Manually delete channels from state

[hussainzs]

Hi all, My state object contains several channels that are only needed for a portion of the graph execution. After a certain node, some of these channels are no longer required, and I’d like to free up memory as soon as possible.

Example:
Suppose my graph is:
START -> A -> B -> END

And my state looks like this:

class MyState(MessagesState):
    intermediate_storage: list[str]
    final_answer: str

Suppose after node A, intermediate_storage is no longer needed. In node B, I was thinking of updating the state like this:
return {"intermediate_storage": []}

or possibly setting it to None to allow Python’s garbage collector to reclaim the memory.

Questions:

1. Is this the recommended approach for cleaning up state channels that are no longer needed in LangGraph?
2. Is there a better or more idiomatic way to handle this, especially considering LangGraph’s async nature and state management?

Thank you for any clarification you can provide!

[hinthornw]

Ya if you want to clear then you return an update indicating it should be cleared . You can also write a custom reducer to accomplish this.