What problems can arise when using Redis under high load?

When using Redis under high load, the following issues may arise:

• Increased latency: Redis is a single-threaded server, so a large number of requests can cause a queue, increasing response time.
• Memory: Redis stores data in memory; with a large volume of data, you may run out of RAM, leading to crashes or the need to use swap, which significantly slows down performance.
• Network congestion: High load can create bottlenecks at the network level, especially if Redis and clients are on different servers.
• Data loss: Using Redis in non-persistent mode or with improper snapshot configuration can lead to data loss during failures.
• Locks: Some Redis commands block the server (e.g., KEYS on large datasets), which can cause delays.

To address these issues, clustering, sharding, command optimization, and load monitoring are used.