InMemorySaver(
self,
*,
serde: SerializerProtocol | None = None,
factory: type[defaultdict] = defaultdictDelete all checkpoints and writes associated with the given run IDs.
| Name | Type | Description |
|---|---|---|
serde | SerializerProtocol | None | Default: None |
| Name | Type |
|---|---|
| serde | SerializerProtocol | None |
| factory | type[defaultdict] |
An in-memory checkpoint saver.
This checkpoint saver stores checkpoints in memory using a defaultdict.
Note:
Only use InMemorySaver for debugging or testing purposes.
For production use cases we recommend installing langgraph-checkpoint-postgres and using PostgresSaver / AsyncPostgresSaver.
If you are using LangSmith Deployment, no checkpointer needs to be specified. The correct managed checkpointer will be used automatically.
Example:
import asyncio
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.graph import StateGraph
builder = StateGraph(int)
builder.add_node("add_one", lambda x: x + 1)
builder.set_entry_point("add_one")
builder.set_finish_point("add_one")
memory = InMemorySaver()
graph = builder.compile(checkpointer=memory)
coro = graph.ainvoke(1, {"configurable": {"thread_id": "thread-1"}})
asyncio.run(coro) # Output: 2The serializer to use for serializing and deserializing checkpoints.
Override: walk the parent chain ONCE for all requested channels.
Each channel terminates independently at the nearest ancestor whose stored blob is non-empty. Other channels keep walking until they find their own terminator or hit the root.
Pre-delta plain-value blobs subsume their ancestor's pending
writes (the value already includes them); _DeltaSnapshot blobs
do not (snapshot is the value AT that ancestor, prior to its own
pending writes that produce the child).
Get a checkpoint tuple from the in-memory storage.
This method retrieves a checkpoint tuple from the in-memory storage based on the
provided config. If the config contains a checkpoint_id key, the checkpoint with
the matching thread ID and timestamp is retrieved. Otherwise, the latest checkpoint
for the given thread ID is retrieved.
List checkpoints from the in-memory storage.
This method retrieves a list of checkpoint tuples from the in-memory storage based on the provided criteria.
Save a checkpoint to the in-memory storage.
This method saves a checkpoint to the in-memory storage. The checkpoint is associated with the provided config.
Save a list of writes to the in-memory storage.
This method saves a list of writes to the in-memory storage. The writes are associated with the provided config.
Delete all checkpoints and writes associated with a thread ID.
Asynchronous version of get_tuple.
This method is an asynchronous wrapper around get_tuple that runs the synchronous
method in a separate thread using asyncio.
Asynchronous version of list.
This method is an asynchronous wrapper around list that runs the synchronous
method in a separate thread using asyncio.
Asynchronous version of put.
Asynchronous version of put_writes.
This method is an asynchronous wrapper around put_writes that runs the synchronous
method in a separate thread using asyncio.
Delete all checkpoints and writes associated with a thread ID.