How do I handle Socket.io memory leaks?
Periodically clean up stale data: iterate through the online users map and remove entries where the socket no longer exists (io.sockets.sockets.get(socketId) returns undefined). Monitor memory with process.memoryUsage() and restart PM2 workers if memory grows too high (max_memory_restart in ecosystem.config.js).
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More FAQs in Socket.io Best Practices and Performance Optimizing Real-Time Node.js
Use WebSocket transport only (transports: ['websocket']), Redis adapter for multi-instance scaling, PM2 cluster mode, limit message size, rate limit events, clean up on disconnect, monitor connections and memory, handle memory leaks, and use acknowledgments for important events.
Use io.engine.clientsCount for total connections, io.sockets.adapter.rooms.size for room count, and process.memoryUsage() for memory. Log periodically with setInterval. Use @socket.io/admin-ui for a visual dashboard. Set up CloudWatch or Datadog for production monitoring.
Yes, in production. Use transports: ['websocket'] to skip the initial HTTP polling and upgrade. This gives faster connections and less overhead. HTTP polling is only needed for very old browsers or restrictive proxies that don't support WebSockets.
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