Redis Pub/Sub and Keyspace Notifications: Sharded Pub/Sub, At-Most-Once and Cache Invalidation Signals
Redis pub/sub delivers a message only to the listeners connected at that moment and stores it nowhere; a message published while a connection is down never arrives. With real output: at-most-once delivery, message order with a handler versus a ChannelMessageQueue, a 40 MB GET dropping a shared connection, L1 invalidation across two API instances, a work-available signal for a queue, sharded pub/sub, late expired events, hash field notifications and a slow subscriber.
14 Nov 2026
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12 min
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12
