It is the blocking version because it blocks the connection when there are no members to pop from any of the given sorted sets. A member with the highest score is popped from first sorted set that is non-empty, with the given keys being checked in the order that they are given.
timeout argument is interpreted as a double value specifying the maximum
number of seconds to block. A timeout of zero can be used to block indefinitely.
See the BZPOPMIN documentation for the exact semantics, since BZPOPMAX is identical to BZPOPMIN with the only difference being that it pops members with the highest scores instead of popping the ones with the lowest scores.
Array reply: specifically:
nilmulti-bulk when no element could be popped and the timeout expired.
- A three-element multi-bulk with the first element being the name of the key where a member was popped, the second element is the popped member itself, and the third element is the score of the popped element.
timeoutis interpreted as a double instead of an integer.
redis> DEL zset1 zset2 (integer) 0 redis> ZADD zset1 0 a 1 b 2 c (integer) 3 redis> BZPOPMAX zset1 zset2 0 1) "zset1" 2) "c" 3) "2"