Zookeeper session management
Bucketing strategy: Put similar sessions in the same block for management,
so that Zookeeper can isolate different blocks of the session
and uniformly process the same block.
Allocation principle: "Next timeout time" (ExpirationTime) for each session
计算公式：
ExpirationTime_ = currentTime + sessionTimeout
ExpirationTime = (ExpirationTime_ / ExpirationInrerval + 1) *ExpirationInterval ,
ExpirationInterval refers to the Zookeeper session timeout check interval, the
default tickTime