Cache Stale Data Issues

Short summary

An in-memory cache for a payments platform failed under production load due to non-thread-safe goroutine access causing balance inconsistencies. The team migrated to Redis with explicit locks and message-queue invalidation, trading 4ms latency for 90% fewer support tickets. Key lesson: production systems require stress-testing concurrency edge cases, not just benchmark optimization.

• •Race conditions in concurrent goroutine access caused cache inconsistency without explicit locking mechanisms
• •Cache invalidation failed to account for out-of-band updates (accounting team balance adjustments)
• •Trade-off: Redis added 4ms latency but eliminated 90% of balance discrepancy support tickets

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