LangGraph MemorySaver is in-memory, so recreating it per request wipes thread state

Create your checkpointer once at startup and reuse it across requests, never inside a per-request object. If memory must survive restarts or multiple processes, use a persistent checkpointer such as the sqlite or postgres saver instead of MemorySaver. Keep passing the same thread_id in config on every invoke, because persistence is keyed on it, and verify with a two-turn test: tell the agent your name, then ask it back in a fresh call.

Context: GitHub issue langchain-ai/langgraph#2146 documents why thread memory silently vanishes. The reporter compiled with MemorySaver and passed a thread_id, but the agent still forgot everything between calls. The maintainer's answer: MemorySaver is an in-memory checkpointer, so re-instantiating the wrapper class on every request wipes all stored thread state. The fix is creating the checkpointer once outside the request-scoped class, or switching to a checkpointer that writes to a file or database like the sqlite or postgres variants.

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Source: Published skill Original query: "LangGraph MemorySaver is in-memory, so recreating it per request wipes thread state" Key terms: langgraph, memory, memorysaver, recreating, request, state, thread, wipes

Source: GitHub issue langchain-ai/langgraph#2146 documents why thread memory silently vanishes. The reporter compiled with MemorySaver and passed a thread_id, but the agent still forgot everything between calls. The maintainer's answer: MemorySaver is an in-memory checkpointer, so re-instantiating the wrapper class on every request wipes all stored thread state. The fix is creating the checkpointer once outside the request-scoped class, or switching to a checkpointer that writes to a file or database like the sqlite or postgres variants.

Verified resolution: Create your checkpointer once at startup and reuse it across requests, never inside a per-request object. If memory must survive restarts or multiple processes, use a persistent checkpointer such as the sqlite or postgres saver instead of MemorySaver. Keep passing the same thread_id in config on every invoke, because persistence is keyed on it, and verify with a two-turn test: tell the agent your name, then ask it back in a fresh call.

Source URL: https://github.com/langchain-ai/langgraph/issues/2146