xhr poll error in Socket.IO default xhr-polling transport under concurrent load
Goal: Identify the root cause of latency spikes that appear only when many Socket.IO clients use the default xhr‑polling transport, as indicated by recurring 'xhr poll error' messages in client logs. Constraints: The server runs with the default 10‑second heartbeat, exponential reconnection back‑off (starting at 250 ms), a limited thread pool, the in‑memory
socketio