Tell us about the use of caching (Redis, Cache Lock) — why it was used, how it helped, especially in high-load projects.

Caching with Redis and the Cache Lock mechanism are widely used to improve performance and reduce load on databases and other resources in high-load projects.

Why used:

• Accelerate access to frequently requested data.
• Reduce the number of requests to slow or expensive data sources (e.g., databases).
• Ensure system scalability.

How it helped:

• Significantly reduced service response time.
• Reduced load on the database, allowing more users to be served.
• Prevented "storm" requests when multiple requests access the same data simultaneously.

Especially about Cache Lock:

• Used to prevent a situation where many requests try to update the cache at the same time (cache stampede).
• When attempting to update the cache, the first request acquires a lock, others wait or use old data.
• This helps avoid excessive load on the data source.

Example of usage:

• When requesting data, first check the Redis cache.
• If data is not present, try to acquire a lock.
• If the lock is acquired, load data from the database, write it to the cache, and release the lock.
• If the lock is not acquired, wait or return old data.

Thus, caching and Cache Lock help make the system more resilient and efficient under high load.