Advanced state management in Node.js applications
Instruction: Explain strategies for managing application state in complex Node.js applications, including session storage and caching.
Context: This question assesses the candidate's approach to managing state in Node.js applications, with a focus on scalability, performance, and reliability, including the use of sessions, caches, and persistent storage.
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Classify state by lifetime and authority. Request-local context belongs to one operation, process-local caches are expendable, sessions identify an interaction across requests, and durable business records need an authoritative store with the required consistency/recovery behavior.
Do not keep essential shared state only in a worker's JavaScript objects when traffic can reach multiple instances. Choose a shared session store with explicit expiry, revocation and outage behavior...