Background

redis-py merged PR #3736 on March 26, 2026, adding asyncio Redis Cluster PubSub support. Key additions:

• New ClusterPubSub class with per-node routing and connection pool management
• RedisCluster.pubsub() factory that can bind to a specific node or lazily select one
• Extended asyncio PubSub to track shard channels (SSUBSCRIBE/SUNSUBSCRIBE)
• Built-in observability recording for smessage events
• Resubscription on reconnect for shard channels

Impact

redis-py is a key library that Scout instruments for database query monitoring. This PR introduces a new code path for async Cluster PubSub that:

1. Has built-in observability hooks — The smessage event recording means redis-py is investing in first-party observability, potentially complementing Scout's instrumentation.
2. New async API surface — If Scout users run Redis Cluster with PubSub in async Python applications, this is a new area that could benefit from APM visibility (subscribe/unsubscribe latency, message throughput).
3. Connection pool changes — The new per-node connection management may affect how Scout traces redis connections in cluster mode.

Suggested Action

1. Review the merged PR to understand the new ClusterPubSub API and its observability hooks.
2. Evaluate whether Scout should instrument the new async Cluster PubSub operations (subscribe, unsubscribe, message handling) for latency and throughput visibility.
3. Verify existing redis-py instrumentation continues to work correctly with the updated connection pool behavior in cluster mode.

References

• redis-py PR #3736: Support Cluster PubSub in asyncio