Message cache management for message queues

A method and apparatus for message cache management for message queues is provided. A plurality of messages from a plurality of enqueuers are enqueued in a queue comprising one or more shards, each shard comprising one or more subshards. A message cache is maintained in memory. Enqueuing a message includes enqueuing the message in a current subshard of a particular shard, which includes storing the message in a cached subshard corresponding to the current subshard of the particular shard. For each dequeuer-shard pair, a dequeue rate is determined. Estimated access time data is generated that includes an earliest estimated access time for each of a plurality of subshards based on the dequeuer-shard pair dequeue rates. A set of subshards is determined for storing as cached subshards in the message cache based on the earliest estimated access times for the plurality of subshards.