Design a thread-safe key-value store

You are working on infrastructure for an AI platform. Inside a single process, many worker threads need to share a simple in-memory key–value store; any thread can concurrently read, write, or delete keys.

Design and discuss a thread-safe key–value store class with the following requirements:

• Environment: Single process, multiple threads (no multi-machine / distributed concerns).
• Operations:
• put(key, value): insert or overwrite the value for key.
• get(key): return the current value for key, or null / None if absent.
• delete(key): remove key if it exists.
• Correctness:
• Operations must be safe under arbitrary concurrent usage (no lost updates, no corrupted internal state).
• Each operation should appear atomic to callers.
• Performance:
• Aim to minimize lock contention; a single global lock is allowed but you should consider and discuss alternatives.
• Data model:
• Keys can be assumed to be strings; values can be arbitrary objects (or generics).

Answer the following sub-questions:

1. What internal data structure(s) would you use to store the key–value pairs, and why?
2. What synchronization strategy would you apply (e.g., a single global lock, per-bucket or per-key locks, lock striping, or a language-provided concurrent map)? Discuss the trade-offs.
3. Suppose you must implement this in a language without a built-in concurrent map (for example, Python with a normal dict). How would you implement your chosen synchronization strategy there? Describe or sketch the implementation of put, get, and delete.
4. How would you test / validate that your implementation is correct and free from race conditions? Consider unit tests, concurrent stress tests, and any tools or techniques you might use.
5. If this store were to be used in production, what additional concerns would you consider (e.g., validation of inputs, logging, metrics, capacity limits, performance tuning, or persistence)?