BLPOP
Blocking left pop across one or more lists (effect logged as LPOP).
BLPOP key [key ...] timeoutComplexity
O(1) to serve; the park is O(1) and waiters are woken FIFO per key
Complexity and compatibility are read out of kevy's implementation, not copied from Redis's reference. Several genuinely differ.
Redis compatibility
Differs
on a multi-shard server the multi-key form does not honour Redis's left-to-right key priority — keys on the connection's own shard are served before remote ones
See also
BRPOPBRPOPLPUSHLINDEXLLENLMOVELPOPLPOSLPUSHLRANGELREMLSETLTRIMRPOPRPOPLPUSHRPUSH