I was interested to hear about semi-sync replication improvements in MySQL’s 5.7.4 DMR release and decided to check it out. I previously blogged about poor semi-sync performance and was pretty disappointed from semi-sync’s performance across WAN distances back then, particularly with many client threads.
The basic environment of these tests was:
- AWS EC2 m3.medium instances
- Master in us-east-1, slave in us-west-1 (~78ms ping RTT)
- CentOS 6.5
- Semi-sync replication plugin installed and enabled.
- GTID’s enabled (except on 5.5)
- sysbench 0.5 update_index.lua test, 60 seconds, 250k table size.
- MySQL 5.7 was …