ADR 0008: Redis Bus Connection Pooling

Status

Accepted

Context

High-frequency invalidations in distributed mode were creating a new Redis connection for every publish call. This led to connection exhaustion on the Redis server and high latency due to TCP handshake overhead.

Decision

1. Use r2d2 Pooling: Implement a connection pool for the RedisPubSubBus.
2. Recycle Connections: Reuse existing connections for metadata publication and listener threads.
3. Exponential Backoff: Implement robust reconnection logic in the listener thread using the pool.

Consequences

• Positive: Extremely stable invalidation bus under extreme load.
• Positive: Lower latency for invalidate() calls in Redis mode.
• Negative: Increased memory usage to maintain the connection pool (configurable).