invoke() and ainvoke()

invoke() runs a graph synchronously; ainvoke() runs it through Python’s async interface. Both normally return the final state after the graph stops.¹

Tiny example

# Synchronous application
result = graph.invoke({"question": "Where is order A-104?"})

# Inside an async application such as FastAPI
result = await graph.ainvoke({"question": "Where is order A-104?"})

Application	Normal choice
Simple script or sync worker	invoke()
FastAPI async route	await graph.ainvoke(...)
Need progress while running	stream() or astream()

await belongs to Python. LangGraph supplies the awaitable ainvoke() method.

Failure note

Use async nodes for async I/O and call the graph with ainvoke() or astream(). Do not hide blocking I/O or time.sleep() inside an async node; it blocks the event loop.

Related

• stream() and astream()
• Async waiting and timeouts
• Nodes

Footnotes

1. LangChain, Use the graph API — Async. ↩