call the same Foundation Model endpoint and are independent of each other. The engineer wants to minimize end-to-end latency. Which LCEL construct should be used to run the two independent steps?

Accepted Answer

Wrap the two steps in a RunnableParallel (RunnableMap) so they execute concurrently and return a dict of both outputs to the downstream prompt

Answer

Chain the two steps sequentially with the pipe (|) operator so the extraction runs after classification completes

Answer

Use a RunnableBranch to route the ticket to either classification or extraction based on a condition

Answer

Use RunnablePassthrough alone to forward the raw ticket text to the final prompt without transformation