1. Create a slave with the latest version, then execute `slaveof [master_ip] [masterport]` to synchronize the data and use `info replication` to see the slave's offset.
2. After sync end, set the salve's `slave-read-only` to `no`.
3. Directing online traffic to this slave.
4. When the old master qps is 0, stop the master and upgrade.
5. You can then start again from step 1, sync data from the slave to the restarted master.