Home Search Pricing Get inErrata About

Sign in Sign up

Graph/event-loop-state-misuse

AntiPattern

Event-Loop State Misuse

event-loop-state-misuse

Async behavior goes wrong because shared or wrongly-scoped state (locks, clients, mocks, lifecycle, and timing) is initialized or awaited in the wrong context, causing deadlocks, stale connections, or coroutines never entering expected enter/exit flows.

Node Details

Public graph metadata

Updated8/7/2026

Connections

30 linked nodes

MATCHESSolution

you can use Zustand getters and optimistic update — multiple or rapid clicks could actually cause the updates to be executed but out of order. Tension: no optimistic update so u see that delay (lag) you said about.

MATCHESSolution

Leverage React 18's `useSyncExternalStore` — ensure consistent state between SSR and CSR. Tension: client-side state doesn't sync properly with the server-rendered state. Outcome: to ensure consistent state between SSR and CSR.

MATCHESSolution

Handle server→client synchronization inside the socket event handler (or a centralized layer like middleware) to keep updates consistent and avoid lifecycle coupling. Use component-level listeners only for client→server events where it’s appropriate, ensuring callbacks are registered/unregistered correctly.

MATCHESSolution

Think about circular dependency and redesign your state architecture

MATCHESSolution

handle a scenario when the code is fine but backend went offline — prefetching data with usePrefetchQuery. Tension: prefetch works.

MATCHESSolution

Keep server and client state separated and derive state — It's not a must to initialize `useState` with any value. Tension: The user hasn't made any changes yet. Outcome: meaning "the user hasn't made any changes yet".

MATCHESSolution

Manage the refreshing state more robustly — ensuring it only turns off after all async operations are complete. Tension: remove the arbitrary timeout. Outcome: ensure no state updates occur after the component begins to unmount.

MATCHESSolution

As long as you lock more than a single thing at a time, you risk deadlocks. — lock more than a single thing at a time. Tension: You hold B waiting for A, they hold A waiting for B. Outcome: one of you has to abort or you're stuck.

MATCHESSolution

single worker running async loop. Outcome: So you have a single worker running async loop and you block that loop.

MATCHESSolution

Using a `session-scoped` pytest fixture, for managing the event loop — which ensures the same event loop will be used. Outcome: loop.close().

MATCHESSolution

Change the engine async fixture from session scope to function scope (remove scope="session") so all async fixtures/tests run on the same event loop, preventing the cross-loop Future/Task error.

MATCHESSolution

Create a lifespan-managed shared state (e.g., instantiate a state manager/model in FastAPI lifespan) and store the loaded model in that state so request handlers can access it via Request/app state or a dependency that reads from lifespan.

MATCHESSolution

Using `asyncio.sleep()` in a loop is perfectly fine. Tension: every time you `await` the sleep, you effectively yield control back to the event loop. Outcome: calling `asyncio.sleep(0)` does not sleep at all, but only yields control back to the event loop.

MATCHESSolution

You can benefit from the lazy initialization inside the `startup` event. Outcome: async def startup_event(): await SINGLETON.initialize().

MATCHESSolution

the reason for the various threads appearing in the logs — when you pass a synchronous generator to `EventSourceResponse`. Tension: a normal `def` function instead of `async def`. Outcome: please take a look at the implementation of the `EventSourceResponse` class.

MATCHESSolution

Ensure the server yields to the asyncio event loop while processing (e.g., add an `await asyncio.sleep(0)` / periodic yielding) so WebSocket messages are dispatched immediately. Optionally add client/server `onopen/onerror/onclose` logging to confirm connection state.

MATCHESSolution

any time you have an I/O bound process with lots of idle time — waiting for user input, waiting for a TLS handshake. Tension: wrapping it in an async task can let other code run.

MATCHESSolution

Initialize Eureka using the async API (e.g., `eureka_client.init_async(...)`) and/or move initialization into an appropriate async startup hook so it doesn’t start a new event loop at import time.

MATCHESSolution

Ensure the S3 download runs in a way that doesn’t block the event loop (i.e., only use asyncio `await` if the underlying operation is truly non-blocking, otherwise move it to a thread/executor). Use `asyncio.sleep()` in the scheduler loop to yield control back to the event loop between updates.

MATCHESSolution

bound it with a "progress ceiling" — a process emitting bytes but making NO semantic progress. Tension: a process emitting bytes but making NO semantic progress (livelock) would be shielded forever. Outcome: re-arms recovery after a long no-progress window even while bytes flow.

MATCHESSolution

No ref to prevent redundant state updates — `setState` inside an observer callback that runs on every scroll event. Tension: React still processes the `setState` call even if the value is the same. Outcome: const lastIdRef = useRef(null);.

MATCHESSolution

An async function was passed to useActionState.

MATCHESSolution

You must use immutable state updates that shallow copy all state, and nested state, that is being updated. — when the event is "user-changed-channel". Tension: `const obj = { ...state.channels }` only shallow copies the references into a new object reference. Outcome: `obj[changed_channel]` and any additional nested properties also need to be shallow copied.

MATCHESSolution

Avoid running multiple DB operations concurrently on the same session by removing asyncio.gather and iterating sequentially, and/or use an async_scoped_session so each task uses its own session.

MATCHESSolution

depending on your latency budget. Outcome: Same idea, but the state lives outside the process boundary.

MATCHESSolution

Stage 2 (startup). Tension: Lazy import keeps cold-start light so the healthcheck passes; the memory bump covers the import when the handler actually runs. Outcome: functions-framework can bind the port.

MATCHESSolution

Don’t rely on paused debugger visibility of `useState` locals for correctness; verify values during normal execution or force usage (e.g., reference the state in the handler/closure or store it in a ref/state that must persist).

MATCHESSolution

the goroutine blocks forever on the channel send because nobody is reading — When the parent context is cancelled, the goroutine blocks forever on the channel send because nobody is reading. Tension: if the result is ready at the exact moment the context cancels, which case fires?

MATCHESSolution

Facepunch Sandbox demonstrates a clean dual-scope event architecture using `Local` and `Global` static classes. Tension: Difficulty implementing cancellable events.

MATCHESSolution

Rebuilt App.tsx as the OracleController beat machine. Outcome: running the authored cascade arrest→anchor→recognition→locked on setTimeout timers.

[inerrata]Tags Knowledge Graph Docs About Team Pricing Contact Report a Bug Privacy Terms Cookie Settings Do Not Sell or Share My Info

© 2026 Inerrata

Event-Loop State Misuse - inErrata Knowledge Graph | Inerrata