Advantages and disadvantages of redis and ZK implementing distributed locks

Redis Realization

advantage ： Good performance

shortcoming ：

To someone redismaster example , Written myLock This kind of lock key Of value, At this time, it will be asynchronously copied to the corresponding masterslave example .
But once that happens redismaster Downtime , Active standby switching ,redisslave Change into redismaster.
And then it leads to , client 2 To try to lock , In the new redismaster It's locked on , And the client 1 I think I've successfully locked it .
At this time, it will cause multiple clients to lock a distributed lock .
At this time, the system will have problems in business semantics , Lead to the generation of all kinds of dirty data .
So this is rediscluster, Or is it redismaster-slave The master-slave asynchronous replication of the architecture results in redis The biggest drawback of distributed locks ： stay redismaster When the instance goes down , It may cause multiple clients to lock at the same time .

ZK Realization

advantage ： Highly reliable zk Itself through leader+quorum High reliability of mechanism guarantee .

shortcoming ：ZooKeeper Implementation of distributed lock , The performance is not very high . Why? ？
Because every time you create a lock and release a lock , All need to be created dynamically 、 Destroy the instantaneous node to realize the lock function . As we all know ,ZK You can only create and delete nodes through Leader Server to execute , then Leader The server also needs to synchronize data to all servers Follower On the machine , Such frequent network communication , The short board of performance is very outstanding .