version 3.6.1
org.apache.zookeeper.server.quorum.Learner.java line:605
Suppose there is a situation
zxid_n is the largest zxid of Participant A (the leader has just resumed from
downtime). Zxid_n has not been recognized by the quorum. Assuming Participant A
is elected as the Leader, then if a follower appears to use DIFF to synchronize
data with the Leader, Leader After sending the UPTODATE, the leader can already
provide external access, but at this time, the latest zxid_n of the leader has
not been supported by the quorum of the follower. At this time, if a client
connects to the leader and sees zxid_n, then at this time both the leader and
the follower are down. For some reason, the leader cannot be started, and the
follower can start normally. At this time, a new leader can only be elected
from the follower. Since the data of the follower when the follower uses the
DIFF method to synchronize with the leader is still in the memory, it has not
had time to persist, then this The newly elected leader does not have the data
of zxid_n, but before zxid_n has been seen by the client on the old leader,
there will be inconsistencies in the data view.
Is the above situation possible?
