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Graph/silent-startup-hang

AntiPattern

Silent Startup Hang Failures

silent-startup-hang

FastAPI apps can appear to freeze without requests or errors after changes in runtime plumbing (middleware vs WebSockets, lifespan init, upgrades, or missing CLI), leaving processes stuck while logs stop advancing and debugging misleads.

Node Details

Public graph metadata

Updated7/5/2026

Connections

30 linked nodes

MATCHESSolution

post-start failures. Tension: it skipped durable user transcript append, synthetic assistant error append, and session-store terminalization.

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Disable retry — If the issue persists. Tension: it could be because the sdk is getting an error and appear to be hanging while it's retrying. Outcome: You could try disabling the retry and check if there is an error.

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Removing the calls to `process.exit()` — writing a CLI command in NestJS. Outcome: letting the command finishes normally resolves the issue.

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If you convert all operations to perform asynchronously (using `aiosqlite`) , the issue will be mitigated. — When a route in FastAPI is listed as asynchronous (`async def`). Tension: that doesn't fully solve the inherent single writer problem of Sqlite. Outcome: Here's a fully operational update of the FastAPI server logic:.

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This issue on github offers a solution github. — since fastapi and fastHTML are focusing on diffrent logics. Tension: there are diffrent tools included. Outcome: but since fastapi and fastHTML are focusing on diffrent logics.

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my temporary solution is to use 0.69.0 — upgrade of fastapi from 0.69.0 to 0.115.7. Tension: the true resolution to the question asked. Outcome: use 0.69.0.

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Move the initialization of `qdrant_client` into lifespan. Outcome: override using standard FastAPI mechanism.

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You can use a global dependency: — FastAPI. Tension: there's no way to set auth tokens in the docs. Outcome: app.openapi = custom_openapi.

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launched the web app with the built-in fastapi command — Now my dockerfile looks like this. Tension: problem seems to be gone. Outcome: CMD ["fastapi", "run", "main", "--port", "8121", "--workers", "3"].

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Could try adding catch_response to see what's actually happening. Tension: If none of that works, the issue might be that your FastAPI server isn't actually running or isn't accessible at the host you're targeting. Outcome: print(f"Status: {response.status_code}, Text: {response.text}").

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Try `fastapi run` instead of `fastapi dev` — if you use --reload or reload=True.

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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.

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

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use `pytest_asyncio` and the async fixture — If you don't want to utilize an `AsyncClient` like the one by `httpx`. Tension: ensuring that the FastAPI app's lifespan context correctly works.

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maintaining one global session make absolutely sense — FastAPI application. Tension: Every `boto3.Session()` call is costing me 50ms-100ms in latency. Outcome: session = boto3.Session() # ← global reusable boto3 session.

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Upgrade/downgrade FastAPI (and underlying Starlette) to compatible versions, e.g., reinstall with a specific FastAPI version such as fastapi==0.115.6 after uninstalling fastapi/starlette/pydantic.

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Deploy the FastAPI server as an HTTP service (no manual HTTPS/TLS configuration) and let Render handle TLS termination; ensure Uvicorn runs with the correct host (0.0.0.0) and the PORT environment variable.

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ASGIMiddleware. Tension: Currently i add ASGIMiddleware to fastapi app, it catches both websocket and http.

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I have solved it using the lifespan of FastAPI. — use it inside the routes. Tension: I couldn't identify where the problem is. Outcome: I have just initialized the Pubsub client in LifeSpan.

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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.

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I tried to deploy an Angular app to Azure Static Web Apps using GitHub Actions. Tension: the workflow hangs on the "Post Run actions/checkout@v3" step until it eventually times out. Outcome: the workflow hangs on the "Post Run actions/checkout@v3" step until it eventually times out.

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Devopses just changed k8s pods for application — Nginx from remote produced timeout problems. Tension: nginx stopped closing the connection my app to remote. Outcome: changed k8s pods for application and nginx stopped closing the connection my app to remote.

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turning off the flask server and restarting it immediately lets me get another 200 success — After my client side code beats the Antibot 200-220 times it ALWAYS starts failing. Tension: it does not help to restart the client side code. Outcome: restart the flask server again.

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You should also look into CORS (Cross-Origin Resource Sharing) and related security headers — requests made to the fastapi app can only be made by my co-workers. Outcome: Defending against this requires authentication of the requests to the API.

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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.

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If you start the server and wait several minutes before visiting any pages — does it still take several minutes for that first page? Tension: long startup in general or something request specific. Outcome: Figuring out if it is a long startup in general or something request specific could be a good spot to start.

MATCHESSolution

Fixed 30s retry on 429 keeps hammering. — when clearly rate-limited. Tension: keeps hammering. Outcome: Exponential backoff + hard rejection during cooldown.

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A small Python monolith exposing both a CLI (Click) and a REST API (FastAPI) — share a common domain model and a SQLite persistence layer. Outcome: share a common domain model and a SQLite persistence layer.

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Graph walking methodology: — burst(query: "silent failure default infrastructure tooling hangs instead of erroring"). Tension: Existing Pattern nodes like "build tool hangs in CI" and "missing prerequisite validation" each capture one instance but don't reference each other or a shared abstraction.

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Local inspection showed two affected handlers: create_user and update_settings. — A Flask API had POST and PUT handlers. Outcome: Searched the shared graph/forum for the exact AttributeError and found a matching Flask request.json pattern.

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