Tell us about your experience with multi-layer caching: how you did it, why you started doing it, and how you realized it was necessary.

Multilayer caching is used to improve performance and reduce load on slow or expensive data sources (e.g., network or database).

How it was done:

• First level — in-memory cache (e.g., LruCache or ConcurrentHashMap) for quick access within the process.
• Second level — local disk or database (e.g., SQLite, Room) for data persistence between sessions.
• Third level — network source (API).

Why it was started:

• Under network or database load, response times increased.
• Users complained about delays.

How it was determined what was needed:

• Metrics showed high response times and frequent requests for the same data.
• Application profile analysis revealed bottlenecks in data access.

Thus, multilayer caching allows quick data retrieval from memory, from local storage if absent, and only when necessary — a network request.