FastAPI WebSocket Patterns at Scale
Practical patterns for handling thousands of concurrent WebSocket connections without sacrificing latency or memory.
The challenge
Real-time dashboards and analytics platforms push WebSocket servers harder than typical REST APIs. Connection churn, backpressure, and fan-out all need explicit design.
Patterns that work
- **Connection registry** with heartbeat and stale cleanup - **Pub/sub bridge** (Redis) for horizontal scale - **Typed event schemas** shared between Python and TypeScript clients
Measuring success
Track p99 message latency, reconnect rate, and memory per 1k connections. Optimize only what those metrics flag.
Takeaway
FastAPI plus asyncio is enough for many real-time workloads when pairing discipline with observability.