What are the reasons for the appearance of an empty cache error when two containerized services with a global cache operate simultaneously?

The empty cache error when running two containerized services with a global cache simultaneously usually occurs due to issues with synchronization and data consistency between instances. The main reasons:

• Lack of a centralized cache or incorrect configuration of it. If each service operates with a local cache, data is not synchronized, and when one service updates, the other sees an empty or outdated cache.
• Problems with distributed locking. Concurrent access to the cache without a locking mechanism can lead to race conditions, where one service clears or updates the cache while another tries to read it.
• Incorrect cache TTL (Time To Live) management. If the cache lifetime is too short or not coordinated, the cache may be cleared unexpectedly.
• Absence of cache invalidation mechanisms between services. For example, if Redis or another distributed cache is used, notifications about changes need to be configured.

To resolve the issue, it is recommended to use a distributed cache (e.g., Redis, Hazelcast) with synchronization support, properly configure TTL and invalidation mechanisms, and ensure correct locking during cache updates.